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描述：主要扩展API的结构体
New fields can be added to the end with minor version bumps. Removal, reordering and changes to existing fields require a major version bump. You can use AVOptions (av_opt* / av_set/get*()) to access these fields from user applications. The name string for AVOptions options matches the associated command line parameter name and can be found in libavcodec/options_table.h The AVOption/command line parameter names differ in some cases from the C structure field names for historic reasons or brevity. sizeof(AVCodecContext) must not be used outside libav*.
typedef struct AVCodecContext { /**
* information on struct for av_log
* - set by avcodec_alloc_context3
*/ const AVClass *av_class; int log_level_offset; enum AVMediaType codec_type; /* see AVMEDIA_TYPE_xxx */ const struct AVCodec *codec;
#if FF_API_CODEC_NAME /**
* @deprecated this field is not used for anything in libavcodec
*/ attribute_deprecated char codec_name[32];
#endif enum AVCodecID codec_id; /* see AV_CODEC_ID_xxx */ /**
* fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
* This is used to work around some encoder bugs.
* A demuxer should set this to what is stored in the field used to identify the codec.
* If there are multiple such fields in a container then the demuxer should choose the one
* which maximizes the information about the used codec.
* If the codec tag field in a container is larger than 32 bits then the demuxer should
* remap the longer ID to 32 bits with a table or other structure. Alternatively a new
* extra_codec_tag + size could be added but for this a clear advantage must be demonstrated
* first.
* - encoding: Set by user, if not then the default based on codec_id will be used.
* - decoding: Set by user, will be converted to uppercase by libavcodec during init.
*/ unsigned int codec_tag;
#if FF_API_STREAM_CODEC_TAG /**
* @deprecated this field is unused
*/ attribute_deprecated
unsigned int stream_codec_tag;
#endif void *priv_data; /**
* Private context used for internal data.
*
* Unlike priv_data, this is not codec-specific. It is used in general
* libavcodec functions.
*/ struct AVCodecInternal *internal; /**
* Private data of the user, can be used to carry app specific stuff.
* - encoding: Set by user.
* - decoding: Set by user.
*/ void *opaque; /**
* the average bitrate
* - encoding: Set by user; unused for constant quantizer encoding.
* - decoding: Set by user, may be overwritten by libavcodec
* if this info is available in the stream
*/ int64_t bit_rate; /**
* number of bits the bitstream is allowed to diverge from the reference.
* the reference can be CBR (for CBR pass1) or VBR (for pass2)
* - encoding: Set by user; unused for constant quantizer encoding.
* - decoding: unused
*/ int bit_rate_tolerance; /**
* Global quality for codecs which cannot change it per frame.
* This should be proportional to MPEG-1/2/4 qscale.
* - encoding: Set by user.
* - decoding: unused
*/ int global_quality; /**
* - encoding: Set by user.
* - decoding: unused
*/ int compression_level;
#define FF_COMPRESSION_DEFAULT -1 /**
* AV_CODEC_FLAG_*.
* - encoding: Set by user.
* - decoding: Set by user.
*/ int flags; /**
* AV_CODEC_FLAG2_*
* - encoding: Set by user.
* - decoding: Set by user.
*/ int flags2; /**
* some codecs need / can use extradata like Huffman tables.
* MJPEG: Huffman tables
* rv10: additional flags
* MPEG-4: global headers (they can be in the bitstream or here)
* The allocated memory should be AV_INPUT_BUFFER_PADDING_SIZE bytes larger
* than extradata_size to avoid problems if it is read with the bitstream reader.
* The bytewise contents of extradata must not depend on the architecture or CPU endianness.
* - encoding: Set/allocated/freed by libavcodec.
* - decoding: Set/allocated/freed by user.
*/ uint8_t *extradata; int extradata_size; /**
* This is the fundamental unit of time (in seconds) in terms
* of which frame timestamps are represented. For fixed-fps content,
* timebase should be 1/framerate and timestamp increments should be
* identically 1.
* This often, but not always is the inverse of the frame rate or field rate
* for video. 1/time_base is not the average frame rate if the frame rate is not
* constant.
*
* Like containers, elementary streams also can store timestamps, 1/time_base
* is the unit in which these timestamps are specified.
* As example of such codec time base see ISO/IEC 14496-2:2001(E)
* vop_time_increment_resolution and fixed_vop_rate
* (fixed_vop_rate == 0 implies that it is different from the framerate)
*
* - encoding: MUST be set by user.
* - decoding: the use of this field for decoding is deprecated.
* Use framerate instead.
*/ AVRational time_base; /**
* For some codecs, the time base is closer to the field rate than the frame rate.
* Most notably, H.264 and MPEG-2 specify time_base as half of frame duration
* if no telecine is used ...
*
* Set to time_base ticks per frame. Default 1, e.g., H.264/MPEG-2 set it to 2.
*/ int ticks_per_frame; /**
* Codec delay.
*
* Encoding: Number of frames delay there will be from the encoder input to
* the decoder output. (we assume the decoder matches the spec)
* Decoding: Number of frames delay in addition to what a standard decoder
* as specified in the spec would produce.
*
* Video:
* Number of frames the decoded output will be delayed relative to the
* encoded input.
*
* Audio:
* For encoding, this field is unused (see initial_padding).
*
* For decoding, this is the number of samples the decoder needs to
* output before the decoder's output is valid. When seeking, you should
* start decoding this many samples prior to your desired seek point.
*
* - encoding: Set by libavcodec.
* - decoding: Set by libavcodec.
*/ int delay; /* video only */ /**
* picture width / height.
*
* @note Those fields may not match the values of the last
* AVFrame output by avcodec_decode_video2 due frame
* reordering.
*
* - encoding: MUST be set by user.
* - decoding: May be set by the user before opening the decoder if known e.g.
* from the container. Some decoders will require the dimensions
* to be set by the caller. During decoding, the decoder may
* overwrite those values as required while parsing the data.
*/ int width, height; /**
* Bitstream width / height, may be different from width/height e.g. when
* the decoded frame is cropped before being output or lowres is enabled.
*
* @note Those field may not match the value of the last
* AVFrame output by avcodec_receive_frame() due frame
* reordering.
*
* - encoding: unused
* - decoding: May be set by the user before opening the decoder if known
* e.g. from the container. During decoding, the decoder may
* overwrite those values as required while parsing the data.
*/ int coded_width, coded_height;
#if FF_API_ASPECT_EXTENDED
#define FF_ASPECT_EXTENDED 15 #endif /**
* the number of pictures in a group of pictures, or 0 for intra_only
* - encoding: Set by user.
* - decoding: unused
*/ int gop_size; /**
* Pixel format, see AV_PIX_FMT_xxx.
* May be set by the demuxer if known from headers.
* May be overridden by the decoder if it knows better.
*
* @note This field may not match the value of the last
* AVFrame output by avcodec_receive_frame() due frame
* reordering.
*
* - encoding: Set by user.
* - decoding: Set by user if known, overridden by libavcodec while
* parsing the data.
*/ enum AVPixelFormat pix_fmt;
#if FF_API_MOTION_EST /**
* This option does nothing
* @deprecated use codec private options instead
*/ attribute_deprecated int me_method;
#endif /**
* If non NULL, 'draw_horiz_band' is called by the libavcodec
* decoder to draw a horizontal band. It improves cache usage. Not
* all codecs can do that. You must check the codec capabilities
* beforehand.
