diff --git a/libavfilter/af_biquads.c b/libavfilter/af_biquads.c
index 5e2d74f8f9..f3ef3660cc 100644
--- a/libavfilter/af_biquads.c
+++ b/libavfilter/af_biquads.c
@@ -94,6 +94,13 @@ enum WidthType {
     NB_WTYPE,
 };
 
+enum TransformType {
+    DI,
+    DII,
+    TDII,
+    NB_TTYPE,
+};
+
 typedef struct ChanCache {
     double i1, i2;
     double o1, o2;
@@ -110,6 +117,7 @@ typedef struct BiquadsContext {
     int poles;
     int csg;
     int reverse;
+    int transform_type;
 
     double gain;
     double frequency;
@@ -363,6 +371,216 @@ BIQUAD_FILTER_REVERSE(s32, int32_t, INT32_MIN, INT32_MAX, 1)
 BIQUAD_FILTER_REVERSE(flt, float,   -1., 1., 0)
 BIQUAD_FILTER_REVERSE(dbl, double,  -1., 1., 0)
 
+#define BIQUAD_DII_FILTER(name, type, min, max, need_clipping)                \
+static void biquad_dii_## name (BiquadsContext *s,                            \
+                            const void *input, void *output, int len,         \
+                            double *z1, double *z2,                           \
+                            double *unused1, double *unused2,                 \
+                            double b0, double b1, double b2,                  \
+                            double a1, double a2, int *clippings,             \
+                            int disabled)                                     \
+{                                                                             \
+    const type *ibuf = input;                                                 \
+    type *obuf = output;                                                      \
+    double w1 = *z1;                                                          \
+    double w2 = *z2;                                                          \
+    double wet = s->mix;                                                      \
+    double dry = 1. - wet;                                                    \
+    double in, out, w0;                                                       \
+                                                                              \
+    a1 = -a1;                                                                 \
+    a2 = -a2;                                                                 \
+                                                                              \
+    for (int i = 0; i < len; i++) {                                           \
+        in = ibuf[i];                                                         \
+        w0 = in + a1 * w1 + a2 * w2;                                          \
+        out = b0 * w0 + b1 * w1 + b2 * w2;                                    \
+        w2 = w1;                                                              \
+        w1 = w0;                                                              \
+        out = out * wet + in * dry;                                           \
+        if (disabled) {                                                       \
+            obuf[i] = in;                                                     \
+        } else if (need_clipping && out < min) {                              \
+            (*clippings)++;                                                   \
+            obuf[i] = min;                                                    \
+        } else if (need_clipping && out > max) {                              \
+            (*clippings)++;                                                   \
+            obuf[i] = max;                                                    \
+        } else {                                                              \
+            obuf[i] = out;                                                    \
+        }                                                                     \
+    }                                                                         \
+    *z1 = w1;                                                                 \
+    *z2 = w2;                                                                 \
+}
+
+BIQUAD_DII_FILTER(s16, int16_t, INT16_MIN, INT16_MAX, 1)
+BIQUAD_DII_FILTER(s32, int32_t, INT32_MIN, INT32_MAX, 1)
+BIQUAD_DII_FILTER(flt, float,   -1., 1., 0)
+BIQUAD_DII_FILTER(dbl, double,  -1., 1., 0)
+
+#define BIQUAD_REVERSE_DII_FILTER(name, type, min, max, need_clipping)        \
+static void biquad_reverse_dii_## name (BiquadsContext *s,                    \
+                            const void *input, void *output, void *dst,       \
+                            int len,                                          \
+                            double *z1, double *z2,                           \
+                            double *unused1, double *unused2,                 \
+                            double b0, double b1, double b2,                  \
+                            double a1, double a2, int *clippings)             \
+{                                                                             \
+    const double *w = s->window_func_lut;                                     \
+    const type *ibuf = input;                                                 \
+    type *obuf = output;                                                      \
+    type *dbuf = dst;                                                         \
+    double w1 = *z1;                                                          \
+    double w2 = *z2;                                                          \
+    double wet = s->mix;                                                      \
+    double dry = 1. - wet;                                                    \
+    double in, out, w0;                                                       \
+                                                                              \
+    a1 = -a1;                                                                 \
+    a2 = -a2;                                                                 \
+                                                                              \
