diff --git a/libavcodec/opus.h b/libavcodec/opus.h
index be042497ea..c3cbaec35d 100644
--- a/libavcodec/opus.h
+++ b/libavcodec/opus.h
@@ -62,7 +62,9 @@ static const uint8_t opus_default_extradata[30] = {
 enum OpusMode {
     OPUS_MODE_SILK,
     OPUS_MODE_HYBRID,
-    OPUS_MODE_CELT
+    OPUS_MODE_CELT,
+
+    OPUS_MODE_NB
 };
 
 enum OpusBandwidth {
@@ -70,12 +72,14 @@ enum OpusBandwidth {
     OPUS_BANDWIDTH_MEDIUMBAND,
     OPUS_BANDWIDTH_WIDEBAND,
     OPUS_BANDWIDTH_SUPERWIDEBAND,
-    OPUS_BANDWIDTH_FULLBAND
+    OPUS_BANDWIDTH_FULLBAND,
+
+    OPUS_BANDWITH_NB
 };
 
 typedef struct SilkContext SilkContext;
 
-typedef struct CeltContext CeltContext;
+typedef struct CeltFrame CeltFrame;
 
 typedef struct OpusPacket {
     int packet_size;                /**< packet size */
@@ -100,7 +104,7 @@ typedef struct OpusStreamContext {
     OpusRangeCoder rc;
     OpusRangeCoder redundancy_rc;
     SilkContext *silk;
-    CeltContext *celt;
+    CeltFrame *celt;
     AVFloatDSPContext *fdsp;
 
     float silk_buf[2][960];
@@ -185,14 +189,4 @@ int ff_silk_decode_superframe(SilkContext *s, OpusRangeCoder *rc,
                               enum OpusBandwidth bandwidth, int coded_channels,
                               int duration_ms);
 
-int ff_celt_init(AVCodecContext *avctx, CeltContext **s, int output_channels);
-
-void ff_celt_free(CeltContext **s);
-
-void ff_celt_flush(CeltContext *s);
-
-int ff_celt_decode_frame(CeltContext *s, OpusRangeCoder *rc,
-                         float **output, int coded_channels, int frame_size,
-                         int startband,  int endband);
-
 #endif /* AVCODEC_OPUS_H */
diff --git a/libavcodec/opus_celt.c b/libavcodec/opus_celt.c
index 71ef8965e2..af3c100e6e 100644
--- a/libavcodec/opus_celt.c
+++ b/libavcodec/opus_celt.c
@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2012 Andrew D'Addesio
  * Copyright (c) 2013-2014 Mozilla Corporation
+ * Copyright (c) 2016 Rostislav Pehlivanov <atomnuker@gmail.com>
  *
  * This file is part of FFmpeg.
  *
@@ -28,7 +29,7 @@
 #include "opustab.h"
 #include "opus_pvq.h"
 
-static void celt_decode_coarse_energy(CeltContext *s, OpusRangeCoder *rc)
+static void celt_decode_coarse_energy(CeltFrame *f, OpusRangeCoder *rc)
 {
     int i, j;
     float prev[2] = {0};
@@ -38,29 +39,29 @@ static void celt_decode_coarse_energy(CeltContext *s, OpusRangeCoder *rc)
     /* use the 2D z-transform to apply prediction in both */
     /* the time domain (alpha) and the frequency domain (beta) */
 
-    if (opus_rc_tell(rc)+3 <= s->framebits && ff_opus_rc_dec_log(rc, 3)) {
+    if (opus_rc_tell(rc)+3 <= f->framebits && ff_opus_rc_dec_log(rc, 3)) {
         /* intra frame */
         alpha = 0;
         beta  = 1.0f - 4915.0f/32768.0f;
-        model = ff_celt_coarse_energy_dist[s->duration][1];
+        model = ff_celt_coarse_energy_dist[f->size][1];
     } else {
-        alpha = ff_celt_alpha_coef[s->duration];
-        beta  = 1.0f - ff_celt_beta_coef[s->duration];
-        model = ff_celt_coarse_energy_dist[s->duration][0];
+        alpha = ff_celt_alpha_coef[f->size];
+        beta  = 1.0f - ff_celt_beta_coef[f->size];
+        model = ff_celt_coarse_energy_dist[f->size][0];
     }
 
     for (i = 0; i < CELT_MAX_BANDS; i++) {
-        for (j = 0; j < s->coded_channels; j++) {
-            CeltFrame *frame = &s->frame[j];
+        for (j = 0; j < f->channels; j++) {
+            CeltBlock *block = &f->block[j];
             float value;
             int available;
 
-            if (i < s->startband || i >= s->endband) {
-                frame->energy[i] = 0.0;
+            if (i < f->start_band || i >= f->end_band) {
+                block->energy[i] = 0.0;
                 continue;
             }
 
-            available = s->framebits - opus_rc_tell(rc);
+            available = f->framebits - opus_rc_tell(rc);
             if (available >= 15) {
                 /* decode using a Laplace distribution */
                 int k = FFMIN(i, 20) << 1;
@@ -72,82 +73,81 @@ static void celt_decode_coarse_energy(CeltContext *s, OpusRangeCoder *rc)
                 value = -(float)ff_opus_rc_dec_log(rc, 1);
             } else value = -1;
 
-            frame->energy[i] = FFMAX(-9.0f, frame->energy[i]) * alpha + prev[j] + value;
+            block->energy[i] = FFMAX(-9.0f, block->energy[i]) * alpha + prev[j] + value;
             prev[j] += beta * value;
         }
     }
 }
 
-static void celt_decode_fine_energy(CeltContext *s, OpusRangeCoder *rc)
+static void celt_decode_fine_energy(CeltFrame *f, OpusRangeCoder *rc)
 {
     int i;
-    for (i = s->startband; i < s->endband; i++) {
+    for (i = f->start_band; i < f->end_band; i++) {
         int j;
-        if (!s->fine_bits[i])
+        if (!f->fine_bits[i])
             continue;
 
-        for (j = 0; j < s->coded_channels; j++) {
-            CeltFrame *frame = &s->frame[j];
+        for (j = 0; j < f->channels; j++) {
+            CeltBlock *block = &f->block[j];
             int q2;
             float offset;
-            q2 = ff_opus_rc_get_raw(rc, s->fine_bits[i]);
-            offset = (q2 + 0.5f) * (1 << (14 - s->fine_bits[i])) / 16384.0f - 0.5f;
-            frame->energy[i] += offset;
+            q2 = ff_opus_rc_get_raw(rc, f->fine_bits[i]);
+            offset = (q2 + 0.5f) * (1 << (14 - f->fine_bits[i])) / 16384.0f - 0.5f;
+            block->energy[i] += offset;
         }
     }
 }
 
-static void celt_decode_final_energy(CeltContext *s, OpusRangeCoder *rc,
-                                     int bits_left)
+static void celt_decode_final_energy(CeltFrame *f, OpusRangeCoder *rc)
 {
     int priority, i, j;
+    int bits_left = f->framebits - opus_rc_tell(rc);
 
     for (priority = 0; priority < 2; priority++) {
-        for (i = s->startband; i < s->endband && bits_left >= s->coded_channels; i++) {
-            if (s->fine_priority[i] != priority || s->fine_bits[i] >= CELT_MAX_FINE_BITS)
+        for (i = f->start_band; i < f->end_band && bits_left >= f->channels; i++) {
+            if (f->fine_priority[i] != priority || f->fine_bits[i] >= CELT_MAX_FINE_BITS)
                 continue;
 
-            for (j = 0; j < s->coded_channels; j++) {
+            for (j = 0; j < f->channels; j++) {
                 int q2;
                 float offset;
                 q2 = ff_opus_rc_get_raw(rc, 1);
-                offset = (q2 - 0.5f) * (1 << (14 - s->fine_bits[i] - 1)) / 16384.0f;
-                s->frame[j].energy[i] += offset;
+                offset = (q2 - 0.5f) * (1 << (14 - f->fine_bits[i] - 1)) / 16384.0f;
+                f->block[j].energy[i] += offset;
                 bits_left--;
             }
         }
     }
 }
 
-static void celt_decode_tf_changes(CeltContext *s, OpusRangeCoder *rc,
-                                   int transient)
+static void celt_decode_tf_changes(CeltFrame *f, OpusRangeCoder *rc)
 {
     int i, diff = 0, tf_select = 0, tf_changed = 0, tf_select_bit;
-    int consumed, bits = transient ? 2 : 4;
+    int consumed, bits = f->transient ? 2 : 4;
 
     consumed = opus_rc_tell(rc);
-    tf_select_bit = (s->duration != 0 && consumed+bits+1 <= s->framebits);
+    tf_select_bit = (f->size != 0 && consumed+bits+1 <= f->framebits);
 
-    for (i = s->startband; i < s->endband; i++) {
-        if (consumed+bits+tf_select_bit <= s->framebits) {
+    for (i = f->start_band; i < f->end_band; i++) {
+        if (consumed+bits+tf_select_bit <= f->framebits) {
             diff ^= ff_opus_rc_dec_log(rc, bits);
             consumed = opus_rc_tell(rc);
             tf_changed |= diff;
         }
-        s->tf_change[i] = diff;
-        bits = transient ? 4 : 5;
+        f->tf_change[i] = diff;
+        bits = f->transient ? 4 : 5;
     }
 
-    if (tf_select_bit && ff_celt_tf_select[s->duration][transient][0][tf_changed] !=
-                         ff_celt_tf_select[s->duration][transient][1][tf_changed])
+    if (tf_select_bit && ff_celt_tf_select[f->size][f->transient][0][tf_changed] !=
+                         ff_celt_tf_select[f->size][f->transient][1][tf_changed])
         tf_select = ff_opus_rc_dec_log(rc, 1);
 
-    for (i = s->startband; i < s->endband; i++) {
-        s->tf_change[i] = ff_celt_tf_select[s->duration][transient][tf_select][s->tf_change[i]];
+    for (i = f->start_band; i < f->end_band; i++) {
+        f->tf_change[i] = ff_celt_tf_select[f->size][f->transient][tf_select][f->tf_change[i]];
     }
 }
 
-static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
+static void celt_decode_allocation(CeltFrame *f, OpusRangeCoder *rc)
 {
     // approx. maximum bit allocation for each band before boost/trim
     int cap[CELT_MAX_BANDS];
@@ -157,14 +157,14 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
     int bits2[CELT_MAX_BANDS];
     int trim_offset[CELT_MAX_BANDS];
 