* When multithreading is used, it may be called from multiple threads
* at the same time; threads might draw different parts of the same AVFrame,
* or multiple AVFrames, and there is no guarantee that slices will be drawn
* in order.
* The function is also used by hardware acceleration APIs.
* It is called at least once during frame decoding to pass
* the data needed for hardware render.
* In that mode instead of pixel data, AVFrame points to
* a structure specific to the acceleration API. The application
* reads the structure and can change some fields to indicate progress
* or mark state.
* - encoding: unused
* - decoding: Set by user.
* @param height the height of the slice
* @param y the y position of the slice
* @param type 1->top field, 2->bottom field, 3->frame
* @param offset offset into the AVFrame.data from which the slice should be read
*/ void (*draw_horiz_band)(struct AVCodecContext *s, const AVFrame *src, int offset[AV_NUM_DATA_POINTERS], int y, int type, int height); /**
* callback to negotiate the pixelFormat
* @param fmt is the list of formats which are supported by the codec,
* it is terminated by -1 as 0 is a valid format, the formats are ordered by quality.
* The first is always the native one.
* @note The callback may be called again immediately if initialization for
* the selected (hardware-accelerated) pixel format failed.
* @warning Behavior is undefined if the callback returns a value not
* in the fmt list of formats.
* @return the chosen format
* - encoding: unused
* - decoding: Set by user, if not set the native format will be chosen.
*/ enum AVPixelFormat (*get_format)(struct AVCodecContext *s, const enum AVPixelFormat * fmt); /**
* maximum number of B-frames between non-B-frames
* Note: The output will be delayed by max_b_frames+1 relative to the input.
* - encoding: Set by user.
* - decoding: unused
*/ int max_b_frames; /**
* qscale factor between IP and B-frames
* If > 0 then the last P-frame quantizer will be used (q= lastp_q*factor+offset).
* If < 0 then normal ratecontrol will be done (q= -normal_q*factor+offset).
* - encoding: Set by user.
* - decoding: unused
*/ float b_quant_factor;
#if FF_API_RC_STRATEGY /** @deprecated use codec private option instead */ attribute_deprecated int rc_strategy;
#define FF_RC_STRATEGY_XVID 1 #endif
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int b_frame_strategy;
#endif /**
* qscale offset between IP and B-frames
* - encoding: Set by user.
* - decoding: unused
*/ float b_quant_offset; /**
* Size of the frame reordering buffer in the decoder.
* For MPEG-2 it is 1 IPB or 0 low delay IP.
* - encoding: Set by libavcodec.
* - decoding: Set by libavcodec.
*/ int has_b_frames;
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int mpeg_quant;
#endif /**
* qscale factor between P- and I-frames
* If > 0 then the last P-frame quantizer will be used (q = lastp_q * factor + offset).
* If < 0 then normal ratecontrol will be done (q= -normal_q*factor+offset).
* - encoding: Set by user.
* - decoding: unused
*/ float i_quant_factor; /**
* qscale offset between P and I-frames
* - encoding: Set by user.
* - decoding: unused
*/ float i_quant_offset; /**
* luminance masking (0-> disabled)
* - encoding: Set by user.
* - decoding: unused
*/ float lumi_masking; /**
* temporary complexity masking (0-> disabled)
* - encoding: Set by user.
* - decoding: unused
*/ float temporal_cplx_masking; /**
* spatial complexity masking (0-> disabled)
* - encoding: Set by user.
* - decoding: unused
*/ float spatial_cplx_masking; /**
* p block masking (0-> disabled)
* - encoding: Set by user.
* - decoding: unused
*/ float p_masking; /**
* darkness masking (0-> disabled)
* - encoding: Set by user.
* - decoding: unused
*/ float dark_masking; /**
* slice count
* - encoding: Set by libavcodec.
* - decoding: Set by user (or 0).
*/ int slice_count;
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int prediction_method;
#define FF_PRED_LEFT 0 #define FF_PRED_PLANE 1 #define FF_PRED_MEDIAN 2 #endif /**
* slice offsets in the frame in bytes
* - encoding: Set/allocated by libavcodec.
* - decoding: Set/allocated by user (or NULL).
*/ int *slice_offset; /**
* sample aspect ratio (0 if unknown)
* That is the width of a pixel divided by the height of the pixel.
* Numerator and denominator must be relatively prime and smaller than 256 for some video standards.
* - encoding: Set by user.
* - decoding: Set by libavcodec.
*/ AVRational sample_aspect_ratio; /**
* motion estimation comparison function
* - encoding: Set by user.
* - decoding: unused
*/ int me_cmp; /**
* subpixel motion estimation comparison function
* - encoding: Set by user.
* - decoding: unused
*/ int me_sub_cmp; /**
* macroblock comparison function (not supported yet)
* - encoding: Set by user.
* - decoding: unused
*/ int mb_cmp; /**
* interlaced DCT comparison function
* - encoding: Set by user.
* - decoding: unused
*/ int ildct_cmp;
#define FF_CMP_SAD 0 #define FF_CMP_SSE 1 #define FF_CMP_SATD 2 #define FF_CMP_DCT 3 #define FF_CMP_PSNR 4 #define FF_CMP_BIT 5 #define FF_CMP_RD 6 #define FF_CMP_ZERO 7 #define FF_CMP_VSAD 8 #define FF_CMP_VSSE 9 #define FF_CMP_NSSE 10 #define FF_CMP_W53 11 #define FF_CMP_W97 12 #define FF_CMP_DCTMAX 13 #define FF_CMP_DCT264 14 #define FF_CMP_CHROMA 256 /**
* ME diamond size & shape
* - encoding: Set by user.
* - decoding: unused
*/ int dia_size; /**
* amount of previous MV predictors (2a+1 x 2a+1 square)
* - encoding: Set by user.
* - decoding: unused
*/ int last_predictor_count;
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int pre_me;
#endif /**
* motion estimation prepass comparison function
* - encoding: Set by user.
* - decoding: unused
*/ int me_pre_cmp; /**
* ME prepass diamond size & shape
* - encoding: Set by user.
* - decoding: unused
*/ int pre_dia_size; /**
* subpel ME quality
* - encoding: Set by user.
* - decoding: unused
*/ int me_subpel_quality;
#if FF_API_AFD /**
* DTG active format information (additional aspect ratio
* information only used in DVB MPEG-2 transport streams)
* 0 if not set.
*
* - encoding: unused
* - decoding: Set by decoder.
* @deprecated Deprecated in favor of AVSideData
*/ attribute_deprecated int dtg_active_format;
#define FF_DTG_AFD_SAME 8 #define FF_DTG_AFD_4_3 9 #define FF_DTG_AFD_16_9 10 #define FF_DTG_AFD_14_9 11 #define FF_DTG_AFD_4_3_SP_14_9 13 #define FF_DTG_AFD_16_9_SP_14_9 14 #define FF_DTG_AFD_SP_4_3 15 #endif /* FF_API_AFD */ /**
* maximum motion estimation search range in subpel units
* If 0 then no limit.
