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/*
* 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/channel_layout.h"
#include "aptx.h"
/*
* 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];
int i;
subbands[0] = low_subband_input + high_subband_input;
subbands[1] = low_subband_input - high_subband_input;
for (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];
int i;
/* Join 4 subbands into 2 intermediate subbands upsampled to 2 samples. */
for (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 (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]);
}
static void aptx_decode_channel(Channel *channel, int32_t samples[4])
{
int32_t subband_samples[4];
int subband;
for (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_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 aptxhd_unpack_codeword(Channel *channel, uint32_t codeword)
{
channel->quantize[0].quantized_sample = sign_extend(codeword >> 0, 9);
channel->quantize[1].quantized_sample = sign_extend(codeword >> 9, 6);
channel->quantize[2].quantized_sample = sign_extend(codeword >> 15, 4);
channel->quantize[3].quantized_sample = sign_extend(codeword >> 19, 5);
channel->quantize[3].quantized_sample = (channel->quantize[3].quantized_sample & ~1)
| aptx_quantized_parity(channel);
}
static int aptx_decode_samples(AptXContext *ctx,
const uint8_t *input,
int32_t samples[NB_CHANNELS][4])
{
int channel, ret;
for (channel = 0; channel < NB_CHANNELS; channel++) {
ff_aptx_generate_dither(&ctx->channels[channel]);
if (ctx->hd)
aptxhd_unpack_codeword(&ctx->channels[channel],
AV_RB24(input + 3*channel));
else
aptx_unpack_codeword(&ctx->channels[channel],
AV_RB16(input + 2*channel));
ff_aptx_invert_quantize_and_prediction(&ctx->channels[channel], ctx->hd);
}
ret = aptx_check_parity(ctx->channels, &ctx->sync_idx);
for (channel = 0; channel < NB_CHANNELS; channel++)
aptx_decode_channel(&ctx->channels[channel], samples[channel]);
return ret;
}
static int aptx_decode_frame(AVCodecContext *avctx, void *data,
int *got_frame_ptr, AVPacket *avpkt)
{
AptXContext *s = avctx->priv_data;
AVFrame *frame = data;
int pos, opos, channel, sample, ret;
if (avpkt->size < s->block_size) {
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 = 4 * avpkt->size / s->block_size;
if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
return ret;
for (pos = 0, opos = 0; opos < frame->nb_samples; pos += s->block_size, opos += 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 (channel = 0; channel < NB_CHANNELS; channel++)
for (sample = 0; sample < 4; sample++)
AV_WN32A(&frame->data[channel][4*(opos+sample)],
samples[channel][sample] * 256);
}
*got_frame_ptr = 1;
return s->block_size * frame->nb_samples / 4;
}
#if CONFIG_APTX_DECODER
const 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 = ff_aptx_init,
.decode = aptx_decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
.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_HD_DECODER
const AVCodec ff_aptx_hd_decoder = {
.name = "aptx_hd",
.long_name = NULL_IF_CONFIG_SMALL("aptX HD (Audio Processing Technology for Bluetooth)"),
.type = AVMEDIA_TYPE_AUDIO,
.id = AV_CODEC_ID_APTX_HD,
.priv_data_size = sizeof(AptXContext),
.init = ff_aptx_init,
.decode = aptx_decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
.channel_layouts = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},
.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,
AV_SAMPLE_FMT_NONE },
};
#endif
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