tor-browser

frame.h (42572B)

---

/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/

/**
* @file
* @ingroup lavu_frame
* reference-counted frame API
*/

#ifndef AVUTIL_FRAME_H
#define AVUTIL_FRAME_H

#include <stddef.h>
#include <stdint.h>

#include "avutil.h"
#include "buffer.h"
#include "channel_layout.h"
#include "dict.h"
#include "rational.h"
#include "samplefmt.h"
#include "pixfmt.h"
#include "version.h"


/**
* @defgroup lavu_frame AVFrame
* @ingroup lavu_data
*
* @{
* AVFrame is an abstraction for reference-counted raw multimedia data.
*/

enum AVFrameSideDataType {
   /**
    * The data is the AVPanScan struct defined in libavcodec.
    */
   AV_FRAME_DATA_PANSCAN,
   /**
    * ATSC A53 Part 4 Closed Captions.
    * A53 CC bitstream is stored as uint8_t in AVFrameSideData.data.
    * The number of bytes of CC data is AVFrameSideData.size.
    */
   AV_FRAME_DATA_A53_CC,
   /**
    * Stereoscopic 3d metadata.
    * The data is the AVStereo3D struct defined in libavutil/stereo3d.h.
    */
   AV_FRAME_DATA_STEREO3D,
   /**
    * The data is the AVMatrixEncoding enum defined in libavutil/channel_layout.h.
    */
   AV_FRAME_DATA_MATRIXENCODING,
   /**
    * Metadata relevant to a downmix procedure.
    * The data is the AVDownmixInfo struct defined in libavutil/downmix_info.h.
    */
   AV_FRAME_DATA_DOWNMIX_INFO,
   /**
    * ReplayGain information in the form of the AVReplayGain struct.
    */
   AV_FRAME_DATA_REPLAYGAIN,
   /**
    * This side data contains a 3x3 transformation matrix describing an affine
    * transformation that needs to be applied to the frame for correct
    * presentation.
    *
    * See libavutil/display.h for a detailed description of the data.
    */
   AV_FRAME_DATA_DISPLAYMATRIX,
   /**
    * Active Format Description data consisting of a single byte as specified
    * in ETSI TS 101 154 using AVActiveFormatDescription enum.
    */
   AV_FRAME_DATA_AFD,
   /**
    * Motion vectors exported by some codecs (on demand through the export_mvs
    * flag set in the libavcodec AVCodecContext flags2 option).
    * The data is the AVMotionVector struct defined in
    * libavutil/motion_vector.h.
    */
   AV_FRAME_DATA_MOTION_VECTORS,
   /**
    * Recommmends skipping the specified number of samples. This is exported
    * only if the "skip_manual" AVOption is set in libavcodec.
    * This has the same format as AV_PKT_DATA_SKIP_SAMPLES.
    * @code
    * u32le number of samples to skip from start of this packet
    * u32le number of samples to skip from end of this packet
    * u8    reason for start skip
    * u8    reason for end   skip (0=padding silence, 1=convergence)
    * @endcode
    */
   AV_FRAME_DATA_SKIP_SAMPLES,
   /**
    * This side data must be associated with an audio frame and corresponds to
    * enum AVAudioServiceType defined in avcodec.h.
    */
   AV_FRAME_DATA_AUDIO_SERVICE_TYPE,
   /**
    * Mastering display metadata associated with a video frame. The payload is
    * an AVMasteringDisplayMetadata type and contains information about the
    * mastering display color volume.
    */
   AV_FRAME_DATA_MASTERING_DISPLAY_METADATA,
   /**
    * The GOP timecode in 25 bit timecode format. Data format is 64-bit integer.
    * This is set on the first frame of a GOP that has a temporal reference of 0.
    */
   AV_FRAME_DATA_GOP_TIMECODE,

   /**
    * The data represents the AVSphericalMapping structure defined in
    * libavutil/spherical.h.
    */
   AV_FRAME_DATA_SPHERICAL,

   /**
    * Content light level (based on CTA-861.3). This payload contains data in
    * the form of the AVContentLightMetadata struct.
    */
   AV_FRAME_DATA_CONTENT_LIGHT_LEVEL,

   /**
    * The data contains an ICC profile as an opaque octet buffer following the
    * format described by ISO 15076-1 with an optional name defined in the
    * metadata key entry "name".
    */
   AV_FRAME_DATA_ICC_PROFILE,

   /**
    * Timecode which conforms to SMPTE ST 12-1. The data is an array of 4 uint32_t
    * where the first uint32_t describes how many (1-3) of the other timecodes are used.
    * The timecode format is described in the documentation of av_timecode_get_smpte_from_framenum()
    * function in libavutil/timecode.h.
    */
   AV_FRAME_DATA_S12M_TIMECODE,

   /**
    * HDR dynamic metadata associated with a video frame. The payload is
    * an AVDynamicHDRPlus type and contains information for color
    * volume transform - application 4 of SMPTE 2094-40:2016 standard.
    */
   AV_FRAME_DATA_DYNAMIC_HDR_PLUS,

