| /* |
| * 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 "aptx.h" |
| |
| /* |
| * Half-band QMF analysis filter realized with a polyphase FIR filter. |
| * Split into 2 subbands and downsample by 2. |
| * So for each pair of samples that goes in, one sample goes out, |
| * split into 2 separate subbands. |
| */ |
| av_always_inline |
| static void aptx_qmf_polyphase_analysis(FilterSignal signal[NB_FILTERS], |
| const int32_t coeffs[NB_FILTERS][FILTER_TAPS], |
| int shift, |
| int32_t samples[NB_FILTERS], |
| int32_t *low_subband_output, |
| int32_t *high_subband_output) |
| { |
| int32_t subbands[NB_FILTERS]; |
| int i; |
| |
| for (i = 0; i < NB_FILTERS; i++) { |
| aptx_qmf_filter_signal_push(&signal[i], samples[NB_FILTERS-1-i]); |
| subbands[i] = aptx_qmf_convolution(&signal[i], coeffs[i], shift); |
| } |
| |
| *low_subband_output = av_clip_intp2(subbands[0] + subbands[1], 23); |
| *high_subband_output = av_clip_intp2(subbands[0] - subbands[1], 23); |
| } |
| |
| /* |
| * Two stage QMF analysis tree. |
| * Split 4 input samples into 4 subbands and downsample by 4. |
| * So for each group of 4 samples that goes in, one sample goes out, |
| * split into 4 separate subbands. |
| */ |
| static void aptx_qmf_tree_analysis(QMFAnalysis *qmf, |
| int32_t samples[4], |
| int32_t subband_samples[4]) |
| { |
| int32_t intermediate_samples[4]; |
| int i; |
| |
| /* Split 4 input samples into 2 intermediate subbands downsampled to 2 samples */ |
| for (i = 0; i < 2; i++) |
| aptx_qmf_polyphase_analysis(qmf->outer_filter_signal, |
| aptx_qmf_outer_coeffs, 23, |
| &samples[2*i], |
| &intermediate_samples[0+i], |
| &intermediate_samples[2+i]); |
| |
| /* Split 2 intermediate subband samples into 4 final subbands downsampled to 1 sample */ |
| for (i = 0; i < 2; i++) |
| aptx_qmf_polyphase_analysis(qmf->inner_filter_signal[i], |
| aptx_qmf_inner_coeffs, 23, |
| &intermediate_samples[2*i], |
| &subband_samples[2*i+0], |
| &subband_samples[2*i+1]); |
| } |
| |
| av_always_inline |
| static int32_t aptx_bin_search(int32_t value, int32_t factor, |
| const int32_t *intervals, int32_t nb_intervals) |
| { |
| int32_t idx = 0; |
| int i; |
| |
| for (i = nb_intervals >> 1; i > 0; i >>= 1) |
| if (MUL64(factor, intervals[idx + i]) <= ((int64_t)value << 24)) |
| idx += i; |
| |
| return idx; |
| } |
| |
| static void aptx_quantize_difference(Quantize *quantize, |
| int32_t sample_difference, |
| int32_t dither, |
| int32_t quantization_factor, |
| ConstTables *tables) |
| { |
| const int32_t *intervals = tables->quantize_intervals; |
| int32_t quantized_sample, dithered_sample, parity_change; |
| int32_t d, mean, interval, inv, sample_difference_abs; |
| int64_t error; |
| |
| sample_difference_abs = FFABS(sample_difference); |
| sample_difference_abs = FFMIN(sample_difference_abs, (1 << 23) - 1); |
| |
| quantized_sample = aptx_bin_search(sample_difference_abs >> 4, |
| quantization_factor, |
| intervals, tables->tables_size); |
| |
| d = rshift32_clip24(MULH(dither, dither), 7) - (1 << 23); |
| d = rshift64(MUL64(d, tables->quantize_dither_factors[quantized_sample]), 23); |
| |
| intervals += quantized_sample; |
| mean = (intervals[1] + intervals[0]) / 2; |
| interval = (intervals[1] - intervals[0]) * (-(sample_difference < 0) | 1); |
| |
| dithered_sample = rshift64_clip24(MUL64(dither, interval) + ((int64_t)av_clip_intp2(mean + d, 23) << 32), 32); |
| error = ((int64_t)sample_difference_abs << 20) - MUL64(dithered_sample, quantization_factor); |
| quantize->error = FFABS(rshift64(error, 23)); |
| |
| parity_change = quantized_sample; |
| if (error < 0) |
| quantized_sample--; |
| else |
| parity_change--; |
| |
| inv = -(sample_difference < 0); |
| quantize->quantized_sample = quantized_sample ^ inv; |
| quantize->quantized_sample_parity_change = parity_change ^ inv; |
| } |
| |
| static void aptx_encode_channel(Channel *channel, int32_t samples[4], int hd) |
| { |
| int32_t subband_samples[4]; |
| int subband; |
| aptx_qmf_tree_analysis(&channel->qmf, samples, subband_samples); |
| ff_aptx_generate_dither(channel); |
| for (subband = 0; subband < NB_SUBBANDS; subband++) { |
| int32_t diff = av_clip_intp2(subband_samples[subband] - channel->prediction[subband].predicted_sample, 23); |
