sbc: implement SBC decoder (low-complexity subband codec)

This was originally based on libsbc, and was fully integrated into ffmpeg.

doc/general.texi

@@ -1141,6 +1141,8 @@ following image formats are supported:
     @tab Real low bitrate AC-3 codec
 @item RealAudio Lossless     @tab     @tab  X
 @item RealAudio SIPR / ACELP.NET @tab     @tab  X
+@item SBC (low-complexity subband codec) @tab     @tab  X
+    @tab Used in Bluetooth A2DP
 @item Shorten                @tab     @tab  X
 @item Sierra VMD audio       @tab     @tab  X
     @tab Used in Sierra VMD files.

libavcodec/Makefile

@@ -587,6 +587,7 @@ OBJS-$(CONFIG_SUBVIEWER_DECODER)       += subviewerdec.o ass.o
 OBJS-$(CONFIG_SUNRAST_DECODER)         += sunrast.o
 OBJS-$(CONFIG_SUNRAST_ENCODER)         += sunrastenc.o
 OBJS-$(CONFIG_LIBRSVG_DECODER)         += librsvgdec.o
+OBJS-$(CONFIG_SBC_DECODER)             += sbcdec.o sbcdec_data.o sbc.o
 OBJS-$(CONFIG_SVQ1_DECODER)            += svq1dec.o svq1.o svq13.o h263data.o
 OBJS-$(CONFIG_SVQ1_ENCODER)            += svq1enc.o svq1.o  h263data.o  \
                                           h263.o ituh263enc.o

libavcodec/allcodecs.c

@@ -453,6 +453,7 @@ extern AVCodec ff_ra_144_encoder;
 extern AVCodec ff_ra_144_decoder;
 extern AVCodec ff_ra_288_decoder;
 extern AVCodec ff_ralf_decoder;
+extern AVCodec ff_sbc_decoder;
 extern AVCodec ff_shorten_decoder;
 extern AVCodec ff_sipr_decoder;
 extern AVCodec ff_smackaud_decoder;

libavcodec/avcodec.h

@@ -636,6 +636,7 @@ enum AVCodecID {
     AV_CODEC_ID_DOLBY_E,
     AV_CODEC_ID_APTX,
     AV_CODEC_ID_APTX_HD,
+    AV_CODEC_ID_SBC,
 
     /* subtitle codecs */
     AV_CODEC_ID_FIRST_SUBTITLE = 0x17000,          ///< A dummy ID pointing at the start of subtitle codecs.

libavcodec/codec_desc.c

@@ -2870,6 +2870,13 @@ static const AVCodecDescriptor codec_descriptors[] = {
         .long_name = NULL_IF_CONFIG_SMALL("aptX HD (Audio Processing Technology for Bluetooth)"),
         .props     = AV_CODEC_PROP_LOSSY,
     },
+    {
+        .id        = AV_CODEC_ID_SBC,
+        .type      = AVMEDIA_TYPE_AUDIO,
+        .name      = "sbc",
+        .long_name = NULL_IF_CONFIG_SMALL("SBC (low-complexity subband codec)"),
+        .props     = AV_CODEC_PROP_LOSSY,
+    },
 