   /**
    * Regions Of Interest, the data is an array of AVRegionOfInterest type, the number of
    * array element is implied by AVFrameSideData.size / AVRegionOfInterest.self_size.
    */
   AV_FRAME_DATA_REGIONS_OF_INTEREST,

   /**
    * Encoding parameters for a video frame, as described by AVVideoEncParams.
    */
   AV_FRAME_DATA_VIDEO_ENC_PARAMS,

   /**
    * User data unregistered metadata associated with a video frame.
    * This is the H.26[45] UDU SEI message, and shouldn't be used for any other purpose
    * The data is stored as uint8_t in AVFrameSideData.data which is 16 bytes of
    * uuid_iso_iec_11578 followed by AVFrameSideData.size - 16 bytes of user_data_payload_byte.
    */
   AV_FRAME_DATA_SEI_UNREGISTERED,

   /**
    * Film grain parameters for a frame, described by AVFilmGrainParams.
    * Must be present for every frame which should have film grain applied.
    *
    * May be present multiple times, for example when there are multiple
    * alternative parameter sets for different video signal characteristics.
    * The user should select the most appropriate set for the application.
    */
   AV_FRAME_DATA_FILM_GRAIN_PARAMS,

   /**
    * Bounding boxes for object detection and classification,
    * as described by AVDetectionBBoxHeader.
    */
   AV_FRAME_DATA_DETECTION_BBOXES,

   /**
    * Dolby Vision RPU raw data, suitable for passing to x265
    * or other libraries. Array of uint8_t, with NAL emulation
    * bytes intact.
    */
   AV_FRAME_DATA_DOVI_RPU_BUFFER,

   /**
    * Parsed Dolby Vision metadata, suitable for passing to a software
    * implementation. The payload is the AVDOVIMetadata struct defined in
    * libavutil/dovi_meta.h.
    */
   AV_FRAME_DATA_DOVI_METADATA,

   /**
    * HDR Vivid dynamic metadata associated with a video frame. The payload is
    * an AVDynamicHDRVivid type and contains information for color
    * volume transform - CUVA 005.1-2021.
    */
   AV_FRAME_DATA_DYNAMIC_HDR_VIVID,

   /**
    * Ambient viewing environment metadata, as defined by H.274.
    */
   AV_FRAME_DATA_AMBIENT_VIEWING_ENVIRONMENT,

   /**
    * Provide encoder-specific hinting information about changed/unchanged
    * portions of a frame.  It can be used to pass information about which
    * macroblocks can be skipped because they didn't change from the
    * corresponding ones in the previous frame. This could be useful for
    * applications which know this information in advance to speed up
    * encoding.
    */
   AV_FRAME_DATA_VIDEO_HINT,

   /**
    * Raw LCEVC payload data, as a uint8_t array, with NAL emulation
    * bytes intact.
    */
   AV_FRAME_DATA_LCEVC,

   /**
    * This side data must be associated with a video frame.
    * The presence of this side data indicates that the video stream is
    * composed of multiple views (e.g. stereoscopic 3D content,
    * cf. H.264 Annex H or H.265 Annex G).
    * The data is an int storing the view ID.
    */
   AV_FRAME_DATA_VIEW_ID,
};

enum AVActiveFormatDescription {
   AV_AFD_SAME         = 8,
   AV_AFD_4_3          = 9,
   AV_AFD_16_9         = 10,
   AV_AFD_14_9         = 11,
   AV_AFD_4_3_SP_14_9  = 13,
   AV_AFD_16_9_SP_14_9 = 14,
   AV_AFD_SP_4_3       = 15,
};


/**
* Structure to hold side data for an AVFrame.
*
* sizeof(AVFrameSideData) is not a part of the public ABI, so new fields may be added
* to the end with a minor bump.
*/
typedef struct AVFrameSideData {
   enum AVFrameSideDataType type;
   uint8_t *data;
   size_t   size;
   AVDictionary *metadata;
   AVBufferRef *buf;
} AVFrameSideData;

enum AVSideDataProps {
   /**
    * The side data type can be used in stream-global structures.
    * Side data types without this property are only meaningful on per-frame
    * basis.
    */
   AV_SIDE_DATA_PROP_GLOBAL = (1 << 0),

   /**
    * Multiple instances of this side data type can be meaningfully present in
    * a single side data array.
    */
   AV_SIDE_DATA_PROP_MULTI  = (1 << 1),

   /**
    * Side data depends on the video dimensions. Side data with this property
    * loses its meaning when rescaling or cropping the image, unless
    * either recomputed or adjusted to the new resolution.
    */
   AV_SIDE_DATA_PROP_SIZE_DEPENDENT = (1 << 2),

   /**
    * Side data depends on the video color space. Side data with this property
    * loses its meaning when changing the video color encoding, e.g. by
    * adapting to a different set of primaries or transfer characteristics.
    */
   AV_SIDE_DATA_PROP_COLOR_DEPENDENT = (1 << 3),
};

