struct AVFrame定义于<libavutil/frame.h>
struct AVFrame frame;AVFrame中存储的是经过解码后的原始数据。在解码中，AVFrame是解码器的输出；在编码中，AVFrame是编码器的输入。下图中，“decoded frames”的数据类型就是AVFrame：
_______ ______________
| | | |
| input | demuxer | encoded data | decoder
| file | ---------> | packets | -----+
|_______| |______________| |
v
_________
| |
| decoded |
| frames |
|_________|
________ ______________ |
| | | | |
| output | <-------- | encoded data | <----+
| file | muxer | packets | encoder
|________| |______________|
AVFrame数据结构非常重要，它的成员非常多，导致数据结构定义篇幅很长。下面引用的数据结构定义中省略冗长的注释以及大部分成员，先总体说明AVFrame的用法，然后再将一些重要成员摘录出来单独进行说明：
/** * 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 { uint8_t *data[AV_NUM_DATA_POINTERS]; int linesize[AV_NUM_DATA_POINTERS]; uint8_t **extended_data; int width, height; int nb_samples; int format; int key_frame; enum AVPictureType pict_type; AVRational sample_aspect_ratio; int64_t pts; ...... } AVFrame;AVFrame的用法：
AVFrame对象必须调用av_frame_alloc()在堆上分配，注意此处指的是AVFrame对象本身，AVFrame对象必须调用av_frame_free()进行销毁。
AVFrame中包含的数据缓冲区是
AVFrame通常只需分配一次，然后可以多次重用，每次重用前应调用av_frame_unref()将frame复位到原始的干净可用的状态。
下面将一些重要的成员摘录出来进行说明：
data
存储原始帧数据(未编码的原始图像或音频格式，作为解码器的输出或编码器的输入)。
data是一个指针数组，数组的每一个元素是一个指针，指向视频中图像的某一plane或音频中某一声道的plane。
关于图像plane的详细说明参考“色彩空间与像素格式”，音频plane的详细说明参数“原始音频格式”。下面简单说明：
对于packet格式，一幅YUV图像的Y、U、V交织存储在一个plane中，形如YUVYUV...，data[0]指向这个plane；
一个双声道的音频帧其左声道L、右声道R交织存储在一个plane中，形如LRLRLR...，data[0]指向这个plane。
对于planar格式，一幅YUV图像有Y、U、V三个plane，data[0]指向Y plane，data[1]指向U plane，data[2]指向V plane；
一个双声道的音频帧有左声道L和右声道R两个plane，data[0]指向L plane，data[1]指向R plane。
linesize
/** * 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];