     /* subtitle codecs */
     {

libavcodec/sbc.c

+/*
+ * Bluetooth low-complexity, subband codec (SBC)
+ *
+ * Copyright (C) 2017  Aurelien Jacobs <aurel@gnuage.org>
+ * Copyright (C) 2012-2013  Intel Corporation
+ * Copyright (C) 2008-2010  Nokia Corporation
+ * Copyright (C) 2004-2010  Marcel Holtmann <marcel@holtmann.org>
+ * Copyright (C) 2004-2005  Henryk Ploetz <henryk@ploetzli.ch>
+ * Copyright (C) 2005-2008  Brad Midgley <bmidgley@xmission.com>
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * SBC common functions for the encoder and decoder
+ */
+
+#include "avcodec.h"
+#include "sbc.h"
+
+/* A2DP specification: Appendix B, page 69 */
+static const int sbc_offset4[4][4] = {
+    { -1, 0, 0, 0 },
+    { -2, 0, 0, 1 },
+    { -2, 0, 0, 1 },
+    { -2, 0, 0, 1 }
+};
+
+/* A2DP specification: Appendix B, page 69 */
+static const int sbc_offset8[4][8] = {
+    { -2, 0, 0, 0, 0, 0, 0, 1 },
+    { -3, 0, 0, 0, 0, 0, 1, 2 },
+    { -4, 0, 0, 0, 0, 0, 1, 2 },
+    { -4, 0, 0, 0, 0, 0, 1, 2 }
+};
+
+/*
+ * Calculates the CRC-8 of the first len bits in data
+ */
+uint8_t sbc_crc8(const AVCRC *ctx, const uint8_t *data, size_t len)
+{
+    size_t byte_length = len >> 3;
+    int bit_length = len & 7;
+    uint8_t crc;
+
+    crc = av_crc(ctx, 0x0F, data, byte_length);
+
+    if (bit_length) {
+        uint8_t bits = data[byte_length];
+        while (bit_length--) {
+            int8_t mask = bits ^ crc;
+            crc = (crc << 1) ^ ((mask >> 7) & 0x1D);
+            bits <<= 1;
+        }
+    }
+
+    return crc;
+}
+
+/*
+ * Code straight from the spec to calculate the bits array
+ * Takes a pointer to the frame in question and a pointer to the bits array
+ */
+void ff_sbc_calculate_bits(const struct sbc_frame *frame, int (*bits)[8])
+{
+    int subbands = frame->subbands;
+    uint8_t sf = frame->frequency;
+
+    if (frame->mode == MONO || frame->mode == DUAL_CHANNEL) {
+        int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice;
+        int ch, sb;
+
+        for (ch = 0; ch < frame->channels; ch++) {
+            max_bitneed = 0;
+            if (frame->allocation == SNR) {
+                for (sb = 0; sb < subbands; sb++) {
+                    bitneed[ch][sb] = frame->scale_factor[ch][sb];
+                    if (bitneed[ch][sb] > max_bitneed)
+                        max_bitneed = bitneed[ch][sb];
+                }
+            } else {
+                for (sb = 0; sb < subbands; sb++) {
+                    if (frame->scale_factor[ch][sb] == 0)
+                        bitneed[ch][sb] = -5;
+                    else {
+                        if (subbands == 4)
+                            loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb];
+                        else
+                            loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb];
+                        if (loudness > 0)
+                            bitneed[ch][sb] = loudness / 2;
+                        else
+                            bitneed[ch][sb] = loudness;
+                    }
+                    if (bitneed[ch][sb] > max_bitneed)
+                        max_bitneed = bitneed[ch][sb];
+                }
+            }
+
+            bitcount = 0;
+            slicecount = 0;
+            bitslice = max_bitneed + 1;
+            do {
+                bitslice--;
+                bitcount += slicecount;
+                slicecount = 0;
+                for (sb = 0; sb < subbands; sb++) {
+                    if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16))
+                        slicecount++;
+                    else if (bitneed[ch][sb] == bitslice + 1)
+                        slicecount += 2;
+                }
+            } while (bitcount + slicecount < frame->bitpool);
+
+            if (bitcount + slicecount == frame->bitpool) {
+                bitcount += slicecount;
+                bitslice--;
+            }
+
+            for (sb = 0; sb < subbands; sb++) {
+                if (bitneed[ch][sb] < bitslice + 2)
+                    bits[ch][sb] = 0;
+                else {
+                    bits[ch][sb] = bitneed[ch][sb] - bitslice;
+                    if (bits[ch][sb] > 16)
+                        bits[ch][sb] = 16;
+                }
+            }
+
+            for (sb = 0; bitcount < frame->bitpool &&
+                            sb < subbands; sb++) {
+                if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) {
+                    bits[ch][sb]++;
+                    bitcount++;
+                } else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) {
+                    bits[ch][sb] = 2;
+                    bitcount += 2;
+                }
+            }
+
+            for (sb = 0; bitcount < frame->bitpool &&
+                            sb < subbands; sb++) {
+                if (bits[ch][sb] < 16) {
+                    bits[ch][sb]++;
+                    bitcount++;
+                }
+            }
+
+        }
+
+    } else if (frame->mode == STEREO || frame->mode == JOINT_STEREO) {
+        int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice;
+        int ch, sb;
+
+        max_bitneed = 0;
+        if (frame->allocation == SNR) {
+            for (ch = 0; ch < 2; ch++) {
+                for (sb = 0; sb < subbands; sb++) {
+                    bitneed[ch][sb] = frame->scale_factor[ch][sb];
+                    if (bitneed[ch][sb] > max_bitneed)
+                        max_bitneed = bitneed[ch][sb];
+                }
+            }
+        } else {
+            for (ch = 0; ch < 2; ch++) {
+                for (sb = 0; sb < subbands; sb++) {
+                    if (frame->scale_factor[ch][sb] == 0)
+                        bitneed[ch][sb] = -5;
+                    else {
+                        if (subbands == 4)
+                            loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb];
+                        else
+                            loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb];
+                        if (loudness > 0)
+                            bitneed[ch][sb] = loudness / 2;
+                        else
+                            bitneed[ch][sb] = loudness;
+                    }
+                    if (bitneed[ch][sb] > max_bitneed)
+                        max_bitneed = bitneed[ch][sb];
+                }
+            }
+        }
+
+        bitcount = 0;
+        slicecount = 0;
+        bitslice = max_bitneed + 1;
+        do {
+            bitslice--;
+            bitcount += slicecount;
+            slicecount = 0;
+            for (ch = 0; ch < 2; ch++) {
+                for (sb = 0; sb < subbands; sb++) {
+                    if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16))
+                        slicecount++;
+                    else if (bitneed[ch][sb] == bitslice + 1)
+                        slicecount += 2;
+                }
+            }
+        } while (bitcount + slicecount < frame->bitpool);
+
+        if (bitcount + slicecount == frame->bitpool) {
+            bitcount += slicecount;
+            bitslice--;
+        }
+
+        for (ch = 0; ch < 2; ch++) {
+            for (sb = 0; sb < subbands; sb++) {
+                if (bitneed[ch][sb] < bitslice + 2) {
+                    bits[ch][sb] = 0;
+                } else {
+                    bits[ch][sb] = bitneed[ch][sb] - bitslice;
+                    if (bits[ch][sb] > 16)
+                        bits[ch][sb] = 16;
+                }
+            }
+        }
+
+        ch = 0;
+        sb = 0;
+        while (bitcount < frame->bitpool) {
+            if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) {
+                bits[ch][sb]++;
+                bitcount++;
+            } else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) {
+                bits[ch][sb] = 2;
+                bitcount += 2;
+            }
+            if (ch == 1) {
+                ch = 0;
+                sb++;
+                if (sb >= subbands)
+                    break;
+            } else
+                ch = 1;
+        }
+
+        ch = 0;
+        sb = 0;
+        while (bitcount < frame->bitpool) {
+            if (bits[ch][sb] < 16) {
+                bits[ch][sb]++;
+                bitcount++;
+            }
+            if (ch == 1) {
+                ch = 0;
+                sb++;
+                if (sb >= subbands)
+                    break;
+            } else
+                ch = 1;
+        }
+
+    }
+
+}