/**
* This struct describes the properties of a side data type. Its instance
* corresponding to a given type can be obtained from av_frame_side_data_desc().
*/
typedef struct AVSideDataDescriptor {
   /**
    * Human-readable side data description.
    */
   const char      *name;

   /**
    * Side data property flags, a combination of AVSideDataProps values.
    */
   unsigned         props;
} AVSideDataDescriptor;

/**
* Structure describing a single Region Of Interest.
*
* When multiple regions are defined in a single side-data block, they
* should be ordered from most to least important - some encoders are only
* capable of supporting a limited number of distinct regions, so will have
* to truncate the list.
*
* When overlapping regions are defined, the first region containing a given
* area of the frame applies.
*/
typedef struct AVRegionOfInterest {
   /**
    * Must be set to the size of this data structure (that is,
    * sizeof(AVRegionOfInterest)).
    */
   uint32_t self_size;
   /**
    * Distance in pixels from the top edge of the frame to the top and
    * bottom edges and from the left edge of the frame to the left and
    * right edges of the rectangle defining this region of interest.
    *
    * The constraints on a region are encoder dependent, so the region
    * actually affected may be slightly larger for alignment or other
    * reasons.
    */
   int top;
   int bottom;
   int left;
   int right;
   /**
    * Quantisation offset.
    *
    * Must be in the range -1 to +1.  A value of zero indicates no quality
    * change.  A negative value asks for better quality (less quantisation),
    * while a positive value asks for worse quality (greater quantisation).
    *
    * The range is calibrated so that the extreme values indicate the
    * largest possible offset - if the rest of the frame is encoded with the
    * worst possible quality, an offset of -1 indicates that this region
    * should be encoded with the best possible quality anyway.  Intermediate
    * values are then interpolated in some codec-dependent way.
    *
    * For example, in 10-bit H.264 the quantisation parameter varies between
    * -12 and 51.  A typical qoffset value of -1/10 therefore indicates that
    * this region should be encoded with a QP around one-tenth of the full
    * range better than the rest of the frame.  So, if most of the frame
    * were to be encoded with a QP of around 30, this region would get a QP
    * of around 24 (an offset of approximately -1/10 * (51 - -12) = -6.3).
    * An extreme value of -1 would indicate that this region should be
    * encoded with the best possible quality regardless of the treatment of
    * the rest of the frame - that is, should be encoded at a QP of -12.
    */
   AVRational qoffset;
} AVRegionOfInterest;

/**
* This structure describes decoded (raw) audio or video data.
*
* AVFrame must be allocated using av_frame_alloc(). Note that this only
* allocates the AVFrame itself, the buffers for the data must be managed
* through other means (see below).
* AVFrame must be freed with av_frame_free().
*
* AVFrame is typically allocated once and then reused multiple times to hold
* different data (e.g. a single AVFrame to hold frames received from a
* decoder). In such a case, av_frame_unref() will free any references held by
* the frame and reset it to its original clean state before it
* is reused again.
*
* The data described by an AVFrame is usually reference counted through the
* AVBuffer API. The underlying buffer references are stored in AVFrame.buf /
* AVFrame.extended_buf. An AVFrame is considered to be reference counted if at
* least one reference is set, i.e. if AVFrame.buf[0] != NULL. In such a case,
* every single data plane must be contained in one of the buffers in
* AVFrame.buf or AVFrame.extended_buf.
* There may be a single buffer for all the data, or one separate buffer for
* each plane, or anything in between.
*
* sizeof(AVFrame) is not a part of the public ABI, so new fields may be added
* to the end with a minor bump.
*
* Fields can be accessed through AVOptions, the name string used, matches the
* C structure field name for fields accessible through AVOptions.
*/
typedef struct AVFrame {
#define AV_NUM_DATA_POINTERS 8
   /**
    * pointer to the picture/channel planes.
    * This might be different from the first allocated byte. For video,
    * it could even point to the end of the image data.
    *
    * All pointers in data and extended_data must point into one of the
    * AVBufferRef in buf or extended_buf.
    *
    * Some decoders access areas outside 0,0 - width,height, please
    * see avcodec_align_dimensions2(). Some filters and swscale can read
    * up to 16 bytes beyond the planes, if these filters are to be used,
    * then 16 extra bytes must be allocated.
    *
    * NOTE: Pointers not needed by the format MUST be set to NULL.
    *
    * @attention In case of video, the data[] pointers can point to the
    * end of image data in order to reverse line order, when used in
    * combination with negative values in the linesize[] array.
    */
   uint8_t *data[AV_NUM_DATA_POINTERS];

   /**
    * For video, a positive or negative value, which is typically indicating
    * the size in bytes of each picture line, but it can also be:
    * - the negative byte size of lines for vertical flipping
    *   (with data[n] pointing to the end of the data
    * - a positive or negative multiple of the byte size as for accessing
    *   even and odd fields of a frame (possibly flipped)
    *
    * For audio, only linesize[0] may be set. For planar audio, each channel
    * plane must be the same size.
    *
    * For video the linesizes should be multiples of the CPUs alignment
    * preference, this is 16 or 32 for modern desktop CPUs.
    * Some code requires such alignment other code can be slower without
    * correct alignment, for yet other it makes no difference.
    *
    * @note The linesize may be larger than the size of usable data -- there
    * may be extra padding present for performance reasons.
    *
    * @attention In case of video, line size values can be negative to achieve
    * a vertically inverted iteration over image lines.
    */
   int linesize[AV_NUM_DATA_POINTERS];

