From d7c728bdb2e78ccfb49a17e7fa75785e771480f6 Mon Sep 17 00:00:00 2001
From: Aurelien Jacobs <aurel@gnuage.org>
Date: Thu, 31 Aug 2017 20:12:54 +0200
Subject: [PATCH 1/2] aptx: implement the aptX bluetooth codec
The encoder was reverse engineered from binary library and from
EP0398973B1 patent (long expired).
The decoder was simply deduced from the encoder.
---
doc/general.texi | 2 +
libavcodec/Makefile | 2 +
libavcodec/allcodecs.c | 1 +
libavcodec/aptx.c | 826 ++++++++++++++++++++++++++++++++++++++++++++++++
libavcodec/avcodec.h | 1 +
libavcodec/codec_desc.c | 7 +
6 files changed, 839 insertions(+)
create mode 100644 libavcodec/aptx.c
@@ -993,6 +993,8 @@ following image formats are supported:
@item Amazing Studio PAF Audio @tab @tab X
@item Apple lossless audio @tab X @tab X
@tab QuickTime fourcc 'alac'
+@item aptX @tab X @tab X
+ @tab Used in Bluetooth A2DP
@item ATRAC1 @tab @tab X
@item ATRAC3 @tab @tab X
@item ATRAC3+ @tab @tab X
@@ -188,6 +188,8 @@ OBJS-$(CONFIG_AMV_ENCODER) += mjpegenc.o mjpegenc_common.o \
OBJS-$(CONFIG_ANM_DECODER) += anm.o
OBJS-$(CONFIG_ANSI_DECODER) += ansi.o cga_data.o
OBJS-$(CONFIG_APE_DECODER) += apedec.o
+OBJS-$(CONFIG_APTX_DECODER) += aptx.o
+OBJS-$(CONFIG_APTX_ENCODER) += aptx.o
OBJS-$(CONFIG_APNG_DECODER) += png.o pngdec.o pngdsp.o
OBJS-$(CONFIG_APNG_ENCODER) += png.o pngenc.o
OBJS-$(CONFIG_SSA_DECODER) += assdec.o ass.o
@@ -406,6 +406,7 @@ static void register_all(void)
REGISTER_DECODER(AMRNB, amrnb);
REGISTER_DECODER(AMRWB, amrwb);
REGISTER_DECODER(APE, ape);
+ REGISTER_ENCDEC (APTX, aptx);
REGISTER_DECODER(ATRAC1, atrac1);
REGISTER_DECODER(ATRAC3, atrac3);
REGISTER_DECODER(ATRAC3AL, atrac3al);
new file mode 100644
@@ -0,0 +1,826 @@
+/*
+ * Audio Processing Technology codec for Bluetooth (aptX)
+ *
+ * Copyright (C) 2017 Aurelien Jacobs <aurel@gnuage.org>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/intreadwrite.h"
+#include "avcodec.h"
+#include "internal.h"
+#include "mathops.h"
+
+
+enum channels {
+ LEFT,
+ RIGHT,
+ NB_CHANNELS
+};
+
+enum subbands {
+ LF, // Low Frequency (0-5.5 kHz)
+ MLF, // Medium-Low Frequency (5.5-11kHz)
+ MHF, // Medium-High Frequency (11-16.5kHz)
+ HF, // High Frequency (16.5-22kHz)
+ NB_SUBBANDS
+};
+
+#define NB_FILTERS 2
+#define FILTER_TAPS 16
+
+typedef struct {
+ int pos;
+ int32_t buffer[2*FILTER_TAPS];
+} FilterSignal;
+
+typedef struct {
+ FilterSignal outer_filter_signal[NB_FILTERS];
+ FilterSignal inner_filter_signal[NB_FILTERS][NB_FILTERS];
+} QMFAnalysis;
+
+typedef struct {
+ int32_t quantized_sample;
+ int32_t quantized_sample_parity_change;
+ int32_t error;
+} Quantize;
+
+typedef struct {
+ int32_t quantization_factor;
+ int32_t factor_select;
+ int32_t reconstructed_difference;
+} InvertQuantize;
+
+typedef struct {
+ int32_t prev_sign[2];
+ int32_t s_weight[2];
+ int32_t d_weight[24];
+ int32_t pos;
+ int32_t reconstructed_differences[48];
+ int32_t previous_reconstructed_sample;
+ int32_t predicted_difference;
+ int32_t predicted_sample;
+} Prediction;
+
+typedef struct {
+ int32_t codeword_history;
+ int32_t dither_parity;
+ int32_t dither[NB_SUBBANDS];
+
+ QMFAnalysis qmf;
+ Quantize quantize[NB_SUBBANDS];
+ InvertQuantize invert_quantize[NB_SUBBANDS];
+ Prediction prediction[NB_SUBBANDS];
+} Channel;
+
+typedef struct {
+ int32_t sync_idx;
+ Channel channels[NB_CHANNELS];
+} AptXContext;
+
+
+static const int32_t quantize_intervals_LF[65] = {
