1 /*
2 * Audio Processing Technology codec for Bluetooth (aptX)
3 *
4 * Copyright (C) 2017 Aurelien Jacobs <aurel@gnuage.org>
5 *
6 * This file is part of FFmpeg.
7 *
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.
12 *
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.
17 *
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
21 */
22
23 #include "aptx.h"
24
25 /*
26 * Half-band QMF analysis filter realized with a polyphase FIR filter.
27 * Split into 2 subbands and downsample by 2.
28 * So for each pair of samples that goes in, one sample goes out,
29 * split into 2 separate subbands.
30 */
31 av_always_inline
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)32 static void aptx_qmf_polyphase_analysis(FilterSignal signal[NB_FILTERS],
33 const int32_t coeffs[NB_FILTERS][FILTER_TAPS],
34 int shift,
35 int32_t samples[NB_FILTERS],
36 int32_t *low_subband_output,
37 int32_t *high_subband_output)
38 {
39 int32_t subbands[NB_FILTERS];
40 int i;
41
42 for (i = 0; i < NB_FILTERS; i++) {
43 aptx_qmf_filter_signal_push(&signal[i], samples[NB_FILTERS-1-i]);
44 subbands[i] = aptx_qmf_convolution(&signal[i], coeffs[i], shift);
45 }
46
47 *low_subband_output = av_clip_intp2(subbands[0] + subbands[1], 23);
48 *high_subband_output = av_clip_intp2(subbands[0] - subbands[1], 23);
49 }
50
51 /*
52 * Two stage QMF analysis tree.
53 * Split 4 input samples into 4 subbands and downsample by 4.
54 * So for each group of 4 samples that goes in, one sample goes out,
55 * split into 4 separate subbands.
56 */
aptx_qmf_tree_analysis(QMFAnalysis * qmf,int32_t samples[4],int32_t subband_samples[4])57 static void aptx_qmf_tree_analysis(QMFAnalysis *qmf,
58 int32_t samples[4],
59 int32_t subband_samples[4])
60 {
61 int32_t intermediate_samples[4];
62 int i;
63
64 /* Split 4 input samples into 2 intermediate subbands downsampled to 2 samples */
65 for (i = 0; i < 2; i++)
66 aptx_qmf_polyphase_analysis(qmf->outer_filter_signal,
67 aptx_qmf_outer_coeffs, 23,
68 &samples[2*i],
69 &intermediate_samples[0+i],
70 &intermediate_samples[2+i]);
71
72 /* Split 2 intermediate subband samples into 4 final subbands downsampled to 1 sample */
73 for (i = 0; i < 2; i++)
74 aptx_qmf_polyphase_analysis(qmf->inner_filter_signal[i],
75 aptx_qmf_inner_coeffs, 23,
76 &intermediate_samples[2*i],
77 &subband_samples[2*i+0],
78 &subband_samples[2*i+1]);
79 }
80
81 av_always_inline
aptx_bin_search(int32_t value,int32_t factor,const int32_t * intervals,int32_t nb_intervals)82 static int32_t aptx_bin_search(int32_t value, int32_t factor,
83 const int32_t *intervals, int32_t nb_intervals)
84 {
85 int32_t idx = 0;
86 int i;
87
88 for (i = nb_intervals >> 1; i > 0; i >>= 1)
89 if (MUL64(factor, intervals[idx + i]) <= ((int64_t)value << 24))
90 idx += i;
91
92 return idx;
93 }
94
aptx_quantize_difference(Quantize * quantize,int32_t sample_difference,int32_t dither,int32_t quantization_factor,ConstTables * tables)95 static void aptx_quantize_difference(Quantize *quantize,
96 int32_t sample_difference,
97 int32_t dither,
98 int32_t quantization_factor,
99 ConstTables *tables)
100 {
101 const int32_t *intervals = tables->quantize_intervals;
102 int32_t quantized_sample, dithered_sample, parity_change;
103 int32_t d, mean, interval, inv, sample_difference_abs;
104 int64_t error;
105
106 sample_difference_abs = FFABS(sample_difference);
107 sample_difference_abs = FFMIN(sample_difference_abs, (1 << 23) - 1);
