205 lines
8.1 KiB
C
205 lines
8.1 KiB
C
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/*
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* Audio Processing Technology codec for Bluetooth (aptX)
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*
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* Copyright (C) 2017 Aurelien Jacobs <aurel@gnuage.org>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "aptx.h"
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/*
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* Half-band QMF synthesis filter realized with a polyphase FIR filter.
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* Join 2 subbands and upsample by 2.
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* So for each 2 subbands sample that goes in, a pair of samples goes out.
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*/
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av_always_inline
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static void aptx_qmf_polyphase_synthesis(FilterSignal signal[NB_FILTERS],
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const int32_t coeffs[NB_FILTERS][FILTER_TAPS],
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int shift,
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int32_t low_subband_input,
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int32_t high_subband_input,
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int32_t samples[NB_FILTERS])
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{
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int32_t subbands[NB_FILTERS];
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int i;
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subbands[0] = low_subband_input + high_subband_input;
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subbands[1] = low_subband_input - high_subband_input;
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for (i = 0; i < NB_FILTERS; i++) {
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aptx_qmf_filter_signal_push(&signal[i], subbands[1-i]);
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samples[i] = aptx_qmf_convolution(&signal[i], coeffs[i], shift);
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}
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}
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/*
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* Two stage QMF synthesis tree.
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* Join 4 subbands and upsample by 4.
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* So for each 4 subbands sample that goes in, a group of 4 samples goes out.
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*/
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static void aptx_qmf_tree_synthesis(QMFAnalysis *qmf,
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int32_t subband_samples[4],
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int32_t samples[4])
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{
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int32_t intermediate_samples[4];
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int i;
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/* Join 4 subbands into 2 intermediate subbands upsampled to 2 samples. */
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for (i = 0; i < 2; i++)
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aptx_qmf_polyphase_synthesis(qmf->inner_filter_signal[i],
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aptx_qmf_inner_coeffs, 22,
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subband_samples[2*i+0],
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subband_samples[2*i+1],
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&intermediate_samples[2*i]);
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/* Join 2 samples from intermediate subbands upsampled to 4 samples. */
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for (i = 0; i < 2; i++)
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aptx_qmf_polyphase_synthesis(qmf->outer_filter_signal,
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aptx_qmf_outer_coeffs, 21,
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intermediate_samples[0+i],
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intermediate_samples[2+i],
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&samples[2*i]);
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}
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static void aptx_decode_channel(Channel *channel, int32_t samples[4])
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{
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int32_t subband_samples[4];
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int subband;
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for (subband = 0; subband < NB_SUBBANDS; subband++)
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subband_samples[subband] = channel->prediction[subband].previous_reconstructed_sample;
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aptx_qmf_tree_synthesis(&channel->qmf, subband_samples, samples);
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}
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static void aptx_unpack_codeword(Channel *channel, uint16_t codeword)
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{
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channel->quantize[0].quantized_sample = sign_extend(codeword >> 0, 7);
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channel->quantize[1].quantized_sample = sign_extend(codeword >> 7, 4);
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channel->quantize[2].quantized_sample = sign_extend(codeword >> 11, 2);
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channel->quantize[3].quantized_sample = sign_extend(codeword >> 13, 3);
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channel->quantize[3].quantized_sample = (channel->quantize[3].quantized_sample & ~1)
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| aptx_quantized_parity(channel);
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}
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static void aptxhd_unpack_codeword(Channel *channel, uint32_t codeword)
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{
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channel->quantize[0].quantized_sample = sign_extend(codeword >> 0, 9);
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channel->quantize[1].quantized_sample = sign_extend(codeword >> 9, 6);
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channel->quantize[2].quantized_sample = sign_extend(codeword >> 15, 4);
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channel->quantize[3].quantized_sample = sign_extend(codeword >> 19, 5);
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channel->quantize[3].quantized_sample = (channel->quantize[3].quantized_sample & ~1)
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| aptx_quantized_parity(channel);
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}
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static int aptx_decode_samples(AptXContext *ctx,
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const uint8_t *input,
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int32_t samples[NB_CHANNELS][4])
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{
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int channel, ret;
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for (channel = 0; channel < NB_CHANNELS; channel++) {
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ff_aptx_generate_dither(&ctx->channels[channel]);
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if (ctx->hd)
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aptxhd_unpack_codeword(&ctx->channels[channel],
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AV_RB24(input + 3*channel));
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else
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aptx_unpack_codeword(&ctx->channels[channel],
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AV_RB16(input + 2*channel));
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ff_aptx_invert_quantize_and_prediction(&ctx->channels[channel], ctx->hd);
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}
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ret = aptx_check_parity(ctx->channels, &ctx->sync_idx);
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for (channel = 0; channel < NB_CHANNELS; channel++)
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aptx_decode_channel(&ctx->channels[channel], samples[channel]);
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return ret;
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}
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static int aptx_decode_frame(AVCodecContext *avctx, void *data,
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int *got_frame_ptr, AVPacket *avpkt)
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{
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AptXContext *s = avctx->priv_data;
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AVFrame *frame = data;
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int pos, opos, channel, sample, ret;
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if (avpkt->size < s->block_size) {
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av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
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return AVERROR_INVALIDDATA;
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}
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/* get output buffer */
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frame->channels = NB_CHANNELS;
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frame->format = AV_SAMPLE_FMT_S32P;
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frame->nb_samples = 4 * avpkt->size / s->block_size;
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if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
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return ret;
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for (pos = 0, opos = 0; opos < frame->nb_samples; pos += s->block_size, opos += 4) {
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int32_t samples[NB_CHANNELS][4];
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if (aptx_decode_samples(s, &avpkt->data[pos], samples)) {
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av_log(avctx, AV_LOG_ERROR, "Synchronization error\n");
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return AVERROR_INVALIDDATA;
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}
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for (channel = 0; channel < NB_CHANNELS; channel++)
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for (sample = 0; sample < 4; sample++)
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AV_WN32A(&frame->data[channel][4*(opos+sample)],
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samples[channel][sample] * 256);
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}
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*got_frame_ptr = 1;
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return s->block_size * frame->nb_samples / 4;
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}
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#if CONFIG_APTX_DECODER
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AVCodec ff_aptx_decoder = {
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.name = "aptx",
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.long_name = NULL_IF_CONFIG_SMALL("aptX (Audio Processing Technology for Bluetooth)"),
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.type = AVMEDIA_TYPE_AUDIO,
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.id = AV_CODEC_ID_APTX,
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.priv_data_size = sizeof(AptXContext),
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.init = ff_aptx_init,
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.decode = aptx_decode_frame,
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.capabilities = AV_CODEC_CAP_DR1,
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.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
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.channel_layouts = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},
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.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,
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AV_SAMPLE_FMT_NONE },
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};
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#endif
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#if CONFIG_APTX_HD_DECODER
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AVCodec ff_aptx_hd_decoder = {
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.name = "aptx_hd",
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.long_name = NULL_IF_CONFIG_SMALL("aptX HD (Audio Processing Technology for Bluetooth)"),
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.type = AVMEDIA_TYPE_AUDIO,
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.id = AV_CODEC_ID_APTX_HD,
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.priv_data_size = sizeof(AptXContext),
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.init = ff_aptx_init,
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.decode = aptx_decode_frame,
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.capabilities = AV_CODEC_CAP_DR1,
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.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
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.channel_layouts = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},
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.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,
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AV_SAMPLE_FMT_NONE },
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};
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#endif
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