-    int skip_startband = s->startband;
+    int skip_start_band = f->start_band;
     int dynalloc       = 6;
     int alloctrim      = 5;
     int extrabits      = 0;
 
-    int skip_bit            = 0;
-    int intensitystereo_bit = 0;
-    int dualstereo_bit      = 0;
+    int skip_bit             = 0;
+    int intensity_stereo_bit = 0;
+    int dual_stereo_bit      = 0;
 
     int remaining, bandbits;
     int low, high, total, done;
@@ -175,25 +175,25 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
     consumed = opus_rc_tell(rc);
 
     /* obtain spread flag */
-    s->spread = CELT_SPREAD_NORMAL;
-    if (consumed + 4 <= s->framebits)
-        s->spread = ff_opus_rc_dec_cdf(rc, ff_celt_model_spread);
+    f->spread = CELT_SPREAD_NORMAL;
+    if (consumed + 4 <= f->framebits)
+        f->spread = ff_opus_rc_dec_cdf(rc, ff_celt_model_spread);
 
     /* generate static allocation caps */
     for (i = 0; i < CELT_MAX_BANDS; i++) {
-        cap[i] = (ff_celt_static_caps[s->duration][s->coded_channels - 1][i] + 64)
-                 * ff_celt_freq_range[i] << (s->coded_channels - 1) << s->duration >> 2;
+        cap[i] = (ff_celt_static_caps[f->size][f->channels - 1][i] + 64)
+                 * ff_celt_freq_range[i] << (f->channels - 1) << f->size >> 2;
     }
 
     /* obtain band boost */
-    totalbits = s->framebits << 3; // convert to 1/8 bits
+    totalbits = f->framebits << 3; // convert to 1/8 bits
     consumed = opus_rc_tell_frac(rc);
-    for (i = s->startband; i < s->endband; i++) {
+    for (i = f->start_band; i < f->end_band; i++) {
         int quanta, band_dynalloc;
 
         boost[i] = 0;
 
-        quanta = ff_celt_freq_range[i] << (s->coded_channels - 1) << s->duration;
+        quanta = ff_celt_freq_range[i] << (f->channels - 1) << f->size;
         quanta = FFMIN(quanta << 3, FFMAX(6 << 3, quanta));
         band_dynalloc = dynalloc;
         while (consumed + (band_dynalloc<<3) < totalbits && boost[i] < cap[i]) {
@@ -216,12 +216,12 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
         alloctrim = ff_opus_rc_dec_cdf(rc, ff_celt_model_alloc_trim);
 
     /* anti-collapse bit reservation */
-    totalbits = (s->framebits << 3) - opus_rc_tell_frac(rc) - 1;
-    s->anticollapse_bit = 0;
-    if (s->blocks > 1 && s->duration >= 2 &&
-        totalbits >= ((s->duration + 2) << 3))
-        s->anticollapse_bit = 1 << 3;
-    totalbits -= s->anticollapse_bit;
+    totalbits = (f->framebits << 3) - opus_rc_tell_frac(rc) - 1;
+    f->anticollapse_needed = 0;
+    if (f->blocks > 1 && f->size >= 2 &&
+        totalbits >= ((f->size + 2) << 3))
+        f->anticollapse_needed = 1 << 3;
+    totalbits -= f->anticollapse_needed;
 
     /* band skip bit reservation */
     if (totalbits >= 1 << 3)
@@ -229,33 +229,33 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
     totalbits -= skip_bit;
 
     /* intensity/dual stereo bit reservation */
-    if (s->coded_channels == 2) {
-        intensitystereo_bit = ff_celt_log2_frac[s->endband - s->startband];
-        if (intensitystereo_bit <= totalbits) {
-            totalbits -= intensitystereo_bit;
+    if (f->channels == 2) {
+        intensity_stereo_bit = ff_celt_log2_frac[f->end_band - f->start_band];
+        if (intensity_stereo_bit <= totalbits) {
+            totalbits -= intensity_stereo_bit;
             if (totalbits >= 1 << 3) {
-                dualstereo_bit = 1 << 3;
+                dual_stereo_bit = 1 << 3;
                 totalbits -= 1 << 3;
             }
         } else
-            intensitystereo_bit = 0;
+            intensity_stereo_bit = 0;
     }
 
-    for (i = s->startband; i < s->endband; i++) {
-        int trim     = alloctrim - 5 - s->duration;
-        int band     = ff_celt_freq_range[i] * (s->endband - i - 1);
-        int duration = s->duration + 3;
-        int scale    = duration + s->coded_channels - 1;
+    for (i = f->start_band; i < f->end_band; i++) {
+        int trim     = alloctrim - 5 - f->size;
+        int band     = ff_celt_freq_range[i] * (f->end_band - i - 1);
+        int duration = f->size + 3;
+        int scale    = duration + f->channels - 1;
 
         /* PVQ minimum allocation threshold, below this value the band is
          * skipped */
         threshold[i] = FFMAX(3 * ff_celt_freq_range[i] << duration >> 4,
-                             s->coded_channels << 3);
+                             f->channels << 3);
 
         trim_offset[i] = trim * (band << scale) >> 6;
 
-        if (ff_celt_freq_range[i] << s->duration == 1)
-            trim_offset[i] -= s->coded_channels << 3;
+        if (ff_celt_freq_range[i] << f->size == 1)
+            trim_offset[i] -= f->channels << 3;
     }
 
     /* bisection */
@@ -265,9 +265,9 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
         int center = (low + high) >> 1;
         done = total = 0;
 
-        for (i = s->endband - 1; i >= s->startband; i--) {
+        for (i = f->end_band - 1; i >= f->start_band; i--) {
             bandbits = ff_celt_freq_range[i] * ff_celt_static_alloc[center][i]
-                       << (s->coded_channels - 1) << s->duration >> 2;
+                       << (f->channels - 1) << f->size >> 2;
 
             if (bandbits)
                 bandbits = FFMAX(0, bandbits + trim_offset[i]);
@@ -276,8 +276,8 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
             if (bandbits >= threshold[i] || done) {
                 done = 1;
                 total += FFMIN(bandbits, cap[i]);
-            } else if (bandbits >= s->coded_channels << 3)
-                total += s->coded_channels << 3;
+            } else if (bandbits >= f->channels << 3)
+                total += f->channels << 3;
         }
 
         if (total > totalbits)
@@ -287,12 +287,12 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
     }
     high = low--;
 
-    for (i = s->startband; i < s->endband; i++) {
+    for (i = f->start_band; i < f->end_band; i++) {
         bits1[i] = ff_celt_freq_range[i] * ff_celt_static_alloc[low][i]
-                   << (s->coded_channels - 1) << s->duration >> 2;
+                   << (f->channels - 1) << f->size >> 2;
         bits2[i] = high >= CELT_VECTORS ? cap[i] :
                    ff_celt_freq_range[i] * ff_celt_static_alloc[high][i]
-                   << (s->coded_channels - 1) << s->duration >> 2;
+                   << (f->channels - 1) << f->size >> 2;
 
         if (bits1[i])
             bits1[i] = FFMAX(0, bits1[i] + trim_offset[i]);
@@ -303,7 +303,7 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
         bits2[i] += boost[i];
 
         if (boost[i])
-            skip_startband = i;
+            skip_start_band = i;
         bits2[i] = FFMAX(0, bits2[i] - bits1[i]);
     }
 
@@ -314,14 +314,14 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
         int center = (low + high) >> 1;
         done = total = 0;
 
-        for (j = s->endband - 1; j >= s->startband; j--) {
+        for (j = f->end_band - 1; j >= f->start_band; j--) {
             bandbits = bits1[j] + (center * bits2[j] >> CELT_ALLOC_STEPS);
 
             if (bandbits >= threshold[j] || done) {
                 done = 1;
                 total += FFMIN(bandbits, cap[j]);
-            } else if (bandbits >= s->coded_channels << 3)
-                total += s->coded_channels << 3;
+            } else if (bandbits >= f->channels << 3)
+                total += f->channels << 3;
         }
         if (total > totalbits)
             high = center;
@@ -330,26 +330,26 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
     }
 
     done = total = 0;
-    for (i = s->endband - 1; i >= s->startband; i--) {
+    for (i = f->end_band - 1; i >= f->start_band; i--) {
         bandbits = bits1[i] + (low * bits2[i] >> CELT_ALLOC_STEPS);
 
         if (bandbits >= threshold[i] || done)
             done = 1;
         else
-            bandbits = (bandbits >= s->coded_channels << 3) ?
-                       s->coded_channels << 3 : 0;
+            bandbits = (bandbits >= f->channels << 3) ?
+                       f->channels << 3 : 0;
 
         bandbits     = FFMIN(bandbits, cap[i]);
-        s->pulses[i] = bandbits;
+        f->pulses[i] = bandbits;
         total      += bandbits;
     }
 
     /* band skipping */
-    for (s->codedbands = s->endband; ; s->codedbands--) {
+    for (f->coded_bands = f->end_band; ; f->coded_bands--) {
         int allocation;
-        j = s->codedbands - 1;
+        j = f->coded_bands - 1;
 
-        if (j == skip_startband) {
+        if (j == skip_start_band) {
             /* all remaining bands are not skipped */
             totalbits += skip_bit;
             break;
@@ -357,14 +357,14 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
 
         /* determine the number of bits available for coding "do not skip" markers */
         remaining   = totalbits - total;
-        bandbits    = remaining / (ff_celt_freq_bands[j+1] - ff_celt_freq_bands[s->startband]);
-        remaining  -= bandbits  * (ff_celt_freq_bands[j+1] - ff_celt_freq_bands[s->startband]);
-        allocation  = s->pulses[j] + bandbits * ff_celt_freq_range[j]
-                      + FFMAX(0, remaining - (ff_celt_freq_bands[j] - ff_celt_freq_bands[s->startband]));
+        bandbits    = remaining / (ff_celt_freq_bands[j+1] - ff_celt_freq_bands[f->start_band]);
+        remaining  -= bandbits  * (ff_celt_freq_bands[j+1] - ff_celt_freq_bands[f->start_band]);
+        allocation  = f->pulses[j] + bandbits * ff_celt_freq_range[j]
+                      + FFMAX(0, remaining - (ff_celt_freq_bands[j] - ff_celt_freq_bands[f->start_band]));
 
