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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

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)
  Flush buffers, should be called when seeking or when switching to a different stream.
 
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.
 
AVBitStreamFilterContext *  av_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.
 
AVBitStreamFilter *  av_bitstream_filter_next (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_realloc (void *ptr, unsigned int *size, size_t min_size)
  Reallocate the given block if it is not large enough, otherwise do nothing.
 
void  av_fast_malloc (void *ptr, unsigned int *size, size_t min_size)
  Allocate a buffer, reusing the given one if large enough.
 
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 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.
 
void  av_register_hwaccel (AVHWAccel *hwaccel)
  Register the hardware accelerator hwaccel.
 
AVHWAccel *  av_hwaccel_next (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 AVCodecDescriptor *  avcodec_descriptor_get (enum AVCodecID id)
 
const AVCodecDescriptor *  avcodec_descriptor_next (const AVCodecDescriptor *prev)
  Iterate over all codec descriptors known to libavcodec.
 
const AVCodecDescriptor *  avcodec_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 4789 of file avcodec.h.

Function Documentation

void avcodec_set_dimensions ( AVCodecContext *  s,
int  width,
int  height 
)

Definition at line 178 of file utils.c.

Referenced by apply_param_change(), av_mpeg4_decode_header(), avcodec_open2(), avpriv_dirac_parse_sequence_header(), avs_decode_init(), brpix_decode_frame(), cdxl_decode_frame(), cmv_process_header(), decode_frame(), decode_frame_headers(), decode_init(), dnxhd_decode_frame(), dvdsub_parse_extradata(), dvvideo_decode_frame(), execute_code(), ff_h263_decode_frame(), ff_ivi_decode_frame(), ff_mjpeg_decode_sof(), ff_rv34_decode_frame(), ff_vc1_decode_entry_point(), ff_vc1_decode_sequence_header(), flashsv_decode_frame(), g2m_decode_frame(), gif_decode_frame(), h261_decode_frame(), init_image(), libopenjpeg_decode_frame(), mpeg_decode_postinit(), mpegvideo_extract_headers(), mvc_decode_init(), parse_presentation_segment(), pcx_decode_frame(), process_frame_obj(), ptx_decode_frame(), rv20_decode_picture_header(), smvjpeg_decode_frame(), sunrast_decode_frame(), svq1_decode_frame(), tgq_decode_frame(), tgv_decode_frame(), theora_header(), tqi_decode_frame(), truemotion1_decode_header(), txd_decode_frame(), update_dimensions(), vp56_size_changed(), vp5_parse_header(), vp6_parse_header(), and vp8_decode().

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
buf_size size in bytes of buf
Returns
the length of the string that would have been generated if enough space had been available, excluding the trailing null

Definition at line 2493 of file utils.c.

Referenced by avcodec_string(), init_muxer(), main(), 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 2513 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
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.

Definition at line 2628 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 908 of file utils.c.

Referenced by avcodec_get_context_defaults3(), and avcodec_thread_execute().

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

Referenced by avcodec_get_context_defaults3().

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
Examples:
doc/examples/decoding_encoding.c, and doc/examples/muxing.c.

Definition at line 341 of file utils.c.

Referenced by audio_encode_example(), and write_audio_frame().

void avcodec_flush_buffers ( AVCodecContext *  avctx )

Flush buffers, should be called when seeking or when switching to a different stream.

Definition at line 2669 of file utils.c.

Referenced by audio_decode_frame(), get_video_frame(), rewind_file(), subtitle_thread(), and video_thread().

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.

Definition at line 2754 of file utils.c.

Referenced by adpcm_encode_init(), aiff_write_header(), avformat_find_stream_info(), caf_write_header(), epaf_read_header(), ff_alsa_open(), ff_audio_interleave_init(), ff_mov_read_stsd_entries(), ff_pcm_read_seek(), ff_voc_get_packet(), g722_read_header(), get_aiff_header(), get_bit_rate(), gxf_packet(), iff_read_header(), init_muxer(), ircam_read_header(), mkv_write_tracks(), mov_get_codec_tag(), mov_write_audio_tag(), mov_write_header(), mxf_set_audio_pts(), mxf_write_generic_sound_common(), oma_read_header(), pcm_decode_frame(), pcm_decode_init(), pcm_encode_frame(), pcm_encode_init(), pcm_read_header(), pulse_read_header(), read_header(), rso_read_header(), and show_stream().

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

Definition at line 2733 of file utils.c.

Referenced by lavfi_read_header().

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.

Definition at line 2683 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
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.

Definition at line 2772 of file utils.c.

Referenced by adp_read_header(), build_frame_code(), do_streamcopy(), ff_get_audio_frame_size(), 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
name the 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 init(), new_output_stream(), 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
bsfc bitstream filter context created by av_bitstream_filter_init()
avctx AVCodecContext 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.
args arguments which specify the filter configuration, may be NULL
poutbuf pointer which is updated to point to the filtered buffer
poutbuf_size pointer which is updated to the filtered buffer size in bytes
buf buffer containing the data to filter
buf_size size in bytes of buf
keyframe set 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 availble in *poutbuf, and is distinct from the input buffer.