   /**
    * pointers to the data planes/channels.
    *
    * For video, this should simply point to data[].
    *
    * For planar audio, each channel has a separate data pointer, and
    * linesize[0] contains the size of each channel buffer.
    * For packed audio, there is just one data pointer, and linesize[0]
    * contains the total size of the buffer for all channels.
    *
    * Note: Both data and extended_data should always be set in a valid frame,
    * but for planar audio with more channels that can fit in data,
    * extended_data must be used in order to access all channels.
    */
   uint8_t **extended_data;

   /**
    * @name Video dimensions
    * Video frames only. The coded dimensions (in pixels) of the video frame,
    * i.e. the size of the rectangle that contains some well-defined values.
    *
    * @note The part of the frame intended for display/presentation is further
    * restricted by the @ref cropping "Cropping rectangle".
    * @{
    */
   int width, height;
   /**
    * @}
    */

   /**
    * number of audio samples (per channel) described by this frame
    */
   int nb_samples;

   /**
    * format of the frame, -1 if unknown or unset
    * Values correspond to enum AVPixelFormat for video frames,
    * enum AVSampleFormat for audio)
    */
   int format;

#if FF_API_FRAME_KEY
   /**
    * 1 -> keyframe, 0-> not
    *
    * @deprecated Use AV_FRAME_FLAG_KEY instead
    */
   attribute_deprecated
   int key_frame;
#endif

   /**
    * Picture type of the frame.
    */
   enum AVPictureType pict_type;

   /**
    * Sample aspect ratio for the video frame, 0/1 if unknown/unspecified.
    */
   AVRational sample_aspect_ratio;

   /**
    * Presentation timestamp in time_base units (time when frame should be shown to user).
    */
   int64_t pts;

   /**
    * DTS copied from the AVPacket that triggered returning this frame. (if frame threading isn't used)
    * This is also the Presentation time of this AVFrame calculated from
    * only AVPacket.dts values without pts values.
    */
   int64_t pkt_dts;

   /**
    * Time base for the timestamps in this frame.
    * In the future, this field may be set on frames output by decoders or
    * filters, but its value will be by default ignored on input to encoders
    * or filters.
    */
   AVRational time_base;

   /**
    * quality (between 1 (good) and FF_LAMBDA_MAX (bad))
    */
   int quality;

   /**
    * Frame owner's private data.
    *
    * This field may be set by the code that allocates/owns the frame data.
    * It is then not touched by any library functions, except:
    * - it is copied to other references by av_frame_copy_props() (and hence by
    *   av_frame_ref());
    * - it is set to NULL when the frame is cleared by av_frame_unref()
    * - on the caller's explicit request. E.g. libavcodec encoders/decoders
    *   will copy this field to/from @ref AVPacket "AVPackets" if the caller sets
    *   @ref AV_CODEC_FLAG_COPY_OPAQUE.
    *
    * @see opaque_ref the reference-counted analogue
    */
   void *opaque;

   /**
    * Number of fields in this frame which should be repeated, i.e. the total
    * duration of this frame should be repeat_pict + 2 normal field durations.
    *
    * For interlaced frames this field may be set to 1, which signals that this
    * frame should be presented as 3 fields: beginning with the first field (as
    * determined by AV_FRAME_FLAG_TOP_FIELD_FIRST being set or not), followed
    * by the second field, and then the first field again.
    *
    * For progressive frames this field may be set to a multiple of 2, which
    * signals that this frame's duration should be (repeat_pict + 2) / 2
    * normal frame durations.
    *
    * @note This field is computed from MPEG2 repeat_first_field flag and its
    * associated flags, H.264 pic_struct from picture timing SEI, and
    * their analogues in other codecs. Typically it should only be used when
    * higher-layer timing information is not available.
    */
   int repeat_pict;

#if FF_API_INTERLACED_FRAME
   /**
    * The content of the picture is interlaced.
    *
    * @deprecated Use AV_FRAME_FLAG_INTERLACED instead
    */
   attribute_deprecated
   int interlaced_frame;

   /**
    * If the content is interlaced, is top field displayed first.
    *
    * @deprecated Use AV_FRAME_FLAG_TOP_FIELD_FIRST instead
    */
   attribute_deprecated
   int top_field_first;
#endif

#if FF_API_PALETTE_HAS_CHANGED
   /**
    * Tell user application that palette has changed from previous frame.
    */
   attribute_deprecated
   int palette_has_changed;
#endif

   /**
    * Sample rate of the audio data.
    */
   int sample_rate;

