Audio channel layouts

Macros
#define	AV_CH_LAYOUT_MONO   (AV_CH_FRONT_CENTER)
#define	AV_CH_LAYOUT_STEREO   (AV_CH_FRONT_LEFT|AV_CH_FRONT_RIGHT)
#define	AV_CH_LAYOUT_2POINT1   (AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY)
#define	AV_CH_LAYOUT_2_1   (AV_CH_LAYOUT_STEREO|AV_CH_BACK_CENTER)
#define	AV_CH_LAYOUT_SURROUND   (AV_CH_LAYOUT_STEREO|AV_CH_FRONT_CENTER)
#define	AV_CH_LAYOUT_3POINT1   (AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY)
#define	AV_CH_LAYOUT_4POINT0   (AV_CH_LAYOUT_SURROUND|AV_CH_BACK_CENTER)
#define	AV_CH_LAYOUT_4POINT1   (AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY)
#define	AV_CH_LAYOUT_2_2   (AV_CH_LAYOUT_STEREO|AV_CH_SIDE_LEFT|AV_CH_SIDE_RIGHT)
#define	AV_CH_LAYOUT_QUAD   (AV_CH_LAYOUT_STEREO|AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT)
#define	AV_CH_LAYOUT_5POINT0   (AV_CH_LAYOUT_SURROUND|AV_CH_SIDE_LEFT|AV_CH_SIDE_RIGHT)
#define	AV_CH_LAYOUT_5POINT1   (AV_CH_LAYOUT_5POINT0|AV_CH_LOW_FREQUENCY)
#define	AV_CH_LAYOUT_5POINT0_BACK   (AV_CH_LAYOUT_SURROUND|AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT)
#define	AV_CH_LAYOUT_5POINT1_BACK   (AV_CH_LAYOUT_5POINT0_BACK|AV_CH_LOW_FREQUENCY)
#define	AV_CH_LAYOUT_6POINT0   (AV_CH_LAYOUT_5POINT0|AV_CH_BACK_CENTER)
#define	AV_CH_LAYOUT_6POINT0_FRONT   (AV_CH_LAYOUT_2_2|AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER)
#define	AV_CH_LAYOUT_HEXAGONAL   (AV_CH_LAYOUT_5POINT0_BACK|AV_CH_BACK_CENTER)
#define	AV_CH_LAYOUT_6POINT1   (AV_CH_LAYOUT_5POINT1|AV_CH_BACK_CENTER)
#define	AV_CH_LAYOUT_6POINT1_BACK   (AV_CH_LAYOUT_5POINT1_BACK|AV_CH_BACK_CENTER)
#define	AV_CH_LAYOUT_6POINT1_FRONT   (AV_CH_LAYOUT_6POINT0_FRONT|AV_CH_LOW_FREQUENCY)
#define	AV_CH_LAYOUT_7POINT0   (AV_CH_LAYOUT_5POINT0|AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT)
#define	AV_CH_LAYOUT_7POINT0_FRONT   (AV_CH_LAYOUT_5POINT0|AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER)
#define	AV_CH_LAYOUT_7POINT1   (AV_CH_LAYOUT_5POINT1|AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT)
#define	AV_CH_LAYOUT_7POINT1_WIDE   (AV_CH_LAYOUT_5POINT1|AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER)
#define	AV_CH_LAYOUT_7POINT1_WIDE_BACK   (AV_CH_LAYOUT_5POINT1_BACK|AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER)
#define	AV_CH_LAYOUT_OCTAGONAL   (AV_CH_LAYOUT_5POINT0|AV_CH_BACK_LEFT|AV_CH_BACK_CENTER|AV_CH_BACK_RIGHT)
#define	AV_CH_LAYOUT_HEXADECAGONAL   (AV_CH_LAYOUT_OCTAGONAL|AV_CH_WIDE_LEFT|AV_CH_WIDE_RIGHT|AV_CH_TOP_BACK_LEFT|AV_CH_TOP_BACK_RIGHT|AV_CH_TOP_BACK_CENTER|AV_CH_TOP_FRONT_CENTER|AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT)
#define	AV_CH_LAYOUT_STEREO_DOWNMIX   (AV_CH_STEREO_LEFT|AV_CH_STEREO_RIGHT)

Enumerations
enum	AVMatrixEncoding {   AV_MATRIX_ENCODING_NONE, AV_MATRIX_ENCODING_DOLBY, AV_MATRIX_ENCODING_DPLII, AV_MATRIX_ENCODING_DPLIIX,   AV_MATRIX_ENCODING_DPLIIZ, AV_MATRIX_ENCODING_DOLBYEX, AV_MATRIX_ENCODING_DOLBYHEADPHONE, AV_MATRIX_ENCODING_NB }