*
* - encoding: Set by user.
* - decoding: unused
*/ int me_range;
#if FF_API_QUANT_BIAS /**
* @deprecated use encoder private option instead
*/ attribute_deprecated int intra_quant_bias;
#define FF_DEFAULT_QUANT_BIAS 999999 /**
* @deprecated use encoder private option instead
*/ attribute_deprecated int inter_quant_bias;
#endif /**
* slice flags
* - encoding: unused
* - decoding: Set by user.
*/ int slice_flags;
#define SLICE_FLAG_CODED_ORDER 0x0001 ///< draw_horiz_band() is called in coded order instead of display #define SLICE_FLAG_ALLOW_FIELD 0x0002 ///< allow draw_horiz_band() with field slices (MPEG-2 field pics) #define SLICE_FLAG_ALLOW_PLANE 0x0004 ///< allow draw_horiz_band() with 1 component at a time (SVQ1) #if FF_API_XVMC /**
* XVideo Motion Acceleration
* - encoding: forbidden
* - decoding: set by decoder
* @deprecated XvMC doesn't need it anymore.
*/ attribute_deprecated int xvmc_acceleration;
#endif /* FF_API_XVMC */ /**
* macroblock decision mode
* - encoding: Set by user.
* - decoding: unused
*/ int mb_decision;
#define FF_MB_DECISION_SIMPLE 0 ///< uses mb_cmp #define FF_MB_DECISION_BITS 1 ///< chooses the one which needs the fewest bits #define FF_MB_DECISION_RD 2 ///< rate distortion /**
* custom intra quantization matrix
* - encoding: Set by user, can be NULL.
* - decoding: Set by libavcodec.
*/ uint16_t *intra_matrix; /**
* custom inter quantization matrix
* - encoding: Set by user, can be NULL.
* - decoding: Set by libavcodec.
*/ uint16_t *inter_matrix;
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int scenechange_threshold; /** @deprecated use encoder private options instead */ attribute_deprecated int noise_reduction;
#endif
#if FF_API_MPV_OPT /**
* @deprecated this field is unused
*/ attribute_deprecated int me_threshold; /**
* @deprecated this field is unused
*/ attribute_deprecated int mb_threshold;
#endif /**
* precision of the intra DC coefficient - 8
* - encoding: Set by user.
* - decoding: Set by libavcodec
*/ int intra_dc_precision; /**
* Number of macroblock rows at the top which are skipped.
* - encoding: unused
* - decoding: Set by user.
*/ int skip_top; /**
* Number of macroblock rows at the bottom which are skipped.
* - encoding: unused
* - decoding: Set by user.
*/ int skip_bottom;
#if FF_API_MPV_OPT /**
* @deprecated use encoder private options instead
*/ attribute_deprecated float border_masking;
#endif /**
* minimum MB Lagrange multiplier
* - encoding: Set by user.
* - decoding: unused
*/ int mb_lmin; /**
* maximum MB Lagrange multiplier
* - encoding: Set by user.
* - decoding: unused
*/ int mb_lmax;
#if FF_API_PRIVATE_OPT /**
* @deprecated use encoder private options instead
*/ attribute_deprecated int me_penalty_compensation;
#endif /**
* - encoding: Set by user.
* - decoding: unused
*/ int bidir_refine;
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int brd_scale;
#endif /**
* minimum GOP size
* - encoding: Set by user.
* - decoding: unused
*/ int keyint_min; /**
* number of reference frames
* - encoding: Set by user.
* - decoding: Set by lavc.
*/ int refs;
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int chromaoffset;
#endif
#if FF_API_UNUSED_MEMBERS /**
* Multiplied by qscale for each frame and added to scene_change_score.
* - encoding: Set by user.
* - decoding: unused
*/ attribute_deprecated int scenechange_factor;
#endif /**
* Note: Value depends upon the compare function used for fullpel ME.
* - encoding: Set by user.
* - decoding: unused
*/ int mv0_threshold;
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int b_sensitivity;
#endif /**
* Chromaticity coordinates of the source primaries.
* - encoding: Set by user
* - decoding: Set by libavcodec
*/ enum AVColorPrimaries color_primaries; /**
* Color Transfer Characteristic.
* - encoding: Set by user
* - decoding: Set by libavcodec
*/ enum AVColorTransferCharacteristic color_trc; /**
* YUV colorspace type.
* - encoding: Set by user
* - decoding: Set by libavcodec
*/ enum AVColorSpace colorspace; /**
* MPEG vs JPEG YUV range.
* - encoding: Set by user
* - decoding: Set by libavcodec
*/ enum AVColorRange color_range; /**
* This defines the location of chroma samples.
* - encoding: Set by user
* - decoding: Set by libavcodec
*/ enum AVChromaLocation chroma_sample_location; /**
* Number of slices.
* Indicates number of picture subdivisions. Used for parallelized
* decoding.
* - encoding: Set by user
* - decoding: unused
*/ int slices; /** Field order
* - encoding: set by libavcodec
* - decoding: Set by user.
*/ enum AVFieldOrder field_order; /* audio only */ int sample_rate; ///< samples per second int channels; ///< number of audio channels /**
* audio sample format
* - encoding: Set by user.
* - decoding: Set by libavcodec.
*/ enum AVSampleFormat sample_fmt; ///< sample format /* The following data should not be initialized. */ /**
* Number of samples per channel in an audio frame.
*
* - encoding: set by libavcodec in avcodec_open2(). Each submitted frame
* except the last must contain exactly frame_size samples per channel.
* May be 0 when the codec has AV_CODEC_CAP_VARIABLE_FRAME_SIZE set, then the
* frame size is not restricted.
* - decoding: may be set by some decoders to indicate constant frame size
*/ int frame_size; /**
* Frame counter, set by libavcodec.
*
* - decoding: total number of frames returned from the decoder so far.
* - encoding: total number of frames passed to the encoder so far.
*
* @note the counter is not incremented if encoding/decoding resulted in
* an error.
*/ int frame_number; /**
* number of bytes per packet if constant and known or 0
* Used by some WAV based audio codecs.
*/ int block_align; /**
* Audio cutoff bandwidth (0 means "automatic")
* - encoding: Set by user.
* - decoding: unused
*/ int cutoff; /**
* Audio channel layout.
* - encoding: set by user.
* - decoding: set by user, may be overwritten by libavcodec.
*/ uint64_t channel_layout; /**
* Request decoder to use this channel layout if it can (0 for default)
* - encoding: unused
* - decoding: Set by user.
*/ uint64_t request_channel_layout; /**
* Type of service that the audio stream conveys.
* - encoding: Set by user.
* - decoding: Set by libavcodec.
*/ enum AVAudioServiceType audio_service_type; /**
* desired sample format
* - encoding: Not used.
* - decoding: Set by user.
* Decoder will decode to this format if it can.
*/ enum AVSampleFormat request_sample_fmt; /**
* This callback is called at the beginning of each frame to get data
* buffer(s) for it. There may be one contiguous buffer for all the data or
* there may be a buffer per each data plane or anything in between. What
* this means is, you may set however many entries in buf[] you feel necessary.
* Each buffer must be reference-counted using the AVBuffer API (see description
* of buf[] below).
