Types and functions for working with AVPacket. More...
Modules | |
Decoding | |
Data Structures | |
struct | AVPacket |
This structure stores compressed data. More... | |
Macros | |
#define | AV_PKT_FLAG_KEY 0x0001 |
The packet contains a keyframe. More... | |
#define | AV_PKT_FLAG_CORRUPT 0x0002 |
The packet content is corrupted. More... | |
Typedefs | |
typedef struct AVPacket | AVPacket |
This structure stores compressed data. More... | |
Enumerations | |
enum | AVPacketSideDataType { AV_PKT_DATA_PALETTE, AV_PKT_DATA_NEW_EXTRADATA, AV_PKT_DATA_PARAM_CHANGE, AV_PKT_DATA_H263_MB_INFO } |
enum | AVSideDataParamChangeFlags { AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT = 0x0001, AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT = 0x0002, AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE = 0x0004, AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS = 0x0008 } |
Functions | |
void | av_destruct_packet (AVPacket *pkt) |
Default packet destructor. More... | |
void | av_init_packet (AVPacket *pkt) |
Initialize optional fields of a packet with default values. More... | |
int | av_new_packet (AVPacket *pkt, int size) |
Allocate the payload of a packet and initialize its fields with default values. More... | |
void | av_shrink_packet (AVPacket *pkt, int size) |
Reduce packet size, correctly zeroing padding. More... | |
int | av_grow_packet (AVPacket *pkt, int grow_by) |
Increase packet size, correctly zeroing padding. More... | |
int | av_dup_packet (AVPacket *pkt) |
void | av_free_packet (AVPacket *pkt) |
Free a packet. More... | |
uint8_t * | av_packet_new_side_data (AVPacket *pkt, enum AVPacketSideDataType type, int size) |
Allocate new information of a packet. More... | |
int | av_packet_shrink_side_data (AVPacket *pkt, enum AVPacketSideDataType type, int size) |
Shrink the already allocated side data buffer. More... | |
uint8_t * | av_packet_get_side_data (AVPacket *pkt, enum AVPacketSideDataType type, int *size) |
Get side information from packet. More... | |
Types and functions for working with AVPacket.
Identify the syntax and semantics of the bitstream. The principle is roughly: Two decoders with the same ID can decode the same streams. Two encoders with the same ID can encode compatible streams. There may be slight deviations from the principle due to implementation details.
If you add a codec ID to this list, add it so that
After adding new codec IDs, do not forget to add an entry to the codec descriptor list and bump libavcodec minor version.
< preferred ID for MPEG-1/2 video decoding
< A dummy id pointing at the start of audio codecs
< preferred ID for decoding MPEG audio layer 1, 2 or 3
< as in Berlin toast format
< A dummy ID pointing at the start of subtitle codecs.
< raw UTF-8 text
< A dummy ID pointing at the start of various fake codecs.
< codec_id is not known (like AV_CODEC_ID_NONE) but lavf should attempt to identify it
< _FAKE_ codec to indicate a raw MPEG-2 TS
stream (only used by libavformat)
< _FAKE_ codec to indicate a MPEG-4 Systems
stream (only used by libavformat)
< Dummy codec for streams containing only metadata information.
< preferred ID for MPEG-1/2 video decoding
< A dummy id pointing at the start of audio codecs
< preferred ID for decoding MPEG audio layer 1, 2 or 3
< as in Berlin toast format
< A dummy ID pointing at the start of subtitle codecs.
< raw UTF-8 text
< A dummy ID pointing at the start of various fake codecs.
< codec_id is not known (like CODEC_ID_NONE) but lavf should attempt to identify it
< FAKE codec to indicate a raw MPEG-2 TS stream (only used by libavformat)
< _FAKE_ codec to indicate a MPEG-4 Systems
stream (only used by libavformat)
< Dummy codec for streams containing only metadata information.
This struct describes the properties of a single codec described by an AVCodecID.
Name of the codec described by this descriptor. It is non-empty and unique for each codec descriptor. It should contain alphanumeric characters and '_' only.
A more descriptive name for this codec. May be NULL.
Codec properties, a combination of AV_CODEC_PROP_* flags.
Codec uses only intra compression. Video codecs only.
Codec supports lossy compression. Audio and video codecs only.
Codec supports lossless compression. Audio and video codecs only.
Required number of additionally allocated bytes at the end of the input bitstream for decoding. This is mainly needed because some optimized bitstream readers read 32 or 64 bit at once and could read over the end.
Note: If the first 23 bits of the additional bytes are not 0, then damaged MPEG bitstreams could cause overread and segfault.
minimum encoding buffer size Used to avoid some checks during header writing.
motion estimation type.
