Utility functions

Miscellaneous utility functions related to both encoding and decoding (or neither). More...

Modules
	Pixel formats
	Functions for working with pixel formats.
	FFT functions

Functions
void	avcodec_string (char *buf, int buf_size, AVCodecContext *enc, int encode)
const char *	av_get_profile_name (const AVCodec *codec, int profile)
	Return a name for the specified profile, if available.
const char *	avcodec_profile_name (enum AVCodecID codec_id, int profile)
	Return a name for the specified profile, if available.
int	avcodec_default_execute (AVCodecContext *c, int(*func)(AVCodecContext *c2, void *arg2), void *arg, int *ret, int count, int size)
int	avcodec_default_execute2 (AVCodecContext *c, int(*func)(AVCodecContext *c2, void *arg2, int, int), void *arg, int *ret, int count)
int	avcodec_fill_audio_frame (AVFrame *frame, int nb_channels, enum AVSampleFormat sample_fmt, const uint8_t *buf, int buf_size, int align)
	Fill AVFrame audio data and linesize pointers.
void	avcodec_flush_buffers (AVCodecContext *avctx)
	Reset the internal codec state / flush internal buffers.
int	av_get_bits_per_sample (enum AVCodecID codec_id)
	Return codec bits per sample.
enum AVCodecID	av_get_pcm_codec (enum AVSampleFormat fmt, int be)
	Return the PCM codec associated with a sample format.
int	av_get_exact_bits_per_sample (enum AVCodecID codec_id)
	Return codec bits per sample.
int	av_get_audio_frame_duration (AVCodecContext *avctx, int frame_bytes)
	Return audio frame duration.
int	av_get_audio_frame_duration2 (AVCodecParameters *par, int frame_bytes)
	This function is the same as av_get_audio_frame_duration(), except it works with AVCodecParameters instead of an AVCodecContext.
void	av_fast_padded_malloc (void *ptr, unsigned int *size, size_t min_size)
	Same behaviour av_fast_malloc but the buffer has additional AV_INPUT_BUFFER_PADDING_SIZE at the end which will always be 0.
void	av_fast_padded_mallocz (void *ptr, unsigned int *size, size_t min_size)
	Same behaviour av_fast_padded_malloc except that buffer will always be 0-initialized after call.
unsigned int	av_xiphlacing (unsigned char *s, unsigned int v)
	Encode extradata length to a buffer.
int	avcodec_is_open (AVCodecContext *s)
AVCPBProperties *	av_cpb_properties_alloc (size_t *size)
	Allocate a CPB properties structure and initialize its fields to default values.

Detailed Description

Miscellaneous utility functions related to both encoding and decoding (or neither).

Function Documentation

avcodec_string()

void avcodec_string	(	char *	buf,
		int	buf_size,
		AVCodecContext *	enc,
		int	encode
	)

av_get_profile_name()

const char * av_get_profile_name	(	const AVCodec *	codec,
		int	profile
	)

Return a name for the specified profile, if available.

Parameters

codec	the codec that is searched for the given profile
profile	the profile value for which a name is requested

Returns

A name for the profile if found, NULL otherwise.

avcodec_profile_name()

const char * avcodec_profile_name	(	enum AVCodecID	codec_id,
		int	profile
	)

Return a name for the specified profile, if available.

Parameters

codec_id	the ID of the codec to which the requested profile belongs
profile	the profile value for which a name is requested

Returns

A name for the profile if found, NULL otherwise.

Note

unlike av_get_profile_name(), which searches a list of profiles supported by a specific decoder or encoder implementation, this function searches the list of profiles from the AVCodecDescriptor

avcodec_default_execute()

int avcodec_default_execute	(	AVCodecContext *	c,
		int(*)(AVCodecContext *c2, void *arg2)	func,
		void *	arg,
		int *	ret,
		int	count,
		int	size
	)

avcodec_default_execute2()

int avcodec_default_execute2	(	AVCodecContext *	c,
		int(*)(AVCodecContext *c2, void *arg2, int, int)	func,
		void *	arg,
		int *	ret,
		int	count
	)

avcodec_fill_audio_frame()

int avcodec_fill_audio_frame	(	AVFrame *	frame,
		int	nb_channels,
		enum AVSampleFormat	sample_fmt,
		const uint8_t *	buf,
		int	buf_size,
		int	align
	)

Fill AVFrame audio data and linesize pointers.