*
* The following fields will be set in the frame before this callback is
* called:
* - format
* - width, height (video only)
* - sample_rate, channel_layout, nb_samples (audio only)
* Their values may differ from the corresponding values in
* AVCodecContext. This callback must use the frame values, not the codec
* context values, to calculate the required buffer size.
*
* This callback must fill the following fields in the frame:
* - data[]
* - linesize[]
* - extended_data:
* * if the data is planar audio with more than 8 channels, then this
* callback must allocate and fill extended_data to contain all pointers
* to all data planes. data[] must hold as many pointers as it can.
* extended_data must be allocated with av_malloc() and will be freed in
* av_frame_unref().
* * otherwise extended_data must point to data
* - buf[] must contain one or more pointers to AVBufferRef structures. Each of
* the frame's data and extended_data pointers must be contained in these. That
* is, one AVBufferRef for each allocated chunk of memory, not necessarily one
* AVBufferRef per data[] entry. See: av_buffer_create(), av_buffer_alloc(),
* and av_buffer_ref().
* - extended_buf and nb_extended_buf must be allocated with av_malloc() by
* this callback and filled with the extra buffers if there are more
* buffers than buf[] can hold. extended_buf will be freed in
* av_frame_unref().
*
* If AV_CODEC_CAP_DR1 is not set then get_buffer2() must call
* avcodec_default_get_buffer2() instead of providing buffers allocated by
* some other means.
*
* Each data plane must be aligned to the maximum required by the target
* CPU.
*
* @see avcodec_default_get_buffer2()
*
* Video:
*
* If AV_GET_BUFFER_FLAG_REF is set in flags then the frame may be reused
* (read and/or written to if it is writable) later by libavcodec.
*
* avcodec_align_dimensions2() should be used to find the required width and
* height, as they normally need to be rounded up to the next multiple of 16.
*
* Some decoders do not support linesizes changing between frames.
*
* If frame multithreading is used and thread_safe_callbacks is set,
* this callback may be called from a different thread, but not from more
* than one at once. Does not need to be reentrant.
*
* @see avcodec_align_dimensions2()
*
* Audio:
*
* Decoders request a buffer of a particular size by setting
* AVFrame.nb_samples prior to calling get_buffer2(). The decoder may,
* however, utilize only part of the buffer by setting AVFrame.nb_samples
* to a smaller value in the output frame.
*
* As a convenience, av_samples_get_buffer_size() and
* av_samples_fill_arrays() in libavutil may be used by custom get_buffer2()
* functions to find the required data size and to fill data pointers and
* linesize. In AVFrame.linesize, only linesize[0] may be set for audio
* since all planes must be the same size.
*
* @see av_samples_get_buffer_size(), av_samples_fill_arrays()
*
* - encoding: unused
* - decoding: Set by libavcodec, user can override.
*/ int (*get_buffer2)(struct AVCodecContext *s, AVFrame *frame, int flags); /**
* If non-zero, the decoded audio and video frames returned from
* avcodec_decode_video2() and avcodec_decode_audio4() are reference-counted
* and are valid indefinitely. The caller must free them with
* av_frame_unref() when they are not needed anymore.
* Otherwise, the decoded frames must not be freed by the caller and are
* only valid until the next decode call.
*
* This is always automatically enabled if avcodec_receive_frame() is used.
*
* - encoding: unused
* - decoding: set by the caller before avcodec_open2().
*/ int refcounted_frames; /* - encoding parameters */ float qcompress; ///< amount of qscale change between easy & hard scenes (0.0-1.0) float qblur; ///< amount of qscale smoothing over time (0.0-1.0) /**
* minimum quantizer
* - encoding: Set by user.
* - decoding: unused
*/ int qmin; /**
* maximum quantizer
* - encoding: Set by user.
* - decoding: unused
*/ int qmax; /**
* maximum quantizer difference between frames
* - encoding: Set by user.
* - decoding: unused
*/ int max_qdiff;
#if FF_API_MPV_OPT /**
* @deprecated use encoder private options instead
*/ attribute_deprecated float rc_qsquish;
attribute_deprecated float rc_qmod_amp;
attribute_deprecated int rc_qmod_freq;
#endif /**
* decoder bitstream buffer size
* - encoding: Set by user.
* - decoding: unused
*/ int rc_buffer_size; /**
* ratecontrol override, see RcOverride
* - encoding: Allocated/set/freed by user.
* - decoding: unused
*/ int rc_override_count;
RcOverride *rc_override;
#if FF_API_MPV_OPT /**
* @deprecated use encoder private options instead
*/ attribute_deprecated const char *rc_eq;
#endif /**
* maximum bitrate
* - encoding: Set by user.
* - decoding: Set by user, may be overwritten by libavcodec.
*/ int64_t rc_max_rate; /**
* minimum bitrate
* - encoding: Set by user.
* - decoding: unused
*/ int64_t rc_min_rate;
#if FF_API_MPV_OPT /**
* @deprecated use encoder private options instead
*/ attribute_deprecated float rc_buffer_aggressivity;
attribute_deprecated float rc_initial_cplx;
#endif /**
* Ratecontrol attempt to use, at maximum,of what can be used without an underflow.
* - encoding: Set by user.
* - decoding: unused.
*/ float rc_max_available_vbv_use; /**
* Ratecontrol attempt to use, at least,times the amount needed to prevent a vbv overflow.
* - encoding: Set by user.
* - decoding: unused.
*/ float rc_min_vbv_overflow_use; /**
* Number of bits which should be loaded into the rc buffer before decoding starts.
* - encoding: Set by user.
* - decoding: unused
*/ int rc_initial_buffer_occupancy;
#if FF_API_CODER_TYPE
#define FF_CODER_TYPE_VLC 0 #define FF_CODER_TYPE_AC 1 #define FF_CODER_TYPE_RAW 2 #define FF_CODER_TYPE_RLE 3 #if FF_API_UNUSED_MEMBERS
#define FF_CODER_TYPE_DEFLATE 4 #endif /* FF_API_UNUSED_MEMBERS */ /**
* @deprecated use encoder private options instead
*/ attribute_deprecated int coder_type;
#endif /* FF_API_CODER_TYPE */ #if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int context_model;
#endif
#if FF_API_MPV_OPT /**
* @deprecated use encoder private options instead
*/ attribute_deprecated int lmin; /**
* @deprecated use encoder private options instead
*/ attribute_deprecated int lmax;
#endif
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int frame_skip_threshold; /** @deprecated use encoder private options instead */ attribute_deprecated int frame_skip_factor; /** @deprecated use encoder private options instead */ attribute_deprecated int frame_skip_exp; /** @deprecated use encoder private options instead */ attribute_deprecated int frame_skip_cmp;
#endif /* FF_API_PRIVATE_OPT */ /**
* trellis RD quantization
* - encoding: Set by user.
