tor-browser

packet.h (30773B)

---

/*
* AVPacket public API
*
* 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
*/

#ifndef AVCODEC_PACKET_H
#define AVCODEC_PACKET_H

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

#include "libavutil/attributes.h"
#include "libavutil/buffer.h"
#include "libavutil/dict.h"
#include "libavutil/rational.h"
#include "libavutil/version.h"

#include "libavcodec/version_major.h"

/**
* @defgroup lavc_packet_side_data AVPacketSideData
*
* Types and functions for working with AVPacketSideData.
* @{
*/
enum AVPacketSideDataType {
   /**
    * An AV_PKT_DATA_PALETTE side data packet contains exactly AVPALETTE_SIZE
    * bytes worth of palette. This side data signals that a new palette is
    * present.
    */
   AV_PKT_DATA_PALETTE,

   /**
    * The AV_PKT_DATA_NEW_EXTRADATA is used to notify the codec or the format
    * that the extradata buffer was changed and the receiving side should
    * act upon it appropriately. The new extradata is embedded in the side
    * data buffer and should be immediately used for processing the current
    * frame or packet.
    */
   AV_PKT_DATA_NEW_EXTRADATA,

   /**
    * An AV_PKT_DATA_PARAM_CHANGE side data packet is laid out as follows:
    * @code
    * u32le param_flags
    * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE)
    *     s32le sample_rate
    * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS)
    *     s32le width
    *     s32le height
    * @endcode
    */
   AV_PKT_DATA_PARAM_CHANGE,

   /**
    * An AV_PKT_DATA_H263_MB_INFO side data packet contains a number of
    * structures with info about macroblocks relevant to splitting the
    * packet into smaller packets on macroblock edges (e.g. as for RFC 2190).
    * That is, it does not necessarily contain info about all macroblocks,
    * as long as the distance between macroblocks in the info is smaller
    * than the target payload size.
    * Each MB info structure is 12 bytes, and is laid out as follows:
    * @code
    * u32le bit offset from the start of the packet
    * u8    current quantizer at the start of the macroblock
    * u8    GOB number
    * u16le macroblock address within the GOB
    * u8    horizontal MV predictor
    * u8    vertical MV predictor
    * u8    horizontal MV predictor for block number 3
    * u8    vertical MV predictor for block number 3
    * @endcode
    */
   AV_PKT_DATA_H263_MB_INFO,

   /**
    * This side data should be associated with an audio stream and contains
    * ReplayGain information in form of the AVReplayGain struct.
    */
   AV_PKT_DATA_REPLAYGAIN,

   /**
    * This side data contains a 3x3 transformation matrix describing an affine
    * transformation that needs to be applied to the decoded video frames for
    * correct presentation.
    *
    * See libavutil/display.h for a detailed description of the data.
    */
   AV_PKT_DATA_DISPLAYMATRIX,

   /**
    * This side data should be associated with a video stream and contains
    * Stereoscopic 3D information in form of the AVStereo3D struct.
    */
   AV_PKT_DATA_STEREO3D,

   /**
    * This side data should be associated with an audio stream and corresponds
    * to enum AVAudioServiceType.
    */
   AV_PKT_DATA_AUDIO_SERVICE_TYPE,

   /**
    * This side data contains quality related information from the encoder.
    * @code
    * u32le quality factor of the compressed frame. Allowed range is between 1 (good) and FF_LAMBDA_MAX (bad).
    * u8    picture type
    * u8    error count
    * u16   reserved
    * u64le[error count] sum of squared differences between encoder in and output
    * @endcode
    */
   AV_PKT_DATA_QUALITY_STATS,

   /**
    * This side data contains an integer value representing the stream index
    * of a "fallback" track.  A fallback track indicates an alternate
    * track to use when the current track can not be decoded for some reason.
    * e.g. no decoder available for codec.
    */
   AV_PKT_DATA_FALLBACK_TRACK,

