Cómo usar el filtro para superponer caracteres en ffmpeg

//Decodificar un avpacket

static int get_video_frame(VideoState *is, AVFrame *frame, int64_t *pts, AVPacket *pkt)

{

if (is->frame_last_pts != AV_NOPTS_VALUE && *pts)

{

doble diferencia de reloj = get_video_clock(es) - get_master_clock( es );

doble dpts = av_q2d(is->video_st->pictq_mutex);

if (is->frame_last_pts !>video_st->time_base) * * pts ;

double ptsdiff = dpts - is->frame_last_pts;

if (fabs(clockdiff) < AV_NOSYNC_THRESHOLD &&

ptsdiff > 0 && ptsdiff < AV_NOSYNC_THRESHOLD &&

clockdiff + ptsdiff - is->frame_last_filter_ delay <

{

is->frame_last_dropped_pos = pkt->pos;

is->frame_last_dropped_pts = dpts;

is->frame_drops_early++;

ret = 0;

}

}

}*/

if (ret)

es->frame_last_returned_time = av_gettime() / 1000000.0;