libavcodec/sbc.h

+/*
+ * Bluetooth low-complexity, subband codec (SBC)
+ *
+ * Copyright (C) 2017  Aurelien Jacobs <aurel@gnuage.org>
+ * Copyright (C) 2012-2014  Intel Corporation
+ * Copyright (C) 2008-2010  Nokia Corporation
+ * Copyright (C) 2004-2010  Marcel Holtmann <marcel@holtmann.org>
+ * Copyright (C) 2004-2005  Henryk Ploetz <henryk@ploetzli.ch>
+ * Copyright (C) 2005-2006  Brad Midgley <bmidgley@xmission.com>
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * SBC common definitions for the encoder and decoder
+ */
+
+#ifndef AVCODEC_SBC_H
+#define AVCODEC_SBC_H
+
+#include "avcodec.h"
+#include "libavutil/crc.h"
+
+#define MSBC_BLOCKS 15
+
+/* sampling frequency */
+#define SBC_FREQ_16000  0x00
+#define SBC_FREQ_32000  0x01
+#define SBC_FREQ_44100  0x02
+#define SBC_FREQ_48000  0x03
+
+/* blocks */
+#define SBC_BLK_4       0x00
+#define SBC_BLK_8       0x01
+#define SBC_BLK_12      0x02
+#define SBC_BLK_16      0x03
+
+/* channel mode */
+#define SBC_MODE_MONO         0x00
+#define SBC_MODE_DUAL_CHANNEL 0x01
+#define SBC_MODE_STEREO       0x02
+#define SBC_MODE_JOINT_STEREO 0x03
+
+/* allocation method */
+#define SBC_AM_LOUDNESS 0x00
+#define SBC_AM_SNR      0x01
+
+/* subbands */
+#define SBC_SB_4        0x00
+#define SBC_SB_8        0x01
+
+/* synchronisation words */
+#define SBC_SYNCWORD   0x9C
+#define MSBC_SYNCWORD  0xAD
+
+/* extra bits of precision for the synthesis filter input data */
+#define SBCDEC_FIXED_EXTRA_BITS 2
+
+/*
+ * Enforce 16 byte alignment for the data, which is supposed to be used
+ * with SIMD optimized code.
+ */
+#define SBC_ALIGN 16
+
+/* This structure contains an unpacked SBC frame.
+   Yes, there is probably quite some unused space herein */
+struct sbc_frame {
+    uint8_t frequency;
+    uint8_t blocks;
+    enum {
+        MONO         = SBC_MODE_MONO,
+        DUAL_CHANNEL = SBC_MODE_DUAL_CHANNEL,
+        STEREO       = SBC_MODE_STEREO,
+        JOINT_STEREO = SBC_MODE_JOINT_STEREO
+    } mode;
+    uint8_t channels;
+    enum {
+        LOUDNESS = SBC_AM_LOUDNESS,
+        SNR      = SBC_AM_SNR
+    } allocation;
+    uint8_t subbands;
+    uint8_t bitpool;
+    uint16_t codesize;
+
+    /* bit number x set means joint stereo has been used in subband x */
+    uint8_t joint;
+
+    /* only the lower 4 bits of every element are to be used */
+    DECLARE_ALIGNED(SBC_ALIGN, uint32_t, scale_factor)[2][8];
+
+    /* raw integer subband samples in the frame */
+    DECLARE_ALIGNED(SBC_ALIGN, int32_t, sb_sample_f)[16][2][8];
+
+    /* modified subband samples */
+    DECLARE_ALIGNED(SBC_ALIGN, int32_t, sb_sample)[16][2][8];
+
+    const AVCRC *crc_ctx;
+};
+
+uint8_t sbc_crc8(const AVCRC *crc_ctx, const uint8_t *data, size_t len);
+void ff_sbc_calculate_bits(const struct sbc_frame *frame, int (*bits)[8]);
+
+#endif /* AVCODEC_SBC_H */

