AVPacket: 存储解码前数据(编码数据:H264/AAC等)
/** * 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). * * AVPacket is one of the few structs in FFmpeg, whose size is a part of public * ABI. Thus it may be allocated on stack and no new fields can be added to it * without libavcodec and libavformat major bump. * * The semantics of data ownership depends on the 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(). * * @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 #if FF_API_CONVERGENCE_DURATION /** * @deprecated Same as the duration field, but as int64_t. This was required * for Matroska subtitles, whose duration values could overflow when the * duration field was still an int. */ attribute_deprecated int64_t convergence_duration; #endif } AVPacket;
AVFrame: 存储解码后数据(像素数据:YUV/RGB/PCM等)
/** * 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. The AVClass * for AVFrame can be obtained from avcodec_get_frame_class() */ typedef struct AVFrame { #define AV_NUM_DATA_POINTERS 8 /** * pointer to the picture/channel planes. * This might be different from the first allocated byte * * 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: Except for hwaccel formats, pointers not needed by the format * MUST be set to NULL. */ uint8_t *data[AV_NUM_DATA_POINTERS]; /** * For video, size in bytes of each picture line. * For audio, size in bytes of each plane. * * 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. */ 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; /** * 1 -> keyframe, 0-> not */ int key_frame; /** * 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; #if FF_API_PKT_PTS /** * PTS copied from the AVPacket that was decoded to produce this frame. * @deprecated use the pts field instead */ attribute_deprecated int64_t pkt_pts; #endif /** * 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; /** * picture number in bitstream order */ int coded_picture_number; /** * picture number in display order */ int display_picture_number; /** * quality (between 1 (good) and FF_LAMBDA_MAX (bad)) */ int quality; /** * for some private data of the user */ void *opaque; #if FF_API_ERROR_FRAME /** * @deprecated unused */ attribute_deprecated uint64_t error[AV_NUM_DATA_POINTERS]; #endif /** * When decoding, this signals how much the picture must be delayed. * extra_delay = repeat_pict / (2*fps) */ int repeat_pict; /** * The content of the picture is interlaced. */ int interlaced_frame; /** * If the content is interlaced, is top field displayed first. */ int top_field_first; /** * Tell user application that palette has changed from previous frame. */ int palette_has_changed; /** * reordered opaque 64 bits (generally an integer or a double precision float * PTS but can be anything). * The user sets AVCodecContext.reordered_opaque to represent the input at * that time, * the decoder reorders values as needed and sets AVFrame.reordered_opaque * to exactly one of the values provided by the user through AVCodecContext.reordered_opaque */ int64_t reordered_opaque; /** * Sample rate of the audio data. */ int sample_rate; /** * Channel layout of the audio data. */ uint64_t channel_layout; /** * AVBuffer references backing the data for this frame. If all elements of * this array are NULL, then this frame is not reference counted. 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 the frames which need to be decoded, but shouldn't be output. */ #define AV_FRAME_FLAG_DISCARD (1 << 2) /** * @} */ /** * 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; /** * reordered pos from the last AVPacket that has been input into the decoder * - encoding: unused * - decoding: Read by user. */ int64_t pkt_pos; /** * duration of the corresponding packet, expressed in * AVStream->time_base units, 0 if unknown. * - encoding: unused * - decoding: Read by user. */ int64_t pkt_duration; /** * 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 /** * number of audio channels, only used for audio. * - encoding: unused * - decoding: Read by user. */ int channels; /** * 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. */ int pkt_size; #if FF_API_FRAME_QP /** * QP table */ attribute_deprecated int8_t *qscale_table; /** * QP store stride */ attribute_deprecated int qstride; attribute_deprecated int qscale_type; attribute_deprecated AVBufferRef *qp_table_buf; #endif /** * For hwaccel-format frames, this should be a reference to the * AVHWFramesContext describing the frame. */ AVBufferRef *hw_frames_ctx; /** * 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 frame is unreferenced. av_frame_copy_props() calls create a new * reference with av_buffer_ref() for the target frame's opaque_ref field. * * This is unrelated to the opaque field, although it serves a similar * purpose. */ 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; } AVFrame;