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libopusenc.c
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1 /*
2  * Opus encoder using libopus
3  * Copyright (c) 2012 Nathan Caldwell
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include <opus.h>
23 #include <opus_multistream.h>
24 
25 #include "libavutil/opt.h"
26 #include "avcodec.h"
27 #include "bytestream.h"
28 #include "internal.h"
29 #include "libopus.h"
30 #include "vorbis.h"
31 #include "audio_frame_queue.h"
32 
33 typedef struct LibopusEncOpts {
34  int vbr;
35  int application;
36  int packet_loss;
37  int complexity;
38  float frame_duration;
39  int packet_size;
40  int max_bandwidth;
41 } LibopusEncOpts;
42 
43 typedef struct LibopusEncContext {
44  AVClass *class;
45  OpusMSEncoder *enc;
46  int stream_count;
47  uint8_t *samples;
48  LibopusEncOpts opts;
49  AudioFrameQueue afq;
50 } LibopusEncContext;
51 
52 static const uint8_t opus_coupled_streams[8] = {
53  0, 1, 1, 2, 2, 2, 2, 3
54 };
55 
56 /* Opus internal to Vorbis channel order mapping written in the header */
57 static const uint8_t opus_vorbis_channel_map[8][8] = {
58  { 0 },
59  { 0, 1 },
60  { 0, 2, 1 },
61  { 0, 1, 2, 3 },
62  { 0, 4, 1, 2, 3 },
63  { 0, 4, 1, 2, 3, 5 },
64  { 0, 4, 1, 2, 3, 5, 6 },
65  { 0, 6, 1, 2, 3, 4, 5, 7 },
66 };
67 
68 /* libavcodec to libopus channel order mapping, passed to libopus */
69 static const uint8_t libavcodec_libopus_channel_map[8][8] = {
70  { 0 },
71  { 0, 1 },
72  { 0, 1, 2 },
73  { 0, 1, 2, 3 },
74  { 0, 1, 3, 4, 2 },
75  { 0, 1, 4, 5, 2, 3 },
76  { 0, 1, 5, 6, 2, 4, 3 },
77  { 0, 1, 6, 7, 4, 5, 2, 3 },
78 };
79 
80 static void libopus_write_header(AVCodecContext *avctx, int stream_count,
81  int coupled_stream_count,
82  const uint8_t *channel_mapping)
83 {
84  uint8_t *p = avctx->extradata;
85  int channels = avctx->channels;
86 
87  bytestream_put_buffer(&p, "OpusHead", 8);
88  bytestream_put_byte(&p, 1); /* Version */
89  bytestream_put_byte(&p, channels);
90  bytestream_put_le16(&p, avctx->delay); /* Lookahead samples at 48kHz */
91  bytestream_put_le32(&p, avctx->sample_rate); /* Original sample rate */
92  bytestream_put_le16(&p, 0); /* Gain of 0dB is recommended. */
93 
94  /* Channel mapping */
95  if (channels > 2) {
96  bytestream_put_byte(&p, channels <= 8 ? 1 : 255);
97  bytestream_put_byte(&p, stream_count);
98  bytestream_put_byte(&p, coupled_stream_count);
99  bytestream_put_buffer(&p, channel_mapping, channels);
100  } else {
101  bytestream_put_byte(&p, 0);
102  }
103 }
104 
105 static int libopus_configure_encoder(AVCodecContext *avctx, OpusMSEncoder *enc,
106  LibopusEncOpts *opts)
107 {
108  int ret;
109 
110  if (avctx->global_quality) {
111  av_log(avctx, AV_LOG_ERROR,
112  "Quality-based encoding not supported, "
113  "please specify a bitrate and VBR setting.\n");
114  return AVERROR(EINVAL);
115  }
116 
117  ret = opus_multistream_encoder_ctl(enc, OPUS_SET_BITRATE(avctx->bit_rate));
118  if (ret != OPUS_OK) {
119  av_log(avctx, AV_LOG_ERROR,
120  "Failed to set bitrate: %s\n", opus_strerror(ret));
121  return ret;
122  }
123 
124  ret = opus_multistream_encoder_ctl(enc,
125  OPUS_SET_COMPLEXITY(opts->complexity));
126  if (ret != OPUS_OK)
127  av_log(avctx, AV_LOG_WARNING,
128  "Unable to set complexity: %s\n", opus_strerror(ret));
129 
130  ret = opus_multistream_encoder_ctl(enc, OPUS_SET_VBR(!!opts->vbr));
131  if (ret != OPUS_OK)
132  av_log(avctx, AV_LOG_WARNING,
133  "Unable to set VBR: %s\n", opus_strerror(ret));
134 
135  ret = opus_multistream_encoder_ctl(enc,
136  OPUS_SET_VBR_CONSTRAINT(opts->vbr == 2));
137  if (ret != OPUS_OK)
138  av_log(avctx, AV_LOG_WARNING,
139  "Unable to set constrained VBR: %s\n", opus_strerror(ret));