+    for (int i = 0; i < len; i++) {                                           \
+        int j = len - 1 - i;                                                  \
+        in = ibuf[j];                                                         \
+        w0 = in + a1 * w1 + a2 * w2;                                          \
+        out = b0 * w0 + b1 * w1 + b2 * w2;                                    \
+        w2 = w1;                                                              \
+        w1 = w0;                                                              \
+        out = out * wet + in * dry;                                           \
+        if (need_clipping && out < min) {                                     \
+            (*clippings)++;                                                   \
+            obuf[j] = min;                                                    \
+        } else if (need_clipping && out > max) {                              \
+            (*clippings)++;                                                   \
+            obuf[j] = max;                                                    \
+        } else {                                                              \
+            obuf[j] = out;                                                    \
+        }                                                                     \
+    }                                                                         \
+    *z1 = w1;                                                                 \
+    *z2 = w2;                                                                 \
+                                                                              \
+    for (int i = 0; i < len; i++)                                             \
+        dbuf[i] += obuf[i] * w[i];                                            \
+    for (int i = 0; i < s->hop_size; i++)                                     \
+        obuf[i] = dbuf[i];                                                    \
+    memmove(dbuf, dbuf + s->hop_size,                                         \
+            (s->window_size * 2 - s->hop_size) * s->block_align);             \
+    memset(dbuf + s->window_size * 2 - s->hop_size, 0,                        \
+           s->hop_size * s->block_align);                                     \
+}
+
+BIQUAD_REVERSE_DII_FILTER(s16, int16_t, INT16_MIN, INT16_MAX, 1)
+BIQUAD_REVERSE_DII_FILTER(s32, int32_t, INT32_MIN, INT32_MAX, 1)
+BIQUAD_REVERSE_DII_FILTER(flt, float,   -1., 1., 0)
+BIQUAD_REVERSE_DII_FILTER(dbl, double,  -1., 1., 0)
+
+#define BIQUAD_TDII_FILTER(name, type, min, max, need_clipping)               \
+static void biquad_tdii_## name (BiquadsContext *s,                           \
+                            const void *input, void *output, int len,         \
+                            double *z1, double *z2,                           \
+                            double *unused1, double *unused2,                 \
+                            double b0, double b1, double b2,                  \
+                            double a1, double a2, int *clippings,             \
+                            int disabled)                                     \
+{                                                                             \
+    const type *ibuf = input;                                                 \
+    type *obuf = output;                                                      \
+    double w1 = *z1;                                                          \
+    double w2 = *z2;                                                          \
+    double wet = s->mix;                                                      \
+    double dry = 1. - wet;                                                    \
+    double in, out;                                                           \
+                                                                              \
+    a1 = -a1;                                                                 \
+    a2 = -a2;                                                                 \
+                                                                              \
+    for (int i = 0; i < len; i++) {                                           \
+        in = ibuf[i];                                                         \
+        out = b0 * in + w1;                                                   \
+        w1 = b1 * in + w2 + a1 * out;                                         \
+        w2 = b2 * in + a2 * out;                                              \
+        out = out * wet + in * dry;                                           \
+        if (disabled) {                                                       \
+            obuf[i] = in;                                                     \
+        } else if (need_clipping && out < min) {                              \
+            (*clippings)++;                                                   \
+            obuf[i] = min;                                                    \
+        } else if (need_clipping && out > max) {                              \
+            (*clippings)++;                                                   \
+            obuf[i] = max;                                                    \
+        } else {                                                              \
+            obuf[i] = out;                                                    \
+        }                                                                     \
+    }                                                                         \
+    *z1 = w1;                                                                 \
+    *z2 = w2;                                                                 \
+}
+
+BIQUAD_TDII_FILTER(s16, int16_t, INT16_MIN, INT16_MAX, 1)
+BIQUAD_TDII_FILTER(s32, int32_t, INT32_MIN, INT32_MAX, 1)
+BIQUAD_TDII_FILTER(flt, float,   -1., 1., 0)
