FFmpeg: Utility functions

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...

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

enum AVMediaType avcodec_get_type (enum AVCodecID codec_id)

Get the type of the given codec. More...

const char * avcodec_get_name (enum AVCodecID id)

Get the name of a 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 AVCodecDescriptor * avcodec_descriptor_get (enum AVCodecID id)

const AVCodecDescriptor * avcodec_descriptor_next (const AVCodecDescriptor *prev)

Iterate over all codec descriptors known to libavcodec. More...

const AVCodecDescriptor * avcodec_descriptor_get_by_name (const char *name)

AVCPBProperties * av_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).

Enumeration Type Documentation

enum AVLockOp

Lock operation used by lockmgr.

Deprecated:: Deprecated together with av_lockmgr_register().

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 6047 of file avcodec.h.

Function Documentation

attribute_deprecated 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 buffer to place codec tag in

buf_size size in bytes of buf

codec_tag codec tag to assign

Returns: the length of the string that would have been generated if enough space had been available, excluding the trailing null

Deprecated:: see av_fourcc_make_string() and av_fourcc2str().

Definition at line 1147 of file utils.c.

void avcodec_string ( char * buf,

int buf_size,

AVCodecContext * enc,

int encode

)

Definition at line 1167 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 1362 of file utils.c.

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

Definition at line 1375 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 431 of file utils.c.

Referenced by init_context_defaults(), and thread_execute().

int avcodec_default_execute2 ( AVCodecContext * c,

int(*)(AVCodecContext *c2, void *arg2, int, int) func,

void * arg,

int * ret,

int count

)

Referenced by init_context_defaults().

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

Definition at line 372 of file utils.c.

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 1946 of file decode.c.

Referenced by compat_decode(), compute_crc_of_packets(), decoder_decode_frame(), process_command(), process_input(), and rewind_file().

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 1495 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_pcm_read_seek(), ff_put_wav_header(), 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_track(), mov_get_codec_tag(), mov_init(), mov_parse_stsd_audio(), mov_write_audio_tag(), mxf_handle_missing_index_segment(), mxf_set_audio_pts(), mxf_write_generic_sound_common(), mxf_write_header(), oma_read_header(), pcm_decode_frame(), pcm_decode_init(), pcm_encode_frame(), pcm_encode_init(), pcm_read_header(), pulse_read_packet(), read_header(), rso_read_header(), show_stream(), and wve_read_header().

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 1473 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_id the codec

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

Definition at line 1413 of file utils.c.

Referenced by av_get_bits_per_sample(), get_audio_frame_duration(), 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 1700 of file utils.c.

Referenced by do_streamcopy().

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.

Definition at line 1709 of file utils.c.

Referenced by adp_read_header(), build_frame_code(), ff_parse_specific_params(), ff_put_wav_header(), ff_voc_get_packet(), get_aiff_header(), mpegts_init(), msf_read_header(), rm_write_header(), rsd_read_header(), rtp_send_ilbc(), and swf_write_audio().

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).

Definition at line 42 of file bitstream_filter.c.

attribute_deprecated AVBitStreamFilterContext* av_bitstream_filter_init ( const char * name )

Deprecated:: the old bitstream filtering API (using AVBitStreamFilterContext) is deprecated. Use av_bsf_get_by_name(), av_bsf_alloc(), and av_bsf_init() from the new bitstream filtering API (using AVBSFContext).

Definition at line 51 of file bitstream_filter.c.

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

)

Deprecated:: the old bitstream filtering API (using AVBitStreamFilterContext) is deprecated. Use av_bsf_send_packet() and av_bsf_receive_packet() from the new bitstream filtering API (using AVBSFContext).

Definition at line 97 of file bitstream_filter.c.

attribute_deprecated void av_bitstream_filter_close ( AVBitStreamFilterContext * bsf )

Deprecated:: the old bitstream filtering API (using AVBitStreamFilterContext) is deprecated. Use av_bsf_free() from the new bitstream filtering API (using AVBSFContext).