         /* a "do not skip" marker is only coded if the allocation is
            above the chosen threshold */
-        if (allocation >= FFMAX(threshold[j], (s->coded_channels + 1) <<3 )) {
+        if (allocation >= FFMAX(threshold[j], (f->channels + 1) <<3 )) {
             if (ff_opus_rc_dec_log(rc, 1))
                 break;
 
@@ -373,43 +373,43 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
         }
 
         /* the band is skipped, so reclaim its bits */
-        total -= s->pulses[j];
-        if (intensitystereo_bit) {
-            total -= intensitystereo_bit;
-            intensitystereo_bit = ff_celt_log2_frac[j - s->startband];
-            total += intensitystereo_bit;
+        total -= f->pulses[j];
+        if (intensity_stereo_bit) {
+            total -= intensity_stereo_bit;
+            intensity_stereo_bit = ff_celt_log2_frac[j - f->start_band];
+            total += intensity_stereo_bit;
         }
 
-        total += s->pulses[j] = (allocation >= s->coded_channels << 3) ?
-                              s->coded_channels << 3 : 0;
+        total += f->pulses[j] = (allocation >= f->channels << 3) ?
+                              f->channels << 3 : 0;
     }
 
     /* obtain stereo flags */
-    s->intensitystereo = 0;
-    s->dualstereo      = 0;
-    if (intensitystereo_bit)
-        s->intensitystereo = s->startband +
-                          ff_opus_rc_dec_uint(rc, s->codedbands + 1 - s->startband);
-    if (s->intensitystereo <= s->startband)
-        totalbits += dualstereo_bit; /* no intensity stereo means no dual stereo */
-    else if (dualstereo_bit)
-        s->dualstereo = ff_opus_rc_dec_log(rc, 1);
+    f->intensity_stereo = 0;
+    f->dual_stereo      = 0;
+    if (intensity_stereo_bit)
+        f->intensity_stereo = f->start_band +
+                          ff_opus_rc_dec_uint(rc, f->coded_bands + 1 - f->start_band);
+    if (f->intensity_stereo <= f->start_band)
+        totalbits += dual_stereo_bit; /* no intensity stereo means no dual stereo */
+    else if (dual_stereo_bit)
+        f->dual_stereo = ff_opus_rc_dec_log(rc, 1);
 
     /* supply the remaining bits in this frame to lower bands */
     remaining = totalbits - total;
-    bandbits  = remaining / (ff_celt_freq_bands[s->codedbands] - ff_celt_freq_bands[s->startband]);
-    remaining -= bandbits * (ff_celt_freq_bands[s->codedbands] - ff_celt_freq_bands[s->startband]);
-    for (i = s->startband; i < s->codedbands; i++) {
+    bandbits  = remaining / (ff_celt_freq_bands[f->coded_bands] - ff_celt_freq_bands[f->start_band]);
+    remaining -= bandbits * (ff_celt_freq_bands[f->coded_bands] - ff_celt_freq_bands[f->start_band]);
+    for (i = f->start_band; i < f->coded_bands; i++) {
         int bits = FFMIN(remaining, ff_celt_freq_range[i]);
 
-        s->pulses[i] += bits + bandbits * ff_celt_freq_range[i];
+        f->pulses[i] += bits + bandbits * ff_celt_freq_range[i];
         remaining    -= bits;
     }
 
-    for (i = s->startband; i < s->codedbands; i++) {
-        int N = ff_celt_freq_range[i] << s->duration;
+    for (i = f->start_band; i < f->coded_bands; i++) {
+        int N = ff_celt_freq_range[i] << f->size;
         int prev_extra = extrabits;
-        s->pulses[i] += extrabits;
+        f->pulses[i] += extrabits;
 
         if (N > 1) {
             int dof;        // degrees of freedom
@@ -419,83 +419,83 @@ static void celt_decode_allocation(CeltContext *s, OpusRangeCoder *rc)
                             // totalbits/dof
             int fine_bits, max_bits;
 
-            extrabits = FFMAX(0, s->pulses[i] - cap[i]);
-            s->pulses[i] -= extrabits;
+            extrabits = FFMAX(0, f->pulses[i] - cap[i]);
+            f->pulses[i] -= extrabits;
 
             /* intensity stereo makes use of an extra degree of freedom */
-            dof = N * s->coded_channels
-                  + (s->coded_channels == 2 && N > 2 && !s->dualstereo && i < s->intensitystereo);
-            temp = dof * (ff_celt_log_freq_range[i] + (s->duration<<3));
+            dof = N * f->channels
+                  + (f->channels == 2 && N > 2 && !f->dual_stereo && i < f->intensity_stereo);
+            temp = dof * (ff_celt_log_freq_range[i] + (f->size<<3));
             offset = (temp >> 1) - dof * CELT_FINE_OFFSET;
             if (N == 2) /* dof=2 is the only case that doesn't fit the model */
                 offset += dof<<1;
 
             /* grant an additional bias for the first and second pulses */
-            if (s->pulses[i] + offset < 2 * (dof << 3))
+            if (f->pulses[i] + offset < 2 * (dof << 3))
                 offset += temp >> 2;
-            else if (s->pulses[i] + offset < 3 * (dof << 3))
+            else if (f->pulses[i] + offset < 3 * (dof << 3))
                 offset += temp >> 3;
 
-            fine_bits = (s->pulses[i] + offset + (dof << 2)) / (dof << 3);
-            max_bits  = FFMIN((s->pulses[i]>>3) >> (s->coded_channels - 1),
+            fine_bits = (f->pulses[i] + offset + (dof << 2)) / (dof << 3);
+            max_bits  = FFMIN((f->pulses[i]>>3) >> (f->channels - 1),
                               CELT_MAX_FINE_BITS);
 
             max_bits  = FFMAX(max_bits, 0);
 
-            s->fine_bits[i] = av_clip(fine_bits, 0, max_bits);
+            f->fine_bits[i] = av_clip(fine_bits, 0, max_bits);
 
             /* if fine_bits was rounded down or capped,
                give priority for the final fine energy pass */
-            s->fine_priority[i] = (s->fine_bits[i] * (dof<<3) >= s->pulses[i] + offset);
+            f->fine_priority[i] = (f->fine_bits[i] * (dof<<3) >= f->pulses[i] + offset);
 
             /* the remaining bits are assigned to PVQ */
-            s->pulses[i] -= s->fine_bits[i] << (s->coded_channels - 1) << 3;
+            f->pulses[i] -= f->fine_bits[i] << (f->channels - 1) << 3;
         } else {
             /* all bits go to fine energy except for the sign bit */
-            extrabits = FFMAX(0, s->pulses[i] - (s->coded_channels << 3));
-            s->pulses[i] -= extrabits;
-            s->fine_bits[i] = 0;
-            s->fine_priority[i] = 1;
+            extrabits = FFMAX(0, f->pulses[i] - (f->channels << 3));
+            f->pulses[i] -= extrabits;
+            f->fine_bits[i] = 0;
+            f->fine_priority[i] = 1;
         }
 
         /* hand back a limited number of extra fine energy bits to this band */
         if (extrabits > 0) {
-            int fineextra = FFMIN(extrabits >> (s->coded_channels + 2),
-                                  CELT_MAX_FINE_BITS - s->fine_bits[i]);
-            s->fine_bits[i] += fineextra;
+            int fineextra = FFMIN(extrabits >> (f->channels + 2),
+                                  CELT_MAX_FINE_BITS - f->fine_bits[i]);
+            f->fine_bits[i] += fineextra;
 
-            fineextra <<= s->coded_channels + 2;
-            s->fine_priority[i] = (fineextra >= extrabits - prev_extra);
+            fineextra <<= f->channels + 2;
+            f->fine_priority[i] = (fineextra >= extrabits - prev_extra);
             extrabits -= fineextra;
         }
     }
-    s->remaining = extrabits;
+    f->remaining = extrabits;
 
     /* skipped bands dedicate all of their bits for fine energy */
-    for (; i < s->endband; i++) {
-        s->fine_bits[i]     = s->pulses[i] >> (s->coded_channels - 1) >> 3;
-        s->pulses[i]        = 0;
-        s->fine_priority[i] = s->fine_bits[i] < 1;
+    for (; i < f->end_band; i++) {
+        f->fine_bits[i]     = f->pulses[i] >> (f->channels - 1) >> 3;
+        f->pulses[i]        = 0;
+        f->fine_priority[i] = f->fine_bits[i] < 1;
     }
 }
 
-static void celt_denormalize(CeltContext *s, CeltFrame *frame, float *data)
+static void celt_denormalize(CeltFrame *f, CeltBlock *block, float *data)
 {
     int i, j;
 
-    for (i = s->startband; i < s->endband; i++) {
-        float *dst = data + (ff_celt_freq_bands[i] << s->duration);
-        float norm = exp2(frame->energy[i] + ff_celt_mean_energy[i]);
+    for (i = f->start_band; i < f->end_band; i++) {
+        float *dst = data + (ff_celt_freq_bands[i] << f->size);
+        float norm = exp2(block->energy[i] + ff_celt_mean_energy[i]);
 
-        for (j = 0; j < ff_celt_freq_range[i] << s->duration; j++)
+        for (j = 0; j < ff_celt_freq_range[i] << f->size; j++)
             dst[j] *= norm;
     }
 }
 
-static void celt_postfilter_apply_transition(CeltFrame *frame, float *data)
+static void celt_postfilter_apply_transition(CeltBlock *block, float *data)
 {
-    const int T0 = frame->pf_period_old;
-    const int T1 = frame->pf_period;
+    const int T0 = block->pf_period_old;
+    const int T1 = block->pf_period;
 
     float g00, g01, g02;
     float g10, g11, g12;
@@ -504,16 +504,16 @@ static void celt_postfilter_apply_transition(CeltFrame *frame, float *data)
 
     int i;
 
-    if (frame->pf_gains[0]     == 0.0 &&
-        frame->pf_gains_old[0] == 0.0)
+    if (block->pf_gains[0]     == 0.0 &&
+        block->pf_gains_old[0] == 0.0)
         return;
 
