Homework
编写—个将ts或mp4中视频文件解码到yuv的程序
yuv数据可以使用如下命令播放:
ffplay -i output yuv-pix_fmt yuv420p-s 1024x436
要求:
- ffmpeg解析到avpacket并打印出pts和dts字段
- 完成解码到avframe并打印任意字段
- 完成yuv数据保存
// teminal orders on bash
cd examples
gcc -o demuxing_decoding demuxing_decoding.c $(pkg-config --cflags --libs libavformat libavcodec libavutil libswscale)export PKG_CONFIG_PATH=/home/ubuntu2204/workspace/ffmpeg/build/lib/pkgconfig:$PKG_CONFIG_PATH
//solve not find head file./demuxing_decoding ubuntu22.04.mp4 a.yuv a.avi /* read frames from the file */// while (av_read_frame(fmt_ctx, pkt) >= 0) {// // check if the packet belongs to a stream we are interested in, otherwise// // skip it// if (pkt->stream_index == video_stream_idx)// ret = decode_packet(video_dec_ctx, pkt);// else if (pkt->stream_index == audio_stream_idx)// ret = decode_packet(audio_dec_ctx, pkt);// av_packet_unref(pkt);// if (ret < 0)// break;// }while (av_read_frame(fmt_ctx, pkt) >= 0) {// 打印PTS和DTS信息if (pkt->stream_index == video_stream_idx || pkt->stream_index == audio_stream_idx) {AVRational *time_base = &fmt_ctx->streams[pkt->stream_index]->time_base;printf("PTS: %s, DTS: %s, duration: %d, stream index: %d\n",av_ts2timestr(pkt->pts, time_base),av_ts2timestr(pkt->dts, time_base),pkt->duration,pkt->stream_index);}
