ffmpeg的函数av_seek_frame [英] ffmpeg av_seek_frame

问题描述

我试图用不过我在最麻烦确定如何生成一个时间戳寻求FFmpeg的函数av_seek_frame方法在电影中寻找。假设我想寻求帧向前或向后多少多少，我知道帧电影目前，我怎么会去这样做？

I am attempting to seek in a movie using ffmpeg's av_seek_frame method however I'm having the most trouble determining how to generate a time-stamp to seek to. Assuming I want to seek x amount of frames either forward or backward and I know what frame the movie is currently on, how would I go about doing this?

推荐答案

下面是我是如何做到的：

Here is how i did it:

// Duration of one frame in AV_TIME_BASE units
int64_t timeBase;

void open(const char* fpath){
    ...
    timeBase = (int64_t(pCodecCtx->time_base.num) * AV_TIME_BASE) / int64_t(pCodecCtx->time_base.den);
    ...
}

bool seek(int frameIndex){

    if(!pFormatCtx)
        return false;

    int64_t seekTarget = int64_t(frameIndex) * timeBase;

    if(av_seek_frame(pFormatCtx, -1, seekTarget, AVSEEK_FLAG_ANY) < 0)
        mexErrMsgTxt("av_seek_frame failed.");

}

该AVSEEK_FLAG_ANY使寻求每一帧，而不只是关键帧。

The AVSEEK_FLAG_ANY enables seeking to every frame and not just keyframes.

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