/* * Audio Processing Technology codec for Bluetooth (aptX) * * Copyright (C) 2017 Aurelien Jacobs * * 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 "config_components.h" #include "libavutil/channel_layout.h" #include "aptx.h" #include "codec_internal.h" #include "decode.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, AVFrame *frame, int *got_frame_ptr, AVPacket *avpkt) { AptXContext *s = avctx->priv_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->ch_layout.nb_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 FFCodec ff_aptx_decoder = { .p.name = "aptx", CODEC_LONG_NAME("aptX (Audio Processing Technology for Bluetooth)"), .p.type = AVMEDIA_TYPE_AUDIO, .p.id = AV_CODEC_ID_APTX, .priv_data_size = sizeof(AptXContext), .init = ff_aptx_init, FF_CODEC_DECODE_CB(aptx_decode_frame), .p.capabilities = AV_CODEC_CAP_DR1, CODEC_OLD_CHANNEL_LAYOUTS(AV_CH_LAYOUT_STEREO) .p.ch_layouts = (const AVChannelLayout[]) { AV_CHANNEL_LAYOUT_STEREO, { 0 } }, .p.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P, AV_SAMPLE_FMT_NONE }, }; #endif #if CONFIG_APTX_HD_DECODER const FFCodec ff_aptx_hd_decoder = { .p.name = "aptx_hd", CODEC_LONG_NAME("aptX HD (Audio Processing Technology for Bluetooth)"), .p.type = AVMEDIA_TYPE_AUDIO, .p.id = AV_CODEC_ID_APTX_HD, .priv_data_size = sizeof(AptXContext), .init = ff_aptx_init, FF_CODEC_DECODE_CB(aptx_decode_frame), .p.capabilities = AV_CODEC_CAP_DR1, CODEC_OLD_CHANNEL_LAYOUTS(AV_CH_LAYOUT_STEREO) .p.ch_layouts = (const AVChannelLayout[]) { AV_CHANNEL_LAYOUT_STEREO, { 0 } }, .p.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P, AV_SAMPLE_FMT_NONE }, }; #endif