   /**
    * AVBuffer references backing the data for this frame. All the pointers in
    * data and extended_data must point inside one of the buffers in buf or
    * extended_buf. This array must be filled contiguously -- if buf[i] is
    * non-NULL then buf[j] must also be non-NULL for all j < i.
    *
    * There may be at most one AVBuffer per data plane, so for video this array
    * always contains all the references. For planar audio with more than
    * AV_NUM_DATA_POINTERS channels, there may be more buffers than can fit in
    * this array. Then the extra AVBufferRef pointers are stored in the
    * extended_buf array.
    */
   AVBufferRef *buf[AV_NUM_DATA_POINTERS];

   /**
    * For planar audio which requires more than AV_NUM_DATA_POINTERS
    * AVBufferRef pointers, this array will hold all the references which
    * cannot fit into AVFrame.buf.
    *
    * Note that this is different from AVFrame.extended_data, which always
    * contains all the pointers. This array only contains the extra pointers,
    * which cannot fit into AVFrame.buf.
    *
    * This array is always allocated using av_malloc() by whoever constructs
    * the frame. It is freed in av_frame_unref().
    */
   AVBufferRef **extended_buf;
   /**
    * Number of elements in extended_buf.
    */
   int        nb_extended_buf;

   AVFrameSideData **side_data;
   int            nb_side_data;

/**
* @defgroup lavu_frame_flags AV_FRAME_FLAGS
* @ingroup lavu_frame
* Flags describing additional frame properties.
*
* @{
*/

/**
* The frame data may be corrupted, e.g. due to decoding errors.
*/
#define AV_FRAME_FLAG_CORRUPT       (1 << 0)
/**
* A flag to mark frames that are keyframes.
*/
#define AV_FRAME_FLAG_KEY (1 << 1)
/**
* A flag to mark the frames which need to be decoded, but shouldn't be output.
*/
#define AV_FRAME_FLAG_DISCARD   (1 << 2)
/**
* A flag to mark frames whose content is interlaced.
*/
#define AV_FRAME_FLAG_INTERLACED (1 << 3)
/**
* A flag to mark frames where the top field is displayed first if the content
* is interlaced.
*/
#define AV_FRAME_FLAG_TOP_FIELD_FIRST (1 << 4)
/**
* A flag to mark frames which were encoded losslessly from the input.
*/
#define AV_FRAME_FLAG_LOSSLESS        (1 << 5)
/**
* @}
*/

   /**
    * Frame flags, a combination of @ref lavu_frame_flags
    */
   int flags;

   /**
    * MPEG vs JPEG YUV range.
    * - encoding: Set by user
    * - decoding: Set by libavcodec
    */
   enum AVColorRange color_range;

   enum AVColorPrimaries color_primaries;

   enum AVColorTransferCharacteristic color_trc;

   /**
    * YUV colorspace type.
    * - encoding: Set by user
    * - decoding: Set by libavcodec
    */
   enum AVColorSpace colorspace;

   enum AVChromaLocation chroma_location;

   /**
    * frame timestamp estimated using various heuristics, in stream time base
    * - encoding: unused
    * - decoding: set by libavcodec, read by user.
    */
   int64_t best_effort_timestamp;

#if FF_API_FRAME_PKT
   /**
    * reordered pos from the last AVPacket that has been input into the decoder
    * - encoding: unused
    * - decoding: Read by user.
    * @deprecated use AV_CODEC_FLAG_COPY_OPAQUE to pass through arbitrary user
    *             data from packets to frames
    */
   attribute_deprecated
   int64_t pkt_pos;
#endif

   /**
    * metadata.
    * - encoding: Set by user.
    * - decoding: Set by libavcodec.
    */
   AVDictionary *metadata;

   /**
    * decode error flags of the frame, set to a combination of
    * FF_DECODE_ERROR_xxx flags if the decoder produced a frame, but there
    * were errors during the decoding.
    * - encoding: unused
    * - decoding: set by libavcodec, read by user.
    */
   int decode_error_flags;
#define FF_DECODE_ERROR_INVALID_BITSTREAM   1
#define FF_DECODE_ERROR_MISSING_REFERENCE   2
#define FF_DECODE_ERROR_CONCEALMENT_ACTIVE  4
#define FF_DECODE_ERROR_DECODE_SLICES       8

#if FF_API_FRAME_PKT
   /**
    * size of the corresponding packet containing the compressed
    * frame.
    * It is set to a negative value if unknown.
    * - encoding: unused
    * - decoding: set by libavcodec, read by user.
    * @deprecated use AV_CODEC_FLAG_COPY_OPAQUE to pass through arbitrary user
    *             data from packets to frames
    */
   attribute_deprecated
   int pkt_size;
#endif

   /**
    * For hwaccel-format frames, this should be a reference to the
    * AVHWFramesContext describing the frame.
    */
   AVBufferRef *hw_frames_ctx;

   /**
    * Frame owner's private data.
    *
    * This field may be set by the code that allocates/owns the frame data.
    * It is then not touched by any library functions, except:
    * - a new reference to the underlying buffer is propagated by
    *   av_frame_copy_props() (and hence by av_frame_ref());
    * - it is unreferenced in av_frame_unref();
    * - on the caller's explicit request. E.g. libavcodec encoders/decoders
    *   will propagate a new reference to/from @ref AVPacket "AVPackets" if the
    *   caller sets @ref AV_CODEC_FLAG_COPY_OPAQUE.
    *
    * @see opaque the plain pointer analogue
    */
   AVBufferRef *opaque_ref;

