Audio sample formats

Audio sample format enumeration and related convenience functions. More...

Enumerations
enum	AVSampleFormat {   AV_SAMPLE_FMT_NONE = -1, AV_SAMPLE_FMT_U8, AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S32,   AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_DBL, AV_SAMPLE_FMT_U8P, AV_SAMPLE_FMT_S16P,   AV_SAMPLE_FMT_S32P, AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_DBLP, AV_SAMPLE_FMT_S64,   AV_SAMPLE_FMT_S64P, AV_SAMPLE_FMT_NB }
	Audio sample formats. More...

Functions
const char *	av_get_sample_fmt_name (enum AVSampleFormat sample_fmt)
	Return the name of sample_fmt, or NULL if sample_fmt is not recognized. More...
enum AVSampleFormat	av_get_sample_fmt (const char *name)
	Return a sample format corresponding to name, or AV_SAMPLE_FMT_NONE on error. More...
enum AVSampleFormat	av_get_alt_sample_fmt (enum AVSampleFormat sample_fmt, int planar)
	Return the planar<->packed alternative form of the given sample format, or AV_SAMPLE_FMT_NONE on error. More...
enum AVSampleFormat	av_get_packed_sample_fmt (enum AVSampleFormat sample_fmt)
	Get the packed alternative form of the given sample format. More...
enum AVSampleFormat	av_get_planar_sample_fmt (enum AVSampleFormat sample_fmt)
	Get the planar alternative form of the given sample format. More...
char *	av_get_sample_fmt_string (char *buf, int buf_size, enum AVSampleFormat sample_fmt)
	Generate a string corresponding to the sample format with sample_fmt, or a header if sample_fmt is negative. More...
int	av_get_bytes_per_sample (enum AVSampleFormat sample_fmt)
	Return number of bytes per sample. More...
int	av_sample_fmt_is_planar (enum AVSampleFormat sample_fmt)
	Check if the sample format is planar. More...
int	av_samples_get_buffer_size (int *linesize, int nb_channels, int nb_samples, enum AVSampleFormat sample_fmt, int align)
	Get the required buffer size for the given audio parameters. More...

Detailed Description

Audio sample format enumeration and related convenience functions.

Enumeration Type Documentation

AVSampleFormat

enum AVSampleFormat

Audio sample formats.

• The data described by the sample format is always in native-endian order. Sample values can be expressed by native C types, hence the lack of a signed 24-bit sample format even though it is a common raw audio data format.
• The floating-point formats are based on full volume being in the range [-1.0, 1.0]. Any values outside this range are beyond full volume level.
• The data layout as used in av_samples_fill_arrays() and elsewhere in FFmpeg (such as AVFrame in libavcodec) is as follows:

For planar sample formats, each audio channel is in a separate data plane, and linesize is the buffer size, in bytes, for a single plane. All data planes must be the same size. For packed sample formats, only the first data plane is used, and samples for each channel are interleaved. In this case, linesize is the buffer size, in bytes, for the 1 plane.

Enumerator
AV_SAMPLE_FMT_NONE
AV_SAMPLE_FMT_U8	unsigned 8 bits
AV_SAMPLE_FMT_S16	signed 16 bits
AV_SAMPLE_FMT_S32	signed 32 bits
AV_SAMPLE_FMT_FLT	float
AV_SAMPLE_FMT_DBL	double
AV_SAMPLE_FMT_U8P	unsigned 8 bits, planar
AV_SAMPLE_FMT_S16P	signed 16 bits, planar
AV_SAMPLE_FMT_S32P	signed 32 bits, planar
AV_SAMPLE_FMT_FLTP	float, planar
AV_SAMPLE_FMT_DBLP	double, planar
AV_SAMPLE_FMT_S64	signed 64 bits
AV_SAMPLE_FMT_S64P	signed 64 bits, planar
AV_SAMPLE_FMT_NB	Number of sample formats. DO NOT USE if linking dynamically.

