tor-browser

packet.h (29044B)

---

/*
* 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_CHANNEL_COUNT)
  *     s32le channel_count
  * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT)
  *     u64le channel_layout
  * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE)
  *     s32le sample_rate
  * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS)
  *     s32le width
  *     s32le height
  * @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,

 /**
  * Recommmends 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 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
};

#if FF_API_QUALITY_FACTOR
#  define AV_PKT_DATA_QUALITY_FACTOR AV_PKT_DATA_QUALITY_STATS  // DEPRECATED
#endif

/**
* 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 AVStream.codecpar.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 AVStream.codecpar.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);

/**
* @}
*/

#endif  // AVCODEC_PACKET_H