Core functions

Functions for querying libavformat capabilities, allocating core structures, etc. More...

Macros
#define	AVFMT_PROGCOPY_MATCH_BY_ID   (1 << 0)
	match streams using stream id
#define	AVFMT_PROGCOPY_MATCH_BY_INDEX   (1 << 1)
	match streams using stream index
#define	AVFMT_PROGCOPY_OVERWRITE   (1 << 8)
	overwrite pre-existing program having same ID

Functions
unsigned	avformat_version (void)
	Return the LIBAVFORMAT_VERSION_INT constant.
const char *	avformat_configuration (void)
	Return the libavformat build-time configuration.
const char *	avformat_license (void)
	Return the libavformat license.
int	avformat_network_init (void)
	Do global initialization of network libraries.
int	avformat_network_deinit (void)
	Undo the initialization done by avformat_network_init.
const AVOutputFormat *	av_muxer_iterate (void **opaque)
	Iterate over all registered muxers.
const AVInputFormat *	av_demuxer_iterate (void **opaque)
	Iterate over all registered demuxers.
AVFormatContext *	avformat_alloc_context (void)
	Allocate an AVFormatContext.
void	avformat_free_context (AVFormatContext *s)
	Free an AVFormatContext and all its streams.
const AVClass *	avformat_get_class (void)
	Get the AVClass for AVFormatContext.
const AVClass *	av_stream_get_class (void)
	Get the AVClass for AVStream.
const AVClass *	av_stream_group_get_class (void)
	Get the AVClass for AVStreamGroup.
const char *	avformat_stream_group_name (enum AVStreamGroupParamsType type)
AVStreamGroup *	avformat_stream_group_create (AVFormatContext *s, enum AVStreamGroupParamsType type, AVDictionary **options)
	Add a new empty stream group to a media file.
AVStream *	avformat_new_stream (AVFormatContext *s, const struct AVCodec *c)
	Add a new stream to a media file.
int	avformat_stream_group_add_stream (AVStreamGroup *stg, AVStream *st)
	Add an already allocated stream to a stream group.
AVProgram *	av_new_program (AVFormatContext *s, int id)
int	av_program_copy (AVFormatContext *dst, const AVFormatContext *src, int progid, int flags)
	Copy an AVProgram from one AVFormatContext to another.

Detailed Description

Functions for querying libavformat capabilities, allocating core structures, etc.

Macro Definition Documentation

AVFMT_PROGCOPY_MATCH_BY_ID

#define AVFMT_PROGCOPY_MATCH_BY_ID   (1 << 0)

match streams using stream id

Definition at line 2127 of file avformat.h.

AVFMT_PROGCOPY_MATCH_BY_INDEX

#define AVFMT_PROGCOPY_MATCH_BY_INDEX   (1 << 1)

match streams using stream index

Definition at line 2128 of file avformat.h.

AVFMT_PROGCOPY_OVERWRITE

#define AVFMT_PROGCOPY_OVERWRITE   (1 << 8)

overwrite pre-existing program having same ID

Definition at line 2129 of file avformat.h.

Function Documentation

avformat_version()

unsigned avformat_version

(

void

)

Return the LIBAVFORMAT_VERSION_INT constant.

avformat_configuration()

const char * avformat_configuration

(

void

)

Return the libavformat build-time configuration.

avformat_license()

const char * avformat_license

(

void

)

Return the libavformat license.

avformat_network_init()

int avformat_network_init

(

void

)

Do global initialization of network libraries.

This is optional, and not recommended anymore.

This functions only exists to work around thread-safety issues with older GnuTLS or OpenSSL libraries. If libavformat is linked to newer versions of those libraries, or if you do not use them, calling this function is unnecessary. Otherwise, you need to call this function before any other threads using them are started.

This function will be deprecated once support for older GnuTLS and OpenSSL libraries is removed, and this function has no purpose anymore.

Examples

avio_list_dir.c.

Referenced by main().

avformat_network_deinit()

int avformat_network_deinit

(

void

)

Undo the initialization done by avformat_network_init.

Call it only once for each time you called avformat_network_init.

Examples

avio_list_dir.c.

Referenced by main().

av_muxer_iterate()

const AVOutputFormat * av_muxer_iterate

(

void **

opaque

)

Iterate over all registered muxers.

Parameters

opaque

a pointer where libavformat will store the iteration state. Must point to NULL to start the iteration.

Returns

the next registered muxer or NULL when the iteration is finished

av_demuxer_iterate()

const AVInputFormat * av_demuxer_iterate

(

void **

opaque

)

Iterate over all registered demuxers.

Parameters

opaque

a pointer where libavformat will store the iteration state. Must point to NULL to start the iteration.