140 
141  ret = opus_multistream_encoder_ctl(enc,
142  OPUS_SET_PACKET_LOSS_PERC(opts->packet_loss));
143  if (ret != OPUS_OK)
144  av_log(avctx, AV_LOG_WARNING,
145  "Unable to set expected packet loss percentage: %s\n",
146  opus_strerror(ret));
147 
148  if (avctx->cutoff) {
149  ret = opus_multistream_encoder_ctl(enc,
150  OPUS_SET_MAX_BANDWIDTH(opts->max_bandwidth));
151  if (ret != OPUS_OK)
152  av_log(avctx, AV_LOG_WARNING,
153  "Unable to set maximum bandwidth: %s\n", opus_strerror(ret));
154  }
155 
156  return OPUS_OK;
157 }
158 
159 static av_cold int libopus_encode_init(AVCodecContext *avctx)
160 {
161  LibopusEncContext *opus = avctx->priv_data;
162  const uint8_t *channel_mapping;
163  OpusMSEncoder *enc;
164  int ret = OPUS_OK;
165  int coupled_stream_count, header_size, frame_size;
166 
167  coupled_stream_count = opus_coupled_streams[avctx->channels - 1];
168  opus->stream_count = avctx->channels - coupled_stream_count;
169  channel_mapping = libavcodec_libopus_channel_map[avctx->channels - 1];
170 
171  /* FIXME: Opus can handle up to 255 channels. However, the mapping for
172  * anything greater than 8 is undefined. */
173  if (avctx->channels > 8)
174  av_log(avctx, AV_LOG_WARNING,
175  "Channel layout undefined for %d channels.\n", avctx->channels);
176 
177  if (!avctx->bit_rate) {
178  /* Sane default copied from opusenc */
179  avctx->bit_rate = 64000 * opus->stream_count +
180  32000 * coupled_stream_count;
181  av_log(avctx, AV_LOG_WARNING,
182  "No bit rate set. Defaulting to %d bps.\n", avctx->bit_rate);
183  }
184 
185  if (avctx->bit_rate < 500 || avctx->bit_rate > 256000 * avctx->channels) {
186  av_log(avctx, AV_LOG_ERROR, "The bit rate %d bps is unsupported. "
187  "Please choose a value between 500 and %d.\n", avctx->bit_rate,
188  256000 * avctx->channels);
189  return AVERROR(EINVAL);
190  }
191 
192  frame_size = opus->opts.frame_duration * 48000 / 1000;
193  switch (frame_size) {
194  case 120:
195  case 240:
196  if (opus->opts.application != OPUS_APPLICATION_RESTRICTED_LOWDELAY)
197  av_log(avctx, AV_LOG_WARNING,
198  "LPC mode cannot be used with a frame duration of less "
199  "than 10ms. Enabling restricted low-delay mode.\n"
200  "Use a longer frame duration if this is not what you want.\n");
201  /* Frame sizes less than 10 ms can only use MDCT mode, so switching to
202  * RESTRICTED_LOWDELAY avoids an unnecessary extra 2.5ms lookahead. */
203  opus->opts.application = OPUS_APPLICATION_RESTRICTED_LOWDELAY;
204  case 480:
205  case 960:
206  case 1920:
207  case 2880:
208  opus->opts.packet_size =
209  avctx->frame_size = frame_size * avctx->sample_rate / 48000;
210  break;
211  default:
212  av_log(avctx, AV_LOG_ERROR, "Invalid frame duration: %g.\n"
213  "Frame duration must be exactly one of: 2.5, 5, 10, 20, 40 or 60.\n",
214  opus->opts.frame_duration);
215  return AVERROR(EINVAL);
216  }
217 
218  if (avctx->compression_level < 0 || avctx->compression_level > 10) {
219  av_log(avctx, AV_LOG_WARNING,
220  "Compression level must be in the range 0 to 10. "
221  "Defaulting to 10.\n");
222  opus->opts.complexity = 10;
223  } else {
224  opus->opts.complexity = avctx->compression_level;
225  }
226 
227  if (avctx->cutoff) {
228  switch (avctx->cutoff) {
229  case 4000:
230  opus->opts.max_bandwidth = OPUS_BANDWIDTH_NARROWBAND;
231  break;
232  case 6000:
233  opus->opts.max_bandwidth = OPUS_BANDWIDTH_MEDIUMBAND;
234  break;
235  case 8000:
236  opus->opts.max_bandwidth = OPUS_BANDWIDTH_WIDEBAND;
237  break;
238  case 12000:
239  opus->opts.max_bandwidth = OPUS_BANDWIDTH_SUPERWIDEBAND;
240  break;
241  case 20000:
242  opus->opts.max_bandwidth = OPUS_BANDWIDTH_FULLBAND;
243  break;
244  default:
245  av_log(avctx, AV_LOG_WARNING,
246  "Invalid frequency cutoff: %d. Using default maximum bandwidth.\n"
247  "Cutoff frequency must be exactly one of: 4000, 6000, 8000, 12000 or 20000.\n",
248  avctx->cutoff);
249  avctx->cutoff = 0;
250  }
251  }
252 
253  enc = opus_multistream_encoder_create(avctx->sample_rate, avctx->channels,
254  opus->stream_count,
255  coupled_stream_count,
256  channel_mapping,
257  opus->opts.application, &ret);
258  if (ret != OPUS_OK) {
259  av_log(avctx, AV_LOG_ERROR,
260  "Failed to create encoder: %s\n", opus_strerror(ret));
261  return ff_opus_error_to_averror(ret);
262  }
263 
264  ret = libopus_configure_encoder(avctx, enc, &opus->opts);
265  if (ret != OPUS_OK) {
266  ret = ff_opus_error_to_averror(ret);
267  goto fail;
268  }
269 
270  header_size = 19 + (avctx->channels > 2 ? 2 + avctx->channels : 0);
271  avctx->extradata = av_malloc(header_size + FF_INPUT_BUFFER_PADDING_SIZE);
272  if (!avctx->extradata) {
273  av_log(avctx, AV_LOG_ERROR, "Failed to allocate extradata.\n");
274  ret = AVERROR(ENOMEM);
275  goto fail;
276  }
277  avctx->extradata_size = header_size;
278 
279  opus->samples = av_mallocz(frame_size * avctx->channels *
280  av_get_bytes_per_sample(avctx->sample_fmt));
281  if (!opus->samples) {
282  av_log(avctx, AV_LOG_ERROR, "Failed to allocate samples buffer.\n");
283  ret = AVERROR(ENOMEM);
284  goto fail;
285  }
286 
287  ret = opus_multistream_encoder_ctl(enc, OPUS_GET_LOOKAHEAD(&avctx->delay));
288  if (ret != OPUS_OK)
289  av_log(avctx, AV_LOG_WARNING,
290  "Unable to get number of lookahead samples: %s\n",
291  opus_strerror(ret));
292 
293  libopus_write_header(avctx, opus->stream_count, coupled_stream_count,
294  opus_vorbis_channel_map[avctx->channels - 1]);
295 
296  ff_af_queue_init(avctx, &opus->afq);
297 
298  opus->enc = enc;
299 
300  return 0;
301 
302 fail:
303  opus_multistream_encoder_destroy(enc);
304  av_freep(&avctx->extradata);
305  return ret;
306 }
307 
308 static int libopus_encode(AVCodecContext *avctx, AVPacket *avpkt,
309  const AVFrame *frame, int *got_packet_ptr)
310 {
311  LibopusEncContext *opus = avctx->priv_data;
312  const int sample_size = avctx->channels *
313  av_get_bytes_per_sample(avctx->sample_fmt);
314  uint8_t *audio;
315  int ret;
316  int discard_padding;
317 
318  if (frame) {
319  ff_af_queue_add(&opus->afq, frame);
320  if (frame->nb_samples < opus->opts.packet_size) {
321  audio = opus->samples;
322  memcpy(audio, frame->data[0], frame->nb_samples * sample_size);
323  } else
324  audio = frame->data[0];
325  } else {
326  if (!opus->afq.remaining_samples)
327  return 0;
328  audio = opus->samples;
329  memset(audio, 0, opus->opts.packet_size * sample_size);
330  }
331 
332  /* Maximum packet size taken from opusenc in opus-tools. 60ms packets
333  * consist of 3 frames in one packet. The maximum frame size is 1275
334  * bytes along with the largest possible packet header of 7 bytes. */
335  if ((ret = ff_alloc_packet2(avctx, avpkt, (1275 * 3 + 7) * opus->stream_count)) < 0)
336  return ret;
337 
338  if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT)
339  ret = opus_multistream_encode_float(opus->enc, (float *)audio,
340  opus->opts.packet_size,
341  avpkt->data, avpkt->size);
342  else
343  ret = opus_multistream_encode(opus->enc, (opus_int16 *)audio,
344  opus->opts.packet_size,
345  avpkt->data, avpkt->size);
346 
347  if (ret < 0) {
348  av_log(avctx, AV_LOG_ERROR,
349  "Error encoding frame: %s\n", opus_strerror(ret));
350  return ff_opus_error_to_averror(ret);
351  }
352 
353  av_shrink_packet(avpkt, ret);
354 
355  ff_af_queue_remove(&opus->afq, opus->opts.packet_size,
356  &avpkt->pts, &avpkt->duration);
357 