< no search, that is use 0,0 vector whenever one is needed
< enhanced predictive zonal search
< reserved for experiments
< hexagon based search
< uneven multi-hexagon search
< iterative search
< transformed exhaustive search algorithm
< discard nothing
< discard useless packets like 0 size packets in avi
< discard all non reference
< discard all bidirectional frames
< discard all frames except keyframes
< discard all
< also ITU-R BT1361 / IEC 61966-2-4 / SMPTE RP177 Annex B
< also ITU-R BT601-6 625 / ITU-R BT1358 625 / ITU-R BT1700 625 PAL & SECAM
< also ITU-R BT601-6 525 / ITU-R BT1358 525 / ITU-R BT1700 NTSC
< functionally identical to above
< Not part of ABI
< also ITU-R BT1361
< also ITU-R BT470M / ITU-R BT1700 625 PAL & SECAM
< also ITU-R BT470BG
< Not part of ABI
< also ITU-R BT1361 / IEC 61966-2-4 xvYCC709 / SMPTE RP177 Annex B
< also ITU-R BT601-6 625 / ITU-R BT1358 625 / ITU-R BT1700 625 PAL & SECAM / IEC 61966-2-4 xvYCC601
< also ITU-R BT601-6 525 / ITU-R BT1358 525 / ITU-R BT1700 NTSC / functionally identical to above
< Used by Dirac / VC-2 and H.264 FRext, see ITU-T SG16
< Not part of ABI
< the normal 219*2^(n-8) "MPEG" YUV ranges
< the normal 2^n-1 "JPEG" YUV ranges
< Not part of ABI
X X 3 4 X X are luma samples, 1 2 1-6 are possible chroma positions X X 5 6 X 0 is undefined/unknown position
< mpeg2/4, h264 default
< mpeg1, jpeg, h263
< DV
< Not part of ABI
< Not part of ABI
The parent program guarantees that the input for B-frames containing streams is not written to for at least s->max_b_frames+1 frames, if this is not set the input will be copied.
Codec uses get_buffer() for allocating buffers and supports custom allocators. If not set, it might not use get_buffer() at all or use operations that assume the buffer was allocated by avcodec_default_get_buffer.
Encoder or decoder requires flushing with NULL input at the end in order to give the complete and correct output.
NOTE: If this flag is not set, the codec is guaranteed to never be fed with with NULL data. The user can still send NULL data to the public encode or decode function, but libavcodec will not pass it along to the codec unless this flag is set.
Decoders: The decoder has a non-zero delay and needs to be fed with avpkt->data=NULL, avpkt->size=0 at the end to get the delayed data until the decoder no longer returns frames.
Encoders: The encoder needs to be fed with NULL data at the end of encoding until the encoder no longer returns data.
NOTE: For encoders implementing the AVCodec.encode2() function, setting this flag also means that the encoder must set the pts and duration for each output packet. If this flag is not set, the pts and duration will be determined by libavcodec from the input frame.
Codec can be fed a final frame with a smaller size. This can be used to prevent truncation of the last audio samples.
Codec can export data for HW decoding (VDPAU).
Codec can output multiple frames per AVPacket Normally demuxers return one frame at a time, demuxers which do not do are connected to a parser to split what they return into proper frames. This flag is reserved to the very rare category of codecs which have a bitstream that cannot be split into frames without timeconsuming operations like full decoding. Demuxers carring such bitstreams thus may return multiple frames in a packet. This has many disadvantages like prohibiting stream copy in many cases thus it should only be considered as a last resort.
Codec is experimental and is thus avoided in favor of non experimental encoders
Codec should fill in channel configuration and samplerate instead of container
Codec is able to deal with negative linesizes
Codec supports frame-level multithreading.
Codec supports slice-based (or partition-based) multithreading.
Codec supports changed parameters at any point.
Codec supports avctx->thread_count == 0 (auto).
Audio encoder supports receiving a different number of samples in each call.
Pan Scan area. This specifies the area which should be displayed. Note there may be multiple such areas for one frame.
id
width and height in 1/16 pel
position of the top left corner in 1/16 pel for up to 3 fields/frames
Types and functions for working with AVPacket.
#define AV_PKT_FLAG_CORRUPT 0x0002 |
#define AV_PKT_FLAG_KEY 0x0001 |
This structure stores compressed data.
It is typically exported by demuxers and then passed as input to decoders, or received as output from encoders and then passed to muxers.
For video, it should typically contain one compressed frame. For audio it may contain several compressed frames.
AVPacket is one of the few structs in Libav, whose size is a part of public ABI. Thus it may be allocated on stack and no new fields can be added to it without libavcodec and libavformat major bump.
The semantics of data ownership depends on the destruct field. If it is set, the packet data is dynamically allocated and is valid indefinitely until av_free_packet() is called (which in turn calls the destruct callback to free the data). If destruct is not set, the packet data is typically backed by some static buffer somewhere and is only valid for a limited time (e.g. until the next read call when demuxing).
