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FFmpeg/libavcodec/sbcdec.c
Aurelien Jacobs 4439887198 sbc: implement SBC decoder (low-complexity subband codec) 
This was originally based on libsbc, and was fully integrated into ffmpeg.
2018-03-07 22:26:53 +01:00

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/*
* 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 },
};
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