+BIQUAD_TDII_FILTER(dbl, double,  -1., 1., 0)
+
+#define BIQUAD_REVERSE_TDII_FILTER(name, type, min, max, need_clipping)       \
+static void biquad_reverse_tdii_## name (BiquadsContext *s,                   \
+                            const void *input, void *output, void *dst,       \
+                            int len,                                          \
+                            double *z1, double *z2,                           \
+                            double *unused1, double *unused2,                 \
+                            double b0, double b1, double b2,                  \
+                            double a1, double a2, int *clippings)             \
+{                                                                             \
+    const double *w = s->window_func_lut;                                     \
+    const type *ibuf = input;                                                 \
+    type *obuf = output;                                                      \
+    type *dbuf = dst;                                                         \
+    double w1 = *z1;                                                          \
+    double w2 = *z2;                                                          \
+    double wet = s->mix;                                                      \
+    double dry = 1. - wet;                                                    \
+    double in, out;                                                           \
+                                                                              \
+    a1 = -a1;                                                                 \
+    a2 = -a2;                                                                 \
+                                                                              \
+    for (int i = 0; i < len; i++) {                                           \
+        int j = len - 1 - i;                                                  \
+        in = ibuf[j];                                                         \
+        out = b0 * in + w1;                                                   \
+        w1 = b1 * in + w2 + a1 * out;                                         \
+        w2 = b2 * in + a2 * out;                                              \
+        out = out * wet + in * dry;                                           \
+        if (need_clipping && out < min) {                                     \
+            (*clippings)++;                                                   \
+            obuf[j] = min;                                                    \
+        } else if (need_clipping && out > max) {                              \
+            (*clippings)++;                                                   \
+            obuf[j] = max;                                                    \
+        } else {                                                              \
+            obuf[j] = out;                                                    \
+        }                                                                     \
+    }                                                                         \
+    *z1 = w1;                                                                 \
+    *z2 = w2;                                                                 \
+                                                                              \
+    for (int i = 0; i < len; i++)                                             \
+        dbuf[i] += obuf[i] * w[i];                                            \
+    for (int i = 0; i < s->hop_size; i++)                                     \
+        obuf[i] = dbuf[i];                                                    \
+    memmove(dbuf, dbuf + s->hop_size,                                         \
+            (s->window_size * 2 - s->hop_size) * s->block_align);             \
+    memset(dbuf + s->window_size * 2 - s->hop_size, 0,                        \
+           s->hop_size * s->block_align);                                     \
+}
+
+BIQUAD_REVERSE_TDII_FILTER(s16, int16_t, INT16_MIN, INT16_MAX, 1)
+BIQUAD_REVERSE_TDII_FILTER(s32, int32_t, INT32_MIN, INT32_MAX, 1)
+BIQUAD_REVERSE_TDII_FILTER(flt, float,   -1., 1., 0)
+BIQUAD_REVERSE_TDII_FILTER(dbl, double,  -1., 1., 0)
+
 static int config_filter(AVFilterLink *outlink, int reset)
 {
     AVFilterContext *ctx    = outlink->src;
@@ -554,24 +772,72 @@ static int config_filter(AVFilterLink *outlink, int reset)
     if (reset)
         memset(s->cache, 0, sizeof(ChanCache) * inlink->channels);
 
-    switch (inlink->format) {
-    case AV_SAMPLE_FMT_S16P:
-        s->filter = biquad_s16;
-        s->reverse_filter = biquad_reverse_s16;
-        break;
-    case AV_SAMPLE_FMT_S32P:
-        s->filter = biquad_s32;
-        s->reverse_filter = biquad_reverse_s32;
+    switch (s->transform_type) {
+    case DI:
+        switch (inlink->format) {
+        case AV_SAMPLE_FMT_S16P:
+            s->filter = biquad_s16;
+            s->reverse_filter = biquad_reverse_s16;
+            break;
+        case AV_SAMPLE_FMT_S32P:
+            s->filter = biquad_s32;
+            s->reverse_filter = biquad_reverse_s32;
+            break;
+        case AV_SAMPLE_FMT_FLTP:
+            s->filter = biquad_flt;
+            s->reverse_filter = biquad_reverse_flt;
+            break;
+        case AV_SAMPLE_FMT_DBLP:
+            s->filter = biquad_dbl;
+            s->reverse_filter = biquad_reverse_dbl;
+            break;
+        default: av_assert0(0);
+        }
         break;
-    case AV_SAMPLE_FMT_FLTP:
-        s->filter = biquad_flt;
-        s->reverse_filter = biquad_reverse_flt;
+    case DII:
+        switch (inlink->format) {
+        case AV_SAMPLE_FMT_S16P:
+            s->filter = biquad_dii_s16;
+            s->reverse_filter = biquad_reverse_dii_s16;
+            break;
+        case AV_SAMPLE_FMT_S32P:
+            s->filter = biquad_dii_s32;