Definition at line 83 of file bitstream_filter.c.

attribute_deprecated const AVBitStreamFilter* av_bitstream_filter_next ( const AVBitStreamFilter * f )

Deprecated:: the old bitstream filtering API (using AVBitStreamFilterContext) is deprecated. Use av_bsf_iterate() from the new bitstream filtering API (using AVBSFContext).

Definition at line 31 of file bitstream_filter.c.

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.

Definition at line 75 of file bitstream_filters.c.

Referenced by av_bitstream_filter_init(), av_bsf_list_append2(), bsfs_init(), cuvid_decode_init(), detect_stream_specific(), extract_extradata_check(), extract_extradata_init(), ff_stream_add_bitstream_filter(), new_output_stream(), and show_help_bsf().

const AVBitStreamFilter* av_bsf_iterate ( void ** opaque )

Iterate over all registered bitstream filters.

Parameters: opaque a 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

Definition at line 58 of file bitstream_filters.c.

Referenced by av_bitstream_filter_next(), av_bsf_get_by_name(), av_bsf_next(), ff_bsf_child_class_next(), and show_bsfs().

attribute_deprecated const AVBitStreamFilter* av_bsf_next ( void ** opaque )

Definition at line 70 of file bitstream_filters.c.

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: filter the filter for which to allocate an instance.

ctx a 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

Definition at line 81 of file bsf.c.

Referenced by av_bitstream_filter_filter(), av_bsf_get_null_filter(), av_bsf_list_append2(), av_bsf_list_finalize(), bsfs_init(), cuvid_decode_init(), detect_stream_specific(), extract_extradata_init(), ff_stream_add_bitstream_filter(), and new_output_stream().

int av_bsf_init ( AVBSFContext * ctx )

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

Definition at line 134 of file bsf.c.

Referenced by av_bitstream_filter_filter(), bsf_list_init(), bsfs_init(), cuvid_decode_init(), detect_stream_specific(), extract_extradata_init(), ff_stream_add_bitstream_filter(), init_output_bsfs(), and open_slave().

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: pkt the 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.

Definition at line 175 of file bsf.c.

Referenced by av_bitstream_filter_filter(), avcodec_send_packet(), bsf_list_filter(), bsfs_poll(), do_packet_auto_bsf(), extract_extradata(), filter_packet(), output_packet(), and tee_write_packet().

int av_bsf_receive_packet ( AVBSFContext * ctx,

AVPacket * pkt

)

Retrieve a filtered packet.

Parameters: [out] pkt this 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.

Definition at line 201 of file bsf.c.

Referenced by av_bitstream_filter_filter(), bsf_list_filter(), bsfs_poll(), do_packet_auto_bsf(), extract_extradata(), filter_packet(), output_packet(), and tee_write_packet().

void av_bsf_free ( AVBSFContext ** ctx )

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

Definition at line 35 of file bsf.c.

Referenced by av_bitstream_filter_close(), av_bitstream_filter_init(), av_bsf_alloc(), av_bsf_list_append2(), av_bsf_list_free(), avformat_find_stream_info(), bsf_list_close(), close_slave(), concat_read_close(), cuvid_decode_end(), cuvid_decode_init(), extract_extradata_init(), ff_decode_bsfs_uninit(), ff_stream_add_bitstream_filter(), ffmpeg_cleanup(), and free_stream().

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().

Definition at line 76 of file bsf.c.

Referenced by show_help_default().

AVBSFList* av_bsf_list_alloc ( void )

Allocate empty list of bitstream filters.

The list must be later freed by av_bsf_list_free() or finalized by av_bsf_list_finalize().

Returns: Pointer to AVBSFList on success, NULL in case of failure

Definition at line 399 of file bsf.c.

Referenced by av_bsf_list_parse_str().

void av_bsf_list_free ( AVBSFList ** lst )

Free list of bitstream filters.

Parameters: lst Pointer to pointer returned by av_bsf_list_alloc()

Definition at line 404 of file bsf.c.