libavcodec/sbcdec.c

+/*
+ * Bluetooth low-complexity, subband codec (SBC)
+ *
+ * Copyright (C) 2017  Aurelien Jacobs <aurel@gnuage.org>
+ * Copyright (C) 2012-2013  Intel Corporation
+ * Copyright (C) 2008-2010  Nokia Corporation
+ * Copyright (C) 2004-2010  Marcel Holtmann <marcel@holtmann.org>
+ * Copyright (C) 2004-2005  Henryk Ploetz <henryk@ploetzli.ch>
+ * Copyright (C) 2005-2008  Brad Midgley <bmidgley@xmission.com>
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * SBC decoder implementation
+ */
+
+#include <stdbool.h>
+#include "avcodec.h"
+#include "internal.h"
+#include "libavutil/intreadwrite.h"
+#include "sbc.h"
+#include "sbcdec_data.h"
+
+struct sbc_decoder_state {
+    int32_t V[2][170];
+    int offset[2][16];
+};
+
+typedef struct SBCDecContext {
+    AVClass *class;
+    DECLARE_ALIGNED(SBC_ALIGN, struct sbc_frame, frame);
+    DECLARE_ALIGNED(SBC_ALIGN, struct sbc_decoder_state, dsp);
+} SBCDecContext;
+
+/*
+ * Unpacks a SBC frame at the beginning of the stream in data,
+ * which has at most len bytes into frame.
+ * Returns the length in bytes of the packed frame, or a negative
+ * value on error. The error codes are:
+ *
+ *  -1   Data stream too short
+ *  -2   Sync byte incorrect
+ *  -3   CRC8 incorrect
+ *  -4   Bitpool value out of bounds
+ */
+static int sbc_unpack_frame(const uint8_t *data, struct sbc_frame *frame,
+                            size_t len)
+{
+    unsigned int consumed;
+    /* Will copy the parts of the header that are relevant to crc
+     * calculation here */
+    uint8_t crc_header[11] = { 0 };
+    int crc_pos;
+    int32_t temp;
+
+    uint32_t audio_sample;
+    int ch, sb, blk, bit;   /* channel, subband, block and bit standard
+                               counters */
+    int bits[2][8];         /* bits distribution */
+    uint32_t levels[2][8];  /* levels derived from that */
+
+    if (len < 4)
+        return -1;
+
+    if (data[0] == MSBC_SYNCWORD) {
+        if (data[1] != 0)
+            return -2;
+        if (data[2] != 0)
+            return -2;
+
+        frame->frequency = SBC_FREQ_16000;
+        frame->blocks = MSBC_BLOCKS;
+        frame->allocation = LOUDNESS;
+        frame->mode = MONO;
+        frame->channels = 1;
+        frame->subbands = 8;
+        frame->bitpool = 26;
+    } else if (data[0] == SBC_SYNCWORD) {
+        frame->frequency  = (data[1] >> 6) & 0x03;
+        frame->blocks = 4 * ((data[1] >> 4) & 0x03) + 4;
+        frame->mode = (data[1] >> 2) & 0x03;
+        frame->channels = frame->mode == MONO ? 1 : 2;
+        frame->allocation = (data[1] >> 1) & 0x01;
+        frame->subbands = data[1] & 0x01 ? 8 : 4;
+        frame->bitpool = data[2];
+
+        if ((frame->mode == MONO || frame->mode == DUAL_CHANNEL) &&
+            frame->bitpool > 16 * frame->subbands)
+            return -4;
+
+        if ((frame->mode == STEREO || frame->mode == JOINT_STEREO) &&
+            frame->bitpool > 32 * frame->subbands)
+            return -4;
+    } else
+        return -2;
+
+    consumed = 32;
+    crc_header[0] = data[1];
+    crc_header[1] = data[2];
+    crc_pos = 16;
+
+    if (frame->mode == JOINT_STEREO) {
+        if (len * 8 < consumed + frame->subbands)
+            return -1;
+
+        frame->joint = 0x00;
+        for (sb = 0; sb < frame->subbands - 1; sb++)
+            frame->joint |= ((data[4] >> (7 - sb)) & 0x01) << sb;
+        if (frame->subbands == 4)
+            crc_header[crc_pos / 8] = data[4] & 0xf0;
+        else
+            crc_header[crc_pos / 8] = data[4];
+
+        consumed += frame->subbands;
+        crc_pos += frame->subbands;
+    }
+
+    if (len * 8 < consumed + (4 * frame->subbands * frame->channels))
+        return -1;
+
+    for (ch = 0; ch < frame->channels; ch++) {
+        for (sb = 0; sb < frame->subbands; sb++) {
+            /* FIXME assert(consumed % 4 == 0); */
+            frame->scale_factor[ch][sb] =
+                (data[consumed >> 3] >> (4 - (consumed & 0x7))) & 0x0F;
+            crc_header[crc_pos >> 3] |=
+                frame->scale_factor[ch][sb] << (4 - (crc_pos & 0x7));
+
+            consumed += 4;
+            crc_pos += 4;
+        }
+    }
+
+    if (data[3] != sbc_crc8(frame->crc_ctx, crc_header, crc_pos))
+        return -3;
+
