一、分配函数
/*** Allocate an AVFrame and set its fields to default values. The resulting* struct must be freed using av_frame_free().** @return An AVFrame filled with default values or NULL on failure.** @note this only allocates the AVFrame itself, not the data buffers. Those* must be allocated through other means, e.g. with av_frame_get_buffer() or* manually.*/
AVFrame *av_frame_alloc(void);根据描述，AVFrame的分配函数是av_frame_alloc，但是仅仅只是分配AVFrame对象，AVFrame的成员变量data是不分配的。
1.1 分配data、buf、extended_data、extended_buf等
/*** Allocate new buffer(s) for audio or video data.** The following fields must be set on frame before calling this function:* - format (pixel format for video, sample format for audio)* - width and height for video* - nb_samples and ch_layout for audio** This function will fill AVFrame.data and AVFrame.buf arrays and, if* necessary, allocate and fill AVFrame.extended_data and AVFrame.extended_buf.* For planar formats, one buffer will be allocated for each plane.** @warning: if frame already has been allocated, calling this function will* leak memory. In addition, undefined behavior can occur in certain* cases.** @param frame frame in which to store the new buffers.* @param align Required buffer size alignment. If equal to 0, alignment will be* chosen automatically for the current CPU. It is highly* recommended to pass 0 here unless you know what you are doing.** @return 0 on success, a negative AVERROR on error.*/
int av_frame_get_buffer(AVFrame *frame, int align);示例：
分配一个解码器的pix_fmt格式的内存：
AVFrame* picture = av_frame_alloc();
if (!picture) {fprintf(stderr, "Could not allocate video frame\n");return;
}
picture->format = codec_ctx->pix_fmt;
picture->width = codec_ctx->width;
picture->height = codec_ctx->height;
ret = av_frame_get_buffer(picture, 0);分配一个BGR格式的内存：
AVFrame* pRGB = av_frame_alloc();
if (!pRGB) {return;
}
pRGB->format = AV_PIX_FMT_BGR24;
pRGB->width = codec_ctx->width;
pRGB->height = codec_ctx->height;
ret = av_frame_get_buffer(pRGB, 0);二、内存释放
/*** Free the frame and any dynamically allocated objects in it,* e.g. extended_data. If the frame is reference counted, it will be* unreferenced first.** @param frame frame to be freed. The pointer will be set to NULL.*/
void av_frame_free(AVFrame **frame);根据描述，使用下面代码可以释放分配的内存
av_frame_free(&pRGB);
av_frame_free(&picture);