| aptx_quantize_difference(&channel->quantize[subband], diff, |
| channel->dither[subband], |
| channel->invert_quantize[subband].quantization_factor, |
| &ff_aptx_quant_tables[hd][subband]); |
| } |
| } |
| |
| static void aptx_insert_sync(Channel channels[NB_CHANNELS], int32_t *idx) |
| { |
| if (aptx_check_parity(channels, idx)) { |
| int i; |
| Channel *c; |
| static const int map[] = { 1, 2, 0, 3 }; |
| Quantize *min = &channels[NB_CHANNELS-1].quantize[map[0]]; |
| for (c = &channels[NB_CHANNELS-1]; c >= channels; c--) |
| for (i = 0; i < NB_SUBBANDS; i++) |
| if (c->quantize[map[i]].error < min->error) |
| min = &c->quantize[map[i]]; |
| |
| /* Forcing the desired parity is done by offsetting by 1 the quantized |
| * sample from the subband featuring the smallest quantization error. */ |
| min->quantized_sample = min->quantized_sample_parity_change; |
| } |
| } |
| |
| static uint16_t aptx_pack_codeword(Channel *channel) |
| { |
| int32_t parity = aptx_quantized_parity(channel); |
| return (((channel->quantize[3].quantized_sample & 0x06) | parity) << 13) |
| | (((channel->quantize[2].quantized_sample & 0x03) ) << 11) |
| | (((channel->quantize[1].quantized_sample & 0x0F) ) << 7) |
| | (((channel->quantize[0].quantized_sample & 0x7F) ) << 0); |
| } |
| |
| static uint32_t aptxhd_pack_codeword(Channel *channel) |
| { |
| int32_t parity = aptx_quantized_parity(channel); |
| return (((channel->quantize[3].quantized_sample & 0x01E) | parity) << 19) |
| | (((channel->quantize[2].quantized_sample & 0x00F) ) << 15) |
| | (((channel->quantize[1].quantized_sample & 0x03F) ) << 9) |
| | (((channel->quantize[0].quantized_sample & 0x1FF) ) << 0); |
| } |
| |
| static void aptx_encode_samples(AptXContext *ctx, |
| int32_t samples[NB_CHANNELS][4], |
| uint8_t *output) |
| { |
| int channel; |
| for (channel = 0; channel < NB_CHANNELS; channel++) |
| aptx_encode_channel(&ctx->channels[channel], samples[channel], ctx->hd); |
| |
| aptx_insert_sync(ctx->channels, &ctx->sync_idx); |
| |
| for (channel = 0; channel < NB_CHANNELS; channel++) { |
| ff_aptx_invert_quantize_and_prediction(&ctx->channels[channel], ctx->hd); |
| if (ctx->hd) |
| AV_WB24(output + 3*channel, |
| aptxhd_pack_codeword(&ctx->channels[channel])); |
| else |
| AV_WB16(output + 2*channel, |
| aptx_pack_codeword(&ctx->channels[channel])); |
| } |
| } |
| |
| static int aptx_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, |
| const AVFrame *frame, int *got_packet_ptr) |
| { |
| AptXContext *s = avctx->priv_data; |
| int pos, ipos, channel, sample, output_size, ret; |
| |
| if ((ret = ff_af_queue_add(&s->afq, frame)) < 0) |
| return ret; |
| |
| output_size = s->block_size * frame->nb_samples/4; |
| if ((ret = ff_alloc_packet2(avctx, avpkt, output_size, 0)) < 0) |
| return ret; |
| |
| for (pos = 0, ipos = 0; pos < output_size; pos += s->block_size, ipos += 4) { |
| int32_t samples[NB_CHANNELS][4]; |
| |
| for (channel = 0; channel < NB_CHANNELS; channel++) |
| for (sample = 0; sample < 4; sample++) |
| samples[channel][sample] = (int32_t)AV_RN32A(&frame->data[channel][4*(ipos+sample)]) >> 8; |
| |
| aptx_encode_samples(s, samples, avpkt->data + pos); |
| } |
| |
| ff_af_queue_remove(&s->afq, frame->nb_samples, &avpkt->pts, &avpkt->duration); |
| *got_packet_ptr = 1; |
| return 0; |
| } |
| |
| static av_cold int aptx_close(AVCodecContext *avctx) |
| { |
| AptXContext *s = avctx->priv_data; |
| ff_af_queue_close(&s->afq); |
| return 0; |
| } |
| |
| #if CONFIG_APTX_ENCODER |
| AVCodec ff_aptx_encoder = { |
| .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, |
| .encode2 = aptx_encode_frame, |
| .close = aptx_close, |
| .capabilities = AV_CODEC_CAP_SMALL_LAST_FRAME, |
| .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 }, |
| .supported_samplerates = (const int[]) {8000, 16000, 24000, 32000, 44100, 48000, 0}, |
| }; |
| #endif |
| |
| #if CONFIG_APTX_HD_ENCODER |
| AVCodec ff_aptx_hd_encoder = { |
| .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, |
| .encode2 = aptx_encode_frame, |
| .close = aptx_close, |
| .capabilities = AV_CODEC_CAP_SMALL_LAST_FRAME, |
| .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 }, |
| .supported_samplerates = (const int[]) {8000, 16000, 24000, 32000, 44100, 48000, 0}, |
| }; |
| #endif |
