libavdevice/alsa-audio.h

   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 Libav.
   7  *
   8  * Libav 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  * Libav 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 Libav; 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 "libavformat/avformat.h"
  36 #include "libavutil/log.h"
  37
  38 /* XXX: we make the assumption that the soundcard accepts this format */
  39 /* XXX: find better solution with "preinit" method, needed also in
  40         other formats */
  41 #define DEFAULT_CODEC_ID AV_NE(AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE)
  42
  43 #define ALSA_BUFFER_SIZE_MAX 32768
  44
  45 typedef struct AlsaData {
  46     AVClass *class;
  47     snd_pcm_t *h;
  48     int frame_size;  ///< preferred size for reads and writes
  49     int period_size; ///< bytes per sample * channels
  50     int sample_rate; ///< sample rate set by user
  51     int channels;    ///< number of channels set by user
  52     void (*reorder_func)(const void *, void *, int);
  53     void *reorder_buf;
  54     int reorder_buf_size; ///< in frames
  55 } AlsaData;
  56
  57 /**
  58  * Open an ALSA PCM.
  59  *
  60  * @param s media file handle
  61  * @param mode either SND_PCM_STREAM_CAPTURE or SND_PCM_STREAM_PLAYBACK
  62  * @param sample_rate in: requested sample rate;
  63  *                    out: actually selected sample rate
  64  * @param channels number of channels
  65  * @param codec_id in: requested AVCodecID or AV_CODEC_ID_NONE;
  66  *                 out: actually selected AVCodecID, changed only if
  67  *                 AV_CODEC_ID_NONE was requested
  68  *
  69  * @return 0 if OK, AVERROR_xxx on error
  70  */
  71 int ff_alsa_open(AVFormatContext *s, snd_pcm_stream_t mode,
  72                  unsigned int *sample_rate,
  73                  int channels, enum AVCodecID *codec_id);
  74
  75 /**
  76  * Close the ALSA PCM.
  77  *
  78  * @param s1 media file handle
  79  *
  80  * @return 0
  81  */
  82 int ff_alsa_close(AVFormatContext *s1);
  83
  84 /**
  85  * Try to recover from ALSA buffer underrun.
  86  *
  87  * @param s1 media file handle
  88  * @param err error code reported by the previous ALSA call
  89  *
  90  * @return 0 if OK, AVERROR_xxx on error
  91  */
  92 int ff_alsa_xrun_recover(AVFormatContext *s1, int err);
  93
  94 int ff_alsa_extend_reorder_buf(AlsaData *s, int size);
  95
  96 #endif /* AVDEVICE_ALSA_AUDIO_H */