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Utility functions
Encoding/Decoding Library

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  AVBitStreamFilter
 

Enumerations

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

Functions

attribute_deprecated void avcodec_set_dimensions (AVCodecContext *s, int width, int height)
 
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.
 
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.
 
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 decoder 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.
 
void av_register_bitstream_filter (AVBitStreamFilter *bsf)
 Register a bitstream filter.
 
AVBitStreamFilterContextav_bitstream_filter_init (const char *name)
 Create and initialize a bitstream filter context given a bitstream filter name.
 
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)
 Filter bitstream.
 
void av_bitstream_filter_close (AVBitStreamFilterContext *bsf)
 Release bitstream filter context.
 
AVBitStreamFilterav_bitstream_filter_next (const AVBitStreamFilter *f)
 If f is NULL, return the first registered bitstream filter, if f is non-NULL, return the next registered bitstream filter after f, or NULL if f is the last one.
 
void av_fast_padded_malloc (void *ptr, unsigned int *size, size_t min_size)
 Same behaviour av_fast_malloc but the buffer has additional FF_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.
 
attribute_deprecated void av_log_missing_feature (void *avc, const char *feature, int want_sample)
 Log a generic warning message about a missing feature.
 
attribute_deprecated void av_log_ask_for_sample (void *avc, const char *msg,...) av_printf_format(2
 Log a generic warning message asking for a sample.
 
attribute_deprecated void void av_register_hwaccel (AVHWAccel *hwaccel)
 Register the hardware accelerator hwaccel.
 
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.
 
int av_lockmgr_register (int(*cb)(void **mutex, enum AVLockOp op))
 Register a user provided lock manager supporting the operations specified by AVLockOp.
 
enum AVMediaType avcodec_get_type (enum AVCodecID codec_id)
 Get the type of the given codec.
 
const char * avcodec_get_name (enum AVCodecID id)
 Get the name of a codec.
 
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.
 
const AVCodecDescriptoravcodec_descriptor_get_by_name (const char *name)
 

Detailed Description

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

Enumeration Type Documentation

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 5161 of file avcodec.h.

Function Documentation

attribute_deprecated void avcodec_set_dimensions ( AVCodecContext s,
int  width,
int  height 
)
Deprecated:
this function is not supposed to be used from outside of lavc

Definition at line 217 of file utils.c.

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

Definition at line 2950 of file utils.c.

Referenced by avcodec_string(), init_muxer(), main(), mjpeg_decode_app(), mov_write_hdlr_tag(), print_pix_fmt_fourccs(), rsd_read_header(), and show_stream().

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

Definition at line 2970 of file utils.c.

Referenced by avformat_find_stream_info(), and dump_stream_format().

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.

Definition at line 3142 of file utils.c.

Referenced by avcodec_string(), and show_stream().

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

Definition at line 1099 of file utils.c.

Referenced by avcodec_get_context_defaults3(), and thread_execute().

int avcodec_default_execute2 ( AVCodecContext c,
int(*)(AVCodecContext *c2, void *arg2, int, int)  func,
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.

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
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
Todo:
return the size in bytes required to store the samples in case of success, at the next libavutil bump
Examples:
decoding_encoding.c.

Definition at line 467 of file utils.c.

Referenced by audio_encode_example(), and avcodec_encode_audio().

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.

Definition at line 3183 of file utils.c.

Referenced by decoder_decode_frame(), and rewind_file().

int av_get_bits_per_sample ( enum AVCodecID  codec_id)
enum AVCodecID av_get_pcm_codec ( enum AVSampleFormat  fmt,
int  be 
)

Return the PCM codec associated with a sample format.

Parameters
beendianness, 0 for little, 1 for big, -1 (or anything else) for native
Returns
AV_CODEC_ID_PCM_* or AV_CODEC_ID_NONE

Definition at line 3251 of file utils.c.

Referenced by lavfi_read_header(), and main().

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.

Definition at line 3197 of file utils.c.

Referenced by av_get_audio_frame_duration(), av_get_bits_per_sample(), and new_output_stream().

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.

Definition at line 3290 of file utils.c.

Referenced by adp_read_header(), build_frame_code(), compute_pkt_fields2(), do_streamcopy(), ff_parse_specific_params(), ff_put_wav_header(), get_aiff_header(), rsd_read_header(), rtp_send_ilbc(), and rtp_write_header().

void av_register_bitstream_filter ( AVBitStreamFilter bsf)

Register a bitstream filter.

The filter will be accessible to the application code through av_bitstream_filter_next() or can be directly initialized with av_bitstream_filter_init().

See Also
avcodec_register_all()

Definition at line 37 of file bitstream_filter.c.

AVBitStreamFilterContext* av_bitstream_filter_init ( const char *  name)

Create and initialize a bitstream filter context given a bitstream filter name.

The returned context must be freed with av_bitstream_filter_close().

Parameters
namethe name of the bitstream filter
Returns
a bitstream filter context if a matching filter was found and successfully initialized, NULL otherwise

Definition at line 44 of file bitstream_filter.c.

Referenced by detect_stream_specific(), init(), new_output_stream(), parse_bsfs(), and Stagefright_init().