   /**
    * @anchor cropping
    * @name Cropping
    * Video frames only. The number of pixels to discard from the the
    * top/bottom/left/right border of the frame to obtain the sub-rectangle of
    * the frame intended for presentation.
    * @{
    */
   size_t crop_top;
   size_t crop_bottom;
   size_t crop_left;
   size_t crop_right;
   /**
    * @}
    */

   /**
    * AVBufferRef for internal use by a single libav* library.
    * Must not be used to transfer data between libraries.
    * Has to be NULL when ownership of the frame leaves the respective library.
    *
    * Code outside the FFmpeg libs should never check or change the contents of the buffer ref.
    *
    * FFmpeg calls av_buffer_unref() on it when the frame is unreferenced.
    * av_frame_copy_props() calls create a new reference with av_buffer_ref()
    * for the target frame's private_ref field.
    */
   AVBufferRef *private_ref;

   /**
    * Channel layout of the audio data.
    */
   AVChannelLayout ch_layout;

   /**
    * Duration of the frame, in the same units as pts. 0 if unknown.
    */
   int64_t duration;
} AVFrame;


/**
* Allocate an AVFrame and set its fields to default values.  The resulting
* struct must be freed using av_frame_free().
*
* @return An AVFrame filled with default values or NULL on failure.
*
* @note this only allocates the AVFrame itself, not the data buffers. Those
* must be allocated through other means, e.g. with av_frame_get_buffer() or
* manually.
*/
AVFrame *av_frame_alloc(void);

/**
* Free the frame and any dynamically allocated objects in it,
* e.g. extended_data. If the frame is reference counted, it will be
* unreferenced first.
*
* @param frame frame to be freed. The pointer will be set to NULL.
*/
void av_frame_free(AVFrame **frame);

/**
* Set up a new reference to the data described by the source frame.
*
* Copy frame properties from src to dst and create a new reference for each
* AVBufferRef from src.
*
* If src is not reference counted, new buffers are allocated and the data is
* copied.
*
* @warning: dst MUST have been either unreferenced with av_frame_unref(dst),
*           or newly allocated with av_frame_alloc() before calling this
*           function, or undefined behavior will occur.
*
* @return 0 on success, a negative AVERROR on error
*/
int av_frame_ref(AVFrame *dst, const AVFrame *src);

/**
* Ensure the destination frame refers to the same data described by the source
* frame, either by creating a new reference for each AVBufferRef from src if
* they differ from those in dst, by allocating new buffers and copying data if
* src is not reference counted, or by unrefencing it if src is empty.
*
* Frame properties on dst will be replaced by those from src.
*
* @return 0 on success, a negative AVERROR on error. On error, dst is
*         unreferenced.
*/
int av_frame_replace(AVFrame *dst, const AVFrame *src);

/**
* Create a new frame that references the same data as src.
*
* This is a shortcut for av_frame_alloc()+av_frame_ref().
*
* @return newly created AVFrame on success, NULL on error.
*/
AVFrame *av_frame_clone(const AVFrame *src);

/**
* Unreference all the buffers referenced by frame and reset the frame fields.
*/
void av_frame_unref(AVFrame *frame);

/**
* Move everything contained in src to dst and reset src.
*
* @warning: dst is not unreferenced, but directly overwritten without reading
*           or deallocating its contents. Call av_frame_unref(dst) manually
*           before calling this function to ensure that no memory is leaked.
*/
void av_frame_move_ref(AVFrame *dst, AVFrame *src);

/**
* Allocate new buffer(s) for audio or video data.
*
* The following fields must be set on frame before calling this function:
* - format (pixel format for video, sample format for audio)
* - width and height for video
* - nb_samples and ch_layout for audio
*
* This function will fill AVFrame.data and AVFrame.buf arrays and, if
* necessary, allocate and fill AVFrame.extended_data and AVFrame.extended_buf.
* For planar formats, one buffer will be allocated for each plane.
*
* @warning: if frame already has been allocated, calling this function will
*           leak memory. In addition, undefined behavior can occur in certain
*           cases.
*
* @param frame frame in which to store the new buffers.
* @param align Required buffer size and data pointer alignment. If equal to 0,
*              alignment will be chosen automatically for the current CPU.
*              It is highly recommended to pass 0 here unless you know what
*              you are doing.
*
* @return 0 on success, a negative AVERROR on error.
*/
int av_frame_get_buffer(AVFrame *frame, int align);

/**
* Check if the frame data is writable.
*
* @return A positive value if the frame data is writable (which is true if and
* only if each of the underlying buffers has only one reference, namely the one
* stored in this frame). Return 0 otherwise.
*
* If 1 is returned the answer is valid until av_buffer_ref() is called on any
* of the underlying AVBufferRefs (e.g. through av_frame_ref() or directly).
*
* @see av_frame_make_writable(), av_buffer_is_writable()
*/
int av_frame_is_writable(AVFrame *frame);