* - decoding: unused
*/ int trellis;
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int min_prediction_order; /** @deprecated use encoder private options instead */ attribute_deprecated int max_prediction_order; /** @deprecated use encoder private options instead */ attribute_deprecated
int64_t timecode_frame_start;
#endif
#if FF_API_RTP_CALLBACK /**
* @deprecated unused
*/ /* The RTP callback: This function is called */ /* every time the encoder has a packet to send. */ /* It depends on the encoder if the data starts */ /* with a Start Code (it should). H.263 does. */ /* mb_nb contains the number of macroblocks */ /* encoded in the RTP payload. */ attribute_deprecated void (*rtp_callback)(struct AVCodecContext *avctx, void *data, int size, int mb_nb);
#endif
#if FF_API_PRIVATE_OPT /** @deprecated use encoder private options instead */ attribute_deprecated int rtp_payload_size; /* The size of the RTP payload: the coder will */ /* do its best to deliver a chunk with size */ /* below rtp_payload_size, the chunk will start */ /* with a start code on some codecs like H.263. */ /* This doesn't take account of any particular */ /* headers inside the transmitted RTP payload. */ #endif
#if FF_API_STAT_BITS /* statistics, used for 2-pass encoding */ attribute_deprecated int mv_bits;
attribute_deprecated int header_bits;
attribute_deprecated int i_tex_bits;
attribute_deprecated int p_tex_bits;
attribute_deprecated int i_count;
attribute_deprecated int p_count;
attribute_deprecated int skip_count;
attribute_deprecated int misc_bits; /** @deprecated this field is unused */ attribute_deprecated int frame_bits;
#endif /**
* pass1 encoding statistics output buffer
* - encoding: Set by libavcodec.
* - decoding: unused
*/ char *stats_out; /**
* pass2 encoding statistics input buffer
* Concatenated stuff from stats_out of pass1 should be placed here.
* - encoding: Allocated/set/freed by user.
* - decoding: unused
*/ char *stats_in; /**
* Work around bugs in encoders which sometimes cannot be detected automatically.
* - encoding: Set by user
* - decoding: Set by user
*/ int workaround_bugs;
#define FF_BUG_AUTODETECT 1 ///< autodetection #if FF_API_OLD_MSMPEG4
#define FF_BUG_OLD_MSMPEG4 2 #endif
#define FF_BUG_XVID_ILACE 4 #define FF_BUG_UMP4 8 #define FF_BUG_NO_PADDING 16 #define FF_BUG_AMV 32 #if FF_API_AC_VLC
#define FF_BUG_AC_VLC 0 ///< Will be removed, libavcodec can now handle these non-compliant files by default. #endif
#define FF_BUG_QPEL_CHROMA 64 #define FF_BUG_STD_QPEL 128 #define FF_BUG_QPEL_CHROMA2 256 #define FF_BUG_DIRECT_BLOCKSIZE 512 #define FF_BUG_EDGE 1024 #define FF_BUG_HPEL_CHROMA 2048 #define FF_BUG_DC_CLIP 4096 #define FF_BUG_MS 8192 ///< Work around various bugs in Microsoft's broken decoders. #define FF_BUG_TRUNCATED 16384 /**
* strictly follow the standard (MPEG-4, ...).
* - encoding: Set by user.
* - decoding: Set by user.
* Setting this to STRICT or higher means the encoder and decoder will
* generally do stupid things, whereas setting it to unofficial or lower
* will mean the encoder might produce output that is not supported by all
* spec-compliant decoders. Decoders don't differentiate between normal,
* unofficial and experimental (that is, they always try to decode things
* when they can) unless they are explicitly asked to behave stupidly
* (=strictly conform to the specs)
*/ int strict_std_compliance;
#define FF_COMPLIANCE_VERY_STRICT 2 ///< Strictly conform to an older more strict version of the spec or reference software. #define FF_COMPLIANCE_STRICT 1 ///< Strictly conform to all the things in the spec no matter what consequences. #define FF_COMPLIANCE_NORMAL 0 #define FF_COMPLIANCE_UNOFFICIAL -1 ///< Allow unofficial extensions #define FF_COMPLIANCE_EXPERIMENTAL -2 ///< Allow nonstandardized experimental things. /**
* error concealment flags
* - encoding: unused
* - decoding: Set by user.
*/ int error_concealment;
#define FF_EC_GUESS_MVS 1 #define FF_EC_DEBLOCK 2 #define FF_EC_FAVOR_INTER 256 /**
* debug
* - encoding: Set by user.
* - decoding: Set by user.
*/ int debug;
#define FF_DEBUG_PICT_INFO 1 #define FF_DEBUG_RC 2 #define FF_DEBUG_BITSTREAM 4 #define FF_DEBUG_MB_TYPE 8 #define FF_DEBUG_QP 16 #if FF_API_DEBUG_MV /**
* @deprecated this option does nothing
*/ #define FF_DEBUG_MV 32 #endif
#define FF_DEBUG_DCT_COEFF 0x00000040 #define FF_DEBUG_SKIP 0x00000080 #define FF_DEBUG_STARTCODE 0x00000100 #if FF_API_UNUSED_MEMBERS
#define FF_DEBUG_PTS 0x00000200 #endif /* FF_API_UNUSED_MEMBERS */ #define FF_DEBUG_ER 0x00000400 #define FF_DEBUG_MMCO 0x00000800 #define FF_DEBUG_BUGS 0x00001000 #if FF_API_DEBUG_MV
#define FF_DEBUG_VIS_QP 0x00002000 ///< only access through AVOptions from outside libavcodec #define FF_DEBUG_VIS_MB_TYPE 0x00004000 ///< only access through AVOptions from outside libavcodec #endif
#define FF_DEBUG_BUFFERS 0x00008000 #define FF_DEBUG_THREADS 0x00010000 #define FF_DEBUG_GREEN_MD 0x00800000 #define FF_DEBUG_NOMC 0x01000000 #if FF_API_DEBUG_MV /**
* debug
* Code outside libavcodec should access this field using AVOptions
* - encoding: Set by user.
* - decoding: Set by user.
*/ int debug_mv;
#define FF_DEBUG_VIS_MV_P_FOR 0x00000001 // visualize forward predicted MVs of P-frames #define FF_DEBUG_VIS_MV_B_FOR 0x00000002 // visualize forward predicted MVs of B-frames #define FF_DEBUG_VIS_MV_B_BACK 0x00000004 // visualize backward predicted MVs of B-frames #endif /**
* Error recognition; may misdetect some more or less valid parts as errors.
* - encoding: unused
* - decoding: Set by user.
*/ int err_recognition; /**
* Verify checksums embedded in the bitstream (could be of either encoded or
* decoded data, depending on the codec) and print an error message on mismatch.
* If AV_EF_EXPLODE is also set, a mismatching checksum will result in the
* decoder returning an error.
*/ #define AV_EF_CRCCHECK (1<<0)
#define AV_EF_BITSTREAM (1<<1) ///< detect bitstream specification deviations #define AV_EF_BUFFER (1<<2) ///< detect improper bitstream length #define AV_EF_EXPLODE (1<<3) ///< abort decoding on minor error detection #define AV_EF_IGNORE_ERR (1<<15) ///< ignore errors and continue #define AV_EF_CAREFUL (1<<16) ///< consider things that violate the spec, are fast to calculate and have not been seen in the wild as errors #define AV_EF_COMPLIANT (1<<17) ///< consider all spec non compliances as errors #define AV_EF_AGGRESSIVE (1<<18) ///< consider things that a sane encoder should not do as an error /**
* opaque 64-bit number (generally a PTS) that will be reordered and
* output in AVFrame.reordered_opaque
* - encoding: unused
* - decoding: Set by user.