+ -9948, 9948, 29860, 49808, 69822, 89926, 110144, 130502,
+ 151026, 171738, 192666, 213832, 235264, 256982, 279014, 301384,
+ 324118, 347244, 370790, 394782, 419250, 444226, 469742, 495832,
+ 522536, 549890, 577936, 606720, 636290, 666700, 698006, 730270,
+ 763562, 797958, 833538, 870398, 908640, 948376, 989740, 1032874,
+ 1077948, 1125150, 1174700, 1226850, 1281900, 1340196, 1402156, 1468282,
+ 1539182, 1615610, 1698514, 1789098, 1888944, 2000168, 2125700, 2269750,
+ 2438670, 2642660, 2899462, 3243240, 3746078, 4535138, 5664098, 7102424,
+ 8897462,
+};
+static const int32_t invert_quantize_dither_factors_LF[65] = {
+ 9948, 9948, 9962, 9988, 10026, 10078, 10142, 10218,
+ 10306, 10408, 10520, 10646, 10784, 10934, 11098, 11274,
+ 11462, 11664, 11880, 12112, 12358, 12618, 12898, 13194,
+ 13510, 13844, 14202, 14582, 14988, 15422, 15884, 16380,
+ 16912, 17484, 18098, 18762, 19480, 20258, 21106, 22030,
+ 23044, 24158, 25390, 26760, 28290, 30008, 31954, 34172,
+ 36728, 39700, 43202, 47382, 52462, 58762, 66770, 77280,
+ 91642, 112348, 144452, 199326, 303512, 485546, 643414, 794914,
+ 1000124,
+};
+static const int32_t quantize_dither_factors_LF[65] = {
+ 0, 4, 7, 10, 13, 16, 19, 22,
+ 26, 28, 32, 35, 38, 41, 44, 47,
+ 51, 54, 58, 62, 65, 70, 74, 79,
+ 84, 90, 95, 102, 109, 116, 124, 133,
+ 143, 154, 166, 180, 195, 212, 231, 254,
+ 279, 308, 343, 383, 430, 487, 555, 639,
+ 743, 876, 1045, 1270, 1575, 2002, 2628, 3591,
+ 5177, 8026, 13719, 26047, 45509, 39467, 37875, 51303,
+ 0,
+};
+static const int16_t quantize_factor_select_offset_LF[65] = {
+ 0, -21, -19, -17, -15, -12, -10, -8,
+ -6, -4, -1, 1, 3, 6, 8, 10,
+ 13, 15, 18, 20, 23, 26, 29, 31,
+ 34, 37, 40, 43, 47, 50, 53, 57,
+ 60, 64, 68, 72, 76, 80, 85, 89,
+ 94, 99, 105, 110, 116, 123, 129, 136,
+ 144, 152, 161, 171, 182, 194, 207, 223,
+ 241, 263, 291, 328, 382, 467, 522, 522,
+ 522,
+};
+
+
+static const int32_t quantize_intervals_MLF[9] = {
+ -89806, 89806, 278502, 494338, 759442, 1113112, 1652322, 2720256, 5190186,
+};
+static const int32_t invert_quantize_dither_factors_MLF[9] = {
+ 89806, 89806, 98890, 116946, 148158, 205512, 333698, 734236, 1735696,
+};
+static const int32_t quantize_dither_factors_MLF[9] = {
+ 0, 2271, 4514, 7803, 14339, 32047, 100135, 250365, 0,
+};
+static const int16_t quantize_factor_select_offset_MLF[9] = {
+ 0, -14, 6, 29, 58, 96, 154, 270, 521,
+};
+
+
+static const int32_t quantize_intervals_MHF[3] = {
+ -194080, 194080, 890562,
+};
+static const int32_t invert_quantize_dither_factors_MHF[3] = {
+ 194080, 194080, 502402,
+};
+static const int32_t quantize_dither_factors_MHF[3] = {
+ 0, 77081, 0,
+};
+static const int16_t quantize_factor_select_offset_MHF[3] = {
+ 0, -33, 136,
+};
+
+
+static const int32_t quantize_intervals_HF[5] = {
+ -163006, 163006, 542708, 1120554, 2669238,
+};
+static const int32_t invert_quantize_dither_factors_HF[5] = {
+ 163006, 163006, 216698, 361148, 1187538,
+};
+static const int32_t quantize_dither_factors_HF[5] = {
+ 0, 13423, 36113, 206598, 0,
+};
+static const int16_t quantize_factor_select_offset_HF[5] = {
+ 0, -8, 33, 95, 262,
+};
+
+typedef const struct {
+ const int32_t *quantize_intervals;
+ const int32_t *invert_quantize_dither_factors;
+ const int32_t *quantize_dither_factors;
+ const int16_t *quantize_factor_select_offset;
+ int tables_size;
+ int32_t quantized_bits;