The side data is always allocated with av_malloc() and is freed in av_free_packet().
enum AVPacketSideDataType |
Enumerator | |
---|---|
AV_PKT_DATA_PALETTE | |
AV_PKT_DATA_NEW_EXTRADATA | |
AV_PKT_DATA_PARAM_CHANGE |
An AV_PKT_DATA_PARAM_CHANGE side data packet is laid out as follows: u32le param_flags
if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT)
s32le channel_count
if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT)
u64le channel_layout
if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE)
s32le sample_rate
if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS)
s32le width
s32le height
|
AV_PKT_DATA_H263_MB_INFO |
An AV_PKT_DATA_H263_MB_INFO side data packet contains a number of structures with info about macroblocks relevant to splitting the packet into smaller packets on macroblock edges (e.g. as for RFC 2190). That is, it does not necessarily contain info about all macroblocks, as long as the distance between macroblocks in the info is smaller than the target payload size. Each MB info structure is 12 bytes, and is laid out as follows: |
Default packet destructor.
Definition at line 28 of file avpacket.c.
Referenced by av_dup_packet(), av_new_packet(), do_streamcopy(), ff_id3v2_parse_apic(), ff_rtp_finalize_packet(), mkv_write_trailer(), new_pes_packet(), parse_picture(), qt_rtp_parse_packet(), vfw_read_close(), and write_frame().
int av_dup_packet | ( | AVPacket * | pkt | ) |
Definition at line 122 of file avpacket.c.
Referenced by av_read_frame(), avformat_find_stream_info(), ff_interleave_add_packet(), packet_queue_put(), and parse_packet().
Free a packet.
pkt | packet to free |
Definition at line 153 of file avpacket.c.
Referenced by adx_read_packet(), amr_read_packet(), asf_read_picture(), asf_read_pts(), asf_reset_header(), asfrtp_parse_packet(), audio_decode_frame(), audio_encode_example(), audio_read_packet(), av_get_packet(), av_interleaved_write_frame(), av_write_trailer(), avcodec_encode_audio2(), avcodec_encode_video2(), avformat_free_context(), avi_read_close(), avs_read_video_packet(), cdxl_read_packet(), cin_read_packet(), decode_thread(), dfa_read_packet(), dxa_read_packet(), ea_read_packet(), encode_frame(), estimate_timings_from_pts(), extract_mpeg4_header(), ff_asf_parse_packet(), ff_raw_read_partial_packet(), ff_read_packet(), ff_rm_free_rmstream(), ffm_read_packet(), flic_read_packet(), fourxm_read_packet(), free_packet_buffer(), free_packet_list(), free_pkt_fifo(), free_variant_list(), g723_1_read_packet(), gsm_read_packet(), hls_read_seek(), http_prepare_data(), ilbc_read_packet(), img_read_packet(), ingenient_read_packet(), interleave_packet(), load_ipmovie_packet(), lxf_read_packet(), main(), matroska_clear_queue(), matroska_merge_packets(), mmf_read_packet(), movie_get_frame(), mp3_queue_flush(), mpc_read_packet(), mpc_read_seek(), mpegts_raw_read_packet(), mxf_interleave_get_packet(), nc_read_packet(), nsv_read_close(), nuv_packet(), packet_queue_flush(), parse_packet(), process_input(), pulse_read_packet(), qt_rtp_parse_packet(), read_frame_internal(), read_packet(), rl2_read_packet(), rm_assemble_video_frame(), rm_read_packet(), rpl_read_packet(), sap_fetch_packet(), search_hi_lo_keyframes(), seek_frame_generic(), seek_subtitle(), spdif_read_packet(), str_read_close(), str_read_packet(), stream_component_close(), subtitle_thread(), thp_read_packet(), video_encode_example(), video_thread(), vmd_read_packet(), vqf_read_packet(), wc3_read_close(), write_frame(), wsvqa_read_packet(), wv_read_packet(), wv_read_seek(), xiph_handle_packet(), xvid_encode_frame(), yop_read_close(), yop_read_packet(), and yop_read_seek().
int av_grow_packet | ( | AVPacket * | pkt, |
int | grow_by | ||
) |
Increase packet size, correctly zeroing padding.
pkt | packet |
grow_by | number of bytes by which to increase the size of the packet |
Definition at line 83 of file avpacket.c.
Referenced by av_append_packet(), and matroska_merge_packets().
Initialize optional fields of a packet with default values.
Note, this does not touch the data and size members, which have to be initialized separately.
pkt | packet |
Definition at line 42 of file avpacket.c.