108
109 quantized_sample = aptx_bin_search(sample_difference_abs >> 4,
110 quantization_factor,
111 intervals, tables->tables_size);
112
113 d = rshift32_clip24(MULH(dither, dither), 7) - (1 << 23);
114 d = rshift64(MUL64(d, tables->quantize_dither_factors[quantized_sample]), 23);
115
116 intervals += quantized_sample;
117 mean = (intervals[1] + intervals[0]) / 2;
118 interval = (intervals[1] - intervals[0]) * (-(sample_difference < 0) | 1);
119
120 dithered_sample = rshift64_clip24(MUL64(dither, interval) + ((int64_t)av_clip_intp2(mean + d, 23) << 32), 32);
121 error = ((int64_t)sample_difference_abs << 20) - MUL64(dithered_sample, quantization_factor);
122 quantize->error = FFABS(rshift64(error, 23));
123
124 parity_change = quantized_sample;
125 if (error < 0)
126 quantized_sample--;
127 else
128 parity_change--;
129
130 inv = -(sample_difference < 0);
131 quantize->quantized_sample = quantized_sample ^ inv;
132 quantize->quantized_sample_parity_change = parity_change ^ inv;
133 }
134
aptx_encode_channel(Channel * channel,int32_t samples[4],int hd)135 static void aptx_encode_channel(Channel *channel, int32_t samples[4], int hd)
136 {
137 int32_t subband_samples[4];
138 int subband;
139 aptx_qmf_tree_analysis(&channel->qmf, samples, subband_samples);
140 ff_aptx_generate_dither(channel);
141 for (subband = 0; subband < NB_SUBBANDS; subband++) {
142 int32_t diff = av_clip_intp2(subband_samples[subband] - channel->prediction[subband].predicted_sample, 23);
143 aptx_quantize_difference(&channel->quantize[subband], diff,
144 channel->dither[subband],
145 channel->invert_quantize[subband].quantization_factor,
146 &ff_aptx_quant_tables[hd][subband]);
147 }
148 }
149
aptx_insert_sync(Channel channels[NB_CHANNELS],int32_t * idx)150 static void aptx_insert_sync(Channel channels[NB_CHANNELS], int32_t *idx)
151 {
152 if (aptx_check_parity(channels, idx)) {
153 int i;
154 Channel *c;
155 static const int map[] = { 1, 2, 0, 3 };
156 Quantize *min = &channels[NB_CHANNELS-1].quantize[map[0]];
157 for (c = &channels[NB_CHANNELS-1]; c >= channels; c--)
158 for (i = 0; i < NB_SUBBANDS; i++)
159 if (c->quantize[map[i]].error < min->error)
160 min = &c->quantize[map[i]];
161
162 /* Forcing the desired parity is done by offsetting by 1 the quantized
163 * sample from the subband featuring the smallest quantization error. */
164 min->quantized_sample = min->quantized_sample_parity_change;
165 }
166 }
167
aptx_pack_codeword(Channel * channel)168 static uint16_t aptx_pack_codeword(Channel *channel)
169 {
170 int32_t parity = aptx_quantized_parity(channel);
171 return (((channel->quantize[3].quantized_sample & 0x06) | parity) << 13)
172 | (((channel->quantize[2].quantized_sample & 0x03) ) << 11)
173 | (((channel->quantize[1].quantized_sample & 0x0F) ) << 7)
174 | (((channel->quantize[0].quantized_sample & 0x7F) ) << 0);
175 }
176
aptxhd_pack_codeword(Channel * channel)177 static uint32_t aptxhd_pack_codeword(Channel *channel)
178 {
179 int32_t parity = aptx_quantized_parity(channel);
180 return (((channel->quantize[3].quantized_sample & 0x01E) | parity) << 19)
181 | (((channel->quantize[2].quantized_sample & 0x00F) ) << 15)
182 | (((channel->quantize[1].quantized_sample & 0x03F) ) << 9)
183 | (((channel->quantize[0].quantized_sample & 0x1FF) ) << 0);
184 }
185
aptx_encode_samples(AptXContext * ctx,int32_t samples[NB_CHANNELS][4],uint8_t * output)186 static void aptx_encode_samples(AptXContext *ctx,
