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libopusdec.c
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1 /*
2  * Opus decoder using libopus
3  * Copyright (c) 2012 Nicolas George
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/avassert.h"
26 #include "libavutil/intreadwrite.h"
27 #include "avcodec.h"
28 #include "internal.h"
29 #include "vorbis.h"
30 #include "mathops.h"
31 #include "libopus.h"
32 
34  OpusMSDecoder *dec;
35  int pre_skip;
36 #ifndef OPUS_SET_GAIN
37  union { int i; double d; } gain;
38 #endif
39 };
40 
41 #define OPUS_HEAD_SIZE 19
42 
44 {
45  struct libopus_context *opus = avc->priv_data;
46  int ret, channel_map = 0, gain_db = 0, nb_streams, nb_coupled;
47  uint8_t mapping_arr[8] = { 0, 1 }, *mapping;
48 
49  avc->sample_rate = 48000;
52  avc->channel_layout = avc->channels > 8 ? 0 :
54 
55  if (avc->extradata_size >= OPUS_HEAD_SIZE) {
56  opus->pre_skip = AV_RL16(avc->extradata + 10);
57  gain_db = sign_extend(AV_RL16(avc->extradata + 16), 16);
58  channel_map = AV_RL8 (avc->extradata + 18);
59  }
60  if (avc->extradata_size >= OPUS_HEAD_SIZE + 2 + avc->channels) {
61  nb_streams = avc->extradata[OPUS_HEAD_SIZE + 0];
62  nb_coupled = avc->extradata[OPUS_HEAD_SIZE + 1];
63  if (nb_streams + nb_coupled != avc->channels)
64  av_log(avc, AV_LOG_WARNING, "Inconsistent channel mapping.\n");
65  mapping = avc->extradata + OPUS_HEAD_SIZE + 2;
66  } else {
67  if (avc->channels > 2 || channel_map) {
68  av_log(avc, AV_LOG_ERROR,
69  "No channel mapping for %d channels.\n", avc->channels);
70  return AVERROR(EINVAL);
71  }
72  nb_streams = 1;
73  nb_coupled = avc->channels > 1;
74  mapping = mapping_arr;
75  }
76 
77  if (avc->channels > 2 && avc->channels <= 8) {
78  const uint8_t *vorbis_offset = ff_vorbis_channel_layout_offsets[avc->channels - 1];
79  int ch;
80 
81  /* Remap channels from vorbis order to ffmpeg order */
82  for (ch = 0; ch < avc->channels; ch++)
83  mapping_arr[ch] = mapping[vorbis_offset[ch]];
84  mapping = mapping_arr;
85  }
86 
87  opus->dec = opus_multistream_decoder_create(avc->sample_rate, avc->channels,
88  nb_streams, nb_coupled,
89  mapping, &ret);
90  if (!opus->dec) {
91  av_log(avc, AV_LOG_ERROR, "Unable to create decoder: %s\n",
92  opus_strerror(ret));
93  return ff_opus_error_to_averror(ret);
94  }
95 
96 #ifdef OPUS_SET_GAIN
97  ret = opus_multistream_decoder_ctl(opus->dec, OPUS_SET_GAIN(gain_db));
98  if (ret != OPUS_OK)
99  av_log(avc, AV_LOG_WARNING, "Failed to set gain: %s\n",
100  opus_strerror(ret));
101 #else
102  {
103  double gain_lin = pow(10, gain_db / (20.0 * 256));
104  if (avc->sample_fmt == AV_SAMPLE_FMT_FLT)
105  opus->gain.d = gain_lin;
106  else
107  opus->gain.i = FFMIN(gain_lin * 65536, INT_MAX);
108  }
109 #endif
110 
111  avc->internal->skip_samples = opus->pre_skip;
112  avc->delay = 3840; /* Decoder delay (in samples) at 48kHz */
113 
114  return 0;
115 }
116 
118 {
119  struct libopus_context *opus = avc->priv_data;
120 
121  opus_multistream_decoder_destroy(opus->dec);
122  return 0;
123 }
124 
125 #define MAX_FRAME_SIZE (960 * 6)
126 
127 static int libopus_decode(AVCodecContext *avc, void *data,
128  int *got_frame_ptr, AVPacket *pkt)
129 {
130  struct libopus_context *opus = avc->priv_data;
131  AVFrame *frame = data;
132  int ret, nb_samples;
133 
134  frame->nb_samples = MAX_FRAME_SIZE;
135  if ((ret = ff_get_buffer(avc, frame, 0)) < 0)
136  return ret;
137 
138  if (avc->sample_fmt == AV_SAMPLE_FMT_S16)
139  nb_samples = opus_multistream_decode(opus->dec, pkt->data, pkt->size,
140  (opus_int16 *)frame->data[0],
141  frame->nb_samples, 0);
142  else
143  nb_samples = opus_multistream_decode_float(opus->dec, pkt->data, pkt->size,
144  (float *)frame->data[0],
145  frame->nb_samples, 0);
146 
147  if (nb_samples < 0) {
148  av_log(avc, AV_LOG_ERROR, "Decoding error: %s\n",
149  opus_strerror(nb_samples));
150  return ff_opus_error_to_averror(nb_samples);
151  }
152 
153 #ifndef OPUS_SET_GAIN
154  {
155  int i = avc->channels * nb_samples;
156  if (avc->sample_fmt == AV_SAMPLE_FMT_FLT) {
157  float *pcm = (float *)frame->data[0];
158  for (; i > 0; i--, pcm++)
159  *pcm = av_clipf(*pcm * opus->gain.d, -1, 1);
160  } else {
161  int16_t *pcm = (int16_t *)frame->data[0];
162  for (; i > 0; i--, pcm++)
163  *pcm = av_clip_int16(((int64_t)opus->gain.i * *pcm) >> 16);
164  }
165  }
166 #endif
167 
168  frame->nb_samples = nb_samples;
169  *got_frame_ptr = 1;
170 
171  return pkt->size;
172 }
173 
174 static void libopus_flush(AVCodecContext *avc)
175 {
176  struct libopus_context *opus = avc->priv_data;
177 
178  opus_multistream_decoder_ctl(opus->dec, OPUS_RESET_STATE);
179  /* The stream can have been extracted by a tool that is not Opus-aware.
180  Therefore, any packet can become the first of the stream. */
181  avc->internal->skip_samples = opus->pre_skip;
182 }
183 
185  .name = "libopus",
186  .type = AVMEDIA_TYPE_AUDIO,
187  .id = AV_CODEC_ID_OPUS,
188  .priv_data_size = sizeof(struct libopus_context),
189  .init = libopus_decode_init,
190  .close = libopus_decode_close,
191  .decode = libopus_decode,
192  .flush = libopus_flush,
193  .capabilities = CODEC_CAP_DR1,
194  .long_name = NULL_IF_CONFIG_SMALL("libopus Opus"),
195  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLT,
198 };