-    g00 = frame->pf_gains_old[0];
-    g01 = frame->pf_gains_old[1];
-    g02 = frame->pf_gains_old[2];
-    g10 = frame->pf_gains[0];
-    g11 = frame->pf_gains[1];
-    g12 = frame->pf_gains[2];
+    g00 = block->pf_gains_old[0];
+    g01 = block->pf_gains_old[1];
+    g02 = block->pf_gains_old[2];
+    g10 = block->pf_gains[0];
+    g11 = block->pf_gains[1];
+    g12 = block->pf_gains[2];
 
     x1 = data[-T1 + 1];
     x2 = data[-T1];
@@ -537,20 +537,19 @@ static void celt_postfilter_apply_transition(CeltFrame *frame, float *data)
     }
 }
 
-static void celt_postfilter_apply(CeltFrame *frame,
-                                  float *data, int len)
+static void celt_postfilter_apply(CeltBlock *block, float *data, int len)
 {
-    const int T = frame->pf_period;
+    const int T = block->pf_period;
     float g0, g1, g2;
     float x0, x1, x2, x3, x4;
     int i;
 
-    if (frame->pf_gains[0] == 0.0 || len <= 0)
+    if (block->pf_gains[0] == 0.0 || len <= 0)
         return;
 
-    g0 = frame->pf_gains[0];
-    g1 = frame->pf_gains[1];
-    g2 = frame->pf_gains[2];
+    g0 = block->pf_gains[0];
+    g1 = block->pf_gains[1];
+    g2 = block->pf_gains[2];
 
     x4 = data[-T - 2];
     x3 = data[-T - 1];
@@ -569,31 +568,31 @@ static void celt_postfilter_apply(CeltFrame *frame,
     }
 }
 
-static void celt_postfilter(CeltContext *s, CeltFrame *frame)
+static void celt_postfilter(CeltFrame *f, CeltBlock *block)
 {
-    int len = s->blocksize * s->blocks;
+    int len = f->blocksize * f->blocks;
 
-    celt_postfilter_apply_transition(frame, frame->buf + 1024);
+    celt_postfilter_apply_transition(block, block->buf + 1024);
 
-    frame->pf_period_old = frame->pf_period;
-    memcpy(frame->pf_gains_old, frame->pf_gains, sizeof(frame->pf_gains));
+    block->pf_period_old = block->pf_period;
+    memcpy(block->pf_gains_old, block->pf_gains, sizeof(block->pf_gains));
 
-    frame->pf_period = frame->pf_period_new;
-    memcpy(frame->pf_gains, frame->pf_gains_new, sizeof(frame->pf_gains));
+    block->pf_period = block->pf_period_new;
+    memcpy(block->pf_gains, block->pf_gains_new, sizeof(block->pf_gains));
 
     if (len > CELT_OVERLAP) {
-        celt_postfilter_apply_transition(frame, frame->buf + 1024 + CELT_OVERLAP);
-        celt_postfilter_apply(frame, frame->buf + 1024 + 2 * CELT_OVERLAP,
+        celt_postfilter_apply_transition(block, block->buf + 1024 + CELT_OVERLAP);
+        celt_postfilter_apply(block, block->buf + 1024 + 2 * CELT_OVERLAP,
                               len - 2 * CELT_OVERLAP);
 
-        frame->pf_period_old = frame->pf_period;
-        memcpy(frame->pf_gains_old, frame->pf_gains, sizeof(frame->pf_gains));
+        block->pf_period_old = block->pf_period;
+        memcpy(block->pf_gains_old, block->pf_gains, sizeof(block->pf_gains));
     }
 
-    memmove(frame->buf, frame->buf + len, (1024 + CELT_OVERLAP / 2) * sizeof(float));
+    memmove(block->buf, block->buf + len, (1024 + CELT_OVERLAP / 2) * sizeof(float));
 }
 
-static int parse_postfilter(CeltContext *s, OpusRangeCoder *rc, int consumed)
+static int parse_postfilter(CeltFrame *f, OpusRangeCoder *rc, int consumed)
 {
     static const float postfilter_taps[3][3] = {
         { 0.3066406250f, 0.2170410156f, 0.1296386719f },
@@ -602,10 +601,10 @@ static int parse_postfilter(CeltContext *s, OpusRangeCoder *rc, int consumed)
     };
     int i;
 
-    memset(s->frame[0].pf_gains_new, 0, sizeof(s->frame[0].pf_gains_new));
-    memset(s->frame[1].pf_gains_new, 0, sizeof(s->frame[1].pf_gains_new));
+    memset(f->block[0].pf_gains_new, 0, sizeof(f->block[0].pf_gains_new));
+    memset(f->block[1].pf_gains_new, 0, sizeof(f->block[1].pf_gains_new));
 
-    if (s->startband == 0 && consumed + 16 <= s->framebits) {
+    if (f->start_band == 0 && consumed + 16 <= f->framebits) {
         int has_postfilter = ff_opus_rc_dec_log(rc, 1);
         if (has_postfilter) {
             float gain;
@@ -614,16 +613,16 @@ static int parse_postfilter(CeltContext *s, OpusRangeCoder *rc, int consumed)
             octave = ff_opus_rc_dec_uint(rc, 6);
             period = (16 << octave) + ff_opus_rc_get_raw(rc, 4 + octave) - 1;
             gain   = 0.09375f * (ff_opus_rc_get_raw(rc, 3) + 1);
-            tapset = (opus_rc_tell(rc) + 2 <= s->framebits) ?
+            tapset = (opus_rc_tell(rc) + 2 <= f->framebits) ?
                      ff_opus_rc_dec_cdf(rc, ff_celt_model_tapset) : 0;
 
             for (i = 0; i < 2; i++) {
-                CeltFrame *frame = &s->frame[i];
+                CeltBlock *block = &f->block[i];
 
-                frame->pf_period_new = FFMAX(period, CELT_POSTFILTER_MINPERIOD);
-                frame->pf_gains_new[0] = gain * postfilter_taps[tapset][0];
-                frame->pf_gains_new[1] = gain * postfilter_taps[tapset][1];
-                frame->pf_gains_new[2] = gain * postfilter_taps[tapset][2];
+                block->pf_period_new = FFMAX(period, CELT_POSTFILTER_MINPERIOD);
+                block->pf_gains_new[0] = gain * postfilter_taps[tapset][0];
+                block->pf_gains_new[1] = gain * postfilter_taps[tapset][1];
+                block->pf_gains_new[2] = gain * postfilter_taps[tapset][2];
             }
         }
 
@@ -633,11 +632,11 @@ static int parse_postfilter(CeltContext *s, OpusRangeCoder *rc, int consumed)
     return consumed;
 }
 
-static void process_anticollapse(CeltContext *s, CeltFrame *frame, float *X)
+static void process_anticollapse(CeltFrame *f, CeltBlock *block, float *X)
 {
     int i, j, k;
 
-    for (i = s->startband; i < s->endband; i++) {
+    for (i = f->start_band; i < f->end_band; i++) {
         int renormalize = 0;
         float *xptr;
         float prev[2];
@@ -646,64 +645,65 @@ static void process_anticollapse(CeltContext *s, CeltFrame *frame, float *X)
         int depth;
 
         /* depth in 1/8 bits */
-        depth = (1 + s->pulses[i]) / (ff_celt_freq_range[i] << s->duration);
+        depth = (1 + f->pulses[i]) / (ff_celt_freq_range[i] << f->size);
         thresh = exp2f(-1.0 - 0.125f * depth);
-        sqrt_1 = 1.0f / sqrtf(ff_celt_freq_range[i] << s->duration);
+        sqrt_1 = 1.0f / sqrtf(ff_celt_freq_range[i] << f->size);
 
-        xptr = X + (ff_celt_freq_bands[i] << s->duration);
+        xptr = X + (ff_celt_freq_bands[i] << f->size);
 
-        prev[0] = frame->prev_energy[0][i];
-        prev[1] = frame->prev_energy[1][i];
-        if (s->coded_channels == 1) {
-            CeltFrame *frame1 = &s->frame[1];
+        prev[0] = block->prev_energy[0][i];
+        prev[1] = block->prev_energy[1][i];
+        if (f->channels == 1) {
+            CeltBlock *block1 = &f->block[1];
 
-            prev[0] = FFMAX(prev[0], frame1->prev_energy[0][i]);
-            prev[1] = FFMAX(prev[1], frame1->prev_energy[1][i]);
+            prev[0] = FFMAX(prev[0], block1->prev_energy[0][i]);
+            prev[1] = FFMAX(prev[1], block1->prev_energy[1][i]);
         }
-        Ediff = frame->energy[i] - FFMIN(prev[0], prev[1]);
+        Ediff = block->energy[i] - FFMIN(prev[0], prev[1]);
         Ediff = FFMAX(0, Ediff);
 
         /* r needs to be multiplied by 2 or 2*sqrt(2) depending on LM because
         short blocks don't have the same energy as long */
         r = exp2(1 - Ediff);
-        if (s->duration == 3)
+        if (f->size == 3)
             r *= M_SQRT2;
         r = FFMIN(thresh, r) * sqrt_1;
-        for (k = 0; k < 1 << s->duration; k++) {
+        for (k = 0; k < 1 << f->size; k++) {
             /* Detect collapse */
-            if (!(frame->collapse_masks[i] & 1 << k)) {
+            if (!(block->collapse_masks[i] & 1 << k)) {
                 /* Fill with noise */
                 for (j = 0; j < ff_celt_freq_range[i]; j++)
-                    xptr[(j << s->duration) + k] = (celt_rng(s) & 0x8000) ? r : -r;
+                    xptr[(j << f->size) + k] = (celt_rng(f) & 0x8000) ? r : -r;
                 renormalize = 1;
             }
         }
 
         /* We just added some energy, so we need to renormalize */
         if (renormalize)
-            celt_renormalize_vector(xptr, ff_celt_freq_range[i] << s->duration, 1.0f);
+            celt_renormalize_vector(xptr, ff_celt_freq_range[i] << f->size, 1.0f);
     }
 }
 
-static void celt_decode_bands(CeltContext *s, OpusRangeCoder *rc)
+static void celt_decode_bands(CeltFrame *f, OpusRangeCoder *rc)
 {
     float lowband_scratch[8 * 22];
     float norm[2 * 8 * 100];
 
-    int totalbits = (s->framebits << 3) - s->anticollapse_bit;
+    int totalbits = (f->framebits << 3) - f->anticollapse_needed;
 
     int update_lowband = 1;
     int lowband_offset = 0;
 
     int i, j;
 