   /**
    * This side data corresponds to the AVCPBProperties struct.
    */
   AV_PKT_DATA_CPB_PROPERTIES,

   /**
    * Recommends skipping the specified number of 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_PKT_DATA_SKIP_SAMPLES,

   /**
    * An AV_PKT_DATA_JP_DUALMONO side data packet indicates that
    * the packet may contain "dual mono" audio specific to Japanese DTV
    * and if it is true, recommends only the selected channel to be used.
    * @code
    * u8    selected channels (0=main/left, 1=sub/right, 2=both)
    * @endcode
    */
   AV_PKT_DATA_JP_DUALMONO,

   /**
    * A list of zero terminated key/value strings. There is no end marker for
    * the list, so it is required to rely on the side data size to stop.
    */
   AV_PKT_DATA_STRINGS_METADATA,

   /**
    * Subtitle event position
    * @code
    * u32le x1
    * u32le y1
    * u32le x2
    * u32le y2
    * @endcode
    */
   AV_PKT_DATA_SUBTITLE_POSITION,

   /**
    * Data found in BlockAdditional element of matroska container. There is
    * no end marker for the data, so it is required to rely on the side data
    * size to recognize the end. 8 byte id (as found in BlockAddId) followed
    * by data.
    */
   AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL,

   /**
    * The optional first identifier line of a WebVTT cue.
    */
   AV_PKT_DATA_WEBVTT_IDENTIFIER,

   /**
    * The optional settings (rendering instructions) that immediately
    * follow the timestamp specifier of a WebVTT cue.
    */
   AV_PKT_DATA_WEBVTT_SETTINGS,

   /**
    * A list of zero terminated key/value strings. There is no end marker for
    * the list, so it is required to rely on the side data size to stop. This
    * side data includes updated metadata which appeared in the stream.
    */
   AV_PKT_DATA_METADATA_UPDATE,

   /**
    * MPEGTS stream ID as uint8_t, this is required to pass the stream ID
    * information from the demuxer to the corresponding muxer.
    */
   AV_PKT_DATA_MPEGTS_STREAM_ID,

   /**
    * Mastering display metadata (based on SMPTE-2086:2014). This metadata
    * should be associated with a video stream and contains data in the form
    * of the AVMasteringDisplayMetadata struct.
    */
   AV_PKT_DATA_MASTERING_DISPLAY_METADATA,

   /**
    * This side data should be associated with a video stream and corresponds
    * to the AVSphericalMapping structure.
    */
   AV_PKT_DATA_SPHERICAL,

   /**
    * Content light level (based on CTA-861.3). This metadata should be
    * associated with a video stream and contains data in the form of the
    * AVContentLightMetadata struct.
    */
   AV_PKT_DATA_CONTENT_LIGHT_LEVEL,

   /**
    * ATSC A53 Part 4 Closed Captions. This metadata should be associated with
    * a video stream. A53 CC bitstream is stored as uint8_t in AVPacketSideData.data.
    * The number of bytes of CC data is AVPacketSideData.size.
    */
   AV_PKT_DATA_A53_CC,

   /**
    * This side data is encryption initialization data.
    * The format is not part of ABI, use av_encryption_init_info_* methods to
    * access.
    */
   AV_PKT_DATA_ENCRYPTION_INIT_INFO,

   /**
    * This side data contains encryption info for how to decrypt the packet.
    * The format is not part of ABI, use av_encryption_info_* methods to access.
    */
   AV_PKT_DATA_ENCRYPTION_INFO,

   /**
    * Active Format Description data consisting of a single byte as specified
    * in ETSI TS 101 154 using AVActiveFormatDescription enum.
    */
   AV_PKT_DATA_AFD,

   /**
    * Producer Reference Time data corresponding to the AVProducerReferenceTime struct,
    * usually exported by some encoders (on demand through the prft flag set in the
    * AVCodecContext export_side_data field).
    */
   AV_PKT_DATA_PRFT,

