libvo-amrwbenc.c
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1 /*
2  * AMR Audio encoder stub
3  * Copyright (c) 2003 the ffmpeg project
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include <vo-amrwbenc/enc_if.h>
23 
24 #include "avcodec.h"
25 #include "libavutil/avstring.h"
26 #include "libavutil/opt.h"
27 
28 typedef struct AMRWBContext {
30  void *state;
31  int mode;
33  int allow_dtx;
34 } AMRWBContext;
35 
36 static const AVOption options[] = {
37  { "dtx", "Allow DTX (generate comfort noise)", offsetof(AMRWBContext, allow_dtx), AV_OPT_TYPE_INT, { 0 }, 0, 1, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM },
38  { NULL }
39 };
40 
41 static const AVClass class = {
43 };
44 
45 static int get_wb_bitrate_mode(int bitrate, void *log_ctx)
46 {
47  /* make the correspondance between bitrate and mode */
48  static const int rates[] = { 6600, 8850, 12650, 14250, 15850, 18250,
49  19850, 23050, 23850 };
50  int i, best = -1, min_diff = 0;
51  char log_buf[200];
52 
53  for (i = 0; i < 9; i++) {
54  if (rates[i] == bitrate)
55  return i;
56  if (best < 0 || abs(rates[i] - bitrate) < min_diff) {
57  best = i;
58  min_diff = abs(rates[i] - bitrate);
59  }
60  }
61  /* no bitrate matching exactly, log a warning */
62  snprintf(log_buf, sizeof(log_buf), "bitrate not supported: use one of ");
63  for (i = 0; i < 9; i++)
64  av_strlcatf(log_buf, sizeof(log_buf), "%.2fk, ", rates[i] / 1000.f);
65  av_strlcatf(log_buf, sizeof(log_buf), "using %.2fk", rates[best] / 1000.f);
66  av_log(log_ctx, AV_LOG_WARNING, "%s\n", log_buf);
67 
68  return best;
69 }
70 
72 {
73  AMRWBContext *s = avctx->priv_data;
74 
75  if (avctx->sample_rate != 16000) {
76  av_log(avctx, AV_LOG_ERROR, "Only 16000Hz sample rate supported\n");
77  return AVERROR(ENOSYS);
78  }
79 
80  if (avctx->channels != 1) {
81  av_log(avctx, AV_LOG_ERROR, "Only mono supported\n");
82  return AVERROR(ENOSYS);
83  }
84 
85  s->mode = get_wb_bitrate_mode(avctx->bit_rate, avctx);
86  s->last_bitrate = avctx->bit_rate;
87 
88  avctx->frame_size = 320;
90 
91  s->state = E_IF_init();
92 
93  return 0;
94 }
95 
97 {
98  AMRWBContext *s = avctx->priv_data;
99 
100  E_IF_exit(s->state);
101  av_freep(&avctx->coded_frame);
102  return 0;
103 }
104 
106  unsigned char *frame/*out*/,
107  int buf_size, void *data/*in*/)
108 {
109  AMRWBContext *s = avctx->priv_data;
110  int size;
111 
112  if (s->last_bitrate != avctx->bit_rate) {
113  s->mode = get_wb_bitrate_mode(avctx->bit_rate, avctx);
114  s->last_bitrate = avctx->bit_rate;
115  }
116  size = E_IF_encode(s->state, s->mode, data, frame, s->allow_dtx);
117  return size;
118 }
119 
121  .name = "libvo_amrwbenc",
122  .type = AVMEDIA_TYPE_AUDIO,
123  .id = CODEC_ID_AMR_WB,
124  .priv_data_size = sizeof(AMRWBContext),
126  .encode = amr_wb_encode_frame,
128  .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},
129  .long_name = NULL_IF_CONFIG_SMALL("Android VisualOn Adaptive Multi-Rate "
130  "(AMR) Wide-Band"),
131  .priv_class = &class,
132 };
133