-    memset(s->coeffs, 0, sizeof(s->coeffs));
+    memset(f->block[0].coeffs, 0, sizeof(f->block[0].coeffs));
+    memset(f->block[1].coeffs, 0, sizeof(f->block[0].coeffs));
 
-    for (i = s->startband; i < s->endband; i++) {
-        int band_offset = ff_celt_freq_bands[i] << s->duration;
-        int band_size   = ff_celt_freq_range[i] << s->duration;
-        float *X = s->coeffs[0] + band_offset;
-        float *Y = (s->coded_channels == 2) ? s->coeffs[1] + band_offset : NULL;
+    for (i = f->start_band; i < f->end_band; i++) {
+        int band_offset = ff_celt_freq_bands[i] << f->size;
+        int band_size   = ff_celt_freq_range[i] << f->size;
+        float *X = f->block[0].coeffs + band_offset;
+        float *Y = (f->channels == 2) ? f->block[1].coeffs + band_offset : NULL;
 
         int consumed = opus_rc_tell_frac(rc);
         float *norm2 = norm + 8 * 100;
@@ -712,27 +712,27 @@ static void celt_decode_bands(CeltContext *s, OpusRangeCoder *rc)
         int b;
 
         /* Compute how many bits we want to allocate to this band */
-        if (i != s->startband)
-            s->remaining -= consumed;
-        s->remaining2 = totalbits - consumed - 1;
-        if (i <= s->codedbands - 1) {
-            int curr_balance = s->remaining / FFMIN(3, s->codedbands-i);
-            b = av_clip_uintp2(FFMIN(s->remaining2 + 1, s->pulses[i] + curr_balance), 14);
+        if (i != f->start_band)
+            f->remaining -= consumed;
+        f->remaining2 = totalbits - consumed - 1;
+        if (i <= f->coded_bands - 1) {
+            int curr_balance = f->remaining / FFMIN(3, f->coded_bands-i);
+            b = av_clip_uintp2(FFMIN(f->remaining2 + 1, f->pulses[i] + curr_balance), 14);
         } else
             b = 0;
 
-        if (ff_celt_freq_bands[i] - ff_celt_freq_range[i] >= ff_celt_freq_bands[s->startband] &&
+        if (ff_celt_freq_bands[i] - ff_celt_freq_range[i] >= ff_celt_freq_bands[f->start_band] &&
             (update_lowband || lowband_offset == 0))
             lowband_offset = i;
 
         /* Get a conservative estimate of the collapse_mask's for the bands we're
         going to be folding from. */
-        if (lowband_offset != 0 && (s->spread != CELT_SPREAD_AGGRESSIVE ||
-                                    s->blocks > 1 || s->tf_change[i] < 0)) {
+        if (lowband_offset != 0 && (f->spread != CELT_SPREAD_AGGRESSIVE ||
+                                    f->blocks > 1 || f->tf_change[i] < 0)) {
             int foldstart, foldend;
 
             /* This ensures we never repeat spectral content within one band */
-            effective_lowband = FFMAX(ff_celt_freq_bands[s->startband],
+            effective_lowband = FFMAX(ff_celt_freq_bands[f->start_band],
                                       ff_celt_freq_bands[lowband_offset] - ff_celt_freq_range[i]);
             foldstart = lowband_offset;
             while (ff_celt_freq_bands[--foldstart] > effective_lowband);
@@ -741,260 +741,260 @@ static void celt_decode_bands(CeltContext *s, OpusRangeCoder *rc)
 
             cm[0] = cm[1] = 0;
             for (j = foldstart; j < foldend; j++) {
-                cm[0] |= s->frame[0].collapse_masks[j];
-                cm[1] |= s->frame[s->coded_channels - 1].collapse_masks[j];
+                cm[0] |= f->block[0].collapse_masks[j];
+                cm[1] |= f->block[f->channels - 1].collapse_masks[j];
             }
         } else
             /* Otherwise, we'll be using the LCG to fold, so all blocks will (almost
             always) be non-zero.*/
-            cm[0] = cm[1] = (1 << s->blocks) - 1;
+            cm[0] = cm[1] = (1 << f->blocks) - 1;
 
-        if (s->dualstereo && i == s->intensitystereo) {
+        if (f->dual_stereo && i == f->intensity_stereo) {
             /* Switch off dual stereo to do intensity */
-            s->dualstereo = 0;
-            for (j = ff_celt_freq_bands[s->startband] << s->duration; j < band_offset; j++)
+            f->dual_stereo = 0;
+            for (j = ff_celt_freq_bands[f->start_band] << f->size; j < band_offset; j++)
                 norm[j] = (norm[j] + norm2[j]) / 2;
         }
 
-        if (s->dualstereo) {
-            cm[0] = ff_celt_decode_band(s, rc, i, X, NULL, band_size, b / 2, s->blocks,
-                                        effective_lowband != -1 ? norm + (effective_lowband << s->duration) : NULL, s->duration,
+        if (f->dual_stereo) {
+            cm[0] = ff_celt_decode_band(f, rc, i, X, NULL, band_size, b / 2, f->blocks,
+                                        effective_lowband != -1 ? norm + (effective_lowband << f->size) : NULL, f->size,
                                         norm + band_offset, 0, 1.0f, lowband_scratch, cm[0]);
 
-            cm[1] = ff_celt_decode_band(s, rc, i, Y, NULL, band_size, b/2, s->blocks,
-                                        effective_lowband != -1 ? norm2 + (effective_lowband << s->duration) : NULL, s->duration,
+            cm[1] = ff_celt_decode_band(f, rc, i, Y, NULL, band_size, b/2, f->blocks,
+                                        effective_lowband != -1 ? norm2 + (effective_lowband << f->size) : NULL, f->size,
                                         norm2 + band_offset, 0, 1.0f, lowband_scratch, cm[1]);
         } else {
-            cm[0] = ff_celt_decode_band(s, rc, i, X, Y, band_size, b, s->blocks,
-                                        effective_lowband != -1 ? norm + (effective_lowband << s->duration) : NULL, s->duration,
+            cm[0] = ff_celt_decode_band(f, rc, i, X, Y, band_size, b, f->blocks,
+                                        effective_lowband != -1 ? norm + (effective_lowband << f->size) : NULL, f->size,
                                         norm + band_offset, 0, 1.0f, lowband_scratch, cm[0]|cm[1]);
             cm[1] = cm[0];
         }
 
-        s->frame[0].collapse_masks[i]                     = (uint8_t)cm[0];
-        s->frame[s->coded_channels - 1].collapse_masks[i] = (uint8_t)cm[1];
-        s->remaining += s->pulses[i] + consumed;
+        f->block[0].collapse_masks[i]               = (uint8_t)cm[0];
+        f->block[f->channels - 1].collapse_masks[i] = (uint8_t)cm[1];
+        f->remaining += f->pulses[i] + consumed;
 
         /* Update the folding position only as long as we have 1 bit/sample depth */
         update_lowband = (b > band_size << 3);
     }
 }
 
-int ff_celt_decode_frame(CeltContext *s, OpusRangeCoder *rc,
-                         float **output, int coded_channels, int frame_size,
-                         int startband,  int endband)
+int ff_celt_decode_frame(CeltFrame *f, OpusRangeCoder *rc,
+                         float **output, int channels, int frame_size,
+                         int start_band,  int end_band)
 {
     int i, j;
-
     int consumed;           // bits of entropy consumed thus far for this frame
-    int silence = 0;
-    int transient = 0;
-    int anticollapse = 0;
     MDCT15Context *imdct;
     float imdct_scale = 1.0;
 
-    if (coded_channels != 1 && coded_channels != 2) {
-        av_log(s->avctx, AV_LOG_ERROR, "Invalid number of coded channels: %d\n",
-               coded_channels);
+    if (channels != 1 && channels != 2) {
+        av_log(f->avctx, AV_LOG_ERROR, "Invalid number of coded channels: %d\n",
+               channels);
         return AVERROR_INVALIDDATA;
     }
-    if (startband < 0 || startband > endband || endband > CELT_MAX_BANDS) {
-        av_log(s->avctx, AV_LOG_ERROR, "Invalid start/end band: %d %d\n",
-               startband, endband);
+    if (start_band < 0 || start_band > end_band || end_band > CELT_MAX_BANDS) {
+        av_log(f->avctx, AV_LOG_ERROR, "Invalid start/end band: %d %d\n",
+               start_band, end_band);
         return AVERROR_INVALIDDATA;
     }
 
-    s->flushed        = 0;
-    s->coded_channels = coded_channels;
-    s->startband      = startband;
-    s->endband        = endband;
-    s->framebits      = rc->rb.bytes * 8;
-
-    s->duration = av_log2(frame_size / CELT_SHORT_BLOCKSIZE);
-    if (s->duration > CELT_MAX_LOG_BLOCKS ||
-        frame_size != CELT_SHORT_BLOCKSIZE * (1 << s->duration)) {
-        av_log(s->avctx, AV_LOG_ERROR, "Invalid CELT frame size: %d\n",
+    f->silence        = 0;
+    f->transient      = 0;
+    f->anticollapse   = 0;
+    f->flushed        = 0;
+    f->channels       = channels;
+    f->start_band     = start_band;
+    f->end_band       = end_band;
+    f->framebits      = rc->rb.bytes * 8;
+
+    f->size = av_log2(frame_size / CELT_SHORT_BLOCKSIZE);
+    if (f->size > CELT_MAX_LOG_BLOCKS ||
+        frame_size != CELT_SHORT_BLOCKSIZE * (1 << f->size)) {
+        av_log(f->avctx, AV_LOG_ERROR, "Invalid CELT frame size: %d\n",
                frame_size);
         return AVERROR_INVALIDDATA;
     }
 
-    if (!s->output_channels)
-        s->output_channels = coded_channels;
+    if (!f->output_channels)
+        f->output_channels = channels;
 
-    memset(s->frame[0].collapse_masks, 0, sizeof(s->frame[0].collapse_masks));
-    memset(s->frame[1].collapse_masks, 0, sizeof(s->frame[1].collapse_masks));
+    memset(f->block[0].collapse_masks, 0, sizeof(f->block[0].collapse_masks));
+    memset(f->block[1].collapse_masks, 0, sizeof(f->block[1].collapse_masks));
 
     consumed = opus_rc_tell(rc);
 