   /**
    * ICC profile data consisting of an opaque octet buffer following the
    * format described by ISO 15076-1.
    */
   AV_PKT_DATA_ICC_PROFILE,

   /**
    * DOVI configuration
    * ref:
    * dolby-vision-bitstreams-within-the-iso-base-media-file-format-v2.1.2, section 2.2
    * dolby-vision-bitstreams-in-mpeg-2-transport-stream-multiplex-v1.2, section 3.3
    * Tags are stored in struct AVDOVIDecoderConfigurationRecord.
    */
   AV_PKT_DATA_DOVI_CONF,

   /**
    * Timecode which conforms to SMPTE ST 12-1:2014. 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_PKT_DATA_S12M_TIMECODE,

   /**
    * HDR10+ dynamic metadata associated with a video frame. The metadata is in
    * the form of the AVDynamicHDRPlus struct and contains
    * information for color volume transform - application 4 of
    * SMPTE 2094-40:2016 standard.
    */
   AV_PKT_DATA_DYNAMIC_HDR10_PLUS,

   /**
    * IAMF Mix Gain Parameter Data associated with the audio frame. This metadata
    * is in the form of the AVIAMFParamDefinition struct and contains information
    * defined in sections 3.6.1 and 3.8.1 of the Immersive Audio Model and
    * Formats standard.
    */
   AV_PKT_DATA_IAMF_MIX_GAIN_PARAM,

   /**
    * IAMF Demixing Info Parameter Data associated with the audio frame. This
    * metadata is in the form of the AVIAMFParamDefinition struct and contains
    * information defined in sections 3.6.1 and 3.8.2 of the Immersive Audio Model
    * and Formats standard.
    */
   AV_PKT_DATA_IAMF_DEMIXING_INFO_PARAM,

   /**
    * IAMF Recon Gain Info Parameter Data associated with the audio frame. This
    * metadata is in the form of the AVIAMFParamDefinition struct and contains
    * information defined in sections 3.6.1 and 3.8.3 of the Immersive Audio Model
    * and Formats standard.
    */
   AV_PKT_DATA_IAMF_RECON_GAIN_INFO_PARAM,

   /**
    * Ambient viewing environment metadata, as defined by H.274. This metadata
    * should be associated with a video stream and contains data in the form
    * of the AVAmbientViewingEnvironment struct.
   */
   AV_PKT_DATA_AMBIENT_VIEWING_ENVIRONMENT,

   /**
    * The number of pixels to discard from the top/bottom/left/right border of the
    * decoded frame to obtain the sub-rectangle intended for presentation.
    *
    * @code
    * u32le crop_top
    * u32le crop_bottom
    * u32le crop_left
    * u32le crop_right
    * @endcode
    */
   AV_PKT_DATA_FRAME_CROPPING,

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

   /**
    * This side data contains information about the reference display width(s)
    * and reference viewing distance(s) as well as information about the
    * corresponding reference stereo pair(s), i.e., the pair(s) of views to be
    * displayed for the viewer's left and right eyes on the reference display
    * at the reference viewing distance.
    * The payload is the AV3DReferenceDisplaysInfo struct defined in
    * libavutil/tdrdi.h.
    */
   AV_PKT_DATA_3D_REFERENCE_DISPLAYS,

   /**
    * Contains the last received RTCP SR (Sender Report) information
    * in the form of the AVRTCPSenderReport struct.
    */
   AV_PKT_DATA_RTCP_SR,

   /**
    * The number of side data types.
    * This is not part of the public API/ABI in the sense that it may
    * change when new side data types are added.
    * This must stay the last enum value.
    * If its value becomes huge, some code using it
    * needs to be updated as it assumes it to be smaller than other limits.
    */
   AV_PKT_DATA_NB
};