Returns

the next registered demuxer or NULL when the iteration is finished

avformat_alloc_context()

AVFormatContext * avformat_alloc_context

(

void

)

Allocate an AVFormatContext.

avformat_free_context() can be used to free the context and everything allocated by the framework within it.

Examples

avio_read_callback.c, and transcode_aac.c.

Referenced by main(), and open_output_file().

avformat_free_context()

void avformat_free_context

(

AVFormatContext *

s

)

Free an AVFormatContext and all its streams.

Parameters

s	context to free

Examples

mux.c, qsv_transcode.c, remux.c, transcode.c, transcode_aac.c, and vaapi_transcode.c.

Referenced by main(), and open_output_file().

avformat_get_class()

const AVClass * avformat_get_class

(

void

)

Get the AVClass for AVFormatContext.

It can be used in combination with AV_OPT_SEARCH_FAKE_OBJ for examining options.

See also

av_opt_find().

av_stream_get_class()

const AVClass * av_stream_get_class

(

void

)

Get the AVClass for AVStream.

It can be used in combination with AV_OPT_SEARCH_FAKE_OBJ for examining options.

See also

av_opt_find().

av_stream_group_get_class()

const AVClass * av_stream_group_get_class

(

void

)

Get the AVClass for AVStreamGroup.

It can be used in combination with AV_OPT_SEARCH_FAKE_OBJ for examining options.

See also

av_opt_find().

avformat_stream_group_name()

const char * avformat_stream_group_name

(

enum AVStreamGroupParamsType

type

)

Returns

a string identifying the stream group type, or NULL if unknown

avformat_stream_group_create()

AVStreamGroup * avformat_stream_group_create	(	AVFormatContext *	s,
		enum AVStreamGroupParamsType	type,
		AVDictionary **	options )

Add a new empty stream group to a media file.

When demuxing, it may be called by the demuxer in read_header(). If the flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also be called in read_packet().

When muxing, may be called by the user before avformat_write_header().

User is required to call avformat_free_context() to clean up the allocation by avformat_stream_group_create().

New streams can be added to the group with avformat_stream_group_add_stream().

Parameters

s	media file handle

Returns

newly created group or NULL on error.

See also

avformat_new_stream, avformat_stream_group_add_stream.

avformat_new_stream()

AVStream * avformat_new_stream	(	AVFormatContext *	s,
		const struct AVCodec *	c )

Add a new stream to a media file.

When demuxing, it is called by the demuxer in read_header(). If the flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also be called in read_packet().

When muxing, should be called by the user before avformat_write_header().

User is required to call avformat_free_context() to clean up the allocation by avformat_new_stream().

Parameters

s	media file handle
c	unused, does nothing

Returns

newly created stream or NULL on error.

Examples

mux.c, qsv_transcode.c, remux.c, transcode.c, transcode_aac.c, and vaapi_transcode.c.

Referenced by add_stream(), dec_enc(), dec_enc(), main(), open_output_file(), and open_output_file().

avformat_stream_group_add_stream()

int avformat_stream_group_add_stream	(	AVStreamGroup *	stg,
		AVStream *	st )

Add an already allocated stream to a stream group.

When demuxing, it may be called by the demuxer in read_header(). If the flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also be called in read_packet().

When muxing, may be called by the user before avformat_write_header() after having allocated a new group with avformat_stream_group_create() and stream with avformat_new_stream().

User is required to call avformat_free_context() to clean up the allocation by avformat_stream_group_add_stream().

Parameters

stg	stream group belonging to a media file.
st	stream in the media file to add to the group.

Return values

0	success
AVERROR(EEXIST)	the stream was already in the group
another negative error code	legitimate errors

See also

avformat_new_stream, avformat_stream_group_create.

av_new_program()

AVProgram * av_new_program	(	AVFormatContext *	s,
		int	id )

av_program_copy()

int av_program_copy	(	AVFormatContext *	dst,
		const AVFormatContext *	src,
		int	progid,
		int	flags )

Copy an AVProgram from one AVFormatContext to another.

Streams in the destination context whose designated attribute match the attribute of the streams in the source AVProgram index are added to the stream index of the copied AVProgram. The attribute is designated using AVFMT_PROGCOPY_MATCH_ flags.

If a new program has to be added, the function expects and requires any existing buffer holding the array of pointers to AVPrograms in the destination context to have its size be a power-of-two value. This should be the case if all earlier programs were created using av_new_program or this function.

Parameters

dst	pointer to the target muxer context
src	pointer to the source muxer context
progid	ID of the program to be copied
flags	combination of flags which determine how streams are matched and whether pre-existing AVProgram in target is overwritten. If no match condition is set, streams will be matched by ids if all source stream ids are non-zero and unique, else by index.

Returns

>= 0 in case of success, Error EEXIST if target already has program with same ID and overwrite flag isn't set, else a negative AVERROR code in case of other failures.