     /* obtain silence flag */
-    if (consumed >= s->framebits)
-        silence = 1;
+    if (consumed >= f->framebits)
+        f->silence = 1;
     else if (consumed == 1)
-        silence = ff_opus_rc_dec_log(rc, 15);
+        f->silence = ff_opus_rc_dec_log(rc, 15);
 
 
-    if (silence) {
-        consumed = s->framebits;
-        rc->total_bits += s->framebits - opus_rc_tell(rc);
+    if (f->silence) {
+        consumed = f->framebits;
+        rc->total_bits += f->framebits - opus_rc_tell(rc);
     }
 
     /* obtain post-filter options */
-    consumed = parse_postfilter(s, rc, consumed);
+    consumed = parse_postfilter(f, rc, consumed);
 
     /* obtain transient flag */
-    if (s->duration != 0 && consumed+3 <= s->framebits)
-        transient = ff_opus_rc_dec_log(rc, 3);
+    if (f->size != 0 && consumed+3 <= f->framebits)
+        f->transient = ff_opus_rc_dec_log(rc, 3);
 
-    s->blocks    = transient ? 1 << s->duration : 1;
-    s->blocksize = frame_size / s->blocks;
+    f->blocks    = f->transient ? 1 << f->size : 1;
+    f->blocksize = frame_size / f->blocks;
 
-    imdct = s->imdct[transient ? 0 : s->duration];
+    imdct = f->imdct[f->transient ? 0 : f->size];
 
-    if (coded_channels == 1) {
+    if (channels == 1) {
         for (i = 0; i < CELT_MAX_BANDS; i++)
-            s->frame[0].energy[i] = FFMAX(s->frame[0].energy[i], s->frame[1].energy[i]);
+            f->block[0].energy[i] = FFMAX(f->block[0].energy[i], f->block[1].energy[i]);
     }
 
-    celt_decode_coarse_energy(s, rc);
-    celt_decode_tf_changes   (s, rc, transient);
-    celt_decode_allocation   (s, rc);
-    celt_decode_fine_energy  (s, rc);
-    celt_decode_bands        (s, rc);
+    celt_decode_coarse_energy(f, rc);
+    celt_decode_tf_changes   (f, rc);
+    celt_decode_allocation   (f, rc);
+    celt_decode_fine_energy  (f, rc);
+    celt_decode_bands        (f, rc);
 
-    if (s->anticollapse_bit)
-        anticollapse = ff_opus_rc_get_raw(rc, 1);
+    if (f->anticollapse_needed)
+        f->anticollapse = ff_opus_rc_get_raw(rc, 1);
 
-    celt_decode_final_energy(s, rc, s->framebits - opus_rc_tell(rc));
+    celt_decode_final_energy(f, rc);
 
     /* apply anti-collapse processing and denormalization to
      * each coded channel */
-    for (i = 0; i < s->coded_channels; i++) {
-        CeltFrame *frame = &s->frame[i];
+    for (i = 0; i < f->channels; i++) {
+        CeltBlock *block = &f->block[i];
 
-        if (anticollapse)
-            process_anticollapse(s, frame, s->coeffs[i]);
+        if (f->anticollapse)
+            process_anticollapse(f, block, f->block[i].coeffs);
 
-        celt_denormalize(s, frame, s->coeffs[i]);
+        celt_denormalize(f, block, f->block[i].coeffs);
     }
 
     /* stereo -> mono downmix */
-    if (s->output_channels < s->coded_channels) {
-        s->dsp->vector_fmac_scalar(s->coeffs[0], s->coeffs[1], 1.0, FFALIGN(frame_size, 16));
+    if (f->output_channels < f->channels) {
+        f->dsp->vector_fmac_scalar(f->block[0].coeffs, f->block[1].coeffs, 1.0, FFALIGN(frame_size, 16));
         imdct_scale = 0.5;
-    } else if (s->output_channels > s->coded_channels)
-        memcpy(s->coeffs[1], s->coeffs[0], frame_size * sizeof(float));
+    } else if (f->output_channels > f->channels)
+        memcpy(f->block[1].coeffs, f->block[0].coeffs, frame_size * sizeof(float));
 
-    if (silence) {
+    if (f->silence) {
         for (i = 0; i < 2; i++) {
-            CeltFrame *frame = &s->frame[i];
+            CeltBlock *block = &f->block[i];
 
-            for (j = 0; j < FF_ARRAY_ELEMS(frame->energy); j++)
-                frame->energy[j] = CELT_ENERGY_SILENCE;
+            for (j = 0; j < FF_ARRAY_ELEMS(block->energy); j++)
+                block->energy[j] = CELT_ENERGY_SILENCE;
         }
-        memset(s->coeffs, 0, sizeof(s->coeffs));
+        memset(f->block[0].coeffs, 0, sizeof(f->block[0].coeffs));
+        memset(f->block[1].coeffs, 0, sizeof(f->block[1].coeffs));
     }
 
     /* transform and output for each output channel */
-    for (i = 0; i < s->output_channels; i++) {
-        CeltFrame *frame = &s->frame[i];
-        float m = frame->deemph_coeff;
+    for (i = 0; i < f->output_channels; i++) {
+        CeltBlock *block = &f->block[i];
+        float m = block->emph_coeff;
 
         /* iMDCT and overlap-add */
-        for (j = 0; j < s->blocks; j++) {
-            float *dst  = frame->buf + 1024 + j * s->blocksize;
+        for (j = 0; j < f->blocks; j++) {
+            float *dst  = block->buf + 1024 + j * f->blocksize;
 
-            imdct->imdct_half(imdct, dst + CELT_OVERLAP / 2, s->coeffs[i] + j,
-                              s->blocks, imdct_scale);
-            s->dsp->vector_fmul_window(dst, dst, dst + CELT_OVERLAP / 2,
+            imdct->imdct_half(imdct, dst + CELT_OVERLAP / 2, f->block[i].coeffs + j,
+                              f->blocks, imdct_scale);
+            f->dsp->vector_fmul_window(dst, dst, dst + CELT_OVERLAP / 2,
                                        ff_celt_window, CELT_OVERLAP / 2);
         }
 
         /* postfilter */
-        celt_postfilter(s, frame);
+        celt_postfilter(f, block);
 
         /* deemphasis and output scaling */
         for (j = 0; j < frame_size; j++) {
-            float tmp = frame->buf[1024 - frame_size + j] + m;
-            m = tmp * CELT_DEEMPH_COEFF;
+            float tmp = block->buf[1024 - frame_size + j] + m;
+            m = tmp * CELT_EMPH_COEFF;
             output[i][j] = tmp / 32768.;
         }
-        frame->deemph_coeff = m;
+        block->emph_coeff = m;
     }
 
-    if (coded_channels == 1)
-        memcpy(s->frame[1].energy, s->frame[0].energy, sizeof(s->frame[0].energy));
+    if (channels == 1)
+        memcpy(f->block[1].energy, f->block[0].energy, sizeof(f->block[0].energy));
 
     for (i = 0; i < 2; i++ ) {
-        CeltFrame *frame = &s->frame[i];
+        CeltBlock *block = &f->block[i];
 
-        if (!transient) {
-            memcpy(frame->prev_energy[1], frame->prev_energy[0], sizeof(frame->prev_energy[0]));
-            memcpy(frame->prev_energy[0], frame->energy,         sizeof(frame->prev_energy[0]));
+        if (!f->transient) {
+            memcpy(block->prev_energy[1], block->prev_energy[0], sizeof(block->prev_energy[0]));
+            memcpy(block->prev_energy[0], block->energy,         sizeof(block->prev_energy[0]));
         } else {
             for (j = 0; j < CELT_MAX_BANDS; j++)
-                frame->prev_energy[0][j] = FFMIN(frame->prev_energy[0][j], frame->energy[j]);
+                block->prev_energy[0][j] = FFMIN(block->prev_energy[0][j], block->energy[j]);
         }
 
-        for (j = 0; j < s->startband; j++) {
-            frame->prev_energy[0][j] = CELT_ENERGY_SILENCE;
-            frame->energy[j]         = 0.0;
+        for (j = 0; j < f->start_band; j++) {
+            block->prev_energy[0][j] = CELT_ENERGY_SILENCE;
+            block->energy[j]         = 0.0;
         }
-        for (j = s->endband; j < CELT_MAX_BANDS; j++) {
-            frame->prev_energy[0][j] = CELT_ENERGY_SILENCE;
-            frame->energy[j]         = 0.0;
+        for (j = f->end_band; j < CELT_MAX_BANDS; j++) {
+            block->prev_energy[0][j] = CELT_ENERGY_SILENCE;
+            block->energy[j]         = 0.0;
         }
     }
 
-    s->seed = rc->range;
+    f->seed = rc->range;
 
     return 0;
 }
 
-void ff_celt_flush(CeltContext *s)
+void ff_celt_flush(CeltFrame *f)
 {
     int i, j;
 
-    if (s->flushed)
+    if (f->flushed)
         return;
 
     for (i = 0; i < 2; i++) {
-        CeltFrame *frame = &s->frame[i];
+        CeltBlock *block = &f->block[i];
 
         for (j = 0; j < CELT_MAX_BANDS; j++)
-            frame->prev_energy[0][j] = frame->prev_energy[1][j] = CELT_ENERGY_SILENCE;
+            block->prev_energy[0][j] = block->prev_energy[1][j] = CELT_ENERGY_SILENCE;
 
-        memset(frame->energy, 0, sizeof(frame->energy));
-        memset(frame->buf,    0, sizeof(frame->buf));
+        memset(block->energy, 0, sizeof(block->energy));
+        memset(block->buf,    0, sizeof(block->buf));
 
-        memset(frame->pf_gains,     0, sizeof(frame->pf_gains));
-        memset(frame->pf_gains_old, 0, sizeof(frame->pf_gains_old));
-        memset(frame->pf_gains_new, 0, sizeof(frame->pf_gains_new));
+        memset(block->pf_gains,     0, sizeof(block->pf_gains));
+        memset(block->pf_gains_old, 0, sizeof(block->pf_gains_old));
+        memset(block->pf_gains_new, 0, sizeof(block->pf_gains_new));
 
-        frame->deemph_coeff = 0.0;
+        block->emph_coeff = 0.0;
     }
-    s->seed = 0;
+    f->seed = 0;
 