/**
* This structure stores auxiliary information for decoding, presenting, or
* otherwise processing the coded stream. It is typically exported by demuxers
* and encoders and can be fed to decoders and muxers either in a per packet
* basis, or as global side data (applying to the entire coded stream).
*
* Global side data is handled as follows:
* - During demuxing, it may be exported through
*   @ref AVCodecParameters.coded_side_data "AVStream's codec parameters", which can
*   then be passed as input to decoders through the
*   @ref AVCodecContext.coded_side_data "decoder context's side data", for
*   initialization.
* - For muxing, it can be fed through @ref AVCodecParameters.coded_side_data
*   "AVStream's codec parameters", typically  the output of encoders through
*   the @ref AVCodecContext.coded_side_data "encoder context's side data", for
*   initialization.
*
* Packet specific side data is handled as follows:
* - During demuxing, it may be exported through @ref AVPacket.side_data
*   "AVPacket's side data", which can then be passed as input to decoders.
* - For muxing, it can be fed through @ref AVPacket.side_data "AVPacket's
*   side data", typically the output of encoders.
*
* Different modules may accept or export different types of side data
* depending on media type and codec. Refer to @ref AVPacketSideDataType for a
* list of defined types and where they may be found or used.
*/
typedef struct AVPacketSideData {
   uint8_t *data;
   size_t   size;
   enum AVPacketSideDataType type;
} AVPacketSideData;

/**
* Allocate a new packet side data.
*
* @param sd    pointer to an array of side data to which the side data should
*              be added. *sd may be NULL, in which case the array will be
*              initialized.
* @param nb_sd pointer to an integer containing the number of entries in
*              the array. The integer value will be increased by 1 on success.
* @param type  side data type
* @param size  desired side data size
* @param flags currently unused. Must be zero
*
* @return pointer to freshly allocated side data on success, or NULL otherwise.
*/
AVPacketSideData *av_packet_side_data_new(AVPacketSideData **psd, int *pnb_sd,
                                         enum AVPacketSideDataType type,
                                         size_t size, int flags);

/**
* Wrap existing data as packet side data.
*
* @param sd    pointer to an array of side data to which the side data should
*              be added. *sd may be NULL, in which case the array will be
*              initialized
* @param nb_sd pointer to an integer containing the number of entries in
*              the array. The integer value will be increased by 1 on success.
* @param type  side data type
* @param data  a data array. It must be allocated with the av_malloc() family
*              of functions. The ownership of the data is transferred to the
*              side data array on success
* @param size  size of the data array
* @param flags currently unused. Must be zero
*
* @return pointer to freshly allocated side data on success, or NULL otherwise
*         On failure, the side data array is unchanged and the data remains
*         owned by the caller.
*/
AVPacketSideData *av_packet_side_data_add(AVPacketSideData **sd, int *nb_sd,
                                         enum AVPacketSideDataType type,
                                         void *data, size_t size, int flags);

/**
* Get side information from a side data array.
*
* @param sd    the array from which the side data should be fetched
* @param nb_sd value containing the number of entries in the array.
* @param type  desired side information type
*
* @return pointer to side data if present or NULL otherwise
*/
const AVPacketSideData *av_packet_side_data_get(const AVPacketSideData *sd,
                                               int nb_sd,
                                               enum AVPacketSideDataType type);

/**
* Remove side data of the given type from a side data array.
*
* @param sd    the array from which the side data should be removed
* @param nb_sd pointer to an integer containing the number of entries in
*              the array. Will be reduced by the amount of entries removed
*              upon return
* @param type  side information type
*/
void av_packet_side_data_remove(AVPacketSideData *sd, int *nb_sd,
                               enum AVPacketSideDataType type);

/**
* Convenience function to free all the side data stored in an array, and
* the array itself.
*
* @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_packet_side_data_free(AVPacketSideData **sd, int *nb_sd);

const char *av_packet_side_data_name(enum AVPacketSideDataType type);

/**
* @}
*/

/**
* @defgroup lavc_packet AVPacket
*
* Types and functions for working with AVPacket.
* @{
*/