*/ int64_t reordered_opaque; /**
* Hardware accelerator in use
* - encoding: unused.
* - decoding: Set by libavcodec
*/ struct AVHWAccel *hwaccel; /**
* Hardware accelerator context.
* For some hardware accelerators, a global context needs to be
* provided by the user. In that case, this holds display-dependent
* data FFmpeg cannot instantiate itself. Please refer to the
* FFmpeg HW accelerator documentation to know how to fill this
* is. e.g. for VA API, this is a struct vaapi_context.
* - encoding: unused
* - decoding: Set by user
*/ void *hwaccel_context; /**
* error
* - encoding: Set by libavcodec if flags & AV_CODEC_FLAG_PSNR.
* - decoding: unused
*/ uint64_t error[AV_NUM_DATA_POINTERS]; /**
* DCT algorithm, see FF_DCT_* below
* - encoding: Set by user.
* - decoding: unused
*/ int dct_algo;
#define FF_DCT_AUTO 0 #define FF_DCT_FASTINT 1 #define FF_DCT_INT 2 #define FF_DCT_MMX 3 #define FF_DCT_ALTIVEC 5 #define FF_DCT_FAAN 6 /**
* IDCT algorithm, see FF_IDCT_* below.
* - encoding: Set by user.
* - decoding: Set by user.
*/ int idct_algo;
#define FF_IDCT_AUTO 0 #define FF_IDCT_INT 1 #define FF_IDCT_SIMPLE 2 #define FF_IDCT_SIMPLEMMX 3 #define FF_IDCT_ARM 7 #define FF_IDCT_ALTIVEC 8 #if FF_API_ARCH_SH4
#define FF_IDCT_SH4 9 #endif
#define FF_IDCT_SIMPLEARM 10 #if FF_API_UNUSED_MEMBERS
#define FF_IDCT_IPP 13 #endif /* FF_API_UNUSED_MEMBERS */ #define FF_IDCT_XVID 14 #if FF_API_IDCT_XVIDMMX
#define FF_IDCT_XVIDMMX 14 #endif /* FF_API_IDCT_XVIDMMX */ #define FF_IDCT_SIMPLEARMV5TE 16 #define FF_IDCT_SIMPLEARMV6 17 #if FF_API_ARCH_SPARC
#define FF_IDCT_SIMPLEVIS 18 #endif
#define FF_IDCT_FAAN 20 #define FF_IDCT_SIMPLENEON 22 #if FF_API_ARCH_ALPHA
#define FF_IDCT_SIMPLEALPHA 23 #endif
#define FF_IDCT_SIMPLEAUTO 128 /**
* bits per sample/pixel from the demuxer (needed for huffyuv).
* - encoding: Set by libavcodec.
* - decoding: Set by user.
*/ int bits_per_coded_sample; /**
* Bits per sample/pixel of internal libavcodec pixel/sample format.
* - encoding: set by user.
* - decoding: set by libavcodec.
*/ int bits_per_raw_sample;
#if FF_API_LOWRES /**
* low resolution decoding, 1-> 1/2 size, 2->1/4 size
* - encoding: unused
* - decoding: Set by user.
* Code outside libavcodec should access this field using:
* av_codec_{get,set}_lowres(avctx)
*/ int lowres;
#endif
#if FF_API_CODED_FRAME /**
* the picture in the bitstream
* - encoding: Set by libavcodec.
* - decoding: unused
*
* @deprecated use the quality factor packet side data instead
*/ attribute_deprecated AVFrame *coded_frame;
#endif /**
* thread count
* is used to decide how many independent tasks should be passed to execute()
* - encoding: Set by user.
* - decoding: Set by user.
*/ int thread_count; /**
* Which multithreading methods to use.
* Use of FF_THREAD_FRAME will increase decoding delay by one frame per thread,
* so clients which cannot provide future frames should not use it.
*
* - encoding: Set by user, otherwise the default is used.
* - decoding: Set by user, otherwise the default is used.
*/ int thread_type;
#define FF_THREAD_FRAME 1 ///< Decode more than one frame at once #define FF_THREAD_SLICE 2 ///< Decode more than one part of a single frame at once /**
* Which multithreading methods are in use by the codec.
* - encoding: Set by libavcodec.
* - decoding: Set by libavcodec.
*/ int active_thread_type; /**
* Set by the client if its custom get_buffer() callback can be called
* synchronously from another thread, which allows faster multithreaded decoding.
* draw_horiz_band() will be called from other threads regardless of this setting.
* Ignored if the default get_buffer() is used.
* - encoding: Set by user.
* - decoding: Set by user.
*/ int thread_safe_callbacks; /**
* The codec may call this to execute several independent things.
* It will return only after finishing all tasks.
* The user may replace this with some multithreaded implementation,
* the default implementation will execute the parts serially.
* @param count the number of things to execute
* - encoding: Set by libavcodec, user can override.
* - decoding: Set by libavcodec, user can override.
*/ int (*execute)(struct AVCodecContext *c, int (*func)(struct AVCodecContext *c2, void *arg), void *arg2, int *ret, int count, int size); /**
* The codec may call this to execute several independent things.
* It will return only after finishing all tasks.
* The user may replace this with some multithreaded implementation,
* the default implementation will execute the parts serially.
* Also see avcodec_thread_init and e.g. the --enable-pthread configure option.
* @param c context passed also to func
* @param count the number of things to execute
* @param arg2 argument passed unchanged to func
* @param ret return values of executed functions, must have space for "count" values. May be NULL.
* @param func function that will be called count times, with jobnr from 0 to count-1.
* threadnr will be in the range 0 to c->thread_count-1 < MAX_THREADS and so that no
* two instances of func executing at the same time will have the same threadnr.
* @return always 0 currently, but code should handle a future improvement where when any call to func
* returns < 0 no further calls to func may be done and < 0 is returned.
* - encoding: Set by libavcodec, user can override.
* - decoding: Set by libavcodec, user can override.
*/ int (*execute2)(struct AVCodecContext *c, int (*func)(struct AVCodecContext *c2, void *arg, int jobnr, int threadnr), void *arg2, int *ret, int count); /**
* noise vs. sse weight for the nsse comparison function
* - encoding: Set by user.
* - decoding: unused
*/ int nsse_weight; /**
* profile
* - encoding: Set by user.
* - decoding: Set by libavcodec.