Referenced by av_bsf_list_parse_str().

int av_bsf_list_append ( AVBSFList * lst,

AVBSFContext * bsf

)

Append bitstream filter to the list of bitstream filters.

Parameters: lst List to append to

bsf Filter context to be appended

Returns: >=0 on success, negative AVERROR in case of failure

Definition at line 417 of file bsf.c.

Referenced by av_bsf_list_append2().

int av_bsf_list_append2 ( AVBSFList * lst,

const char * bsf_name,

AVDictionary ** options

)

Construct new bitstream filter context given it's name and options and append it to the list of bitstream filters.

Parameters: lst List to append to

bsf_name Name of the bitstream filter

options Options for the bitstream filter, can be set to NULL

Returns: >=0 on success, negative AVERROR in case of failure

Definition at line 422 of file bsf.c.

Referenced by bsf_parse_single().

int av_bsf_list_finalize ( AVBSFList ** lst,

AVBSFContext ** bsf

)

Finalize list of bitstream filters.

This function will transform AVBSFList to single AVBSFContext, so the whole chain of bitstream filters can be treated as single filter freshly allocated by av_bsf_alloc(). If the call is successful, AVBSFList structure is freed and lst will be set to NULL. In case of failure, caller is responsible for freeing the structure by av_bsf_list_free()

Parameters: lst Filter list structure to be transformed

[out] bsf Pointer to be set to newly created AVBSFContext structure representing the chain of bitstream filters

Returns: >=0 on success, negative AVERROR in case of failure

Definition at line 451 of file bsf.c.

Referenced by av_bsf_list_parse_str().

int av_bsf_list_parse_str ( const char * str,

AVBSFContext ** bsf

)

Parse string describing list of bitstream filters and create single AVBSFContext describing the whole chain of bitstream filters.

Resulting AVBSFContext can be treated as any other AVBSFContext freshly allocated by av_bsf_alloc().

Parameters: str String describing chain of bitstream filters in format bsf1[=opt1=val1:opt2=val2][,bsf2]

[out] bsf Pointer to be set to newly created AVBSFContext structure representing the chain of bitstream filters

Returns: >=0 on success, negative AVERROR in case of failure

Definition at line 506 of file bsf.c.

Referenced by open_slave().

int av_bsf_get_null_filter ( AVBSFContext ** bsf )

Get null/pass-through bitstream filter.

Parameters: [out] bsf Pointer to be set to new instance of pass-through bitstream filter

Returns

Definition at line 544 of file bsf.c.

Referenced by av_bsf_list_parse_str(), and open_slave().

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.

Definition at line 70 of file utils.c.

Referenced by allocate_buffers(), allocate_buffers2(), ape_decode_frame(), cdxl_decode_frame(), cllc_decode_frame(), dcadec_decode_frame(), decode(), decode_block(), decode_frame(), decode_i_frame(), decode_idat_chunk(), decode_p_frame(), deinvert_buffer(), encode_frame(), ff_alloc_packet2(), ff_h2645_packet_split(), ff_mjpeg_find_marker(), ff_mpeg4_frame_end(), ff_mpv_reallocate_putbitbuffer(), generate_fake_vps(), mimic_decode_frame(), mp_decode_frame(), mpc7_decode_frame(), parse_nal_units(), parse_object_segment(), raw_decode(), svq1_decode_frame(), svq3_decode_frame(), tiff_unpack_fax(), tiff_unpack_strip(), tqi_decode_frame(), utvideo_encode_frame(), wavpack_encode_block(), wavpack_encode_frame(), wv_stereo(), and xpm_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 82 of file utils.c.

Referenced by decode_idat_chunk(), encode_frame(), and init_buffers().

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 1726 of file utils.c.

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

attribute_deprecated void av_register_hwaccel ( AVHWAccel * hwaccel )

Deprecated:: This function doesn't do anything.

Definition at line 1764 of file utils.c.

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.

Definition at line 1759 of file utils.c.

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

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: cb User 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.