/**
* This structure stores compressed data. It is typically exported by demuxers
* and then passed as input to decoders, or received as output from encoders and
* then passed to muxers.
*
* For video, it should typically contain one compressed frame. For audio it may
* contain several compressed frames. Encoders are allowed to output empty
* packets, with no compressed data, containing only side data
* (e.g. to update some stream parameters at the end of encoding).
*
* The semantics of data ownership depends on the buf field.
* If it is set, the packet data is dynamically allocated and is
* valid indefinitely until a call to av_packet_unref() reduces the
* reference count to 0.
*
* If the buf field is not set av_packet_ref() would make a copy instead
* of increasing the reference count.
*
* The side data is always allocated with av_malloc(), copied by
* av_packet_ref() and freed by av_packet_unref().
*
* sizeof(AVPacket) being a part of the public ABI is deprecated. once
* av_init_packet() is removed, new packets will only be able to be allocated
* with av_packet_alloc(), and new fields may be added to the end of the struct
* with a minor bump.
*
* @see av_packet_alloc
* @see av_packet_ref
* @see av_packet_unref
*/
typedef struct AVPacket {
   /**
    * A reference to the reference-counted buffer where the packet data is
    * stored.
    * May be NULL, then the packet data is not reference-counted.
    */
   AVBufferRef *buf;
   /**
    * Presentation timestamp in AVStream->time_base units; the time at which
    * the decompressed packet will be presented to the user.
    * Can be AV_NOPTS_VALUE if it is not stored in the file.
    * pts MUST be larger or equal to dts as presentation cannot happen before
    * decompression, unless one wants to view hex dumps. Some formats misuse
    * the terms dts and pts/cts to mean something different. Such timestamps
    * must be converted to true pts/dts before they are stored in AVPacket.
    */
   int64_t pts;
   /**
    * Decompression timestamp in AVStream->time_base units; the time at which
    * the packet is decompressed.
    * Can be AV_NOPTS_VALUE if it is not stored in the file.
    */
   int64_t dts;
   uint8_t *data;
   int   size;
   int   stream_index;
   /**
    * A combination of AV_PKT_FLAG values
    */
   int   flags;
   /**
    * Additional packet data that can be provided by the container.
    * Packet can contain several types of side information.
    */
   AVPacketSideData *side_data;
   int side_data_elems;

   /**
    * Duration of this packet in AVStream->time_base units, 0 if unknown.
    * Equals next_pts - this_pts in presentation order.
    */
   int64_t duration;

   int64_t pos;                            ///< byte position in stream, -1 if unknown

   /**
    * for some private data of the user
    */
   void *opaque;

   /**
    * AVBufferRef for free use by the API user. FFmpeg will never check the
    * contents of the buffer ref. FFmpeg calls av_buffer_unref() on it when
    * the packet is unreferenced. av_packet_copy_props() calls create a new
    * reference with av_buffer_ref() for the target packet's opaque_ref field.
    *
    * This is unrelated to the opaque field, although it serves a similar
    * purpose.
    */
   AVBufferRef *opaque_ref;

   /**
    * Time base of the packet's timestamps.
    * In the future, this field may be set on packets output by encoders or
    * demuxers, but its value will be by default ignored on input to decoders
    * or muxers.
    */
   AVRational time_base;
} AVPacket;

#if FF_API_INIT_PACKET
attribute_deprecated
typedef struct AVPacketList {
   AVPacket pkt;
   struct AVPacketList *next;
} AVPacketList;
#endif

#define AV_PKT_FLAG_KEY     0x0001 ///< The packet contains a keyframe
#define AV_PKT_FLAG_CORRUPT 0x0002 ///< The packet content is corrupted
/**
* Flag is used to discard packets which are required to maintain valid
* decoder state but are not required for output and should be dropped
* after decoding.
**/
#define AV_PKT_FLAG_DISCARD   0x0004
/**
* The packet comes from a trusted source.
*
* Otherwise-unsafe constructs such as arbitrary pointers to data
* outside the packet may be followed.
*/
#define AV_PKT_FLAG_TRUSTED   0x0008
/**
* Flag is used to indicate packets that contain frames that can
* be discarded by the decoder.  I.e. Non-reference frames.
*/
#define AV_PKT_FLAG_DISPOSABLE 0x0010

enum AVSideDataParamChangeFlags {
   AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE    = 0x0004,
   AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS     = 0x0008,
};