Referenced by audio_decode_example(), audio_encode_example(), av_new_packet(), avcodec_encode_audio2(), avcodec_encode_video2(), avformat_find_stream_info(), avi_write_packet(), avpriv_dv_produce_packet(), dc1394_read_common(), decode_thread(), do_audio_out(), do_streamcopy(), do_subtitle_out(), do_video_out(), dv_extract_audio_info(), encode_frame(), ff_alloc_packet(), ff_id3v2_parse_apic(), ff_interleave_packet_per_dts(), ff_mov_add_hinted_packet(), ff_read_packet(), ff_rtp_finalize_packet(), flush_encoders(), main(), mkv_write_header(), mpegts_write_packet_internal(), mxf_interleave_get_packet(), new_pes_packet(), output_packet(), parse_packet(), parse_picture(), qt_rtp_parse_packet(), read_frame_internal(), reset_packet(), show_packets(), sp5x_decode_frame(), v4l2_read_packet(), video_decode_example(), video_encode_example(), wc3_read_header(), write_audio_frame(), write_video_frame(), and x11grab_read_packet().
int av_new_packet | ( | AVPacket * | pkt, |
int | size | ||
) |
Allocate the payload of a packet and initialize its fields with default values.
pkt | packet |
size | wanted payload size |
Definition at line 56 of file avpacket.c.
Referenced by aac_parse_packet(), amr_handle_packet(), amr_read_packet(), ape_read_packet(), audio_read_packet(), av_get_packet(), av_grow_packet(), avisynth_read_packet(), avs_read_video_packet(), bmv_read_packet(), cdxl_read_packet(), cin_read_packet(), decode_frame(), dxa_read_packet(), encode_frame(), fbdev_read_packet(), ff_alloc_packet(), ff_asf_parse_packet(), ff_h263_handle_packet(), ff_interleave_new_audio_packet(), ff_raw_read_partial_packet(), ff_rm_retrieve_cache(), ffm_read_packet(), film_read_packet(), flic_read_packet(), fourxm_read_packet(), g723_1_read_packet(), grab_read_packet(), h264_handle_packet(), ilbc_read_packet(), img_read_packet(), ingenient_read_packet(), latm_parse_packet(), load_ipmovie_packet(), lxf_read_packet(), matroska_parse_frame(), matroska_parse_rm_audio(), mmf_read_packet(), mpc_read_packet(), mpegts_raw_read_packet(), nuv_packet(), ogg_read_packet(), pulse_read_packet(), qdm2_restore_block(), qt_rtp_parse_packet(), read_frame(), read_packet(), return_stored_frame(), rm_assemble_video_frame(), rm_read_audio_stream_info(), roq_read_packet(), rtp_parse_packet_internal(), seq_read_packet(), siff_read_packet(), smacker_read_packet(), spdif_read_packet(), srt_read_packet(), store_packet(), str_read_packet(), supply_new_packets(), svq1_encode_frame(), swf_read_packet(), videostream_cb(), vmd_read_packet(), vqf_read_packet(), wsaud_read_packet(), wsvqa_read_packet(), wv_read_packet(), xiph_handle_packet(), xmv_fetch_video_packet(), xvid_encode_frame(), and yop_read_packet().
uint8_t* av_packet_get_side_data | ( | AVPacket * | pkt, |
enum AVPacketSideDataType | type, | ||
int * | size | ||
) |
Get side information from packet.
pkt | packet |
type | desired side information type |
size | pointer for side information size to store (optional) |
Definition at line 190 of file avpacket.c.
Referenced by aac_decode_frame(), apply_param_change(), cinepak_decode_frame(), decode_frame(), idcin_decode_frame(), ipvideo_decode_frame(), msrle_decode_frame(), msvideo1_decode_frame(), qtrle_decode_frame(), raw_decode(), rtp_write_packet(), and smc_decode_frame().
uint8_t* av_packet_new_side_data | ( | AVPacket * | pkt, |
enum AVPacketSideDataType | type, | ||
int | size | ||
) |
Allocate new information of a packet.
pkt | packet |
type | side information type |
size | side information size |
Definition at line 165 of file avpacket.c.
Referenced by ff_add_param_change(), ff_asf_parse_packet(), ff_MPV_encode_picture(), flv_read_packet(), idcin_read_packet(), load_ipmovie_packet(), mov_read_packet(), and read_frame().
int av_packet_shrink_side_data | ( | AVPacket * | pkt, |
enum AVPacketSideDataType | type, | ||
int | size | ||
) |
Shrink the already allocated side data buffer.
pkt | packet |
type | side information type |
size | new side information size |
Definition at line 205 of file avpacket.c.
Referenced by ff_MPV_encode_picture().
Reduce packet size, correctly zeroing padding.
pkt | packet |
size | new size |
Definition at line 75 of file avpacket.c.
Referenced by av_append_packet(), av_get_packet(), cdxl_read_packet(), cin_read_packet(), ff_asf_parse_packet(), libopus_encode(), mxf_decrypt_triplet(), mxf_get_d10_aes3_packet(), nuv_packet(), and yop_read_packet().