+ int32_t prediction_order;
+} ConstTables;
+
+static ConstTables tables[NB_SUBBANDS] = {
+ [LF] = { quantize_intervals_LF,
+ invert_quantize_dither_factors_LF,
+ quantize_dither_factors_LF,
+ quantize_factor_select_offset_LF,
+ FF_ARRAY_ELEMS(quantize_intervals_LF),
+ 7, 24 },
+ [MLF] = { quantize_intervals_MLF,
+ invert_quantize_dither_factors_MLF,
+ quantize_dither_factors_MLF,
+ quantize_factor_select_offset_MLF,
+ FF_ARRAY_ELEMS(quantize_intervals_MLF),
+ 4, 12 },
+ [MHF] = { quantize_intervals_MHF,
+ invert_quantize_dither_factors_MHF,
+ quantize_dither_factors_MHF,
+ quantize_factor_select_offset_MHF,
+ FF_ARRAY_ELEMS(quantize_intervals_MHF),
+ 2, 6 },
+ [HF] = { quantize_intervals_HF,
+ invert_quantize_dither_factors_HF,
+ quantize_dither_factors_HF,
+ quantize_factor_select_offset_HF,
+ FF_ARRAY_ELEMS(quantize_intervals_HF),
+ 3, 12 },
+};
+
+static const int16_t quantization_factors[32] = {
+ 2048, 2093, 2139, 2186, 2233, 2282, 2332, 2383,
+ 2435, 2489, 2543, 2599, 2656, 2714, 2774, 2834,
+ 2896, 2960, 3025, 3091, 3158, 3228, 3298, 3371,
+ 3444, 3520, 3597, 3676, 3756, 3838, 3922, 4008,
+};
+
+
+/* Rounded right shift with optionnal clipping */
+#define RSHIFT_SIZE(size) \
+av_always_inline \
+static int##size##_t rshift##size(int##size##_t value, int shift) \
+{ \
+ int##size##_t rounding = (int##size##_t)1 << (shift - 1); \
+ int##size##_t mask = ((int##size##_t)1 << (shift + 1)) - 1; \
+ return ((value + rounding) >> shift) - ((value & mask) == rounding); \
+} \
+av_always_inline \
+static int##size##_t rshift##size##_clip24(int##size##_t value, int shift) \
+{ \
+ return av_clip_intp2(rshift##size(value, shift), 23); \
+}
+RSHIFT_SIZE(32)
+RSHIFT_SIZE(64)
+
+
+av_always_inline
+static void aptx_update_codeword_history(Channel *channel)
+{
+ int32_t cw = ((channel->quantize[0].quantized_sample & 3) << 0) +
+ ((channel->quantize[1].quantized_sample & 2) << 1) +
+ ((channel->quantize[2].quantized_sample & 1) << 3);
+ channel->codeword_history = (cw << 8) + (channel->codeword_history << 4);
+}
+
+static void aptx_generate_dither(Channel *channel)
+{
+ int64_t m;
+ int32_t d;
+
+ aptx_update_codeword_history(channel);
+
+ m = (int64_t)5184443 * (channel->codeword_history >> 7);
+ d = (m << 2) + (m >> 22);
+ for (int subband = 0; subband < NB_SUBBANDS; subband++)
+ channel->dither[subband] = d << (23 - 5*subband);
+ channel->dither_parity = (d >> 25) & 1;
+}
+
+/*
+ * Convolution filter coefficients for the outer QMF of the QMF tree.
+ * The 2 sets are a mirror of each other.
+ */
+static const int32_t aptx_qmf_outer_coeffs[NB_FILTERS][FILTER_TAPS] = {
+ {
+ 730, -413, -9611, 43626, -121026, 269973, -585547, 2801966,
+ 697128, -160481, 27611, 8478, -10043, 3511, 688, -897,
+ },
+ {
+ -897, 688, 3511, -10043, 8478, 27611, -160481, 697128,
+ 2801966, -585547, 269973, -121026, 43626, -9611, -413, 730,
+ },
+};
+
+/*
+ * Convolution filter coefficients for the inner QMF of the QMF tree.
+ * The 2 sets are a mirror of each other.
+ */
+static const int32_t aptx_qmf_inner_coeffs[NB_FILTERS][FILTER_TAPS] = {
+ {
+ 1033, -584, -13592, 61697, -171156, 381799, -828088, 3962579,
+ 985888, -226954, 39048, 11990, -14203, 4966, 973, -1268,
+ },
+ {
+ -1268, 973, 4966, -14203, 11990, 39048, -226954, 985888,
+ 3962579, -828088, 381799, -171156, 61697, -13592, -584, 1033,
+ },
+};
+
+/*
+ * Push one sample into a circular signal buffer.
