如何在ffmpeg中使用滤镜，进行叠加字符

Answer 1

以下是本人的部分代码：//解码一个avpacketstatic int get_video_frame(VideoState *is, AVFrame *frame, int64_t *pts, AVPacket *pkt){int got_picture, i; int ret = 1;//if (packet_queue_get(&is->videoq, pkt, 1) < 0)// return -1;if ((i = av_read_frame(is->ic, pkt)) < 0)//如果读到文件尾部就退出return 0;i=avcodec_decode_video2(is->video_st->codec, frame, &got_picture, pkt);if (got_picture==0);//return 0;*pts = frame->pkt_dts;if (*pts == AV_NOPTS_VALUE)*pts = 0;/*if (((is->av_sync_type == AV_SYNC_AUDIO_MASTER && is->audio_st) ||is->av_sync_type == AV_SYNC_EXTERNAL_CLOCK) &&(framedrop>0 || (framedrop && is->audio_st))){//SDL_LockMutex(is->pictq_mutex);if (is->frame_last_pts != AV_NOPTS_VALUE && *pts){double clockdiff = get_video_clock(is) - get_master_clock(is);double dpts = av_q2d(is->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 < 0){is->frame_last_dropped_pos = pkt->pos;is->frame_last_dropped_pts = dpts;is->frame_drops_early++;ret = 0;}}}*/if (ret)is->frame_last_returned_time = av_gettime() / 1000000.0;