358  discard_padding = opus->opts.packet_size - avpkt->duration;
359  // Check if subtraction resulted in an overflow
360  if ((discard_padding < opus->opts.packet_size) != (avpkt->duration > 0)) {
361  av_free_packet(avpkt);
362  av_free(avpkt);
363  return AVERROR(EINVAL);
364  }
365  if (discard_padding > 0) {
366  uint8_t* side_data = av_packet_new_side_data(avpkt,
367  AV_PKT_DATA_SKIP_SAMPLES,
368  10);
369  if(side_data == NULL) {
370  av_free_packet(avpkt);
371  av_free(avpkt);
372  return AVERROR(ENOMEM);
373  }
374  AV_WL32(side_data + 4, discard_padding);
375  }
376 
377  *got_packet_ptr = 1;
378 
379  return 0;
380 }
381 
382 static av_cold int libopus_encode_close(AVCodecContext *avctx)
383 {
384  LibopusEncContext *opus = avctx->priv_data;
385 
386  opus_multistream_encoder_destroy(opus->enc);
387 
388  ff_af_queue_close(&opus->afq);
389 
390  av_freep(&opus->samples);
391  av_freep(&avctx->extradata);
392 
393  return 0;
394 }
395 
396 #define OFFSET(x) offsetof(LibopusEncContext, opts.x)
397 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
398 static const AVOption libopus_options[] = {
399  { "application", "Intended application type", OFFSET(application), AV_OPT_TYPE_INT, { .i64 = OPUS_APPLICATION_AUDIO }, OPUS_APPLICATION_VOIP, OPUS_APPLICATION_RESTRICTED_LOWDELAY, FLAGS, "application" },
400  { "voip", "Favor improved speech intelligibility", 0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_VOIP }, 0, 0, FLAGS, "application" },
401  { "audio", "Favor faithfulness to the input", 0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_AUDIO }, 0, 0, FLAGS, "application" },
402  { "lowdelay", "Restrict to only the lowest delay modes", 0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_RESTRICTED_LOWDELAY }, 0, 0, FLAGS, "application" },
403  { "frame_duration", "Duration of a frame in milliseconds", OFFSET(frame_duration), AV_OPT_TYPE_FLOAT, { .dbl = 20.0 }, 2.5, 60.0, FLAGS },
404  { "packet_loss", "Expected packet loss percentage", OFFSET(packet_loss), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 100, FLAGS },
405  { "vbr", "Variable bit rate mode", OFFSET(vbr), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 2, FLAGS, "vbr" },
406  { "off", "Use constant bit rate", 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, 0, 0, FLAGS, "vbr" },
407  { "on", "Use variable bit rate", 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, FLAGS, "vbr" },
408  { "constrained", "Use constrained VBR", 0, AV_OPT_TYPE_CONST, { .i64 = 2 }, 0, 0, FLAGS, "vbr" },
409  { NULL },
410 };
411 
412 static const AVClass libopus_class = {
413  .class_name = "libopus",
414  .item_name = av_default_item_name,
415  .option = libopus_options,
416  .version = LIBAVUTIL_VERSION_INT,
417 };
418 
419 static const AVCodecDefault libopus_defaults[] = {
420  { "b", "0" },
421  { "compression_level", "10" },
422  { NULL },
423 };
424 
425 static const int libopus_sample_rates[] = {
426  48000, 24000, 16000, 12000, 8000, 0,
427 };
428 
429 AVCodec ff_libopus_encoder = {
430  .name = "libopus",
431  .long_name = NULL_IF_CONFIG_SMALL("libopus Opus"),
432  .type = AVMEDIA_TYPE_AUDIO,
433  .id = AV_CODEC_ID_OPUS,
434  .priv_data_size = sizeof(LibopusEncContext),
435  .init = libopus_encode_init,
436  .encode2 = libopus_encode,
437  .close = libopus_encode_close,
438  .capabilities = CODEC_CAP_DELAY | CODEC_CAP_SMALL_LAST_FRAME,
439  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
440  AV_SAMPLE_FMT_FLT,
441  AV_SAMPLE_FMT_NONE },
442  .channel_layouts = ff_vorbis_channel_layouts,
443  .supported_samplerates = libopus_sample_rates,
444  .priv_class = &libopus_class,
445  .defaults = libopus_defaults,
446 };
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