*/ int profile;
#define FF_PROFILE_UNKNOWN -99 #define FF_PROFILE_RESERVED -100 #define FF_PROFILE_AAC_MAIN 0 #define FF_PROFILE_AAC_LOW 1 #define FF_PROFILE_AAC_SSR 2 #define FF_PROFILE_AAC_LTP 3 #define FF_PROFILE_AAC_HE 4 #define FF_PROFILE_AAC_HE_V2 28 #define FF_PROFILE_AAC_LD 22 #define FF_PROFILE_AAC_ELD 38 #define FF_PROFILE_MPEG2_AAC_LOW 128 #define FF_PROFILE_MPEG2_AAC_HE 131 #define FF_PROFILE_DTS 20 #define FF_PROFILE_DTS_ES 30 #define FF_PROFILE_DTS_96_24 40 #define FF_PROFILE_DTS_HD_HRA 50 #define FF_PROFILE_DTS_HD_MA 60 #define FF_PROFILE_DTS_EXPRESS 70 #define FF_PROFILE_MPEG2_422 0 #define FF_PROFILE_MPEG2_HIGH 1 #define FF_PROFILE_MPEG2_SS 2 #define FF_PROFILE_MPEG2_SNR_SCALABLE 3 #define FF_PROFILE_MPEG2_MAIN 4 #define FF_PROFILE_MPEG2_SIMPLE 5 #define FF_PROFILE_H264_CONSTRAINED (1<<9) // 8+1; constraint_set1_flag #define FF_PROFILE_H264_INTRA (1<<11) // 8+3; constraint_set3_flag #define FF_PROFILE_H264_BASELINE 66 #define FF_PROFILE_H264_CONSTRAINED_BASELINE (66|FF_PROFILE_H264_CONSTRAINED)
#define FF_PROFILE_H264_MAIN 77 #define FF_PROFILE_H264_EXTENDED 88 #define FF_PROFILE_H264_HIGH 100 #define FF_PROFILE_H264_HIGH_10 110 #define FF_PROFILE_H264_HIGH_10_INTRA (110|FF_PROFILE_H264_INTRA)
#define FF_PROFILE_H264_HIGH_422 122 #define FF_PROFILE_H264_HIGH_422_INTRA (122|FF_PROFILE_H264_INTRA)
#define FF_PROFILE_H264_HIGH_444 144 #define FF_PROFILE_H264_HIGH_444_PREDICTIVE 244 #define FF_PROFILE_H264_HIGH_444_INTRA (244|FF_PROFILE_H264_INTRA)
#define FF_PROFILE_H264_CAVLC_444 44 #define FF_PROFILE_VC1_SIMPLE 0 #define FF_PROFILE_VC1_MAIN 1 #define FF_PROFILE_VC1_COMPLEX 2 #define FF_PROFILE_VC1_ADVANCED 3 #define FF_PROFILE_MPEG4_SIMPLE 0 #define FF_PROFILE_MPEG4_SIMPLE_SCALABLE 1 #define FF_PROFILE_MPEG4_CORE 2 #define FF_PROFILE_MPEG4_MAIN 3 #define FF_PROFILE_MPEG4_N_BIT 4 #define FF_PROFILE_MPEG4_SCALABLE_TEXTURE 5 #define FF_PROFILE_MPEG4_SIMPLE_FACE_ANIMATION 6 #define FF_PROFILE_MPEG4_BASIC_ANIMATED_TEXTURE 7 #define FF_PROFILE_MPEG4_HYBRID 8 #define FF_PROFILE_MPEG4_ADVANCED_REAL_TIME 9 #define FF_PROFILE_MPEG4_CORE_SCALABLE 10 #define FF_PROFILE_MPEG4_ADVANCED_CODING 11 #define FF_PROFILE_MPEG4_ADVANCED_CORE 12 #define FF_PROFILE_MPEG4_ADVANCED_SCALABLE_TEXTURE 13 #define FF_PROFILE_MPEG4_SIMPLE_STUDIO 14 #define FF_PROFILE_MPEG4_ADVANCED_SIMPLE 15 #define FF_PROFILE_JPEG2000_CSTREAM_RESTRICTION_0 1 #define FF_PROFILE_JPEG2000_CSTREAM_RESTRICTION_1 2 #define FF_PROFILE_JPEG2000_CSTREAM_NO_RESTRICTION 32768 #define FF_PROFILE_JPEG2000_DCINEMA_2K 3 #define FF_PROFILE_JPEG2000_DCINEMA_4K 4 #define FF_PROFILE_VP9_0 0 #define FF_PROFILE_VP9_1 1 #define FF_PROFILE_VP9_2 2 #define FF_PROFILE_VP9_3 3 #define FF_PROFILE_HEVC_MAIN 1 #define FF_PROFILE_HEVC_MAIN_10 2 #define FF_PROFILE_HEVC_MAIN_STILL_PICTURE 3 #define FF_PROFILE_HEVC_REXT 4 /**
* level
* - encoding: Set by user.
* - decoding: Set by libavcodec.
*/ int level;
#define FF_LEVEL_UNKNOWN -99 /**
* Skip loop filtering for selected frames.
* - encoding: unused
* - decoding: Set by user.
*/ enum AVDiscard skip_loop_filter; /**
* Skip IDCT/dequantization for selected frames.
* - encoding: unused
* - decoding: Set by user.
*/ enum AVDiscard skip_idct; /**
* Skip decoding for selected frames.
* - encoding: unused
* - decoding: Set by user.
*/ enum AVDiscard skip_frame; /**
* Header containing style information for text subtitles.
* For SUBTITLE_ASS subtitle type, it should contain the whole ASS
* [Script Info] and [V4+ Styles] section, plus the [Events] line and
* the Format line following. It shouldn't include any Dialogue line.
* - encoding: Set/allocated/freed by user (before avcodec_open2())
* - decoding: Set/allocated/freed by libavcodec (by avcodec_open2())
*/ uint8_t *subtitle_header; int subtitle_header_size;
#if FF_API_ERROR_RATE /**
* @deprecated use the 'error_rate' private AVOption of the mpegvideo
* encoders
*/ attribute_deprecated int error_rate;
#endif
#if FF_API_VBV_DELAY /**
* VBV delay coded in the last frame (in periods of a 27 MHz clock).
* Used for compliant TS muxing.
* - encoding: Set by libavcodec.
* - decoding: unused.
* @deprecated this value is now exported as a part of
* AV_PKT_DATA_CPB_PROPERTIES packet side data
*/ attribute_deprecated
uint64_t vbv_delay;
#endif
#if FF_API_SIDEDATA_ONLY_PKT /**
* Encoding only and set by default. Allow encoders to output packets
* that do not contain any encoded data, only side data.
*
* Some encoders need to output such packets, e.g. to update some stream
* parameters at the end of encoding.
*
* @deprecated this field disables the default behaviour and
* it is kept only for compatibility.
*/ attribute_deprecated int side_data_only_packets;
#endif /**
* Audio only. The number of "priming" samples (padding) inserted by the
* encoder at the beginning of the audio. I.e. this number of leading
* decoded samples must be discarded by the caller to get the original audio
* without leading padding.
*
* - decoding: unused
* - encoding: Set by libavcodec. The timestamps on the output packets are
* adjusted by the encoder so that they always refer to the
* first sample of the data actually contained in the packet,
* including any added padding. E.g. if the timebase is
* 1/samplerate and the timestamp of the first input sample is
* 0, the timestamp of the first output packet will be
* -initial_padding.
*/ int initial_padding; /**
* - decoding: For codecs that store a framerate value in the compressed
* bitstream, the decoder may export it here. { 0, 1} when
* unknown.
* - encoding: May be used to signal the framerate of CFR content to an
* encoder.
*/ AVRational framerate; /**
* Nominal unaccelerated pixel format, see AV_PIX_FMT_xxx.
* - encoding: unused.
