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
 

Data Structures

struct  AVBitStreamFilterContext
 
struct  AVBSFContext
 The bitstream filter state. More...
 
struct  AVBitStreamFilter
 

Typedefs

typedef struct AVBSFInternal AVBSFInternal
 

Enumerations

enum  AVLockOp { AV_LOCK_CREATE, AV_LOCK_OBTAIN, AV_LOCK_RELEASE, AV_LOCK_DESTROY }
 Lock operation used by lockmgr. More...
 

Functions

size_t av_get_codec_tag_string (char *buf, size_t buf_size, unsigned int codec_tag)
 Put a string representing the codec tag codec_tag in buf. More...
 
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. More...
 
const char * avcodec_profile_name (enum AVCodecID codec_id, int profile)
 Return a name for the specified profile, if available. More...
 
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 audio frame data and linesize. More...
 
void avcodec_flush_buffers (AVCodecContext *avctx)
 Reset the internal decoder state / flush internal buffers. More...
 
int av_get_bits_per_sample (enum AVCodecID codec_id)
 Return codec bits per sample. More...
 
int av_get_exact_bits_per_sample (enum AVCodecID codec_id)
 Return codec bits per sample. More...
 
int av_get_audio_frame_duration (AVCodecContext *avctx, int frame_bytes)
 Return audio frame duration. More...
 
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. More...
 
attribute_deprecated void av_register_bitstream_filter (AVBitStreamFilter *bsf)
 
attribute_deprecated AVBitStreamFilterContextav_bitstream_filter_init (const char *name)
 
attribute_deprecated int av_bitstream_filter_filter (AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args, uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size, int keyframe)
 
attribute_deprecated void av_bitstream_filter_close (AVBitStreamFilterContext *bsf)
 
attribute_deprecated AVBitStreamFilterav_bitstream_filter_next (const AVBitStreamFilter *f)
 
const AVBitStreamFilterav_bsf_get_by_name (const char *name)
 
const AVBitStreamFilterav_bsf_next (void **opaque)
 Iterate over all registered bitstream filters. More...
 
int av_bsf_alloc (const AVBitStreamFilter *filter, AVBSFContext **ctx)
 Allocate a context for a given bitstream filter. More...
 
int av_bsf_init (AVBSFContext *ctx)
 Prepare the filter for use, after all the parameters and options have been set. More...
 
int av_bsf_send_packet (AVBSFContext *ctx, AVPacket *pkt)
 Submit a packet for filtering. More...
 
int av_bsf_receive_packet (AVBSFContext *ctx, AVPacket *pkt)
 Retrieve a filtered packet. More...
 
void av_bsf_flush (AVBSFContext *ctx)
 Reset the internal bitstream filter state / flush internal buffers. More...
 
void av_bsf_free (AVBSFContext **ctx)
 Free a bitstream filter context and everything associated with it; write NULL into the supplied pointer. More...
 
const AVClassav_bsf_get_class (void)
 Get the AVClass for AVBSFContext. More...
 
void av_fast_padded_malloc (void *ptr, unsigned int *size, size_t min_size)
 Allocate a buffer with padding, reusing the given one if large enough. More...
 
unsigned int av_xiphlacing (unsigned char *s, unsigned int v)
 Encode extradata length to a buffer. More...
 
attribute_deprecated void av_register_hwaccel (AVHWAccel *hwaccel)
 Register the hardware accelerator hwaccel. More...
 
attribute_deprecated AVHWAccelav_hwaccel_next (const AVHWAccel *hwaccel)
 If hwaccel is NULL, returns the first registered hardware accelerator, if hwaccel is non-NULL, returns the next registered hardware accelerator after hwaccel, or NULL if hwaccel is the last one. More...
 
int av_lockmgr_register (int(*cb)(void **mutex, enum AVLockOp op))
 Register a user provided lock manager supporting the operations specified by AVLockOp. More...
 
enum AVMediaType avcodec_get_type (enum AVCodecID codec_id)
 Get the type of the given codec. More...
 
int avcodec_is_open (AVCodecContext *s)
 
int av_codec_is_encoder (const AVCodec *codec)
 
int av_codec_is_decoder (const AVCodec *codec)
 
const AVCodecDescriptoravcodec_descriptor_get (enum AVCodecID id)
 
const AVCodecDescriptoravcodec_descriptor_next (const AVCodecDescriptor *prev)
 Iterate over all codec descriptors known to libavcodec. More...
 
const AVCodecDescriptoravcodec_descriptor_get_by_name (const char *name)
 
AVCPBPropertiesav_cpb_properties_alloc (size_t *size)
 Allocate a CPB properties structure and initialize its fields to default values. More...
 

Detailed Description

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

Typedef Documentation

◆ AVBSFInternal

typedef struct AVBSFInternal AVBSFInternal

Definition at line 4846 of file avcodec.h.