+    ff_sbc_calculate_bits(frame, bits);
+
+    for (ch = 0; ch < frame->channels; ch++) {
+        for (sb = 0; sb < frame->subbands; sb++)
+            levels[ch][sb] = (1 << bits[ch][sb]) - 1;
+    }
+
+    for (blk = 0; blk < frame->blocks; blk++) {
+        for (ch = 0; ch < frame->channels; ch++) {
+            for (sb = 0; sb < frame->subbands; sb++) {
+                uint32_t shift;
+
+                if (levels[ch][sb] == 0) {
+                    frame->sb_sample[blk][ch][sb] = 0;
+                    continue;
+                }
+
+                shift = frame->scale_factor[ch][sb] +
+                        1 + SBCDEC_FIXED_EXTRA_BITS;
+
+                audio_sample = 0;
+                for (bit = 0; bit < bits[ch][sb]; bit++) {
+                    if (consumed > len * 8)
+                        return -1;
+
+                    if ((data[consumed >> 3] >> (7 - (consumed & 0x7))) & 0x01)
+                        audio_sample |= 1 << (bits[ch][sb] - bit - 1);
+
+                    consumed++;
+                }
+
+                frame->sb_sample[blk][ch][sb] = (int32_t)
+                    (((((uint64_t) audio_sample << 1) | 1) << shift) /
+                    levels[ch][sb]) - (1 << shift);
+            }
+        }
+    }
+
+    if (frame->mode == JOINT_STEREO) {
+        for (blk = 0; blk < frame->blocks; blk++) {
+            for (sb = 0; sb < frame->subbands; sb++) {
+                if (frame->joint & (0x01 << sb)) {
+                    temp = frame->sb_sample[blk][0][sb] +
+                           frame->sb_sample[blk][1][sb];
+                    frame->sb_sample[blk][1][sb] =
+                        frame->sb_sample[blk][0][sb] -
+                        frame->sb_sample[blk][1][sb];
+                    frame->sb_sample[blk][0][sb] = temp;
+                }
+            }
+        }
+    }
+
+    if ((consumed & 0x7) != 0)
+        consumed += 8 - (consumed & 0x7);
+
+    return consumed >> 3;
+}
+
+static inline void sbc_synthesize_four(struct sbc_decoder_state *state,
+                                       struct sbc_frame *frame,
+                                       int ch, int blk, AVFrame *output_frame)
+{
+    int i, k, idx;
+    int32_t *v = state->V[ch];
+    int *offset = state->offset[ch];
+
+    for (i = 0; i < 8; i++) {
+        /* Shifting */
+        offset[i]--;
+        if (offset[i] < 0) {
+            offset[i] = 79;
+            memcpy(v + 80, v, 9 * sizeof(*v));
+        }
+
+        /* Distribute the new matrix value to the shifted position */
+        v[offset[i]] =
+            ( ff_synmatrix4[i][0] * frame->sb_sample[blk][ch][0] +
+              ff_synmatrix4[i][1] * frame->sb_sample[blk][ch][1] +
+              ff_synmatrix4[i][2] * frame->sb_sample[blk][ch][2] +
+              ff_synmatrix4[i][3] * frame->sb_sample[blk][ch][3] ) >> 15;
+    }
+
+    /* Compute the samples */
+    for (idx = 0, i = 0; i < 4; i++, idx += 5) {
+        k = (i + 4) & 0xf;
+
+        /* Store in output, Q0 */
+        AV_WN16A(&output_frame->data[ch][blk * 8 + i * 2], av_clip_int16(
+            ( v[offset[i] + 0] * ff_sbc_proto_4_40m0[idx + 0] +
+              v[offset[k] + 1] * ff_sbc_proto_4_40m1[idx + 0] +
+              v[offset[i] + 2] * ff_sbc_proto_4_40m0[idx + 1] +
+              v[offset[k] + 3] * ff_sbc_proto_4_40m1[idx + 1] +
+              v[offset[i] + 4] * ff_sbc_proto_4_40m0[idx + 2] +
+              v[offset[k] + 5] * ff_sbc_proto_4_40m1[idx + 2] +
+              v[offset[i] + 6] * ff_sbc_proto_4_40m0[idx + 3] +
+              v[offset[k] + 7] * ff_sbc_proto_4_40m1[idx + 3] +
+              v[offset[i] + 8] * ff_sbc_proto_4_40m0[idx + 4] +
+              v[offset[k] + 9] * ff_sbc_proto_4_40m1[idx + 4] ) >> 15));
+    }
+}
+
+static inline void sbc_synthesize_eight(struct sbc_decoder_state *state,
+                                        struct sbc_frame *frame,
+                                        int ch, int blk, AVFrame *output_frame)
+{
+    int i, k, idx;
+    int32_t *v = state->V[ch];
+    int *offset = state->offset[ch];
+
+    for (i = 0; i < 16; i++) {
+        /* Shifting */
+        offset[i]--;
+        if (offset[i] < 0) {
+            offset[i] = 159;
+            memcpy(v + 160, v, 9 * sizeof(*v));
+        }
+