+ */
+av_always_inline
+static void aptx_qmf_filter_signal_push(FilterSignal *signal, int32_t sample)
+{
+ signal->buffer[signal->pos ] = sample;
+ signal->buffer[signal->pos+FILTER_TAPS] = sample;
+ signal->pos = (signal->pos + 1) & (FILTER_TAPS - 1);
+}
+
+/*
+ * Compute the convolution of the signal with the coefficients, and reduce
+ * to 24 bits by applying the specified right shifting.
+ */
+av_always_inline
+static int32_t aptx_qmf_convolution(FilterSignal *signal,
+ const int32_t coeffs[FILTER_TAPS],
+ int shift)
+{
+ int32_t *sig = &signal->buffer[signal->pos];
+ int64_t e = 0;
+
+ for (int i = 0; i < FILTER_TAPS; i++)
+ e += MUL64(sig[i], coeffs[i]);
+
+ return rshift64_clip24(e, shift);
+}
+
+/*
+ * Half-band QMF analysis filter realized with a polyphase FIR filter.
+ * Split into 2 subbands and downsample by 2.
+ * So for each pair of samples that goes in, one sample goes out,
+ * split into 2 separate subbands.
+ */
+av_always_inline
+static void aptx_qmf_polyphase_analysis(FilterSignal signal[NB_FILTERS],
+ const int32_t coeffs[NB_FILTERS][FILTER_TAPS],
+ int shift,
+ int32_t samples[NB_FILTERS],
+ int32_t *low_subband_output,
+ int32_t *high_subband_output)
+{
+ int32_t subbands[NB_FILTERS];
+
+ for (int i = 0; i < NB_FILTERS; i++) {
+ aptx_qmf_filter_signal_push(&signal[i], samples[NB_FILTERS-1-i]);
+ subbands[i] = aptx_qmf_convolution(&signal[i], coeffs[i], shift);
+ }
+
+ *low_subband_output = av_clip_intp2(subbands[0] + subbands[1], 23);
+ *high_subband_output = av_clip_intp2(subbands[0] - subbands[1], 23);
+}
+
+/*
+ * Two stage QMF analysis tree.
+ * Split 4 input samples into 4 subbands and downsample by 4.
+ * So for each group of 4 samples that goes in, one sample goes out,
+ * split into 4 separate subbands.
+ */
+static void aptx_qmf_tree_analysis(QMFAnalysis *qmf,
+ int32_t samples[4],
+ int32_t subband_samples[4])
+{
+ int32_t intermediate_samples[4];
+
+ /* Split 4 input samples into 2 intermediate subbands downsampled to 2 samples */
+ for (int i = 0; i < 2; i++)
+ aptx_qmf_polyphase_analysis(qmf->outer_filter_signal,
+ aptx_qmf_outer_coeffs, 23,
+ &samples[2*i],
+ &intermediate_samples[0+i],
+ &intermediate_samples[2+i]);
+
+ /* Split 2 intermediate subband samples into 4 final subbands downsampled to 1 sample */
+ for (int i = 0; i < 2; i++)
+ aptx_qmf_polyphase_analysis(qmf->inner_filter_signal[i],
+ aptx_qmf_inner_coeffs, 23,
+ &intermediate_samples[2*i],
+ &subband_samples[2*i+0],
+ &subband_samples[2*i+1]);
+}
+
+/*
+ * Half-band QMF synthesis filter realized with a polyphase FIR filter.
+ * Join 2 subbands and upsample by 2.
+ * So for each 2 subbands sample that goes in, a pair of samples goes out.
+ */
+av_always_inline
+static void aptx_qmf_polyphase_synthesis(FilterSignal signal[NB_FILTERS],
+ const int32_t coeffs[NB_FILTERS][FILTER_TAPS],
+ int shift,
+ int32_t low_subband_input,
+ int32_t high_subband_input,
+ int32_t samples[NB_FILTERS])
+{
+ int32_t subbands[NB_FILTERS];
+
+ subbands[0] = low_subband_input + high_subband_input;
+ subbands[1] = low_subband_input - high_subband_input;
+
+ for (int i = 0; i < NB_FILTERS; i++) {
+ aptx_qmf_filter_signal_push(&signal[i], subbands[1-i]);
+ samples[i] = aptx_qmf_convolution(&signal[i], coeffs[i], shift);
+ }
+}
+
+/*
+ * Two stage QMF synthesis tree.
+ * Join 4 subbands and upsample by 4.
+ * So for each 4 subbands sample that goes in, a group of 4 samples goes out.