+            s->reverse_filter = biquad_reverse_dii_s32;
+            break;
+        case AV_SAMPLE_FMT_FLTP:
+            s->filter = biquad_dii_flt;
+            s->reverse_filter = biquad_reverse_dii_flt;
+            break;
+        case AV_SAMPLE_FMT_DBLP:
+            s->filter = biquad_dii_dbl;
+            s->reverse_filter = biquad_reverse_dii_dbl;
+            break;
+        default: av_assert0(0);
+        }
         break;
-    case AV_SAMPLE_FMT_DBLP:
-        s->filter = biquad_dbl;
-        s->reverse_filter = biquad_reverse_dbl;
+    case TDII:
+        switch (inlink->format) {
+        case AV_SAMPLE_FMT_S16P:
+            s->filter = biquad_tdii_s16;
+            s->reverse_filter = biquad_reverse_tdii_s16;
+            break;
+        case AV_SAMPLE_FMT_S32P:
+            s->filter = biquad_tdii_s32;
+            s->reverse_filter = biquad_reverse_tdii_s32;
+            break;
+        case AV_SAMPLE_FMT_FLTP:
+            s->filter = biquad_tdii_flt;
+            s->reverse_filter = biquad_reverse_tdii_flt;
+            break;
+        case AV_SAMPLE_FMT_DBLP:
+            s->filter = biquad_tdii_dbl;
+            s->reverse_filter = biquad_reverse_tdii_dbl;
+            break;
+        default: av_assert0(0);
+        }
         break;
-    default: av_assert0(0);
+    default:
+        av_assert0(0);
     }
 
     s->block_align = av_get_bytes_per_sample(inlink->format);
@@ -846,6 +1112,11 @@ static const AVOption equalizer_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"reverse", "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"r",       "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"size", "set window size for reverse filtering", OFFSET(hop_size), AV_OPT_TYPE_INT, {.i64=2048}, 256, 32768, AF},
@@ -876,6 +1147,11 @@ static const AVOption bass_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"reverse", "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"r",       "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"size", "set window size for reverse filtering", OFFSET(hop_size), AV_OPT_TYPE_INT, {.i64=2048}, 256, 32768, AF},
@@ -906,6 +1182,11 @@ static const AVOption treble_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"reverse", "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"r",       "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"size", "set window size for reverse filtering", OFFSET(hop_size), AV_OPT_TYPE_INT, {.i64=2048}, 256, 32768, AF},
@@ -935,6 +1216,11 @@ static const AVOption bandpass_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"reverse", "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"r",       "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"size", "set window size for reverse filtering", OFFSET(hop_size), AV_OPT_TYPE_INT, {.i64=2048}, 256, 32768, AF},
@@ -963,6 +1249,11 @@ static const AVOption bandreject_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"reverse", "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"r",       "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"size", "set window size for reverse filtering", OFFSET(hop_size), AV_OPT_TYPE_INT, {.i64=2048}, 256, 32768, AF},
@@ -993,6 +1284,11 @@ static const AVOption lowpass_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"reverse", "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"r",       "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"size", "set window size for reverse filtering", OFFSET(hop_size), AV_OPT_TYPE_INT, {.i64=2048}, 256, 32768, AF},
@@ -1023,6 +1319,11 @@ static const AVOption highpass_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"reverse", "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"r",       "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"size", "set window size for reverse filtering", OFFSET(hop_size), AV_OPT_TYPE_INT, {.i64=2048}, 256, 32768, AF},
@@ -1051,6 +1352,11 @@ static const AVOption allpass_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"order", "set filter order", OFFSET(order), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, FLAGS},
     {"o",     "set filter order", OFFSET(order), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, FLAGS},
     {NULL}
@@ -1079,6 +1385,11 @@ static const AVOption lowshelf_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"reverse", "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"r",       "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"size", "set window size for reverse filtering", OFFSET(hop_size), AV_OPT_TYPE_INT, {.i64=2048}, 256, 32768, AF},
@@ -1109,6 +1420,11 @@ static const AVOption highshelf_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"reverse", "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"r",       "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"size", "set window size for reverse filtering", OFFSET(hop_size), AV_OPT_TYPE_INT, {.i64=2048}, 256, 32768, AF},
@@ -1132,6 +1448,11 @@ static const AVOption biquad_options[] = {
     {"c",        "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
     {"normalize", "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
     {"n",         "normalize coefficients", OFFSET(normalize), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS},
+    {"transform", "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"a",         "set transform type", OFFSET(transform_type), AV_OPT_TYPE_INT, {.i64=0}, 0, NB_TTYPE-1, AF, "transform_type"},
+    {"di",   "direct form I",  0, AV_OPT_TYPE_CONST, {.i64=DI}, 0, 0, AF, "transform_type"},
+    {"dii",  "direct form II", 0, AV_OPT_TYPE_CONST, {.i64=DII}, 0, 0, AF, "transform_type"},
+    {"tdii", "transposed direct form II", 0, AV_OPT_TYPE_CONST, {.i64=TDII}, 0, 0, AF, "transform_type"},
     {"reverse", "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"r",       "reverse filtering", OFFSET(reverse), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF},
     {"size", "set window size for reverse filtering", OFFSET(hop_size), AV_OPT_TYPE_INT, {.i64=2048}, 256, 32768, AF},