+        /* Distribute the new matrix value to the shifted position */
+        v[offset[i]] =
+            ( ff_synmatrix8[i][0] * frame->sb_sample[blk][ch][0] +
+              ff_synmatrix8[i][1] * frame->sb_sample[blk][ch][1] +
+              ff_synmatrix8[i][2] * frame->sb_sample[blk][ch][2] +
+              ff_synmatrix8[i][3] * frame->sb_sample[blk][ch][3] +
+              ff_synmatrix8[i][4] * frame->sb_sample[blk][ch][4] +
+              ff_synmatrix8[i][5] * frame->sb_sample[blk][ch][5] +
+              ff_synmatrix8[i][6] * frame->sb_sample[blk][ch][6] +
+              ff_synmatrix8[i][7] * frame->sb_sample[blk][ch][7] ) >> 15;
+    }
+
+    /* Compute the samples */
+    for (idx = 0, i = 0; i < 8; i++, idx += 5) {
+        k = (i + 8) & 0xf;
+
+        /* Store in output, Q0 */
+        AV_WN16A(&output_frame->data[ch][blk * 16 + i * 2], av_clip_int16(
+            ( v[offset[i] + 0] * ff_sbc_proto_8_80m0[idx + 0] +
+              v[offset[k] + 1] * ff_sbc_proto_8_80m1[idx + 0] +
+              v[offset[i] + 2] * ff_sbc_proto_8_80m0[idx + 1] +
+              v[offset[k] + 3] * ff_sbc_proto_8_80m1[idx + 1] +
+              v[offset[i] + 4] * ff_sbc_proto_8_80m0[idx + 2] +
+              v[offset[k] + 5] * ff_sbc_proto_8_80m1[idx + 2] +
+              v[offset[i] + 6] * ff_sbc_proto_8_80m0[idx + 3] +
+              v[offset[k] + 7] * ff_sbc_proto_8_80m1[idx + 3] +
+              v[offset[i] + 8] * ff_sbc_proto_8_80m0[idx + 4] +
+              v[offset[k] + 9] * ff_sbc_proto_8_80m1[idx + 4] ) >> 15));
+    }
+}
+
+static void sbc_synthesize_audio(struct sbc_decoder_state *state,
+                                 struct sbc_frame *frame, AVFrame *output_frame)
+{
+    int ch, blk;
+
+    switch (frame->subbands) {
+    case 4:
+        for (ch = 0; ch < frame->channels; ch++)
+            for (blk = 0; blk < frame->blocks; blk++)
+                sbc_synthesize_four(state, frame, ch, blk, output_frame);
+        break;
+
+    case 8:
+        for (ch = 0; ch < frame->channels; ch++)
+            for (blk = 0; blk < frame->blocks; blk++)
+                sbc_synthesize_eight(state, frame, ch, blk, output_frame);
+        break;
+    }
+}
+
+static int sbc_decode_init(AVCodecContext *avctx)
+{
+    SBCDecContext *sbc = avctx->priv_data;
+    int i, ch;
+
+    sbc->frame.crc_ctx = av_crc_get_table(AV_CRC_8_EBU);
+
+    memset(sbc->dsp.V, 0, sizeof(sbc->dsp.V));
+    for (ch = 0; ch < 2; ch++)
+        for (i = 0; i < FF_ARRAY_ELEMS(sbc->dsp.offset[0]); i++)
+            sbc->dsp.offset[ch][i] = (10 * i + 10);
+    return 0;
+}
+
+static int sbc_decode_frame(AVCodecContext *avctx,
+                            void *data, int *got_frame_ptr,
+                            AVPacket *avpkt)
+{
+    SBCDecContext *sbc = avctx->priv_data;
+    AVFrame *frame = data;
+    int ret, frame_length;
+
+    if (!sbc)
+        return AVERROR(EIO);
+
+    frame_length = sbc_unpack_frame(avpkt->data, &sbc->frame, avpkt->size);
+    if (frame_length <= 0)
+        return frame_length;
+
+    frame->channels = sbc->frame.channels;
+    frame->format = AV_SAMPLE_FMT_S16P;
+    frame->nb_samples = sbc->frame.blocks * sbc->frame.subbands;
+    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
+        return ret;
+
+    sbc_synthesize_audio(&sbc->dsp, &sbc->frame, frame);
+
+    *got_frame_ptr = 1;
+
+    return frame_length;
+}
+
+AVCodec ff_sbc_decoder = {
+    .name                  = "sbc",
+    .long_name             = NULL_IF_CONFIG_SMALL("SBC (low-complexity subband codec)"),
+    .type                  = AVMEDIA_TYPE_AUDIO,
+    .id                    = AV_CODEC_ID_SBC,
+    .priv_data_size        = sizeof(SBCDecContext),
+    .init                  = sbc_decode_init,
+    .decode                = sbc_decode_frame,
+    .capabilities          = AV_CODEC_CAP_DR1,
+    .caps_internal         = FF_CODEC_CAP_INIT_THREADSAFE,
+    .channel_layouts       = (const uint64_t[]) { AV_CH_LAYOUT_MONO,
+                                                  AV_CH_LAYOUT_STEREO, 0},
+    .sample_fmts           = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,
+                                                             AV_SAMPLE_FMT_NONE },
+    .supported_samplerates = (const int[]) { 16000, 32000, 44100, 48000, 0 },
+};