Definition at line 58 of file samplefmt.h.

Function Documentation

av_get_sample_fmt_name()

const char* av_get_sample_fmt_name

(

enum AVSampleFormat

sample_fmt

)

Return the name of sample_fmt, or NULL if sample_fmt is not recognized.

Examples:

demuxing_decoding.c, encode_audio.c, filter_audio.c, filtering_audio.c, resampling_audio.c, and transcoding.c.

Referenced by get_format_from_sample_fmt(), init_filter(), init_filter_graph(), init_filters(), and main().

av_get_sample_fmt()

enum AVSampleFormat av_get_sample_fmt

(

const char *

name

)

Return a sample format corresponding to name, or AV_SAMPLE_FMT_NONE on error.

av_get_alt_sample_fmt()

enum AVSampleFormat av_get_alt_sample_fmt	(	enum AVSampleFormat	sample_fmt,
		int	planar
	)

Return the planar<->packed alternative form of the given sample format, or AV_SAMPLE_FMT_NONE on error.

If the passed sample_fmt is already in the requested planar/packed format, the format returned is the same as the input.

av_get_packed_sample_fmt()

enum AVSampleFormat av_get_packed_sample_fmt

(

enum AVSampleFormat

sample_fmt

)

Get the packed alternative form of the given sample format.

If the passed sample_fmt is already in packed format, the format returned is the same as the input.

Returns

the packed alternative form of the given sample format or AV_SAMPLE_FMT_NONE on error.

Examples:

demuxing_decoding.c.

Referenced by main().

av_get_planar_sample_fmt()

enum AVSampleFormat av_get_planar_sample_fmt

(

enum AVSampleFormat

sample_fmt

)

Get the planar alternative form of the given sample format.

If the passed sample_fmt is already in planar format, the format returned is the same as the input.

Returns

the planar alternative form of the given sample format or AV_SAMPLE_FMT_NONE on error.

av_get_sample_fmt_string()

char* av_get_sample_fmt_string	(	char *	buf,
		int	buf_size,
		enum AVSampleFormat	sample_fmt
	)

Generate a string corresponding to the sample format with sample_fmt, or a header if sample_fmt is negative.

Parameters

buf	the buffer where to write the string
buf_size	the size of buf
sample_fmt	the number of the sample format to print the corresponding info string, or a negative value to print the corresponding header.

Returns

the pointer to the filled buffer or NULL if sample_fmt is unknown or in case of other errors

av_get_bytes_per_sample()

int av_get_bytes_per_sample

(

enum AVSampleFormat

sample_fmt

)

Return number of bytes per sample.

Parameters

sample_fmt

the sample format

Returns

number of bytes per sample or zero if unknown for the given sample format

Examples:

decode_audio.c, demuxing_decoding.c, and filter_audio.c.

Referenced by decode(), decode_packet(), and process_output().

av_sample_fmt_is_planar()

int av_sample_fmt_is_planar

(

enum AVSampleFormat

sample_fmt

)

Check if the sample format is planar.

Parameters

sample_fmt

the sample format to inspect

Returns

1 if the sample format is planar, 0 if it is interleaved

Examples:

demuxing_decoding.c, and filter_audio.c.

Referenced by main(), and process_output().

av_samples_get_buffer_size()

int av_samples_get_buffer_size	(	int *	linesize,
		int	nb_channels,
		int	nb_samples,
		enum AVSampleFormat	sample_fmt,
		int	align
	)

Get the required buffer size for the given audio parameters.

Parameters

[out]	linesize	calculated linesize, may be NULL
	nb_channels	the number of channels
	nb_samples	the number of samples in a single channel
	sample_fmt	the sample format
	align	buffer size alignment (0 = default, 1 = no alignment)

Returns

required buffer size, or negative error code on failure

Examples:

resampling_audio.c.

Referenced by main().