/**
* Ensure that the frame data is writable, avoiding data copy if possible.
*
* Do nothing if the frame is writable, allocate new buffers and copy the data
* if it is not. Non-refcounted frames behave as non-writable, i.e. a copy
* is always made.
*
* @return 0 on success, a negative AVERROR on error.
*
* @see av_frame_is_writable(), av_buffer_is_writable(),
* av_buffer_make_writable()
*/
int av_frame_make_writable(AVFrame *frame);

/**
* Copy the frame data from src to dst.
*
* This function does not allocate anything, dst must be already initialized and
* allocated with the same parameters as src.
*
* This function only copies the frame data (i.e. the contents of the data /
* extended data arrays), not any other properties.
*
* @return >= 0 on success, a negative AVERROR on error.
*/
int av_frame_copy(AVFrame *dst, const AVFrame *src);

/**
* Copy only "metadata" fields from src to dst.
*
* Metadata for the purpose of this function are those fields that do not affect
* the data layout in the buffers.  E.g. pts, sample rate (for audio) or sample
* aspect ratio (for video), but not width/height or channel layout.
* Side data is also copied.
*/
int av_frame_copy_props(AVFrame *dst, const AVFrame *src);

/**
* Get the buffer reference a given data plane is stored in.
*
* @param frame the frame to get the plane's buffer from
* @param plane index of the data plane of interest in frame->extended_data.
*
* @return the buffer reference that contains the plane or NULL if the input
* frame is not valid.
*/
AVBufferRef *av_frame_get_plane_buffer(const AVFrame *frame, int plane);

/**
* Add a new side data to a frame.
*
* @param frame a frame to which the side data should be added
* @param type type of the added side data
* @param size size of the side data
*
* @return newly added side data on success, NULL on error
*/
AVFrameSideData *av_frame_new_side_data(AVFrame *frame,
                                       enum AVFrameSideDataType type,
                                       size_t size);

/**
* Add a new side data to a frame from an existing AVBufferRef
*
* @param frame a frame to which the side data should be added
* @param type  the type of the added side data
* @param buf   an AVBufferRef to add as side data. The ownership of
*              the reference is transferred to the frame.
*
* @return newly added side data on success, NULL on error. On failure
*         the frame is unchanged and the AVBufferRef remains owned by
*         the caller.
*/
AVFrameSideData *av_frame_new_side_data_from_buf(AVFrame *frame,
                                                enum AVFrameSideDataType type,
                                                AVBufferRef *buf);

/**
* @return a pointer to the side data of a given type on success, NULL if there
* is no side data with such type in this frame.
*/
AVFrameSideData *av_frame_get_side_data(const AVFrame *frame,
                                       enum AVFrameSideDataType type);

/**
* Remove and free all side data instances of the given type.
*/
void av_frame_remove_side_data(AVFrame *frame, enum AVFrameSideDataType type);


/**
* Flags for frame cropping.
*/
enum {
   /**
    * Apply the maximum possible cropping, even if it requires setting the
    * AVFrame.data[] entries to unaligned pointers. Passing unaligned data
    * to FFmpeg API is generally not allowed, and causes undefined behavior
    * (such as crashes). You can pass unaligned data only to FFmpeg APIs that
    * are explicitly documented to accept it. Use this flag only if you
    * absolutely know what you are doing.
    */
   AV_FRAME_CROP_UNALIGNED     = 1 << 0,
};

/**
* Crop the given video AVFrame according to its crop_left/crop_top/crop_right/
* crop_bottom fields. If cropping is successful, the function will adjust the
* data pointers and the width/height fields, and set the crop fields to 0.
*
* In all cases, the cropping boundaries will be rounded to the inherent
* alignment of the pixel format. In some cases, such as for opaque hwaccel
* formats, the left/top cropping is ignored. The crop fields are set to 0 even
* if the cropping was rounded or ignored.
*
* @param frame the frame which should be cropped
* @param flags Some combination of AV_FRAME_CROP_* flags, or 0.
*
* @return >= 0 on success, a negative AVERROR on error. If the cropping fields
* were invalid, AVERROR(ERANGE) is returned, and nothing is changed.
*/
int av_frame_apply_cropping(AVFrame *frame, int flags);

/**
* @return a string identifying the side data type
*/
const char *av_frame_side_data_name(enum AVFrameSideDataType type);

/**
* @return side data descriptor corresponding to a given side data type, NULL
*         when not available.
*/
const AVSideDataDescriptor *av_frame_side_data_desc(enum AVFrameSideDataType type);

/**
* Free all side data entries and their contents, then zeroes out the
* values which the pointers are pointing to.
*
* @param sd    pointer to array of side data to free. Will be set to NULL
*              upon return.
* @param nb_sd pointer to an integer containing the number of entries in
*              the array. Will be set to 0 upon return.
*/
void av_frame_side_data_free(AVFrameSideData ***sd, int *nb_sd);

