来源:http://blog.csdn.net/chance_yin/article/details/16817957
一、AVPacket
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- /**
- * AVPacket 作为解码器的输入 或 编码器的输出。
- * 当作为解码器的输入时,它由demuxer生成,然后传递给解码器
- * 当作为编码器的输出时,由编码器生成,然后传递给muxer
- * 在视频中,AVPacket 只能包含不大于1帧的内容,而视频的1帧可能要包含在多个AVPacket中,AVPacket < AVFrame
- *
- *
- * AVPacket 是ffmpeg中少数的几个公共ABI,它只能被libavcodec和libformat在栈上分配
- *
- * The side data is always allocated with av_malloc() and is freed in
- * av_free_packet().
- */
- typedef struct AVPacket {
- /**
- * packet的内存空间来自于一个叫做“引用计数缓冲区”的地方,这个指针就指向一块引用计数缓冲区
- */
- AVBufferRef *buf;
- /**
- * 显示时间戳 单位是 AVStream->time_base units
- */
- int64_t pts;
- /**
- * 解压时间戳,在这个时刻该包需要被解码
- */
- int64_t dts;
- uint8_t *data;
- int size;
- int stream_index;
- /**
- * A combination of AV_PKT_FLAG values
- */
- int flags;
- /**
- * 存放额外的包信息
- */
- struct {
- uint8_t *data;
- int size;
- enum AVPacketSideDataType type;
- } *side_data;
- int side_data_elems;
- /**
- * 这个包的时间长度 in AVStream->time_base units, 设置0 表示未知.
- * duration = next_pts - this_pts i.
- */
- int duration;
- int64_t pos; ///< 在数据流中的字节偏移量, -1 if unknown
- int64_t convergence_duration;
- } AVPacket;
二、AVPicture
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- typedef struct AVPicture {
- uint8_t *data[AV_NUM_DATA_POINTERS]; ///< pointers to the image data planes
- int linesize[AV_NUM_DATA_POINTERS]; ///< number of bytes per line
- }
三、AVFrame
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- /**
- * AVFrame表示解码过后的一个数据帧
- *
- * AVFrame 通过使用 av_frame_alloc()来创建. 这个函数只是创建了AVFrame结构本身,在结构
- * 中定义的指向其他内存块的缓冲区指针要用其他方法来分配
- * 使用 av_frame_free()来释放AVFrame.
- *
- */
- typedef struct AVFrame {
- #define AV_NUM_DATA_POINTERS 8
- /**
- * pointer to the picture/channel planes.
- */
- uint8_t *data[AV_NUM_DATA_POINTERS];
- /**
- * For video, size in bytes of each picture line.
- * For audio, size in bytes of each plane.
- */
- int linesize[AV_NUM_DATA_POINTERS];
- /**
- * pointers to the data planes/channels.
- */
- uint8_t **extended_data;
- /**
- * width and height of the video frame
- */
- 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
- */
- 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;
- /**
- * PTS copied from the AVPacket that was decoded to produce this frame.
- */
- int64_t pkt_pts;
- /**
- * DTS copied from the AVPacket that triggered returning this frame. (if frame threading isnt 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;
- /**
- * error
- */
- uint64_t error[AV_NUM_DATA_POINTERS];
- /**
- * 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;
- /**
- * Sample rate of the audio data.
- */
- int sample_rate;
- /**
- * Channel layout of the audio data.
- */
- uint64_t channel_layout;
- /**
- * 指向这个帧要用到的AVBuffer中的数据缓冲区.
- *
- * 一般每个图像位面(就时data[0],data[1] data[2])只有一个指向AVBuffer的缓冲区, 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.
- */
- AVBufferRef **extended_buf;
- /**
- * Number of elements in extended_buf.
- */
- int nb_extended_buf;
- AVFrameSideData **side_data;
- int nb_side_data;
- /**
- * 可能因为解码错误,数据帧Frame会成为无效的帧,下面的结构就是当数据帧无效时使用的
- */
- #define AV_FRAME_FLAG_CORRUPT (1 << 0)
- /**
- * Frame flags, a combination of AV_FRAME_FLAG_*
- */
- int flags;
- int64_t best_effort_timestamp;
- int64_t pkt_pos;
- int64_t pkt_duration;
- AVDictionary *metadata;
- int decode_error_flags;
- #define FF_DECODE_ERROR_INVALID_BITSTREAM 1
- #define FF_DECODE_ERROR_MISSING_REFERENCE 2
- int channels;
- int pkt_size;
- enum AVColorSpace colorspace;
- enum AVColorRange color_range;
- /**
- * Not to be accessed directly from outside libavutil
- */
- AVBufferRef *qp_table_buf;
- } AVFrame;
时间: 2024-10-22 11:03:23