+ */
+static void aptx_qmf_tree_synthesis(QMFAnalysis *qmf,
+ int32_t subband_samples[4],
+ int32_t samples[4])
+{
+ int32_t intermediate_samples[4];
+
+ /* Join 4 subbands into 2 intermediate subbands upsampled to 2 samples. */
+ for (int i = 0; i < 2; i++)
+ aptx_qmf_polyphase_synthesis(qmf->inner_filter_signal[i],
+ aptx_qmf_inner_coeffs, 22,
+ subband_samples[2*i+0],
+ subband_samples[2*i+1],
+ &intermediate_samples[2*i]);
+
+ /* Join 2 samples from intermediate subbands upsampled to 4 samples. */
+ for (int i = 0; i < 2; i++)
+ aptx_qmf_polyphase_synthesis(qmf->outer_filter_signal,
+ aptx_qmf_outer_coeffs, 21,
+ intermediate_samples[0+i],
+ intermediate_samples[2+i],
+ &samples[2*i]);
+}
+
+
+av_always_inline
+static int32_t aptx_bin_search(int32_t value, int32_t factor,
+ const int32_t *intervals, int32_t nb_intervals)
+{
+ int32_t idx = 0;
+
+ for (int i = nb_intervals >> 1; i > 0; i >>= 1)
+ if (MUL64(factor, intervals[idx + i]) <= ((int64_t)value << 24))
+ idx += i;
+
+ return idx;
+}
+
+static void aptx_quantize_difference(Quantize *quantize,
+ int32_t sample_difference,
+ int32_t dither,
+ int32_t quantization_factor,
+ ConstTables *tables)
+{
+ const int32_t *intervals = tables->quantize_intervals;
+ int32_t quantized_sample, dithered_sample, parity_change;
+ int32_t d, mean, interval, inv;
+ int64_t error;
+
+ quantized_sample = aptx_bin_search(FFABS(sample_difference) >> 4,
+ quantization_factor,
+ intervals, tables->tables_size);
+
+ d = rshift32_clip24(MULH(dither, dither), 7) - (1 << 23);
+ d = rshift64(MUL64(d, tables->quantize_dither_factors[quantized_sample]), 23);
+
+ intervals += quantized_sample;
+ mean = (intervals[1] + intervals[0]) / 2;
+ interval = (intervals[1] - intervals[0]) * (-(sample_difference < 0) | 1);
+
+ dithered_sample = rshift64_clip24(MUL64(dither, interval) + ((int64_t)(mean + d) << 32), 32);
+ error = ((int64_t)FFABS(sample_difference) << 20) - MUL64(dithered_sample, quantization_factor);
+ quantize->error = FFABS(rshift64(error, 23));
+
+ parity_change = quantized_sample;
+ if (error < 0)
+ quantized_sample--;
+ else
+ parity_change--;
+
+ inv = -(sample_difference < 0);
+ quantize->quantized_sample = quantized_sample ^ inv;
+ quantize->quantized_sample_parity_change = parity_change ^ inv;
+}
+
+static void aptx_encode_channel(Channel *channel, int32_t samples[4])
+{
+ int32_t subband_samples[4];
+ aptx_qmf_tree_analysis(&channel->qmf, samples, subband_samples);
+ aptx_generate_dither(channel);
+ for (int subband = 0; subband < NB_SUBBANDS; subband++) {
+ int32_t diff = av_clip_intp2(subband_samples[subband] - channel->prediction[subband].predicted_sample, 23);
+ aptx_quantize_difference(&channel->quantize[subband], diff,
+ channel->dither[subband],
+ channel->invert_quantize[subband].quantization_factor,
+ &tables[subband]);
+ }
+}
+
+static void aptx_decode_channel(Channel *channel, int32_t samples[4])
+{
+ int32_t subband_samples[4];
+ for (int subband = 0; subband < NB_SUBBANDS; subband++)
+ subband_samples[subband] = channel->prediction[subband].previous_reconstructed_sample;
+ aptx_qmf_tree_synthesis(&channel->qmf, subband_samples, samples);
+}
+
+
+static void aptx_invert_quantization(InvertQuantize *invert_quantize,
+ int32_t quantized_sample, int32_t dither,
+ ConstTables *tables)
+{
+ int32_t qr, idx, shift, factor_select;
+
+ idx = (quantized_sample ^ -(quantized_sample < 0)) + 1;
+ qr = tables->quantize_intervals[idx] / 2;
+ if (quantized_sample < 0)
+ qr = -qr;
+
+ qr = rshift64_clip24(((int64_t)qr<<32) + MUL64(dither, tables->invert_quantize_dither_factors[idx]), 32);
+ invert_quantize->reconstructed_difference = MUL64(invert_quantize->quantization_factor, qr) >> 19;