Enumeration Type Documentation

◆ AVLockOp

enum AVLockOp

Lock operation used by lockmgr.

Enumerator
AV_LOCK_CREATE 

Create a mutex.

AV_LOCK_OBTAIN 

Lock the mutex.

AV_LOCK_RELEASE 

Unlock the mutex.

AV_LOCK_DESTROY 

Free mutex resources.

Definition at line 5106 of file avcodec.h.

Function Documentation

◆ av_get_codec_tag_string()

size_t av_get_codec_tag_string ( char *  buf,
size_t  buf_size,
unsigned int  codec_tag 
)

Put a string representing the codec tag codec_tag in buf.

Parameters
bufbuffer to place codec tag in
buf_sizesize in bytes of buf
codec_tagcodec tag to assign
Returns
the length of the string that would have been generated if enough space had been available, excluding the trailing null

◆ 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
codecthe codec that is searched for the given profile
profilethe 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_idthe ID of the codec to which the requested profile belongs
profilethe 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 audio frame data and linesize.

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

Parameters
framethe 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_channelschannel count
sample_fmtsample format
bufbuffer to use for frame data
buf_sizesize of buffer
alignplane size sample alignment (0 = default)
Returns
0 on success, negative error code on failure

◆ avcodec_flush_buffers()

void avcodec_flush_buffers ( AVCodecContext avctx)

Reset the internal decoder state / flush internal buffers.

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

Note
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.

◆ av_get_bits_per_sample()

int av_get_bits_per_sample ( enum AVCodecID  codec_id)

Return codec bits per sample.

Parameters
[in]codec_idthe codec
Returns
Number of bits per sample or zero if unknown for the given codec.

◆ 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_idthe 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
avctxcodec context
frame_bytessize 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_register_bitstream_filter()

attribute_deprecated void av_register_bitstream_filter ( AVBitStreamFilter bsf)
Deprecated:
the old bitstream filtering API (using AVBitStreamFilterContext) is deprecated.

Use the new bitstream filtering API (using AVBSFContext).

◆ av_bitstream_filter_init()

attribute_deprecated AVBitStreamFilterContext* av_bitstream_filter_init ( const char *  name)

◆ av_bitstream_filter_filter()

attribute_deprecated int av_bitstream_filter_filter ( AVBitStreamFilterContext bsfc,
AVCodecContext avctx,
const char *  args,
uint8_t **  poutbuf,
int *  poutbuf_size,
const uint8_t *  buf,
int  buf_size,
int  keyframe 
)

◆ av_bitstream_filter_close()

attribute_deprecated void av_bitstream_filter_close ( AVBitStreamFilterContext bsf)

◆ av_bitstream_filter_next()

attribute_deprecated AVBitStreamFilter* av_bitstream_filter_next ( const AVBitStreamFilter f)

◆ av_bsf_get_by_name()

const AVBitStreamFilter* av_bsf_get_by_name ( const char *  name)
Returns
a bitstream filter with the specified name or NULL if no such bitstream filter exists.

◆ av_bsf_next()

const AVBitStreamFilter* av_bsf_next ( void **  opaque)

Iterate over all registered bitstream filters.

Parameters
opaquea pointer where libavcodec will store the iteration state. Must point to NULL to start the iteration.
Returns
the next registered bitstream filter or NULL when the iteration is finished

◆ av_bsf_alloc()

int av_bsf_alloc ( const AVBitStreamFilter filter,
AVBSFContext **  ctx 
)

Allocate a context for a given bitstream filter.

The caller must fill in the context parameters as described in the documentation and then call av_bsf_init() before sending any data to the filter.

Parameters
filterthe filter for which to allocate an instance.
ctxa pointer into which the pointer to the newly-allocated context will be written. It must be freed with av_bsf_free() after the filtering is done.
Returns
0 on success, a negative AVERROR code on failure

◆ av_bsf_init()

int av_bsf_init ( AVBSFContext ctx)

Prepare the filter for use, after all the parameters and options have been set.

◆ av_bsf_send_packet()

int av_bsf_send_packet ( AVBSFContext ctx,
AVPacket pkt 
)

Submit a packet for filtering.

After sending each packet, the filter must be completely drained by calling av_bsf_receive_packet() repeatedly until it returns AVERROR(EAGAIN) or AVERROR_EOF.

Parameters
pktthe packet to filter. The bitstream filter will take ownership of the packet and reset the contents of pkt. pkt is not touched if an error occurs. This parameter may be NULL, which signals the end of the stream (i.e. no more packets will be sent). That will cause the filter to output any packets it may have buffered internally.
Returns
0 on success, a negative AVERROR on error.

◆ av_bsf_receive_packet()

int av_bsf_receive_packet ( AVBSFContext ctx,
AVPacket pkt 
)

Retrieve a filtered packet.

