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oss_audio.c
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1 /*
2  * Linux audio play and grab 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 <string.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/log.h"
39 
40 #include "libavcodec/avcodec.h"
41 #include "avdevice.h"
42 
43 #include "oss_audio.h"
44 
45 int ff_oss_audio_open(AVFormatContext *s1, int is_output,
46  const char *audio_device)
47 {
48  OSSAudioData *s = s1->priv_data;
49  int audio_fd;
50  int tmp, err;
51  char *flip = getenv("AUDIO_FLIP_LEFT");
52 
53  if (is_output)
54  audio_fd = avpriv_open(audio_device, O_WRONLY);
55  else
56  audio_fd = avpriv_open(audio_device, O_RDONLY);
57  if (audio_fd < 0) {
58  av_log(s1, AV_LOG_ERROR, "%s: %s\n", audio_device, strerror(errno));
59  return AVERROR(EIO);
60  }
61 
62  if (flip && *flip == '1') {
63  s->flip_left = 1;
64  }
65 
66  /* non blocking mode */
67  if (!is_output) {
68  if (fcntl(audio_fd, F_SETFL, O_NONBLOCK) < 0) {
69  av_log(s1, AV_LOG_WARNING, "%s: Could not enable non block mode (%s)\n", audio_device, strerror(errno));
70  }
71  }
72 
74 
75 #define CHECK_IOCTL_ERROR(event) \
76  if (err < 0) { \
77  av_log(s1, AV_LOG_ERROR, #event ": %s\n", strerror(errno)); \
78  goto fail; \
79  }
80 
81  /* select format : favour native format
82  * We don't CHECK_IOCTL_ERROR here because even if failed OSS still may be
83  * usable. If OSS is not usable the SNDCTL_DSP_SETFMTS later is going to
84  * fail anyway. `err =` kept to eliminate compiler warning. */
85  err = ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &tmp);
86 
87 #if HAVE_BIGENDIAN
88  if (tmp & AFMT_S16_BE) {
89  tmp = AFMT_S16_BE;
90  } else if (tmp & AFMT_S16_LE) {
91  tmp = AFMT_S16_LE;
92  } else {
93  tmp = 0;
94  }
95 #else
96  if (tmp & AFMT_S16_LE) {
97  tmp = AFMT_S16_LE;
98  } else if (tmp & AFMT_S16_BE) {
99  tmp = AFMT_S16_BE;
100  } else {
101  tmp = 0;
102  }
103 #endif
104 
105  switch(tmp) {
106  case AFMT_S16_LE:
108  break;
109  case AFMT_S16_BE:
111  break;
112  default:
113  av_log(s1, AV_LOG_ERROR, "Soundcard does not support 16 bit sample format\n");
114  close(audio_fd);
115  return AVERROR(EIO);
116  }
117  err=ioctl(audio_fd, SNDCTL_DSP_SETFMT, &tmp);
118  CHECK_IOCTL_ERROR(SNDCTL_DSP_SETFMTS)
119 
120  tmp = (s->channels == 2);
121  err = ioctl(audio_fd, SNDCTL_DSP_STEREO, &tmp);
122  CHECK_IOCTL_ERROR(SNDCTL_DSP_STEREO)
123 
124  tmp = s->sample_rate;
125  err = ioctl(audio_fd, SNDCTL_DSP_SPEED, &tmp);
126  CHECK_IOCTL_ERROR(SNDCTL_DSP_SPEED)
127  s->sample_rate = tmp; /* store real sample rate */
128  s->fd = audio_fd;
129 
130  return 0;
131  fail:
132  close(audio_fd);
133  return AVERROR(EIO);
134 #undef CHECK_IOCTL_ERROR
135 }
136 
138 {
139  close(s->fd);
140  return 0;
141 }