libavcodec/sbcdec_data.c

+/*
+ * Bluetooth low-complexity, subband codec (SBC)
+ *
+ * Copyright (C) 2017  Aurelien Jacobs <aurel@gnuage.org>
+ * Copyright (C) 2008-2010  Nokia Corporation
+ * Copyright (C) 2004-2010  Marcel Holtmann <marcel@holtmann.org>
+ * Copyright (C) 2004-2005  Henryk Ploetz <henryk@ploetzli.ch>
+ * Copyright (C) 2005-2006  Brad Midgley <bmidgley@xmission.com>
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * SBC decoder tables
+ */
+
+#include <stdint.h>
+#include "sbcdec_data.h"
+#include "sbc.h"
+
+#define SS4(val)  ((int32_t)val >> 12)
+#define SS8(val)  ((int32_t)val >> 14)
+#define SN4(val)  ((int32_t)val >> 11 + 1 + SBCDEC_FIXED_EXTRA_BITS)
+#define SN8(val)  ((int32_t)val >> 11 + 1 + SBCDEC_FIXED_EXTRA_BITS)
+
+const int32_t ff_sbc_proto_4_40m0[] = {
+    SS4(0x00000000), SS4(0xffa6982f), SS4(0xfba93848), SS4(0x0456c7b8),
+    SS4(0x005967d1), SS4(0xfffb9ac7), SS4(0xff589157), SS4(0xf9c2a8d8),
+    SS4(0x027c1434), SS4(0x0019118b), SS4(0xfff3c74c), SS4(0xff137330),
+    SS4(0xf81b8d70), SS4(0x00ec1b8b), SS4(0xfff0b71a), SS4(0xffe99b00),
+    SS4(0xfef84470), SS4(0xf6fb4370), SS4(0xffcdc351), SS4(0xffe01dc7)
+};
+
+const int32_t ff_sbc_proto_4_40m1[] = {
+    SS4(0xffe090ce), SS4(0xff2c0475), SS4(0xf694f800), SS4(0xff2c0475),
+    SS4(0xffe090ce), SS4(0xffe01dc7), SS4(0xffcdc351), SS4(0xf6fb4370),
+    SS4(0xfef84470), SS4(0xffe99b00), SS4(0xfff0b71a), SS4(0x00ec1b8b),
+    SS4(0xf81b8d70), SS4(0xff137330), SS4(0xfff3c74c), SS4(0x0019118b),
+    SS4(0x027c1434), SS4(0xf9c2a8d8), SS4(0xff589157), SS4(0xfffb9ac7)
+};
+
+const int32_t ff_sbc_proto_8_80m0[] = {
+    SS8(0x00000000), SS8(0xfe8d1970), SS8(0xee979f00), SS8(0x11686100),
+    SS8(0x0172e690), SS8(0xfff5bd1a), SS8(0xfdf1c8d4), SS8(0xeac182c0),
+    SS8(0x0d9daee0), SS8(0x00e530da), SS8(0xffe9811d), SS8(0xfd52986c),
+    SS8(0xe7054ca0), SS8(0x0a00d410), SS8(0x006c1de4), SS8(0xffdba705),
+    SS8(0xfcbc98e8), SS8(0xe3889d20), SS8(0x06af2308), SS8(0x000bb7db),
+    SS8(0xffca00ed), SS8(0xfc3fbb68), SS8(0xe071bc00), SS8(0x03bf7948),
+    SS8(0xffc4e05c), SS8(0xffb54b3b), SS8(0xfbedadc0), SS8(0xdde26200),
+    SS8(0x0142291c), SS8(0xff960e94), SS8(0xff9f3e17), SS8(0xfbd8f358),
+    SS8(0xdbf79400), SS8(0xff405e01), SS8(0xff7d4914), SS8(0xff8b1a31),
+    SS8(0xfc1417b8), SS8(0xdac7bb40), SS8(0xfdbb828c), SS8(0xff762170)
+};
+
+const int32_t ff_sbc_proto_8_80m1[] = {
+    SS8(0xff7c272c), SS8(0xfcb02620), SS8(0xda612700), SS8(0xfcb02620),
+    SS8(0xff7c272c), SS8(0xff762170), SS8(0xfdbb828c), SS8(0xdac7bb40),
+    SS8(0xfc1417b8), SS8(0xff8b1a31), SS8(0xff7d4914), SS8(0xff405e01),
+    SS8(0xdbf79400), SS8(0xfbd8f358), SS8(0xff9f3e17), SS8(0xff960e94),
+    SS8(0x0142291c), SS8(0xdde26200), SS8(0xfbedadc0), SS8(0xffb54b3b),
+    SS8(0xffc4e05c), SS8(0x03bf7948), SS8(0xe071bc00), SS8(0xfc3fbb68),
+    SS8(0xffca00ed), SS8(0x000bb7db), SS8(0x06af2308), SS8(0xe3889d20),
+    SS8(0xfcbc98e8), SS8(0xffdba705), SS8(0x006c1de4), SS8(0x0a00d410),
+    SS8(0xe7054ca0), SS8(0xfd52986c), SS8(0xffe9811d), SS8(0x00e530da),
+    SS8(0x0d9daee0), SS8(0xeac182c0), SS8(0xfdf1c8d4), SS8(0xfff5bd1a)
+};
+
+const int32_t ff_synmatrix4[8][4] = {
+    { SN4(0x05a82798), SN4(0xfa57d868), SN4(0xfa57d868), SN4(0x05a82798) },
+    { SN4(0x030fbc54), SN4(0xf89be510), SN4(0x07641af0), SN4(0xfcf043ac) },
+    { SN4(0x00000000), SN4(0x00000000), SN4(0x00000000), SN4(0x00000000) },
+    { SN4(0xfcf043ac), SN4(0x07641af0), SN4(0xf89be510), SN4(0x030fbc54) },
+    { SN4(0xfa57d868), SN4(0x05a82798), SN4(0x05a82798), SN4(0xfa57d868) },