The buffer buf must be a preallocated buffer with a size big enough to contain the specified samples amount. The filled AVFrame data pointers will point to this buffer.

AVFrame extended_data channel pointers are allocated if necessary for planar audio.

Parameters

frame	the AVFrame frame->nb_samples must be set prior to calling the function. This function fills in frame->data, frame->extended_data, frame->linesize[0].
nb_channels	channel count
sample_fmt	sample format
buf	buffer to use for frame data
buf_size	size of buffer
align	plane size sample alignment (0 = default)

Returns

>=0 on success, negative error code on failure

Todo:

return the size in bytes required to store the samples in case of success, at the next libavutil bump

avcodec_flush_buffers()

void avcodec_flush_buffers

(

AVCodecContext *

avctx

)

Reset the internal codec state / flush internal buffers.

Should be called e.g. when seeking or when switching to a different stream.

Note

for decoders, when refcounted frames are not used (i.e. avctx->refcounted_frames is 0), this invalidates the frames previously returned from the decoder. When refcounted frames are used, the decoder just releases any references it might keep internally, but the caller's reference remains valid.

for encoders, this function will only do something if the encoder declares support for AV_CODEC_CAP_ENCODER_FLUSH. When called, the encoder will drain any remaining packets, and can then be re-used for a different stream (as opposed to sending a null frame which will leave the encoder in a permanent EOF state after draining). This can be desirable if the cost of tearing down and replacing the encoder instance is high.

av_get_bits_per_sample()

int av_get_bits_per_sample

(

enum AVCodecID

codec_id

)

Return codec bits per sample.

Parameters

[in]

codec_id

the codec

Returns

Number of bits per sample or zero if unknown for the given codec.

av_get_pcm_codec()

enum AVCodecID av_get_pcm_codec	(	enum AVSampleFormat	fmt,
		int	be
	)

Return the PCM codec associated with a sample format.

Parameters

be	endianness, 0 for little, 1 for big, -1 (or anything else) for native

Returns

AV_CODEC_ID_PCM_* or AV_CODEC_ID_NONE

av_get_exact_bits_per_sample()

int av_get_exact_bits_per_sample

(

enum AVCodecID

codec_id

)

Return codec bits per sample.

Only return non-zero if the bits per sample is exactly correct, not an approximation.

Parameters

[in]

codec_id

the codec

Returns

Number of bits per sample or zero if unknown for the given codec.

av_get_audio_frame_duration()

int av_get_audio_frame_duration	(	AVCodecContext *	avctx,
		int	frame_bytes
	)

Return audio frame duration.

Parameters

avctx	codec context
frame_bytes	size of the frame, or 0 if unknown

Returns

frame duration, in samples, if known. 0 if not able to determine.

av_get_audio_frame_duration2()

int av_get_audio_frame_duration2	(	AVCodecParameters *	par,
		int	frame_bytes
	)

This function is the same as av_get_audio_frame_duration(), except it works with AVCodecParameters instead of an AVCodecContext.

av_fast_padded_malloc()

void av_fast_padded_malloc	(	void *	ptr,
		unsigned int *	size,
		size_t	min_size
	)

Same behaviour av_fast_malloc but the buffer has additional AV_INPUT_BUFFER_PADDING_SIZE at the end which will always be 0.

In addition the whole buffer will initially and after resizes be 0-initialized so that no uninitialized data will ever appear.

av_fast_padded_mallocz()

void av_fast_padded_mallocz	(	void *	ptr,
		unsigned int *	size,
		size_t	min_size
	)

Same behaviour av_fast_padded_malloc except that buffer will always be 0-initialized after call.

av_xiphlacing()

unsigned int av_xiphlacing	(	unsigned char *	s,
		unsigned int	v
	)

Encode extradata length to a buffer.

Used by xiph codecs.

Parameters

s	buffer to write to; must be at least (v/255+1) bytes long
v	size of extradata in bytes

Returns

number of bytes written to the buffer.

avcodec_is_open()

int avcodec_is_open

(

AVCodecContext *

s

)

Returns

a positive value if s is open (i.e. avcodec_open2() was called on it with no corresponding avcodec_close()), 0 otherwise.

av_cpb_properties_alloc()

AVCPBProperties * av_cpb_properties_alloc

(

size_t *

size

)

Allocate a CPB properties structure and initialize its fields to default values.

Parameters

size	if non-NULL, the size of the allocated struct will be written here. This is useful for embedding it in side data.

Returns

the newly allocated struct or NULL on failure