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oss_audio_dec.c
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1 /*
2  * Linux audio play interface
3  * Copyright (c) 2000, 2001 Fabrice Bellard
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 "config.h"
23 
24 #include <stdint.h>
25 
26 #if HAVE_SOUNDCARD_H
27 #include <soundcard.h>
28 #else
29 #include <sys/soundcard.h>
30 #endif
31 
32 #if HAVE_UNISTD_H
33 #include <unistd.h>
34 #endif
35 #include <fcntl.h>
36 #include <sys/ioctl.h>
37 
38 #include "libavutil/internal.h"
39 #include "libavutil/opt.h"
40 #include "libavutil/time.h"
41 
42 #include "libavcodec/avcodec.h"
43 
44 #include "avdevice.h"
45 #include "libavformat/internal.h"
46 
47 #include "oss_audio.h"
48 
50 {
51  OSSAudioData *s = s1->priv_data;
52  AVStream *st;
53  int ret;
54 
55  st = avformat_new_stream(s1, NULL);
56  if (!st) {
57  return AVERROR(ENOMEM);
58  }
59 
60  ret = ff_oss_audio_open(s1, 0, s1->filename);
61  if (ret < 0) {
62  return AVERROR(EIO);
63  }
64 
65  /* take real parameters */
67  st->codec->codec_id = s->codec_id;
68  st->codec->sample_rate = s->sample_rate;
69  st->codec->channels = s->channels;
70 
71  avpriv_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
72  return 0;
73 }
74 
76 {
77  OSSAudioData *s = s1->priv_data;
78  int ret, bdelay;
79  int64_t cur_time;
80  struct audio_buf_info abufi;
81 
82  if ((ret=av_new_packet(pkt, s->frame_size)) < 0)
83  return ret;
84 
85  ret = read(s->fd, pkt->data, pkt->size);
86  if (ret <= 0){
87  av_free_packet(pkt);
88  pkt->size = 0;
89  if (ret<0) return AVERROR(errno);
90  else return AVERROR_EOF;
91  }
92  pkt->size = ret;
93 
94  /* compute pts of the start of the packet */
95  cur_time = av_gettime();
96  bdelay = ret;
97  if (ioctl(s->fd, SNDCTL_DSP_GETISPACE, &abufi) == 0) {
98  bdelay += abufi.bytes;
99  }
100  /* subtract time represented by the number of bytes in the audio fifo */
101  cur_time -= (bdelay * 1000000LL) / (s->sample_rate * s->channels);
102 
103  /* convert to wanted units */
104  pkt->pts = cur_time;
105 
106  if (s->flip_left && s->channels == 2) {
107  int i;
108  short *p = (short *) pkt->data;
109 
110  for (i = 0; i < ret; i += 4) {
111  *p = ~*p;
112  p += 2;
113  }
114  }
115  return 0;
116 }
117 
119 {
120  OSSAudioData *s = s1->priv_data;
121 
123  return 0;
124 }
125 
126 static const AVOption options[] = {
127  { "sample_rate", "", offsetof(OSSAudioData, sample_rate), AV_OPT_TYPE_INT, {.i64 = 48000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
128  { "channels", "", offsetof(OSSAudioData, channels), AV_OPT_TYPE_INT, {.i64 = 2}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
129  { NULL },
130 };
131 
132 static const AVClass oss_demuxer_class = {
133  .class_name = "OSS demuxer",
134  .item_name = av_default_item_name,
135  .option = options,
136  .version = LIBAVUTIL_VERSION_INT,
138 };
139 
141  .name = "oss",
142  .long_name = NULL_IF_CONFIG_SMALL("OSS (Open Sound System) capture"),
143  .priv_data_size = sizeof(OSSAudioData),
147  .flags = AVFMT_NOFILE,
148  .priv_class = &oss_demuxer_class,
149 };