* - decoding: Set by libavcodec before calling get_format()
*/ enum AVPixelFormat sw_pix_fmt; /**
* Timebase in which pkt_dts/pts and AVPacket.dts/pts are.
* Code outside libavcodec should access this field using:
* av_codec_{get,set}_pkt_timebase(avctx)
* - encoding unused.
* - decoding set by user.
*/ AVRational pkt_timebase; /**
* AVCodecDescriptor
* Code outside libavcodec should access this field using:
* av_codec_{get,set}_codec_descriptor(avctx)
* - encoding: unused.
* - decoding: set by libavcodec.
*/ const AVCodecDescriptor *codec_descriptor;
#if !FF_API_LOWRES /**
* low resolution decoding, 1-> 1/2 size, 2->1/4 size
* - encoding: unused
* - decoding: Set by user.
* Code outside libavcodec should access this field using:
* av_codec_{get,set}_lowres(avctx)
*/ int lowres;
#endif /**
* Current statistics for PTS correction.
* - decoding: maintained and used by libavcodec, not intended to be used by user apps
* - encoding: unused
*/ int64_t pts_correction_num_faulty_pts; /// Number of incorrect PTS values so far int64_t pts_correction_num_faulty_dts; /// Number of incorrect DTS values so far int64_t pts_correction_last_pts; /// PTS of the last frame int64_t pts_correction_last_dts; /// DTS of the last frame /**
* Character encoding of the input subtitles file.
* - decoding: set by user
* - encoding: unused
*/ char *sub_charenc; /**
* Subtitles character encoding mode. Formats or codecs might be adjusting
* this setting (if they are doing the conversion themselves for instance).
* - decoding: set by libavcodec
* - encoding: unused
*/ int sub_charenc_mode;
#define FF_SUB_CHARENC_MODE_DO_NOTHING -1 ///< do nothing (demuxer outputs a stream supposed to be already in UTF-8, or the codec is bitmap for instance) #define FF_SUB_CHARENC_MODE_AUTOMATIC 0 ///< libavcodec will select the mode itself #define FF_SUB_CHARENC_MODE_PRE_DECODER 1 ///< the AVPacket data needs to be recoded to UTF-8 before being fed to the decoder, requires iconv /**
* Skip processing alpha if supported by codec.
* Note that if the format uses pre-multiplied alpha (common with VP6,
* and recommended due to better video quality/compression)
* the image will look as if alpha-blended onto a black background.
* However for formats that do not use pre-multiplied alpha
* there might be serious artefacts (though e.g. libswscale currently
* assumes pre-multiplied alpha anyway).
* Code outside libavcodec should access this field using AVOptions
*
* - decoding: set by user
* - encoding: unused
*/ int skip_alpha; /**
* Number of samples to skip after a discontinuity
* - decoding: unused
* - encoding: set by libavcodec
*/ int seek_preroll;
#if !FF_API_DEBUG_MV /**
* debug motion vectors
* Code outside libavcodec should access this field using AVOptions
* - encoding: Set by user.
* - decoding: Set by user.
*/ int debug_mv;
#define FF_DEBUG_VIS_MV_P_FOR 0x00000001 //visualize forward predicted MVs of P frames #define FF_DEBUG_VIS_MV_B_FOR 0x00000002 //visualize forward predicted MVs of B frames #define FF_DEBUG_VIS_MV_B_BACK 0x00000004 //visualize backward predicted MVs of B frames #endif /**
* custom intra quantization matrix
* Code outside libavcodec should access this field using av_codec_g/set_chroma_intra_matrix()
* - encoding: Set by user, can be NULL.
* - decoding: unused.
*/ uint16_t *chroma_intra_matrix; /**
* dump format separator.
* can be ", " or "\n " or anything else
* Code outside libavcodec should access this field using AVOptions
* (NO direct access).
* - encoding: Set by user.
* - decoding: Set by user.
*/ uint8_t *dump_separator; /**
* ',' separated list of allowed decoders.
* If NULL then all are allowed
* - encoding: unused
* - decoding: set by user through AVOPtions (NO direct access)
*/ char *codec_whitelist; /*
* Properties of the stream that gets decoded
* To be accessed through av_codec_get_properties() (NO direct access)
* - encoding: unused
* - decoding: set by libavcodec
*/ unsigned properties;
#define FF_CODEC_PROPERTY_LOSSLESS 0x00000001 #define FF_CODEC_PROPERTY_CLOSED_CAPTIONS 0x00000002 /**
* Additional data associated with the entire coded stream.
*
* - decoding: unused
* - encoding: may be set by libavcodec after avcodec_open2().
*/ AVPacketSideData *coded_side_data; int nb_coded_side_data; /**
* Encoding only.
*
* For hardware encoders configured to use a hwaccel pixel format, this
* field should be set by the caller to a reference to the AVHWFramesContext
* describing input frames. AVHWFramesContext.format must be equal to
* AVCodecContext.pix_fmt.
*
* This field should be set before avcodec_open2() is called and is
* afterwards owned and managed by libavcodec.
*/ AVBufferRef *hw_frames_ctx; /**
* Control the form of AVSubtitle.rects[N]->ass
* - decoding: set by user
* - encoding: unused
*/ int sub_text_format;
#define FF_SUB_TEXT_FMT_ASS 0 #if FF_API_ASS_TIMING
#define FF_SUB_TEXT_FMT_ASS_WITH_TIMINGS 1 #endif
} AVCodecContext;
int width, height; 视频有关，画面宽高
int coded_width, coded_height; 码流宽高，不同于width/height，当解码出来帧在裁剪出来前输出时画面
int gop_size; (group of pictures) GOP画面组大小
int max_b_frames; B帧最大值
int has_b_frames; 解码器的帧重新排序缓冲区的大小，MPEG-2 1个IBP
int sample_rate; 音频采样率
int channels; 声道数目
enum AVSampleFormat sample_fmt; 音频采样格式，枚举类型
enum AVSampleFormat {
AV_SAMPLE_FMT_NONE = -1,
AV_SAMPLE_FMT_U8, ///< unsigned 8 bits AV_SAMPLE_FMT_S16, ///< signed 16 bits AV_SAMPLE_FMT_S32, ///< signed 32 bits AV_SAMPLE_FMT_FLT, ///< float AV_SAMPLE_FMT_DBL, ///< double AV_SAMPLE_FMT_U8P, ///< unsigned 8 bits, planar AV_SAMPLE_FMT_S16P, ///< signed 16 bits, planar AV_SAMPLE_FMT_S32P, ///< signed 32 bits, planar AV_SAMPLE_FMT_FLTP, ///< float, planar AV_SAMPLE_FMT_DBLP, ///< double, planar AV_SAMPLE_FMT_NB ///< Number of sample formats. DO NOT USE if linking dynamically };
int frame_size; 一个音频帧里每个声道采样数目
int frame_number; 帧数目，解码时是解码器总解码的帧数目，编码时是编码过的帧数目
int (*get_buffer2)(struct AVCodecContext *s, AVFrame *frame, int flags);这个回调被调用，当从buffer中得到每帧的数据时，每个buffer必须使用AVBuffer API进行引用技数
如下属性将被设置在callback回调之前
- format
- width, height(视频)
- sample_rate, channel_layout, nb_samples(音频)