If the return value is 0, the output output buffer is not allocated and the output buffer 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 73 of file bitstream_filter.c.

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

void av_bitstream_filter_close ( AVBitStreamFilterContext *  bsf )

Release bitstream filter context.

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

Definition at line 62 of file bitstream_filter.c.

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

AVBitStreamFilter* av_bitstream_filter_next ( 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 show_bsfs().

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

Reallocate the given block if it is not large enough, otherwise do nothing.

See Also
av_realloc

Definition at line 65 of file utils.c.

Referenced by caf_write_packet(), decode_frame(), dirac_combine_frame(), ff_add_index_entry(), ff_af_queue_add(), ff_combine_frame(), ff_mms_asf_header_parser(), ff_subtitles_queue_insert(), ff_thread_release_buffer(), ff_vaapi_alloc_slice(), ff_vaapi_commit_slices(), ff_vdpau_add_buffer(), ff_vdpau_add_data_chunk(), flac_fifo_read_wrap(), get_stats(), mxg_update_cache(), read_frame(), shorten_decode_frame(), spdif_header_eac3(), and vda_h264_decode_slice().

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

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

Contrary to av_fast_realloc the current buffer contents might not be preserved and on error the old buffer is freed, thus no special handling to avoid memleaks is necessary.

Parameters
ptr pointer to pointer to already allocated buffer, overwritten with pointer to new buffer
size size of the buffer *ptr points to
min_size minimum size of *ptr buffer after returning, *ptr will be NULL and *size 0 if an error occurred.

Definition at line 98 of file utils.c.

Referenced by allocate_buffers(), ape_decode_frame(), audio_decode_frame(), codec_reinit(), dca_decode_frame(), decode_8(), decode_frame(), decode_i_frame(), decode_p_frame(), ff_h263_decode_frame(), ff_mpeg_update_thread_context(), gif_decode_frame(), gif_read_image(), id3v2_parse(), ljpeg_decode_rgb_scan(), mp_decode_frame(), parse_picture_segment(), pmp_packet(), reconfigure_at_keyframe(), spdif_header_dts4(), spdif_write_packet(), submit_packet(), svq3_decode_frame(), tak_decode_frame(), truemotion1_decode_header(), truemotion1_decode_init(), update_md5_sum(), and utvideo_encode_frame().

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 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.

Definition at line 103 of file utils.c.

Referenced by cdxl_decode_frame(), cllc_decode_frame(), decode_block(), decode_frame(), deinvert_buffer(), ebml_read_binary(), encode_frame(), ff_alloc_packet2(), ff_h264_decode_nal(), ff_mjpeg_find_marker(), init_buffers(), mimic_decode_frame(), mpc7_decode_frame(), and tqi_decode_frame().

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 115 of file utils.c.

Referenced by encode_frame().

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.

Definition at line 2945 of file utils.c.

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

void av_register_hwaccel ( AVHWAccel *  hwaccel )

Register the hardware accelerator hwaccel.

Definition at line 2995 of file utils.c.

AVHWAccel* av_hwaccel_next ( 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 3003 of file utils.c.

Referenced by ff_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.

mutex points to a (void *) where the lockmgr should store/get a pointer to a user allocated mutex. It's NULL upon AV_LOCK_CREATE and != NULL for all other ops.

Parameters
cb User defined callback. Note: FFmpeg may invoke calls to this callback during the call to av_lockmgr_register(). Thus, the application must be prepared to handle that. If cb is set to NULL the lockmgr will be unregistered. Also note that during unregistration the previously registered lockmgr callback may also be invoked.

Definition at line 3019 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 3151 of file utils.c.

Referenced by mkv_query_codec().

const char* avcodec_get_name ( enum AVCodecID  id )

Get the name of a codec.

Returns
a static string identifying the codec; never NULL
Examples:
doc/examples/muxing.c.

Definition at line 2473 of file utils.c.

Referenced by add_stream(), avcodec_string(), avformat_find_stream_info(), device_try_init(), flv_write_header(), flv_write_packet(), get_audio_flags(), init_input_stream(), mkv_write_codecprivate(), mkv_write_header(), mxf_parse_structural_metadata(), read_frame_internal(), rtp_write_header(), srt_write_header(), and transcode_init().

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 3171 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 150 of file utils.c.

Referenced by avcodec_close(), avcodec_find_encoder_by_name(), avcodec_open2(), ff_jpeg2000_init_component(), 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 155 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 2595 of file codec_desc.c.

Referenced by avcodec_get_name(), avcodec_open2(), is_intra_only(), and show_help_muxer().

const AVCodecDescriptor* avcodec_descriptor_next ( const AVCodecDescriptor *  prev )

Iterate over all codec descriptors known to libavcodec.

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

Definition at line 2605 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 2614 of file codec_desc.c.

Referenced by find_codec_or_die(), and show_help_codec().

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