-    s->flushed = 1;
+    f->flushed = 1;
 }
 
-void ff_celt_free(CeltContext **ps)
+void ff_celt_free(CeltFrame **f)
 {
-    CeltContext *s = *ps;
+    CeltFrame *frm = *f;
     int i;
 
-    if (!s)
+    if (!frm)
         return;
 
-    for (i = 0; i < FF_ARRAY_ELEMS(s->imdct); i++)
-        ff_mdct15_uninit(&s->imdct[i]);
+    for (i = 0; i < FF_ARRAY_ELEMS(frm->imdct); i++)
+        ff_mdct15_uninit(&frm->imdct[i]);
 
-    av_freep(&s->dsp);
-    av_freep(ps);
+    av_freep(&frm->dsp);
+    av_freep(f);
 }
 
-int ff_celt_init(AVCodecContext *avctx, CeltContext **ps, int output_channels)
+int ff_celt_init(AVCodecContext *avctx, CeltFrame **f, int output_channels)
 {
-    CeltContext *s;
+    CeltFrame *frm;
     int i, ret;
 
     if (output_channels != 1 && output_channels != 2) {
@@ -1003,31 +1003,31 @@ int ff_celt_init(AVCodecContext *avctx, CeltContext **ps, int output_channels)
         return AVERROR(EINVAL);
     }
 
-    s = av_mallocz(sizeof(*s));
-    if (!s)
+    frm = av_mallocz(sizeof(*frm));
+    if (!frm)
         return AVERROR(ENOMEM);
 
-    s->avctx           = avctx;
-    s->output_channels = output_channels;
+    frm->avctx           = avctx;
+    frm->output_channels = output_channels;
 
-    for (i = 0; i < FF_ARRAY_ELEMS(s->imdct); i++) {
-        ret = ff_mdct15_init(&s->imdct[i], 1, i + 3, -1.0f);
+    for (i = 0; i < FF_ARRAY_ELEMS(frm->imdct); i++) {
+        ret = ff_mdct15_init(&frm->imdct[i], 1, i + 3, -1.0f);
         if (ret < 0)
             goto fail;
     }
 
-    s->dsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);
-    if (!s->dsp) {
+    frm->dsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);
+    if (!frm->dsp) {
         ret = AVERROR(ENOMEM);
         goto fail;
     }
 
-    ff_celt_flush(s);
+    ff_celt_flush(frm);
 
-    *ps = s;
+    *f = frm;
 
     return 0;
 fail:
-    ff_celt_free(&s);
+    ff_celt_free(&frm);
     return ret;
 }
diff --git a/libavcodec/opus_celt.h b/libavcodec/opus_celt.h
index e9b5946642..7b46a5116b 100644
--- a/libavcodec/opus_celt.h
+++ b/libavcodec/opus_celt.h
@@ -24,6 +24,8 @@
 #ifndef AVCODEC_OPUS_CELT_H
 #define AVCODEC_OPUS_CELT_H
 
+#include <float.h>
+
 #include "opus.h"
 
 #include "mdct15.h"
@@ -37,7 +39,7 @@
 #define CELT_NORM_SCALE              16384
 #define CELT_QTHETA_OFFSET           4
 #define CELT_QTHETA_OFFSET_TWOPHASE  16
-#define CELT_DEEMPH_COEFF            0.85000610f
+#define CELT_EMPH_COEFF              0.85000610f
 #define CELT_POSTFILTER_MINPERIOD    15
 #define CELT_ENERGY_SILENCE          (-28.0f)
 
@@ -48,7 +50,16 @@ enum CeltSpread {
     CELT_SPREAD_AGGRESSIVE
 };
 
-typedef struct CeltFrame {
+enum CeltBlockSize {
+    CELT_BLOCK_120,
+    CELT_BLOCK_240,
+    CELT_BLOCK_480,
+    CELT_BLOCK_960,
+
+    CELT_BLOCK_NB
+};
+
+typedef struct CeltBlock {
     float energy[CELT_MAX_BANDS];
     float prev_energy[2][CELT_MAX_BANDS];
 
@@ -56,50 +67,46 @@ typedef struct CeltFrame {
 
     /* buffer for mdct output + postfilter */
     DECLARE_ALIGNED(32, float, buf)[2048];
+    DECLARE_ALIGNED(32, float, coeffs)[CELT_MAX_FRAME_SIZE];
 
     /* postfilter parameters */
-    int pf_period_new;
+    int   pf_period_new;
     float pf_gains_new[3];
-    int pf_period;
+    int   pf_period;
     float pf_gains[3];
-    int pf_period_old;
+    int   pf_period_old;
     float pf_gains_old[3];
 
-    float deemph_coeff;
-} CeltFrame;
+    float emph_coeff;
+} CeltBlock;
 
-struct CeltContext {
+struct CeltFrame {
     // constant values that do not change during context lifetime
-    AVCodecContext    *avctx;
-    MDCT15Context     *imdct[4];
-    AVFloatDSPContext  *dsp;
+    AVCodecContext      *avctx;
+    MDCT15Context       *imdct[4];
+    AVFloatDSPContext   *dsp;
+    CeltBlock           block[2];
+    int channels;
     int output_channels;
 
-    // values that have inter-frame effect and must be reset on flush
-    CeltFrame frame[2];
-    uint32_t seed;
+    enum CeltBlockSize size;
+    int start_band;
+    int end_band;
+    int coded_bands;
+    int transient;
+    int blocks;        /* number of iMDCT blocks in the frame, depends on transient */
+    int blocksize;     /* size of each block */
+    int silence;       /* Frame is filled with silence */
+    int anticollapse_needed; /* Whether to expect an anticollapse bit */
+    int anticollapse;  /* Encoded anticollapse bit */
+    int intensity_stereo;
+    int dual_stereo;
     int flushed;
-
-    // values that only affect a single frame
-    int coded_channels;
-    int framebits;
-    int duration;
-
-    /* number of iMDCT blocks in the frame */
-    int blocks;
-    /* size of each block */
-    int blocksize;
-
-    int startband;
-    int endband;
-    int codedbands;
-
-    int anticollapse_bit;
-
-    int intensitystereo;
-    int dualstereo;
+    uint32_t seed;
     enum CeltSpread spread;
 
+    /* Bit allocation */
+    int framebits;
     int remaining;
     int remaining2;
     int fine_bits    [CELT_MAX_BANDS];
@@ -107,15 +114,14 @@ struct CeltContext {
     int pulses       [CELT_MAX_BANDS];
     int tf_change    [CELT_MAX_BANDS];
 
-    DECLARE_ALIGNED(32, float, coeffs)[2][CELT_MAX_FRAME_SIZE];
     DECLARE_ALIGNED(32, float, scratch)[22 * 8]; // MAX(ff_celt_freq_range) * 1<<CELT_MAX_LOG_BLOCKS
 };
 
 /* LCG for noise generation */
-static av_always_inline uint32_t celt_rng(CeltContext *s)
+static av_always_inline uint32_t celt_rng(CeltFrame *f)
 {
-    s->seed = 1664525 * s->seed + 1013904223;
-    return s->seed;
+    f->seed = 1664525 * f->seed + 1013904223;
+    return f->seed;
 }
 
 static av_always_inline void celt_renormalize_vector(float *X, int N, float gain)
@@ -130,4 +136,13 @@ static av_always_inline void celt_renormalize_vector(float *X, int N, float gain
         X[i] *= g;
 }
 
+int ff_celt_init(AVCodecContext *avctx, CeltFrame **f, int output_channels);
+
+void ff_celt_free(CeltFrame **f);
+
+void ff_celt_flush(CeltFrame *f);
+
+int ff_celt_decode_frame(CeltFrame *f, OpusRangeCoder *rc, float **output,
+                         int coded_channels, int frame_size, int startband, int endband);
+
 #endif /* AVCODEC_OPUS_CELT_H */
diff --git a/libavcodec/opus_pvq.c b/libavcodec/opus_pvq.c
index b4e23c86b8..ddc5fc2895 100644
--- a/libavcodec/opus_pvq.c
+++ b/libavcodec/opus_pvq.c
@@ -375,7 +375,7 @@ static uint32_t celt_alg_unquant(OpusRangeCoder *rc, float *X, uint32_t N, uint3
     return celt_extract_collapse_mask(y, N, blocks);
 }
 
-uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
+uint32_t ff_celt_decode_band(CeltFrame *f, OpusRangeCoder *rc, const int band,
                              float *X, float *Y, int N, int b, uint32_t blocks,
                              float *lowband, int duration, float *lowband_out, int level,
                              float gain, float *lowband_scratch, int fill)
@@ -403,9 +403,9 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
         float *x = X;
         for (i = 0; i <= dualstereo; i++) {
             int sign = 0;
-            if (s->remaining2 >= 1<<3) {
+            if (f->remaining2 >= 1<<3) {
                 sign           = ff_opus_rc_get_raw(rc, 1);
-                s->remaining2 -= 1 << 3;
+                f->remaining2 -= 1 << 3;
                 b             -= 1 << 3;
             }
             x[0] = sign ? -1.0f : 1.0f;
@@ -417,7 +417,7 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
     }
 
     if (!dualstereo && level == 0) {
-        int tf_change = s->tf_change[band];
+        int tf_change = f->tf_change[band];
         int k;
         if (tf_change > 0)
             recombine = tf_change;
@@ -454,7 +454,7 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
 
         /* Reorganize the samples in time order instead of frequency order */
         if (B0 > 1 && lowband)
-            celt_deinterleave_hadamard(s->scratch, lowband, N_B >> recombine,
+            celt_deinterleave_hadamard(f->scratch, lowband, N_B >> recombine,
                                        B0 << recombine, longblocks);
     }
 