+    { SN4(0xf89be510), SN4(0xfcf043ac), SN4(0x030fbc54), SN4(0x07641af0) },
+    { SN4(0xf8000000), SN4(0xf8000000), SN4(0xf8000000), SN4(0xf8000000) },
+    { SN4(0xf89be510), SN4(0xfcf043ac), SN4(0x030fbc54), SN4(0x07641af0) }
+};
+
+const int32_t ff_synmatrix8[16][8] = {
+    { SN8(0x05a82798), SN8(0xfa57d868), SN8(0xfa57d868), SN8(0x05a82798),
+      SN8(0x05a82798), SN8(0xfa57d868), SN8(0xfa57d868), SN8(0x05a82798) },
+    { SN8(0x0471ced0), SN8(0xf8275a10), SN8(0x018f8b84), SN8(0x06a6d988),
+      SN8(0xf9592678), SN8(0xfe70747c), SN8(0x07d8a5f0), SN8(0xfb8e3130) },
+    { SN8(0x030fbc54), SN8(0xf89be510), SN8(0x07641af0), SN8(0xfcf043ac),
+      SN8(0xfcf043ac), SN8(0x07641af0), SN8(0xf89be510), SN8(0x030fbc54) },
+    { SN8(0x018f8b84), SN8(0xfb8e3130), SN8(0x06a6d988), SN8(0xf8275a10),
+      SN8(0x07d8a5f0), SN8(0xf9592678), SN8(0x0471ced0), SN8(0xfe70747c) },
+    { SN8(0x00000000), SN8(0x00000000), SN8(0x00000000), SN8(0x00000000),
+      SN8(0x00000000), SN8(0x00000000), SN8(0x00000000), SN8(0x00000000) },
+    { SN8(0xfe70747c), SN8(0x0471ced0), SN8(0xf9592678), SN8(0x07d8a5f0),
+      SN8(0xf8275a10), SN8(0x06a6d988), SN8(0xfb8e3130), SN8(0x018f8b84) },
+    { SN8(0xfcf043ac), SN8(0x07641af0), SN8(0xf89be510), SN8(0x030fbc54),
+      SN8(0x030fbc54), SN8(0xf89be510), SN8(0x07641af0), SN8(0xfcf043ac) },
+    { SN8(0xfb8e3130), SN8(0x07d8a5f0), SN8(0xfe70747c), SN8(0xf9592678),
+      SN8(0x06a6d988), SN8(0x018f8b84), SN8(0xf8275a10), SN8(0x0471ced0) },
+    { SN8(0xfa57d868), SN8(0x05a82798), SN8(0x05a82798), SN8(0xfa57d868),
+      SN8(0xfa57d868), SN8(0x05a82798), SN8(0x05a82798), SN8(0xfa57d868) },
+    { SN8(0xf9592678), SN8(0x018f8b84), SN8(0x07d8a5f0), SN8(0x0471ced0),
+      SN8(0xfb8e3130), SN8(0xf8275a10), SN8(0xfe70747c), SN8(0x06a6d988) },
+    { SN8(0xf89be510), SN8(0xfcf043ac), SN8(0x030fbc54), SN8(0x07641af0),
+      SN8(0x07641af0), SN8(0x030fbc54), SN8(0xfcf043ac), SN8(0xf89be510) },
+    { SN8(0xf8275a10), SN8(0xf9592678), SN8(0xfb8e3130), SN8(0xfe70747c),
+      SN8(0x018f8b84), SN8(0x0471ced0), SN8(0x06a6d988), SN8(0x07d8a5f0) },
+    { SN8(0xf8000000), SN8(0xf8000000), SN8(0xf8000000), SN8(0xf8000000),
+      SN8(0xf8000000), SN8(0xf8000000), SN8(0xf8000000), SN8(0xf8000000) },
+    { SN8(0xf8275a10), SN8(0xf9592678), SN8(0xfb8e3130), SN8(0xfe70747c),
+      SN8(0x018f8b84), SN8(0x0471ced0), SN8(0x06a6d988), SN8(0x07d8a5f0) },
+    { SN8(0xf89be510), SN8(0xfcf043ac), SN8(0x030fbc54), SN8(0x07641af0),
+      SN8(0x07641af0), SN8(0x030fbc54), SN8(0xfcf043ac), SN8(0xf89be510) },
+    { SN8(0xf9592678), SN8(0x018f8b84), SN8(0x07d8a5f0), SN8(0x0471ced0),
+      SN8(0xfb8e3130), SN8(0xf8275a10), SN8(0xfe70747c), SN8(0x06a6d988) }
+};

libavcodec/sbcdec_data.h

+/*
+ * Bluetooth low-complexity, subband codec (SBC)
+ *
+ * Copyright (C) 2017  Aurelien Jacobs <aurel@gnuage.org>
+ * Copyright (C) 2008-2010  Nokia Corporation
+ * Copyright (C) 2004-2010  Marcel Holtmann <marcel@holtmann.org>
+ * Copyright (C) 2004-2005  Henryk Ploetz <henryk@ploetzli.ch>
+ * Copyright (C) 2005-2006  Brad Midgley <bmidgley@xmission.com>
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * SBC decoder tables
+ */
+
+#ifndef AVCODEC_SBCDEC_DATA_H
+#define AVCODEC_SBCDEC_DATA_H
+
+#include <stdint.h>
+
+extern const int32_t ff_sbc_proto_4_40m0[];
+extern const int32_t ff_sbc_proto_4_40m1[];
+extern const int32_t ff_sbc_proto_8_80m0[];
+extern const int32_t ff_sbc_proto_8_80m1[];
+extern const int32_t ff_synmatrix4[8][4];
+extern const int32_t ff_synmatrix8[16][8];
+
+#endif /* AVCODEC_SBCDEC_DATA_H */