ffmpeg # time_base转换函数av_rescale

    AVRational src_time_base = (AVRational){1, 25};

    AVRational dst_time_base = (AVRational){1, 90000};

    int64_t pts = 2;

    int64_t new_pts = av_rescale_q(pts, src_time_base , dst_time_base);