/**
* Remove existing entries before adding new ones.
*/
#define AV_FRAME_SIDE_DATA_FLAG_UNIQUE (1 << 0)
/**
* Don't add a new entry if another of the same type exists.
* Applies only for side data types without the AV_SIDE_DATA_PROP_MULTI prop.
*/
#define AV_FRAME_SIDE_DATA_FLAG_REPLACE (1 << 1)

/**
* Add new side data entry to an array.
*
* @param sd    pointer to array of side data to which to add another entry,
*              or to NULL in order to start a new array.
* @param nb_sd pointer to an integer containing the number of entries in
*              the array.
* @param type  type of the added side data
* @param size  size of the side data
* @param flags Some combination of AV_FRAME_SIDE_DATA_FLAG_* flags, or 0.
*
* @return newly added side data on success, NULL on error.
* @note In case of AV_FRAME_SIDE_DATA_FLAG_UNIQUE being set, entries of
*       matching AVFrameSideDataType will be removed before the addition
*       is attempted.
* @note In case of AV_FRAME_SIDE_DATA_FLAG_REPLACE being set, if an
*       entry of the same type already exists, it will be replaced instead.
*/
AVFrameSideData *av_frame_side_data_new(AVFrameSideData ***sd, int *nb_sd,
                                       enum AVFrameSideDataType type,
                                       size_t size, unsigned int flags);

/**
* Add a new side data entry to an array from an existing AVBufferRef.
*
* @param sd    pointer to array of side data to which to add another entry,
*              or to NULL in order to start a new array.
* @param nb_sd pointer to an integer containing the number of entries in
*              the array.
* @param type  type of the added side data
* @param buf   Pointer to AVBufferRef to add to the array. On success,
*              the function takes ownership of the AVBufferRef and *buf is
*              set to NULL, unless AV_FRAME_SIDE_DATA_FLAG_NEW_REF is set
*              in which case the ownership will remain with the caller.
* @param flags Some combination of AV_FRAME_SIDE_DATA_FLAG_* flags, or 0.
*
* @return newly added side data on success, NULL on error.
* @note In case of AV_FRAME_SIDE_DATA_FLAG_UNIQUE being set, entries of
*       matching AVFrameSideDataType will be removed before the addition
*       is attempted.
* @note In case of AV_FRAME_SIDE_DATA_FLAG_REPLACE being set, if an
*       entry of the same type already exists, it will be replaced instead.
*
*/
AVFrameSideData *av_frame_side_data_add(AVFrameSideData ***sd, int *nb_sd,
                                       enum AVFrameSideDataType type,
                                       AVBufferRef **buf, unsigned int flags);

/**
* Add a new side data entry to an array based on existing side data, taking
* a reference towards the contained AVBufferRef.
*
* @param sd    pointer to array of side data to which to add another entry,
*              or to NULL in order to start a new array.
* @param nb_sd pointer to an integer containing the number of entries in
*              the array.
* @param src   side data to be cloned, with a new reference utilized
*              for the buffer.
* @param flags Some combination of AV_FRAME_SIDE_DATA_FLAG_* flags, or 0.
*
* @return negative error code on failure, >=0 on success.
* @note In case of AV_FRAME_SIDE_DATA_FLAG_UNIQUE being set, entries of
*       matching AVFrameSideDataType will be removed before the addition
*       is attempted.
* @note In case of AV_FRAME_SIDE_DATA_FLAG_REPLACE being set, if an
*       entry of the same type already exists, it will be replaced instead.
*/
int av_frame_side_data_clone(AVFrameSideData ***sd, int *nb_sd,
                            const AVFrameSideData *src, unsigned int flags);

/**
* Get a side data entry of a specific type from an array.
*
* @param sd    array of side data.
* @param nb_sd integer containing the number of entries in the array.
* @param type  type of side data to be queried
*
* @return a pointer to the side data of a given type on success, NULL if there
*         is no side data with such type in this set.
*/
const AVFrameSideData *av_frame_side_data_get_c(const AVFrameSideData * const *sd,
                                               const int nb_sd,
                                               enum AVFrameSideDataType type);

/**
* Wrapper around av_frame_side_data_get_c() to workaround the limitation
* that for any type T the conversion from T * const * to const T * const *
* is not performed automatically in C.
* @see av_frame_side_data_get_c()
*/
static inline
const AVFrameSideData *av_frame_side_data_get(AVFrameSideData * const *sd,
                                             const int nb_sd,
                                             enum AVFrameSideDataType type)
{
   return av_frame_side_data_get_c((const AVFrameSideData * const *)sd,
                                   nb_sd, type);
}

/**
* Remove and free all side data instances of the given type from an array.
*/
void av_frame_side_data_remove(AVFrameSideData ***sd, int *nb_sd,
                              enum AVFrameSideDataType type);

/**
* Remove and free all side data instances that match any of the given
* side data properties. (See enum AVSideDataProps)
*/
void av_frame_side_data_remove_by_props(AVFrameSideData ***sd, int *nb_sd,
                                       int props);

/**
* @}
*/

#endif /* AVUTIL_FRAME_H */