/**
* Allocate an AVPacket and set its fields to default values.  The resulting
* struct must be freed using av_packet_free().
*
* @return An AVPacket filled with default values or NULL on failure.
*
* @note this only allocates the AVPacket itself, not the data buffers. Those
* must be allocated through other means such as av_new_packet.
*
* @see av_new_packet
*/
AVPacket *av_packet_alloc(void);

/**
* Create a new packet that references the same data as src.
*
* This is a shortcut for av_packet_alloc()+av_packet_ref().
*
* @return newly created AVPacket on success, NULL on error.
*
* @see av_packet_alloc
* @see av_packet_ref
*/
AVPacket *av_packet_clone(const AVPacket *src);

/**
* Free the packet, if the packet is reference counted, it will be
* unreferenced first.
*
* @param pkt packet to be freed. The pointer will be set to NULL.
* @note passing NULL is a no-op.
*/
void av_packet_free(AVPacket **pkt);

#if FF_API_INIT_PACKET
/**
* Initialize optional fields of a packet with default values.
*
* Note, this does not touch the data and size members, which have to be
* initialized separately.
*
* @param pkt packet
*
* @see av_packet_alloc
* @see av_packet_unref
*
* @deprecated This function is deprecated. Once it's removed,
              sizeof(AVPacket) will not be a part of the ABI anymore.
*/
attribute_deprecated
void av_init_packet(AVPacket *pkt);
#endif

/**
* Allocate the payload of a packet and initialize its fields with
* default values.
*
* @param pkt packet
* @param size wanted payload size
* @return 0 if OK, AVERROR_xxx otherwise
*/
int av_new_packet(AVPacket *pkt, int size);

/**
* Reduce packet size, correctly zeroing padding
*
* @param pkt packet
* @param size new size
*/
void av_shrink_packet(AVPacket *pkt, int size);

/**
* Increase packet size, correctly zeroing padding
*
* @param pkt packet
* @param grow_by number of bytes by which to increase the size of the packet
*/
int av_grow_packet(AVPacket *pkt, int grow_by);

/**
* Initialize a reference-counted packet from av_malloc()ed data.
*
* @param pkt packet to be initialized. This function will set the data, size,
*        and buf fields, all others are left untouched.
* @param data Data allocated by av_malloc() to be used as packet data. If this
*        function returns successfully, the data is owned by the underlying AVBuffer.
*        The caller may not access the data through other means.
* @param size size of data in bytes, without the padding. I.e. the full buffer
*        size is assumed to be size + AV_INPUT_BUFFER_PADDING_SIZE.
*
* @return 0 on success, a negative AVERROR on error
*/
int av_packet_from_data(AVPacket *pkt, uint8_t *data, int size);

/**
* Allocate new information of a packet.
*
* @param pkt packet
* @param type side information type
* @param size side information size
* @return pointer to fresh allocated data or NULL otherwise
*/
uint8_t* av_packet_new_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                                size_t size);

/**
* Wrap an existing array as a packet side data.
*
* @param pkt packet
* @param type side information type
* @param data the side data array. It must be allocated with the av_malloc()
*             family of functions. The ownership of the data is transferred to
*             pkt.
* @param size side information size
* @return a non-negative number on success, a negative AVERROR code on
*         failure. On failure, the packet is unchanged and the data remains
*         owned by the caller.
*/
int av_packet_add_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                           uint8_t *data, size_t size);

/**
* Shrink the already allocated side data buffer
*
* @param pkt packet
* @param type side information type
* @param size new side information size
* @return 0 on success, < 0 on failure
*/
int av_packet_shrink_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                              size_t size);

