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alsa-audio.h
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1 /*
2  * ALSA input and output
3  * Copyright (c) 2007 Luca Abeni ( lucabe72 email it )
4  * Copyright (c) 2007 Benoit Fouet ( benoit fouet free fr )
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * ALSA input and output: definitions and structures
26  * @author Luca Abeni ( lucabe72 email it )
27  * @author Benoit Fouet ( benoit fouet free fr )
28  */
29 
30 #ifndef AVDEVICE_ALSA_AUDIO_H
31 #define AVDEVICE_ALSA_AUDIO_H
32 
33 #include <alsa/asoundlib.h>
34 #include "config.h"
35 #include "libavutil/log.h"
36 #include "timefilter.h"
37 #include "avdevice.h"
38 
39 /* XXX: we make the assumption that the soundcard accepts this format */
40 /* XXX: find better solution with "preinit" method, needed also in
41  other formats */
42 #define DEFAULT_CODEC_ID AV_NE(AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE)
43 
44 typedef void (*ff_reorder_func)(const void *, void *, int);
45 
46 #define ALSA_BUFFER_SIZE_MAX 65536
47 
48 typedef struct AlsaData {
49  AVClass *class;
50  snd_pcm_t *h;
51  int frame_size; ///< bytes per sample * channels
52  int period_size; ///< preferred size for reads and writes, in frames
53  int sample_rate; ///< sample rate set by user
54  int channels; ///< number of channels set by user
57  void (*reorder_func)(const void *, void *, int);
58  void *reorder_buf;
59  int reorder_buf_size; ///< in frames
60 } AlsaData;
61 
62 /**
63  * Open an ALSA PCM.
64  *
65  * @param s media file handle
66  * @param mode either SND_PCM_STREAM_CAPTURE or SND_PCM_STREAM_PLAYBACK
67  * @param sample_rate in: requested sample rate;
68  * out: actually selected sample rate
69  * @param channels number of channels
70  * @param codec_id in: requested AVCodecID or AV_CODEC_ID_NONE;
71  * out: actually selected AVCodecID, changed only if
72  * AV_CODEC_ID_NONE was requested
73  *
74  * @return 0 if OK, AVERROR_xxx on error
75  */
76 int ff_alsa_open(AVFormatContext *s, snd_pcm_stream_t mode,
77  unsigned int *sample_rate,
78  int channels, enum AVCodecID *codec_id);
79 
80 /**
81  * Close the ALSA PCM.
82  *
83  * @param s1 media file handle
84  *
85  * @return 0
86  */
88 
89 /**
90  * Try to recover from ALSA buffer underrun.
91  *
92  * @param s1 media file handle
93  * @param err error code reported by the previous ALSA call
94  *
95  * @return 0 if OK, AVERROR_xxx on error
96  */
98 
100 
101 #endif /* AVDEVICE_ALSA_AUDIO_H */