Functions
uint64_t	av_get_channel_layout (const char *name)
	Return a channel layout id that matches name, or 0 if no match is found. More...
int	av_get_extended_channel_layout (const char *name, uint64_t *channel_layout, int *nb_channels)
	Return a channel layout and the number of channels based on the specified name. More...
void	av_get_channel_layout_string (char *buf, int buf_size, int nb_channels, uint64_t channel_layout)
	Return a description of a channel layout. More...
void	av_bprint_channel_layout (struct AVBPrint *bp, int nb_channels, uint64_t channel_layout)
	Append a description of a channel layout to a bprint buffer.
int	av_get_channel_layout_nb_channels (uint64_t channel_layout)
	Return the number of channels in the channel layout.
int64_t	av_get_default_channel_layout (int nb_channels)
	Return default channel layout for a given number of channels.
int	av_get_channel_layout_channel_index (uint64_t channel_layout, uint64_t channel)
	Get the index of a channel in channel_layout. More...
uint64_t	av_channel_layout_extract_channel (uint64_t channel_layout, int index)
	Get the channel with the given index in channel_layout.
const char *	av_get_channel_name (uint64_t channel)
	Get the name of a given channel. More...
const char *	av_get_channel_description (uint64_t channel)
	Get the description of a given channel. More...
int	av_get_standard_channel_layout (unsigned index, uint64_t *layout, const char **name)
	Get the value and name of a standard channel layout. More...

Detailed Description

Function Documentation

av_get_channel_description()

const char* av_get_channel_description

(

uint64_t

channel

)

Get the description of a given channel.

Parameters

channel

a channel layout with a single channel

Returns

channel description on success, NULL on error

av_get_channel_layout()

uint64_t av_get_channel_layout

(

const char *

name

)

Return a channel layout id that matches name, or 0 if no match is found.

name can be one or several of the following notations, separated by '+' or '|':

• the name of an usual channel layout (mono, stereo, 4.0, quad, 5.0, 5.0(side), 5.1, 5.1(side), 7.1, 7.1(wide), downmix);
• the name of a single channel (FL, FR, FC, LFE, BL, BR, FLC, FRC, BC, SL, SR, TC, TFL, TFC, TFR, TBL, TBC, TBR, DL, DR);
• a number of channels, in decimal, followed by 'c', yielding the default channel layout for that number of channels (

  See also

  av_get_default_channel_layout);

• a channel layout mask, in hexadecimal starting with "0x" (see the AV_CH_* macros).

Example: "stereo+FC" = "2c+FC" = "2c+1c" = "0x7"

av_get_channel_layout_channel_index()

int av_get_channel_layout_channel_index	(	uint64_t	channel_layout,
		uint64_t	channel
	)

Get the index of a channel in channel_layout.

Parameters

channel

a channel layout describing exactly one channel which must be present in channel_layout.

Returns

index of channel in channel_layout on success, a negative AVERROR on error.

av_get_channel_layout_string()

void av_get_channel_layout_string	(	char *	buf,
		int	buf_size,
		int	nb_channels,
		uint64_t	channel_layout
	)

Return a description of a channel layout.

If nb_channels is <= 0, it is guessed from the channel_layout.

Parameters

buf	put here the string containing the channel layout
buf_size	size in bytes of the buffer

av_get_channel_name()

const char* av_get_channel_name

(

uint64_t

channel

)

Get the name of a given channel.

Returns

channel name on success, NULL on error.

av_get_extended_channel_layout()

int av_get_extended_channel_layout	(	const char *	name,
		uint64_t *	channel_layout,
		int *	nb_channels
	)

Return a channel layout and the number of channels based on the specified name.

This function is similar to (

See also

av_get_channel_layout), but can also parse unknown channel layout specifications.

Parameters

[in]	name	channel layout specification string
[out]	channel_layout	parsed channel layout (0 if unknown)
[out]	nb_channels	number of channels

Returns

0 on success, AVERROR(EINVAL) if the parsing fails.

av_get_standard_channel_layout()

int av_get_standard_channel_layout	(	unsigned	index,
		uint64_t *	layout,
		const char **	name
	)

Get the value and name of a standard channel layout.

Parameters

[in]	index	index in an internal list, starting at 0
[out]	layout	channel layout mask
[out]	name	name of the layout

Returns

0 if the layout exists, <0 if index is beyond the limits