+
+ shift = 24 - tables->quantized_bits;
+
+ /* update factor_select */
+ factor_select = 32620 * invert_quantize->factor_select;
+ factor_select = rshift32(factor_select + (tables->quantize_factor_select_offset[idx] << 15), 15);
+ invert_quantize->factor_select = av_clip(factor_select, 0, (shift << 8) | 0xFF);
+
+ /* update quantization factor */
+ idx = (invert_quantize->factor_select & 0xFF) >> 3;
+ shift -= invert_quantize->factor_select >> 8;
+ invert_quantize->quantization_factor = (quantization_factors[idx] << 11) >> shift;
+}
+
+static int32_t *aptx_reconstructed_differences_update(Prediction *prediction,
+ int32_t reconstructed_difference,
+ int order)
+{
+ int32_t *rd1 = prediction->reconstructed_differences, *rd2 = rd1 + order;
+ int p = prediction->pos;
+
+ rd1[p] = rd2[p];
+ prediction->pos = p = (p + 1) % order;
+ rd2[p] = reconstructed_difference;
+ return &rd2[p];
+}
+
+static void aptx_prediction_filtering(Prediction *prediction,
+ int32_t reconstructed_difference,
+ int order)
+{
+ int32_t reconstructed_sample, predictor, srd0;
+ int32_t *reconstructed_differences;
+ int64_t predicted_difference = 0;
+
+ reconstructed_sample = av_clip_intp2(reconstructed_difference + prediction->predicted_sample, 23);
+ predictor = av_clip_intp2((MUL64(prediction->s_weight[0], prediction->previous_reconstructed_sample)
+ + MUL64(prediction->s_weight[1], reconstructed_sample)) >> 22, 23);
+ prediction->previous_reconstructed_sample = reconstructed_sample;
+
+ reconstructed_differences = aptx_reconstructed_differences_update(prediction, reconstructed_difference, order);
+ srd0 = FFDIFFSIGN(reconstructed_difference, 0) << 23;
+ for (int i = 0; i < order; i++) {
+ int32_t srd = FF_SIGNBIT(reconstructed_differences[-i-1]) | 1;
+ prediction->d_weight[i] -= rshift32(prediction->d_weight[i] - srd*srd0, 8);
+ predicted_difference += MUL64(reconstructed_differences[-i], prediction->d_weight[i]);
+ }
+
+ prediction->predicted_difference = av_clip_intp2(predicted_difference >> 22, 23);
+ prediction->predicted_sample = av_clip_intp2(predictor + prediction->predicted_difference, 23);
+}
+
+static void aptx_process_subband(InvertQuantize *invert_quantize,
+ Prediction *prediction,
+ int32_t quantized_sample, int32_t dither,
+ ConstTables *tables)
+{
+ int32_t sign, same_sign[2], weight[2], sw1, range;
+
+ aptx_invert_quantization(invert_quantize, quantized_sample, dither, tables);
+
+ sign = FFDIFFSIGN(invert_quantize->reconstructed_difference,
+ -prediction->predicted_difference);
+ same_sign[0] = sign * prediction->prev_sign[0];
+ same_sign[1] = sign * prediction->prev_sign[1];
+ prediction->prev_sign[0] = prediction->prev_sign[1];
+ prediction->prev_sign[1] = sign | 1;
+
+ range = 0x100000;
+ sw1 = rshift32(-same_sign[1] * prediction->s_weight[1], 1);
+ sw1 = (av_clip(sw1, -range, range) & ~0xF) << 4;
+
+ range = 0x300000;
+ weight[0] = 254 * prediction->s_weight[0] + 0x800000*same_sign[0] + sw1;
+ prediction->s_weight[0] = av_clip(rshift32(weight[0], 8), -range, range);
+
+ range = 0x3C0000 - prediction->s_weight[0];
+ weight[1] = 255 * prediction->s_weight[1] + 0xC00000*same_sign[1];
+ prediction->s_weight[1] = av_clip(rshift32(weight[1], 8), -range, range);
+
+ aptx_prediction_filtering(prediction,
+ invert_quantize->reconstructed_difference,
+ tables->prediction_order);
+}
+
+static void aptx_invert_quantize_and_prediction(Channel *channel)
+{
+ for (int subband = 0; subband < NB_SUBBANDS; subband++)
+ aptx_process_subband(&channel->invert_quantize[subband],
+ &channel->prediction[subband],
+ channel->quantize[subband].quantized_sample,