Parameters
[out]pktthis struct will be filled with the contents of the filtered packet. It is owned by the caller and must be freed using av_packet_unref() when it is no longer needed. This parameter should be "clean" (i.e. freshly allocated with av_packet_alloc() or unreffed with av_packet_unref()) when this function is called. If this function returns successfully, the contents of pkt will be completely overwritten by the returned data. On failure, pkt is not touched.
Returns
0 on success. AVERROR(EAGAIN) if more packets need to be sent to the filter (using av_bsf_send_packet()) to get more output. AVERROR_EOF if there will be no further output from the filter. Another negative AVERROR value if an error occurs.
Note
one input packet may result in several output packets, so after sending a packet with av_bsf_send_packet(), this function needs to be called repeatedly until it stops returning 0. It is also possible for a filter to output fewer packets than were sent to it, so this function may return AVERROR(EAGAIN) immediately after a successful av_bsf_send_packet() call.

◆ av_bsf_flush()

void av_bsf_flush ( AVBSFContext ctx)

Reset the internal bitstream filter state / flush internal buffers.

◆ av_bsf_free()

void av_bsf_free ( AVBSFContext **  ctx)

Free a bitstream filter context and everything associated with it; write NULL into the supplied pointer.

◆ av_bsf_get_class()

const AVClass* av_bsf_get_class ( void  )

Get the AVClass for AVBSFContext.

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

See also
av_opt_find().

◆ av_fast_padded_malloc()

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

Allocate a buffer with padding, reusing the given one if large enough.

Same behaviour av_fast_malloc but the buffer has additional AV_INPUT_PADDING_SIZE at the end which will always memset to 0.

◆ av_xiphlacing()

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

Encode extradata length to a buffer.

Used by xiph codecs.

Parameters
sbuffer to write to; must be at least (v/255+1) bytes long
vsize of extradata in bytes
Returns
number of bytes written to the buffer.

◆ av_register_hwaccel()

attribute_deprecated void av_register_hwaccel ( AVHWAccel hwaccel)

Register the hardware accelerator hwaccel.

Deprecated:
This function doesn't do anything.

◆ av_hwaccel_next()

attribute_deprecated AVHWAccel* av_hwaccel_next ( const AVHWAccel hwaccel)

If hwaccel is NULL, returns the first registered hardware accelerator, if hwaccel is non-NULL, returns the next registered hardware accelerator after hwaccel, or NULL if hwaccel is the last one.

Deprecated:
AVHWaccel structures contain no user-serviceable parts, so this function should not be used.

◆ av_lockmgr_register()

int av_lockmgr_register ( int(*)(void **mutex, enum AVLockOp op)  cb)

Register a user provided lock manager supporting the operations specified by AVLockOp.

The "mutex" argument to the function points to a (void *) where the lockmgr should store/get a pointer to a user allocated mutex. It is NULL upon AV_LOCK_CREATE and equal to the value left by the last call for all other ops. If the lock manager is unable to perform the op then it should leave the mutex in the same state as when it was called and return a non-zero value. However, when called with AV_LOCK_DESTROY the mutex will always be assumed to have been successfully destroyed. If av_lockmgr_register succeeds it will return a non-negative value, if it fails it will return a negative value and destroy all mutex and unregister all callbacks. av_lockmgr_register is not thread-safe, it must be called from a single thread before any calls which make use of locking are used.

Parameters
cbUser defined callback. av_lockmgr_register invokes calls to this callback and the previously registered callback. The callback will be used to create more than one mutex each of which must be backed by its own underlying locking mechanism (i.e. do not use a single static object to implement your lock manager). If cb is set to NULL the lockmgr will be unregistered.

◆ avcodec_get_type()

enum AVMediaType avcodec_get_type ( enum AVCodecID  codec_id)

Get the type of the given codec.

◆ 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_codec_is_encoder()

int av_codec_is_encoder ( const AVCodec codec)
Returns
a non-zero number if codec is an encoder, zero otherwise

◆ av_codec_is_decoder()

int av_codec_is_decoder ( const AVCodec codec)
Returns
a non-zero number if codec is a decoder, zero otherwise

◆ avcodec_descriptor_get()

const AVCodecDescriptor* avcodec_descriptor_get ( enum AVCodecID  id)
Returns
descriptor for given codec ID or NULL if no descriptor exists.

◆ avcodec_descriptor_next()

const AVCodecDescriptor* avcodec_descriptor_next ( const AVCodecDescriptor prev)

Iterate over all codec descriptors known to libavcodec.

Parameters
prevprevious descriptor. NULL to get the first descriptor.
Returns
next descriptor or NULL after the last descriptor

◆ avcodec_descriptor_get_by_name()

const AVCodecDescriptor* avcodec_descriptor_get_by_name ( const char *  name)
Returns
codec descriptor with the given name or NULL if no such descriptor exists.

◆ 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
sizeif 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