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 
)

Filter bitstream.

This function filters the buffer buf with size buf_size, and places the filtered buffer in the buffer pointed to by poutbuf.

The output buffer must be freed by the caller.

Parameters
bsfcbitstream filter context created by av_bitstream_filter_init()
avctxAVCodecContext accessed by the filter, may be NULL. If specified, this must point to the encoder context of the output stream the packet is sent to.
argsarguments which specify the filter configuration, may be NULL
poutbufpointer which is updated to point to the filtered buffer
poutbuf_sizepointer which is updated to the filtered buffer size in bytes
bufbuffer containing the data to filter
buf_sizesize in bytes of buf
keyframeset to non-zero if the buffer to filter corresponds to a key-frame packet data
Returns
>= 0 in case of success, or a negative error code in case of failure

If the return value is positive, an output buffer is allocated and is available in *poutbuf, and is distinct from the input buffer.

If the return value is 0, the output buffer is not allocated and should be considered identical to the input buffer, or in case *poutbuf was set it points to the input buffer (not necessarily to its starting address).

Definition at line 72 of file bitstream_filter.c.

Referenced by decode(), filter_packet(), init(), Stagefright_decode_frame(), and write_frame().

void av_bitstream_filter_close ( AVBitStreamFilterContext bsf)

Release bitstream filter context.

Parameters
bsfthe bitstream filter context created with av_bitstream_filter_init(), can be NULL

Definition at line 61 of file bitstream_filter.c.

Referenced by close_slaves(), ffmpeg_cleanup(), Stagefright_close(), Stagefright_init(), and uninit().

AVBitStreamFilter* av_bitstream_filter_next ( const AVBitStreamFilter f)

If f is NULL, return the first registered bitstream filter, if f is non-NULL, return the next registered bitstream filter after f, or NULL if f is the last one.

This function can be used to iterate over all registered bitstream filters.

Definition at line 29 of file bitstream_filter.c.

Referenced by av_bitstream_filter_init(), and show_bsfs().

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

Definition at line 148 of file utils.c.

Referenced by decode_frame(), and encode_frame().

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.

Definition at line 3474 of file utils.c.

Referenced by fixup_vorbis_headers(), libvorbis_encode_init(), parse_packed_headers(), and put_main_header().

attribute_deprecated void av_log_missing_feature ( void avc,
const char *  feature,
int  want_sample 
)

Log a generic warning message about a missing feature.

This function is intended to be used internally by FFmpeg (libavcodec, libavformat, etc.) only, and would normally not be used by applications.

Parameters
[in]avca pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct
[in]featurestring containing the name of the missing feature
[in]want_sampleindicates if samples are wanted which exhibit this feature. If want_sample is non-zero, additional verbage will be added to the log message which tells the user how to report samples to the development mailing list.
Deprecated:
Use avpriv_report_missing_feature() instead.

Definition at line 3497 of file utils.c.

attribute_deprecated void av_log_ask_for_sample ( void avc,
const char *  msg,
  ... 
)

Log a generic warning message asking for a sample.

This function is intended to be used internally by FFmpeg (libavcodec, libavformat, etc.) only, and would normally not be used by applications.

Parameters
[in]avca pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct
[in]msgstring containing an optional message, or NULL if no message
Deprecated:
Use avpriv_request_sample() instead.

Referenced by av_log_missing_feature(), and decode_video().

attribute_deprecated void void av_register_hwaccel ( AVHWAccel hwaccel)

Register the hardware accelerator hwaccel.

Definition at line 3527 of file utils.c.

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.

Definition at line 3536 of file utils.c.

Referenced by find_hwaccel().

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.

Definition at line 3541 of file utils.c.

Referenced by do_exit(), and main().

enum AVMediaType avcodec_get_type ( enum AVCodecID  codec_id)

Get the type of the given codec.

Definition at line 3706 of file utils.c.

Referenced by mkv_query_codec().

const char* avcodec_get_name ( enum AVCodecID  id)
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.

Definition at line 3726 of file utils.c.

Referenced by avcodec_close(), avcodec_copy_context(), avcodec_open2(), ff_mp4_read_dec_config_descr(), mpegts_find_stream_type(), mpegts_set_stream_info(), and try_decode_frame().

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

Definition at line 184 of file utils.c.

Referenced by alloc_frame_buffer(), avcodec_close(), avcodec_find_encoder_by_name(), avcodec_open2(), ff_jpeg2000_init_component(), ff_snow_get_buffer(), find_encdec(), next_codec_for_id(), and print_codec().

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

Definition at line 189 of file utils.c.

Referenced by avcodec_find_decoder_by_name(), avcodec_open2(), find_encdec(), and next_codec_for_id().

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

Definition at line 2846 of file codec_desc.c.

Referenced by asf_write_header1(), avcodec_get_name(), avcodec_open2(), ico_check_attributes(), is_intra_only(), open_output_file(), show_help_muxer(), and show_stream().

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

Definition at line 2856 of file codec_desc.c.

Referenced by avcodec_descriptor_get_by_name(), and get_codecs_sorted().

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

Definition at line 2865 of file codec_desc.c.

Referenced by find_codec_or_die(), and show_help_codec().