Muxing

Data Structures
struct	AVOutputFormat

Functions
int	avformat_write_header (AVFormatContext *s, AVDictionary **options)
	Allocate the stream private data and write the stream header to an output media file.
int	av_write_frame (AVFormatContext *s, AVPacket *pkt)
	Write a packet to an output media file.
int	av_interleaved_write_frame (AVFormatContext *s, AVPacket *pkt)
	Write a packet to an output media file ensuring correct interleaving.
int	av_write_trailer (AVFormatContext *s)
	Write the stream trailer to an output media file and free the file private data.
AVOutputFormat *	av_guess_format (const char *short_name, const char *filename, const char *mime_type)
	Return the output format in the list of registered output formats which best matches the provided parameters, or return NULL if there is no match.
enum AVCodecID	av_guess_codec (AVOutputFormat *fmt, const char *short_name, const char *filename, const char *mime_type, enum AVMediaType type)
	Guess the codec ID based upon muxer and filename.
int	av_get_output_timestamp (struct AVFormatContext *s, int stream, int64_t *dts, int64_t *wall)
	Get timing information for the data currently output.

Detailed Description

Function Documentation

int avformat_write_header	(	AVFormatContext *	s,
		AVDictionary **	options
	)

Allocate the stream private data and write the stream header to an output media file.

Parameters

s	Media file handle, must be allocated with avformat_alloc_context(). Its oformat field must be set to the desired output format; Its pb field must be set to an already opened AVIOContext.
options	An AVDictionary filled with AVFormatContext and muxer-private options. On return this parameter will be destroyed and replaced with a dict containing options that were not found. May be NULL.

Returns

0 on success, negative AVERROR on failure.

See Also

av_opt_find, av_dict_set, avio_open, av_oformat_next.

Examples:

doc/examples/muxing.c.

Definition at line 387 of file mux.c.

Referenced by build_feed_streams(), ff_rtp_chain_mux_open(), hls_write_header(), http_prepare_data(), ism_write_header(), main(), mpegts_write_header(), open_slave(), rtp_new_av_stream(), seg_write_header(), segment_start(), and write_packet().

int av_write_frame	(	AVFormatContext *	s,
		AVPacket *	pkt
	)

Write a packet to an output media file.

The packet shall contain one audio or video frame. The packet must be correctly interleaved according to the container specification, if not then av_interleaved_write_frame must be used.

Parameters

s	media file handle
pkt	The packet, which contains the stream_index, buf/buf_size, dts/pts, ... This can be NULL (at any time, not just at the end), in order to immediately flush data buffered within the muxer, for muxers that buffer up data internally before writing it to the output.

Returns

< 0 on error, = 0 if OK, 1 if flushed and there is no more data to flush

Definition at line 548 of file mux.c.

Referenced by ff_write_chained(), hls_write_packet(), http_prepare_data(), ism_flush(), mpegts_write_packet_internal(), and segment_end().

int av_interleaved_write_frame	(	AVFormatContext *	s,
		AVPacket *	pkt
	)

Write a packet to an output media file ensuring correct interleaving.

The packet must contain one audio or video frame. If the packets are already correctly interleaved, the application should call av_write_frame() instead as it is slightly faster. It is also important to keep in mind that completely non-interleaved input will need huge amounts of memory to interleave with this, so it is preferable to interleave at the demuxer level.

Parameters

s

media file handle

pkt

The packet containing the data to be written. pkt->buf must be set to a valid AVBufferRef describing the packet data. Libavformat takes ownership of this reference and will unref it when it sees fit. The caller must not access the data through this reference after this function returns. This can be NULL (at any time, not just at the end), to flush the interleaving queues. Packet's stream_index field must be set to the index of the corresponding stream in s.streams. It is very strongly recommended that timing information (pts, dts duration) is set to correct values.

Returns

0 on success, a negative AVERROR on error.

Examples:

doc/examples/muxing.c.

Definition at line 757 of file mux.c.

Referenced by tee_write_packet(), write_audio_frame(), write_frame(), write_packet(), and write_video_frame().

int av_write_trailer

(

AVFormatContext *

s

)

Write the stream trailer to an output media file and free the file private data.

May only be called after a successful call to avformat_write_header.

Parameters

s	media file handle

Returns

0 if OK, AVERROR_xxx on error

Examples:

doc/examples/muxing.c.

Definition at line 800 of file mux.c.

Referenced by close_connection(), ff_mov_close_hinting(), ff_rtsp_undo_setup(), hls_write_trailer(), http_prepare_data(), ism_free(), main(), sap_write_close(), seg_write_trailer(), segment_end(), tee_write_trailer(), transcode(), and write_packet().

AVOutputFormat* av_guess_format	(	const char *	short_name,
		const char *	filename,
		const char *	mime_type
	)

Return the output format in the list of registered output formats which best matches the provided parameters, or return NULL if there is no match.

Parameters

short_name	if non-NULL checks if short_name matches with the names of the registered formats
filename	if non-NULL checks if filename terminates with the extensions of the registered formats
mime_type	if non-NULL checks if mime_type matches with the MIME type of the registered formats

Definition at line 115 of file format.c.

Referenced by av_guess_codec(), av_guess_format(), avformat_alloc_output_context2(), ff_rtp_chain_mux_open(), ffserver_guess_format(), hls_write_header(), ism_write_header(), mpegts_write_header(), parse_ffconfig(), prepare_sdp_description(), rtp_new_av_stream(), seg_write_header(), and show_help_muxer().

enum AVCodecID av_guess_codec	(	AVOutputFormat *	fmt,
		const char *	short_name,
		const char *	filename,
		const char *	mime_type,
		enum AVMediaType	type
	)

Guess the codec ID based upon muxer and filename.

Definition at line 150 of file format.c.

Referenced by choose_encoder().

int av_get_output_timestamp	(	struct AVFormatContext *	s,
		int	stream,
		int64_t *	dts,
		int64_t *	wall
	)

Get timing information for the data currently output.

The exact meaning of "currently output" depends on the format. It is mostly relevant for devices that have an internal buffer and/or work in real time.

Parameters

	s	media file handle
	stream	stream in the media file
[out]	dts	DTS of the last packet output for the stream, in stream time_base units
[out]	wall	absolute time when that packet whas output, in microsecond

Returns

0 if OK, AVERROR(ENOSYS) if the format does not support it Note: some formats or devices may not allow to measure dts and wall atomically.

Definition at line 842 of file mux.c.