187 int32_t samples[NB_CHANNELS][4],
188 uint8_t *output)
189 {
190 int channel;
191 for (channel = 0; channel < NB_CHANNELS; channel++)
192 aptx_encode_channel(&ctx->channels[channel], samples[channel], ctx->hd);
193
194 aptx_insert_sync(ctx->channels, &ctx->sync_idx);
195
196 for (channel = 0; channel < NB_CHANNELS; channel++) {
197 ff_aptx_invert_quantize_and_prediction(&ctx->channels[channel], ctx->hd);
198 if (ctx->hd)
199 AV_WB24(output + 3*channel,
200 aptxhd_pack_codeword(&ctx->channels[channel]));
201 else
202 AV_WB16(output + 2*channel,
203 aptx_pack_codeword(&ctx->channels[channel]));
204 }
205 }
206
aptx_encode_frame(AVCodecContext * avctx,AVPacket * avpkt,const AVFrame * frame,int * got_packet_ptr)207 static int aptx_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
208 const AVFrame *frame, int *got_packet_ptr)
209 {
210 AptXContext *s = avctx->priv_data;
211 int pos, ipos, channel, sample, output_size, ret;
212
213 if ((ret = ff_af_queue_add(&s->afq, frame)) < 0)
214 return ret;
215
216 output_size = s->block_size * frame->nb_samples/4;
217 if ((ret = ff_alloc_packet2(avctx, avpkt, output_size, 0)) < 0)
218 return ret;
219
220 for (pos = 0, ipos = 0; pos < output_size; pos += s->block_size, ipos += 4) {
221 int32_t samples[NB_CHANNELS][4];
222
223 for (channel = 0; channel < NB_CHANNELS; channel++)
224 for (sample = 0; sample < 4; sample++)
225 samples[channel][sample] = (int32_t)AV_RN32A(&frame->data[channel][4*(ipos+sample)]) >> 8;
226
227 aptx_encode_samples(s, samples, avpkt->data + pos);
228 }
229
230 ff_af_queue_remove(&s->afq, frame->nb_samples, &avpkt->pts, &avpkt->duration);
231 *got_packet_ptr = 1;
232 return 0;
233 }
234
aptx_close(AVCodecContext * avctx)235 static av_cold int aptx_close(AVCodecContext *avctx)
236 {
237 AptXContext *s = avctx->priv_data;
238 ff_af_queue_close(&s->afq);
239 return 0;
240 }
241
242 #if CONFIG_APTX_ENCODER
243 AVCodec ff_aptx_encoder = {
244 .name = "aptx",
245 .long_name = NULL_IF_CONFIG_SMALL("aptX (Audio Processing Technology for Bluetooth)"),
246 .type = AVMEDIA_TYPE_AUDIO,
247 .id = AV_CODEC_ID_APTX,
248 .priv_data_size = sizeof(AptXContext),
249 .init = ff_aptx_init,
250 .encode2 = aptx_encode_frame,
251 .close = aptx_close,
252 .capabilities = AV_CODEC_CAP_SMALL_LAST_FRAME,
253 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
254 .channel_layouts = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},
255 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,
256 AV_SAMPLE_FMT_NONE },
257 .supported_samplerates = (const int[]) {8000, 16000, 24000, 32000, 44100, 48000, 0},
258 };
259 #endif
260
261 #if CONFIG_APTX_HD_ENCODER
262 AVCodec ff_aptx_hd_encoder = {
263 .name = "aptx_hd",
264 .long_name = NULL_IF_CONFIG_SMALL("aptX HD (Audio Processing Technology for Bluetooth)"),
265 .type = AVMEDIA_TYPE_AUDIO,
266 .id = AV_CODEC_ID_APTX_HD,
267 .priv_data_size = sizeof(AptXContext),
268 .init = ff_aptx_init,
269 .encode2 = aptx_encode_frame,
270 .close = aptx_close,
271 .capabilities = AV_CODEC_CAP_SMALL_LAST_FRAME,
272 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
273 .channel_layouts = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},
274 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,
275 AV_SAMPLE_FMT_NONE },
276 .supported_samplerates = (const int[]) {8000, 16000, 24000, 32000, 44100, 48000, 0},
277 };
278 #endif
279