FFmpeg: Utility functions

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)

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.

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.

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 5222 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 220 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: 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

Definition at line 2973 of file utils.c.

Referenced by apng_read_packet(), 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 2993 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 3165 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 1100 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

)

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:: decoding_encoding.c.

Definition at line 474 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 3206 of file utils.c.

Referenced by decoder_decode_frame(), 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 3295 of file utils.c.

Referenced by adpcm_encode_init(), aiff_write_header(), avcodec_encode_audio(), 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_parse_stsd_audio(), mov_write_audio_tag(), mov_write_header(), mxf_handle_missing_index_segment(), 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_packet(), 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 3274 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 3220 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 3313 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(), ff_voc_get_packet(), get_aiff_header(), rsd_read_header(), and rtp_send_ilbc().

void av_register_bitstream_filter ( AVBitStreamFilter * bsf )

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 detect_stream_specific(), init(), new_output_stream(), parse_bsfs(), qsv_decode_init(), 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 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 80 of file bitstream_filter.c.

Referenced by decode(), filter_packet(), init(), qsv_decode_frame(), 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 69 of file bitstream_filter.c.

Referenced by close_slaves(), ffmpeg_cleanup(), qsv_decode_close(), 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

)

Same behaviour av_fast_malloc but the buffer has additional FF_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 139 of file utils.c.

Referenced by allocate_buffers(), allocate_buffers2(), ape_decode_frame(), cdxl_decode_frame(), cllc_decode_frame(), decode_block(), decode_frame(), decode_i_frame(), decode_idat_chunk(), decode_p_frame(), deinvert_buffer(), ebml_read_binary(), encode_frame(), encode_thread(), ff_alloc_packet2(), ff_h264_decode_nal(), ff_mjpeg_find_marker(), ff_mpeg4_frame_end(), init_buffers(), mimic_decode_frame(), mp_decode_frame(), mpc7_decode_frame(), parse_object_segment(), raw_decode(), svq1_decode_frame(), svq3_decode_frame(), tiff_unpack_strip(), tqi_decode_frame(), utvideo_encode_frame(), wavpack_encode_block(), wavpack_encode_frame(), and wv_stereo().

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 151 of file utils.c.

Referenced by decode_idat_chunk(), and 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 3498 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] avc a pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct

[in] feature string containing the name of the missing feature

[in] want_sample indicates 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 3521 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] avc a pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct

[in] msg string 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 )

Definition at line 3551 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 3560 of file utils.c.

Referenced by find_hwaccel().

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.

Definition at line 3565 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 3732 of file utils.c.

Referenced by mkv_query_codec().

const char* avcodec_get_name ( enum AVCodecID id )

Get the name of a codec.