+ channel->dither[subband],
+ &tables[subband]);
+}
+
+static int32_t aptx_quantized_parity(Channel *channel)
+{
+ int32_t parity = channel->dither_parity;
+
+ for (int subband = 0; subband < NB_SUBBANDS; subband++)
+ parity ^= channel->quantize[subband].quantized_sample;
+
+ return parity & 1;
+}
+
+/* For each sample, ensure that the parity of all subbands of all channels
+ * is 0 except once every 8 samples where the parity is forced to 1. */
+static int aptx_check_parity(Channel channels[NB_CHANNELS], int32_t *idx)
+{
+ int32_t parity = aptx_quantized_parity(&channels[LEFT])
+ ^ aptx_quantized_parity(&channels[RIGHT]);
+
+ int eighth = *idx == 7;
+ *idx = (*idx + 1) & 7;
+
+ return parity ^ eighth;
+}
+
+static void aptx_insert_sync(Channel channels[NB_CHANNELS], int32_t *idx)
+{
+ if (aptx_check_parity(channels, idx)) {
+ static const int map[] = { 1, 2, 0, 3 };
+ Quantize *min = &channels[NB_CHANNELS-1].quantize[map[0]];
+ for (Channel *c = &channels[NB_CHANNELS-1]; c >= channels; c--)
+ for (int i = 0; i < NB_SUBBANDS; i++)
+ if (c->quantize[map[i]].error < min->error)
+ min = &c->quantize[map[i]];
+
+ /* Forcing the desired parity is done by offsetting by 1 the quantized
+ * sample from the subband featuring the smallest quantization error. */
+ min->quantized_sample = min->quantized_sample_parity_change;
+ }
+}
+
+static uint16_t aptx_pack_codeword(Channel *channel)
+{
+ int32_t parity = aptx_quantized_parity(channel);
+ return (((channel->quantize[3].quantized_sample & 0x06) | parity) << 13)
+ | (((channel->quantize[2].quantized_sample & 0x03) ) << 11)
+ | (((channel->quantize[1].quantized_sample & 0x0F) ) << 7)
+ | (((channel->quantize[0].quantized_sample & 0x7F) ) << 0);
+}
+
+static void aptx_unpack_codeword(Channel *channel, uint16_t codeword)
+{
+ channel->quantize[0].quantized_sample = sign_extend(codeword >> 0, 7);
+ channel->quantize[1].quantized_sample = sign_extend(codeword >> 7, 4);
+ channel->quantize[2].quantized_sample = sign_extend(codeword >> 11, 2);
+ channel->quantize[3].quantized_sample = sign_extend(codeword >> 13, 3);
+ channel->quantize[3].quantized_sample = (channel->quantize[3].quantized_sample & ~1)
+ | aptx_quantized_parity(channel);
+}
+
+static void aptx_encode_samples(AptXContext *ctx,
+ int32_t samples[NB_CHANNELS][4],
+ uint8_t output[2*NB_CHANNELS])
+{
+ for (int channel = 0; channel < NB_CHANNELS; channel++)
+ aptx_encode_channel(&ctx->channels[channel], samples[channel]);
+
+ aptx_insert_sync(ctx->channels, &ctx->sync_idx);
+
+ for (int channel = 0; channel < NB_CHANNELS; channel++) {
+ aptx_invert_quantize_and_prediction(&ctx->channels[channel]);
+ AV_WB16(output + 2*channel, aptx_pack_codeword(&ctx->channels[channel]));
+ }
+}
+
+static int aptx_decode_samples(AptXContext *ctx,
+ const uint8_t input[2*NB_CHANNELS],
+ int32_t samples[NB_CHANNELS][4])
+{
+ int ret;
+
+ for (int channel = 0; channel < NB_CHANNELS; channel++) {
+ uint16_t codeword;
+ aptx_generate_dither(&ctx->channels[channel]);
+
+ codeword = AV_RB16(input + 2*channel);
+ aptx_unpack_codeword(&ctx->channels[channel], codeword);
+ aptx_invert_quantize_and_prediction(&ctx->channels[channel]);
+ }
+
+ ret = aptx_check_parity(ctx->channels, &ctx->sync_idx);
+
+ for (int channel = 0; channel < NB_CHANNELS; channel++)
+ aptx_decode_channel(&ctx->channels[channel], samples[channel]);
+
+ return ret;
+}
+
+
+static av_cold int aptx_init(AVCodecContext *avctx)
+{
+ AptXContext *s = avctx->priv_data;
+
+ for (int chan = 0; chan < NB_CHANNELS; chan++) {
+ Channel *channel = &s->channels[chan];
+ for (int subband = 0; subband < NB_SUBBANDS; subband++) {
+ Prediction *prediction = &channel->prediction[subband];
