alsa.c File Reference

ALSA input and output: common code. More...

#include <alsa/asoundlib.h>
#include "avdevice.h"
#include "libavutil/avassert.h"
#include "libavutil/channel_layout.h"
#include "alsa.h"

Go to the source code of this file.

Macros
#define	MAKE_REORDER_FUNC(NAME, TYPE, CHANNELS, LAYOUT, MAP)
#define	MAKE_REORDER_FUNCS(CHANNELS, LAYOUT, MAP)
#define	FORMAT_I8   0
#define	FORMAT_I16   1
#define	FORMAT_I32   2
#define	FORMAT_F32   3
#define	PICK_REORDER(layout)

Functions
static av_cold snd_pcm_format_t	codec_id_to_pcm_format (int codec_id)
	MAKE_REORDER_FUNCS (5, out_50, out[0]=in[0];out[1]=in[1];out[2]=in[3];out[3]=in[4];out[4]=in[2];)
av_cold int	ff_alsa_open (AVFormatContext *ctx, snd_pcm_stream_t mode, unsigned int *sample_rate, int channels, enum AVCodecID *codec_id)
	Open an ALSA PCM. More...
av_cold int	ff_alsa_close (AVFormatContext *s1)
	Close the ALSA PCM. More...
int	ff_alsa_xrun_recover (AVFormatContext *s1, int err)
	Try to recover from ALSA buffer underrun. More...
int	ff_alsa_extend_reorder_buf (AlsaData *s, int min_size)
int	ff_alsa_get_device_list (AVDeviceInfoList *device_list, snd_pcm_stream_t stream_type)

Detailed Description

ALSA input and output: common code.

Author

Luca Abeni ( lucabe72 email it )

Benoit Fouet ( benoit fouet free fr )

Nicolas George ( nicolas george normalesup org )

Definition in file alsa.c.

Macro Definition Documentation

#define MAKE_REORDER_FUNC	(		NAME,
			TYPE,
			CHANNELS,
			LAYOUT,
			MAP
	)

Value:

static void alsa_reorder_ ## NAME ## _ ## LAYOUT(const void *in_v,          \
                                                 void *out_v,               \
                                                 int n)                     \
{                                                                           \
    const TYPE *in = in_v;                                                  \
    TYPE      *out = out_v;                                                 \
                                                                            \
    while (n-- > 0) {                                                       \
        MAP                                                                 \
        in  += CHANNELS;                                                    \
        out += CHANNELS;                                                    \
    }                                                                       \
}

Definition at line 65 of file alsa.c.

#define MAKE_REORDER_FUNCS	(		CHANNELS,
			LAYOUT,
			MAP
	)

Value:

MAKE_REORDER_FUNC(int8,  int8_t,  CHANNELS, LAYOUT, MAP) \
    MAKE_REORDER_FUNC(int16, int16_t, CHANNELS, LAYOUT, MAP) \
    MAKE_REORDER_FUNC(int32, int32_t, CHANNELS, LAYOUT, MAP) \
    MAKE_REORDER_FUNC(f32,   float,   CHANNELS, LAYOUT, MAP)

Definition at line 80 of file alsa.c.

#define FORMAT_I8   0

Referenced by MAKE_REORDER_FUNCS().

#define FORMAT_I16   1

Referenced by MAKE_REORDER_FUNCS().

#define FORMAT_I32   2

Referenced by MAKE_REORDER_FUNCS().

#define FORMAT_F32   3

Referenced by MAKE_REORDER_FUNCS().

#define PICK_REORDER

(

layout

)

Value:

switch(format) {\
    case FORMAT_I8:  s->reorder_func = alsa_reorder_int8_out_ ##layout;  break;\
    case FORMAT_I16: s->reorder_func = alsa_reorder_int16_out_ ##layout; break;\
    case FORMAT_I32: s->reorder_func = alsa_reorder_int32_out_ ##layout; break;\
    case FORMAT_F32: s->reorder_func = alsa_reorder_f32_out_ ##layout;   break;\
}

Function Documentation

static av_cold snd_pcm_format_t codec_id_to_pcm_format ( int  codec_id )

static

Definition at line 38 of file alsa.c.

Referenced by ff_alsa_open().

MAKE_REORDER_FUNCS	(	5	,
		out_50	,
		out	[0] = in[0]; out[1] = in[1]; out[2] = in[3]; out[3] = in[4]; out[4] = in[2];
	)

Definition at line 86 of file alsa.c.

av_cold int ff_alsa_open	(	AVFormatContext *	s,
		snd_pcm_stream_t	mode,
		unsigned int *	sample_rate,
		int	channels,
		enum AVCodecID *	codec_id
	)

Open an ALSA PCM.

Parameters

s	media file handle
mode	either SND_PCM_STREAM_CAPTURE or SND_PCM_STREAM_PLAYBACK
sample_rate	in: requested sample rate; out: actually selected sample rate
channels	number of channels
codec_id	in: requested AVCodecID or AV_CODEC_ID_NONE; out: actually selected AVCodecID, changed only if AV_CODEC_ID_NONE was requested

Returns

0 if OK, AVERROR_xxx on error

Definition at line 167 of file alsa.c.

Referenced by audio_read_header(), and audio_write_header().

av_cold int ff_alsa_close

(

AVFormatContext *

s1

)

Close the ALSA PCM.

Parameters

s1	media file handle

Returns

0

Definition at line 299 of file alsa.c.

int ff_alsa_xrun_recover	(	AVFormatContext *	s1,
		int	err
	)

Try to recover from ALSA buffer underrun.

Parameters

s1	media file handle
err	error code reported by the previous ALSA call

Returns

0 if OK, AVERROR_xxx on error

Definition at line 310 of file alsa.c.

Referenced by audio_read_packet(), and audio_write_packet().

int ff_alsa_extend_reorder_buf	(	AlsaData *	s,
		int	min_size
	)

Definition at line 331 of file alsa.c.

Referenced by audio_write_packet().

int ff_alsa_get_device_list	(	AVDeviceInfoList *	device_list,
		snd_pcm_stream_t	stream_type
	)

Definition at line 348 of file alsa.c.

Referenced by audio_get_device_list().