@@ -485,7 +485,7 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
         pulse_cap = ff_celt_log_freq_range[band] + duration * 8;
         offset = (pulse_cap >> 1) - (dualstereo && N == 2 ? CELT_QTHETA_OFFSET_TWOPHASE :
                                                           CELT_QTHETA_OFFSET);
-        qn = (dualstereo && band >= s->intensitystereo) ? 1 :
+        qn = (dualstereo && band >= f->intensity_stereo) ? 1 :
              celt_compute_qn(N, b, offset, pulse_cap, dualstereo);
         tell = opus_rc_tell_frac(rc);
         if (qn != 1) {
@@ -501,7 +501,7 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
             /* NOTE: Renormalising X and Y *may* help fixed-point a bit at very high rate.
             Let's do that at higher complexity */
         } else if (dualstereo) {
-            inv = (b > 2 << 3 && s->remaining2 > 2 << 3) ? ff_opus_rc_dec_log(rc, 2) : 0;
+            inv = (b > 2 << 3 && f->remaining2 > 2 << 3) ? ff_opus_rc_dec_log(rc, 2) : 0;
             itheta = 0;
         }
         qalloc = opus_rc_tell_frac(rc) - tell;
@@ -542,7 +542,7 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
             sbits = (itheta != 0 && itheta != 16384) ? 1 << 3 : 0;
             mbits -= sbits;
             c = (itheta > 8192);
-            s->remaining2 -= qalloc+sbits;
+            f->remaining2 -= qalloc+sbits;
 
             x2 = c ? Y : X;
             y2 = c ? X : Y;
@@ -551,7 +551,7 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
             sign = 1 - 2 * sign;
             /* We use orig_fill here because we want to fold the side, but if
             itheta==16384, we'll have cleared the low bits of fill. */
-            cm = ff_celt_decode_band(s, rc, band, x2, NULL, N, mbits, blocks,
+            cm = ff_celt_decode_band(f, rc, band, x2, NULL, N, mbits, blocks,
                                      lowband, duration, lowband_out, level, gain,
                                      lowband_scratch, orig_fill);
             /* We don't split N=2 bands, so cm is either 1 or 0 (for a fold-collapse),
@@ -588,7 +588,7 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
             }
             mbits = av_clip((b - delta) / 2, 0, b);
             sbits = b - mbits;
-            s->remaining2 -= qalloc;
+            f->remaining2 -= qalloc;
 
             if (lowband && !dualstereo)
                 next_lowband2 = lowband + N; /* >32-bit split case */
@@ -600,40 +600,40 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
             else
                 next_level = level + 1;
 
-            rebalance = s->remaining2;
+            rebalance = f->remaining2;
             if (mbits >= sbits) {
                 /* In stereo mode, we do not apply a scaling to the mid
                  * because we need the normalized mid for folding later */
-                cm = ff_celt_decode_band(s, rc, band, X, NULL, N, mbits, blocks,
+                cm = ff_celt_decode_band(f, rc, band, X, NULL, N, mbits, blocks,
                                          lowband, duration, next_lowband_out1,
                                          next_level, dualstereo ? 1.0f : (gain * mid),
                                          lowband_scratch, fill);
 
-                rebalance = mbits - (rebalance - s->remaining2);
+                rebalance = mbits - (rebalance - f->remaining2);
                 if (rebalance > 3 << 3 && itheta != 0)
                     sbits += rebalance - (3 << 3);
 
                 /* For a stereo split, the high bits of fill are always zero,
                  * so no folding will be done to the side. */
-                cm |= ff_celt_decode_band(s, rc, band, Y, NULL, N, sbits, blocks,
+                cm |= ff_celt_decode_band(f, rc, band, Y, NULL, N, sbits, blocks,
                                           next_lowband2, duration, NULL,
                                           next_level, gain * side, NULL,
                                           fill >> blocks) << ((B0 >> 1) & (dualstereo - 1));
             } else {
                 /* For a stereo split, the high bits of fill are always zero,
                  * so no folding will be done to the side. */
-                cm = ff_celt_decode_band(s, rc, band, Y, NULL, N, sbits, blocks,
+                cm = ff_celt_decode_band(f, rc, band, Y, NULL, N, sbits, blocks,
                                          next_lowband2, duration, NULL,
                                          next_level, gain * side, NULL,
                                          fill >> blocks) << ((B0 >> 1) & (dualstereo - 1));
 
-                rebalance = sbits - (rebalance - s->remaining2);
+                rebalance = sbits - (rebalance - f->remaining2);
                 if (rebalance > 3 << 3 && itheta != 16384)
                     mbits += rebalance - (3 << 3);
 
                 /* In stereo mode, we do not apply a scaling to the mid because
                  * we need the normalized mid for folding later */
-                cm |= ff_celt_decode_band(s, rc, band, X, NULL, N, mbits, blocks,
+                cm |= ff_celt_decode_band(f, rc, band, X, NULL, N, mbits, blocks,
                                           lowband, duration, next_lowband_out1,
                                           next_level, dualstereo ? 1.0f : (gain * mid),
                                           lowband_scratch, fill);
@@ -643,19 +643,19 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
         /* This is the basic no-split case */
         uint32_t q         = celt_bits2pulses(cache, b);
         uint32_t curr_bits = celt_pulses2bits(cache, q);
-        s->remaining2 -= curr_bits;
+        f->remaining2 -= curr_bits;
 
         /* Ensures we can never bust the budget */
-        while (s->remaining2 < 0 && q > 0) {
-            s->remaining2 += curr_bits;
+        while (f->remaining2 < 0 && q > 0) {
+            f->remaining2 += curr_bits;
             curr_bits      = celt_pulses2bits(cache, --q);
-            s->remaining2 -= curr_bits;
+            f->remaining2 -= curr_bits;
         }
 
         if (q != 0) {
             /* Finally do the actual quantization */
             cm = celt_alg_unquant(rc, X, N, (q < 8) ? q : (8 + (q & 7)) << ((q >> 3) - 1),
-                                  s->spread, blocks, gain);
+                                  f->spread, blocks, gain);
         } else {
             /* If there's no pulse, fill the band anyway */
             int j;
@@ -668,13 +668,13 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
                 if (!lowband) {
                     /* Noise */
                     for (j = 0; j < N; j++)
-                        X[j] = (((int32_t)celt_rng(s)) >> 20);
+                        X[j] = (((int32_t)celt_rng(f)) >> 20);
                     cm = cm_mask;
                 } else {
                     /* Folded spectrum */
                     for (j = 0; j < N; j++) {
                         /* About 48 dB below the "normal" folding level */
-                        X[j] = lowband[j] + (((celt_rng(s)) & 0x8000) ? 1.0f / 256 : -1.0f / 256);
+                        X[j] = lowband[j] + (((celt_rng(f)) & 0x8000) ? 1.0f / 256 : -1.0f / 256);
                     }
                     cm = fill;
                 }
@@ -697,7 +697,7 @@ uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
 
         /* Undo the sample reorganization going from time order to frequency order */
         if (B0 > 1)
-            celt_interleave_hadamard(s->scratch, X, N_B>>recombine,
+            celt_interleave_hadamard(f->scratch, X, N_B>>recombine,
                                      B0<<recombine, longblocks);
 
         /* Undo time-freq changes that we did earlier */
diff --git a/libavcodec/opus_pvq.h b/libavcodec/opus_pvq.h
index 1083f35db9..0354a3c960 100644
--- a/libavcodec/opus_pvq.h
+++ b/libavcodec/opus_pvq.h
@@ -27,7 +27,7 @@
 #include "opus_celt.h"
 
 /* Decodes a band using PVQ */
-uint32_t ff_celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band,
+uint32_t ff_celt_decode_band(CeltFrame *f, OpusRangeCoder *rc, const int band,
                              float *X, float *Y, int N, int b, uint32_t blocks,
                              float *lowband, int duration, float *lowband_out, int level,
                              float gain, float *lowband_scratch, int fill);
diff --git a/libavcodec/opusdec.c b/libavcodec/opusdec.c
index 556acfe2df..1110302f9c 100644
--- a/libavcodec/opusdec.c
+++ b/libavcodec/opusdec.c
@@ -48,6 +48,7 @@
 #include "mathops.h"
 #include "opus.h"
 #include "opustab.h"
+#include "opus_celt.h"
 
 static const uint16_t silk_frame_duration_ms[16] = {
     10, 20, 40, 60,
@@ -63,8 +64,6 @@ static const int silk_resample_delay[] = {
     4, 8, 11, 11, 11
 };
 
-static const uint8_t celt_band_end[] = { 13, 17, 17, 19, 21 };
-
 static int get_silk_samplerate(int config)
 {
     if (config < 4)
@@ -168,7 +167,7 @@ static int opus_decode_redundancy(OpusStreamContext *s, const uint8_t *data, int
     ret = ff_celt_decode_frame(s->celt, &s->redundancy_rc,
                                s->redundancy_output,
                                s->packet.stereo + 1, 240,
-                               0, celt_band_end[s->packet.bandwidth]);
+                               0, ff_celt_band_end[s->packet.bandwidth]);
     if (ret < 0)
         goto fail;
 
@@ -279,7 +278,7 @@ static int opus_decode_frame(OpusStreamContext *s, const uint8_t *data, int size
                                    s->packet.stereo + 1,
                                    s->packet.frame_duration,
                                    (s->packet.mode == OPUS_MODE_HYBRID) ? 17 : 0,
-                                   celt_band_end[s->packet.bandwidth]);
+                                   ff_celt_band_end[s->packet.bandwidth]);
         if (ret < 0)
             return ret;
 
diff --git a/libavcodec/opustab.c b/libavcodec/opustab.c
index cfe56ba94f..02d548e71a 100644
--- a/libavcodec/opustab.c
+++ b/libavcodec/opustab.c
@@ -22,6 +22,10 @@
 
 #include "opustab.h"
 
+const uint8_t ff_opus_default_coupled_streams[] = { 0, 1, 1, 2, 2, 2, 2, 3 };
+
+const uint8_t ff_celt_band_end[] = { 13, 17, 17, 19, 21 };
+
 const uint16_t ff_silk_model_stereo_s1[] = {
     256,   7,   9,  10,  11,  12,  22,  46,  54,  55,  56,  59,  82, 174, 197, 200,
     201, 202, 210, 234, 244, 245, 246, 247, 249, 256
diff --git a/libavcodec/opustab.h b/libavcodec/opustab.h
index e6527c0270..b6be073659 100644
--- a/libavcodec/opustab.h
+++ b/libavcodec/opustab.h
@@ -27,6 +27,10 @@
 
 #include <stdint.h>
 
+extern const uint8_t  ff_celt_band_end[];
+
+extern const uint8_t  ff_opus_default_coupled_streams[];
+
 extern const uint16_t ff_silk_model_stereo_s1[];
 extern const uint16_t ff_silk_model_stereo_s2[];
 extern const uint16_t ff_silk_model_stereo_s3[];