+ prediction->prev_sign[0] = 1;
+ prediction->prev_sign[1] = 1;
+ }
+ }
+
+ return 0;
+}
+
+static int aptx_decode_frame(AVCodecContext *avctx, void *data,
+ int *got_frame_ptr, AVPacket *avpkt)
+{
+ AptXContext *s = avctx->priv_data;
+ AVFrame *frame = data;
+ int ret;
+
+ if (avpkt->size < 4) {
+ av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
+ return AVERROR_INVALIDDATA;
+ }
+
+ /* get output buffer */
+ frame->channels = NB_CHANNELS;
+ frame->format = AV_SAMPLE_FMT_S32P;
+ frame->nb_samples = avpkt->size & ~3;
+ if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
+ return ret;
+
+ for (int pos = 0; pos < frame->nb_samples; pos += 4) {
+ int32_t samples[NB_CHANNELS][4];
+
+ if (aptx_decode_samples(s, &avpkt->data[pos], samples)) {
+ av_log(avctx, AV_LOG_ERROR, "Synchronization error\n");
+ return AVERROR_INVALIDDATA;
+ }
+
+ for (int channel = 0; channel < NB_CHANNELS; channel++)
+ for (int sample = 0; sample < 4; sample++)
+ AV_WN32A(&frame->data[channel][4*(sample+pos)],
+ samples[channel][sample] << 8);
+ }
+
+ *got_frame_ptr = 1;
+ return frame->nb_samples;
+}
+
+static int aptx_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
+ const AVFrame *frame, int *got_packet_ptr)
+{
+ AptXContext *s = avctx->priv_data;
+ int ret;
+
+ /* input must contain a multiple of 4 samples */
+ if (frame->nb_samples & 3 || frame->nb_samples == 0) {
+ av_log(avctx, AV_LOG_ERROR, "Frame must have a multiple of 4 samples\n");
+ return 0;
+ }
+
+ if ((ret = ff_alloc_packet2(avctx, avpkt, frame->nb_samples, 0)) < 0)
+ return ret;
+
+ for (int pos = 0; pos < frame->nb_samples; pos += 4) {
+ int32_t samples[NB_CHANNELS][4];
+
+ for (int channel = 0; channel < NB_CHANNELS; channel++)
+ for (int sample = 0; sample < 4; sample++)
+ samples[channel][sample] = (int32_t)AV_RN32A(&frame->data[channel][4*(sample+pos)]) >> 8;
+
+ aptx_encode_samples(s, samples, avpkt->data + pos);
+ }
+
+ *got_packet_ptr = 1;
+ return 0;
+}
+
+
+#if CONFIG_APTX_DECODER
+AVCodec ff_aptx_decoder = {
+ .name = "aptx",
+ .long_name = NULL_IF_CONFIG_SMALL("aptX (Audio Processing Technology for Bluetooth)"),
+ .type = AVMEDIA_TYPE_AUDIO,
+ .id = AV_CODEC_ID_APTX,
+ .priv_data_size = sizeof(AptXContext),
+ .init = aptx_init,
+ .decode = aptx_decode_frame,
+ .capabilities = AV_CODEC_CAP_DR1,
+ .channel_layouts = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},
+ .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,
+ AV_SAMPLE_FMT_NONE },
+};
+#endif
+
+#if CONFIG_APTX_ENCODER
+AVCodec ff_aptx_encoder = {
+ .name = "aptx",
+ .long_name = NULL_IF_CONFIG_SMALL("aptX (Audio Processing Technology for Bluetooth)"),
+ .type = AVMEDIA_TYPE_AUDIO,
+ .id = AV_CODEC_ID_APTX,
+ .priv_data_size = sizeof(AptXContext),
+ .init = aptx_init,
+ .encode2 = aptx_encode_frame,
+ .capabilities = AV_CODEC_CAP_VARIABLE_FRAME_SIZE,
+ .channel_layouts = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},
+ .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,
+ AV_SAMPLE_FMT_NONE },
+};
+#endif
@@ -632,6 +632,7 @@ enum AVCodecID {
AV_CODEC_ID_ATRAC3AL,
AV_CODEC_ID_ATRAC3PAL,
AV_CODEC_ID_DOLBY_E,
+ AV_CODEC_ID_APTX,
/* subtitle codecs */
AV_CODEC_ID_FIRST_SUBTITLE = 0x17000, ///< A dummy ID pointing at the start of subtitle codecs.
@@ -2859,6 +2859,13 @@ static const AVCodecDescriptor codec_descriptors[] = {
.long_name = NULL_IF_CONFIG_SMALL("ADPCM MTAF"),
.props = AV_CODEC_PROP_LOSSY,
},
+ {
+ .id = AV_CODEC_ID_APTX,
+ .type = AVMEDIA_TYPE_AUDIO,
+ .name = "aptx",
+ .long_name = NULL_IF_CONFIG_SMALL("aptX (Audio Processing Technology for Bluetooth)"),
+ .props = AV_CODEC_PROP_LOSSY,
+ },
/* subtitle codecs */
{
--
2.15.0