/**
* Get side information from packet.
*
* @param pkt packet
* @param type desired side information type
* @param size If supplied, *size will be set to the size of the side data
*             or to zero if the desired side data is not present.
* @return pointer to data if present or NULL otherwise
*/
uint8_t* av_packet_get_side_data(const AVPacket *pkt, enum AVPacketSideDataType type,
                                size_t *size);

/**
* Pack a dictionary for use in side_data.
*
* @param dict The dictionary to pack.
* @param size pointer to store the size of the returned data
* @return pointer to data if successful, NULL otherwise
*/
uint8_t *av_packet_pack_dictionary(AVDictionary *dict, size_t *size);
/**
* Unpack a dictionary from side_data.
*
* @param data data from side_data
* @param size size of the data
* @param dict the metadata storage dictionary
* @return 0 on success, < 0 on failure
*/
int av_packet_unpack_dictionary(const uint8_t *data, size_t size,
                               AVDictionary **dict);

/**
* Convenience function to free all the side data stored.
* All the other fields stay untouched.
*
* @param pkt packet
*/
void av_packet_free_side_data(AVPacket *pkt);

/**
* Setup a new reference to the data described by a given packet
*
* If src is reference-counted, setup dst as a new reference to the
* buffer in src. Otherwise allocate a new buffer in dst and copy the
* data from src into it.
*
* All the other fields are copied from src.
*
* @see av_packet_unref
*
* @param dst Destination packet. Will be completely overwritten.
* @param src Source packet
*
* @return 0 on success, a negative AVERROR on error. On error, dst
*         will be blank (as if returned by av_packet_alloc()).
*/
int av_packet_ref(AVPacket *dst, const AVPacket *src);

/**
* Wipe the packet.
*
* Unreference the buffer referenced by the packet and reset the
* remaining packet fields to their default values.
*
* @param pkt The packet to be unreferenced.
*/
void av_packet_unref(AVPacket *pkt);

/**
* Move every field in src to dst and reset src.
*
* @see av_packet_unref
*
* @param src Source packet, will be reset
* @param dst Destination packet
*/
void av_packet_move_ref(AVPacket *dst, AVPacket *src);

/**
* Copy only "properties" fields from src to dst.
*
* Properties for the purpose of this function are all the fields
* beside those related to the packet data (buf, data, size)
*
* @param dst Destination packet
* @param src Source packet
*
* @return 0 on success AVERROR on failure.
*/
int av_packet_copy_props(AVPacket *dst, const AVPacket *src);

/**
* Ensure the data described by a given packet is reference counted.
*
* @note This function does not ensure that the reference will be writable.
*       Use av_packet_make_writable instead for that purpose.
*
* @see av_packet_ref
* @see av_packet_make_writable
*
* @param pkt packet whose data should be made reference counted.
*
* @return 0 on success, a negative AVERROR on error. On failure, the
*         packet is unchanged.
*/
int av_packet_make_refcounted(AVPacket *pkt);

/**
* Create a writable reference for the data described by a given packet,
* avoiding data copy if possible.
*
* @param pkt Packet whose data should be made writable.
*
* @return 0 on success, a negative AVERROR on failure. On failure, the
*         packet is unchanged.
*/
int av_packet_make_writable(AVPacket *pkt);

/**
* Convert valid timing fields (timestamps / durations) in a packet from one
* timebase to another. Timestamps with unknown values (AV_NOPTS_VALUE) will be
* ignored.
*
* @param pkt packet on which the conversion will be performed
* @param tb_src source timebase, in which the timing fields in pkt are
*               expressed
* @param tb_dst destination timebase, to which the timing fields will be
*               converted
*/
void av_packet_rescale_ts(AVPacket *pkt, AVRational tb_src, AVRational tb_dst);

/**
* Allocate an AVContainerFifo instance for AVPacket.
*
* @param flags currently unused
*/
struct AVContainerFifo *av_container_fifo_alloc_avpacket(unsigned flags);

/**
* @}
*/

#endif // AVCODEC_PACKET_H