2 * Audio Processing Technology codec for Bluetooth (aptX)
4 * Copyright (C) 2017 Aurelien Jacobs <aurel@gnuage.org>
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 * Half-band QMF synthesis filter realized with a polyphase FIR filter.
27 * Join 2 subbands and upsample by 2.
28 * So for each 2 subbands sample that goes in, a pair of samples goes out.
31 static void aptx_qmf_polyphase_synthesis(FilterSignal signal[NB_FILTERS],
32 const int32_t coeffs[NB_FILTERS][FILTER_TAPS],
34 int32_t low_subband_input,
35 int32_t high_subband_input,
36 int32_t samples[NB_FILTERS])
38 int32_t subbands[NB_FILTERS];
41 subbands[0] = low_subband_input + high_subband_input;
42 subbands[1] = low_subband_input - high_subband_input;
44 for (i = 0; i < NB_FILTERS; i++) {
45 aptx_qmf_filter_signal_push(&signal[i], subbands[1-i]);
46 samples[i] = aptx_qmf_convolution(&signal[i], coeffs[i], shift);
51 * Two stage QMF synthesis tree.
52 * Join 4 subbands and upsample by 4.
53 * So for each 4 subbands sample that goes in, a group of 4 samples goes out.
55 static void aptx_qmf_tree_synthesis(QMFAnalysis *qmf,
56 int32_t subband_samples[4],
59 int32_t intermediate_samples[4];
62 /* Join 4 subbands into 2 intermediate subbands upsampled to 2 samples. */
63 for (i = 0; i < 2; i++)
64 aptx_qmf_polyphase_synthesis(qmf->inner_filter_signal[i],
65 aptx_qmf_inner_coeffs, 22,
66 subband_samples[2*i+0],
67 subband_samples[2*i+1],
68 &intermediate_samples[2*i]);
70 /* Join 2 samples from intermediate subbands upsampled to 4 samples. */
71 for (i = 0; i < 2; i++)
72 aptx_qmf_polyphase_synthesis(qmf->outer_filter_signal,
73 aptx_qmf_outer_coeffs, 21,
74 intermediate_samples[0+i],
75 intermediate_samples[2+i],
80 static void aptx_decode_channel(Channel *channel, int32_t samples[4])
82 int32_t subband_samples[4];
84 for (subband = 0; subband < NB_SUBBANDS; subband++)
85 subband_samples[subband] = channel->prediction[subband].previous_reconstructed_sample;
86 aptx_qmf_tree_synthesis(&channel->qmf, subband_samples, samples);
89 static void aptx_unpack_codeword(Channel *channel, uint16_t codeword)
91 channel->quantize[0].quantized_sample = sign_extend(codeword >> 0, 7);
92 channel->quantize[1].quantized_sample = sign_extend(codeword >> 7, 4);
93 channel->quantize[2].quantized_sample = sign_extend(codeword >> 11, 2);
94 channel->quantize[3].quantized_sample = sign_extend(codeword >> 13, 3);
95 channel->quantize[3].quantized_sample = (channel->quantize[3].quantized_sample & ~1)
96 | aptx_quantized_parity(channel);
99 static void aptxhd_unpack_codeword(Channel *channel, uint32_t codeword)
101 channel->quantize[0].quantized_sample = sign_extend(codeword >> 0, 9);
102 channel->quantize[1].quantized_sample = sign_extend(codeword >> 9, 6);
103 channel->quantize[2].quantized_sample = sign_extend(codeword >> 15, 4);
104 channel->quantize[3].quantized_sample = sign_extend(codeword >> 19, 5);
105 channel->quantize[3].quantized_sample = (channel->quantize[3].quantized_sample & ~1)
106 | aptx_quantized_parity(channel);
109 static int aptx_decode_samples(AptXContext *ctx,
110 const uint8_t *input,
111 int32_t samples[NB_CHANNELS][4])
115 for (channel = 0; channel < NB_CHANNELS; channel++) {
116 ff_aptx_generate_dither(&ctx->channels[channel]);
119 aptxhd_unpack_codeword(&ctx->channels[channel],
120 AV_RB24(input + 3*channel));
122 aptx_unpack_codeword(&ctx->channels[channel],
123 AV_RB16(input + 2*channel));
124 ff_aptx_invert_quantize_and_prediction(&ctx->channels[channel], ctx->hd);
127 ret = aptx_check_parity(ctx->channels, &ctx->sync_idx);
129 for (channel = 0; channel < NB_CHANNELS; channel++)
130 aptx_decode_channel(&ctx->channels[channel], samples[channel]);
135 static int aptx_decode_frame(AVCodecContext *avctx, void *data,
136 int *got_frame_ptr, AVPacket *avpkt)
138 AptXContext *s = avctx->priv_data;
139 AVFrame *frame = data;
140 int pos, opos, channel, sample, ret;
142 if (avpkt->size < s->block_size) {
143 av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
144 return AVERROR_INVALIDDATA;
147 /* get output buffer */
148 frame->channels = NB_CHANNELS;
149 frame->format = AV_SAMPLE_FMT_S32P;
150 frame->nb_samples = 4 * avpkt->size / s->block_size;
151 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
154 for (pos = 0, opos = 0; opos < frame->nb_samples; pos += s->block_size, opos += 4) {
155 int32_t samples[NB_CHANNELS][4];
157 if (aptx_decode_samples(s, &avpkt->data[pos], samples)) {
158 av_log(avctx, AV_LOG_ERROR, "Synchronization error\n");
159 return AVERROR_INVALIDDATA;
162 for (channel = 0; channel < NB_CHANNELS; channel++)
163 for (sample = 0; sample < 4; sample++)
164 AV_WN32A(&frame->data[channel][4*(opos+sample)],
165 samples[channel][sample] * 256);
169 return s->block_size * frame->nb_samples / 4;
172 #if CONFIG_APTX_DECODER
173 AVCodec ff_aptx_decoder = {
175 .long_name = NULL_IF_CONFIG_SMALL("aptX (Audio Processing Technology for Bluetooth)"),
176 .type = AVMEDIA_TYPE_AUDIO,
177 .id = AV_CODEC_ID_APTX,
178 .priv_data_size = sizeof(AptXContext),
179 .init = ff_aptx_init,
180 .decode = aptx_decode_frame,
181 .capabilities = AV_CODEC_CAP_DR1,
182 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
183 .channel_layouts = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},
184 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,
185 AV_SAMPLE_FMT_NONE },
189 #if CONFIG_APTX_HD_DECODER
190 AVCodec ff_aptx_hd_decoder = {
192 .long_name = NULL_IF_CONFIG_SMALL("aptX HD (Audio Processing Technology for Bluetooth)"),
193 .type = AVMEDIA_TYPE_AUDIO,
194 .id = AV_CODEC_ID_APTX_HD,
195 .priv_data_size = sizeof(AptXContext),
196 .init = ff_aptx_init,
197 .decode = aptx_decode_frame,
198 .capabilities = AV_CODEC_CAP_DR1,
199 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
200 .channel_layouts = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},
201 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,
202 AV_SAMPLE_FMT_NONE },