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POGetting artifacts when trying to read video stream from YouTube
 

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  1. POGetting artifacts when trying to read video stream from YouTube
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    <p>I'm trying to read the video frames from the RTSP stream that I get from YouTube. Here is the link for my test video:</p> <blockquote> <p>rtsp://v8.cache5.c.youtube.com/CiILENy73wIaGQkJlrXMiAG8BxMYDSANFEgGUgZ2aWRlb3MM/0/0/0/video.3gp</p> </blockquote> <p>If I'm reading frames from the local file - everything is fine, but when read them from a stream I get nothing but lots of artifacts. I've googled around and found out that there might be a problem with UDP packets and switching to TCP may help but I really can't find where it is possible to change this.</p> <p>Here is the function for reading a frame:</p> <pre><code>bool nextFrame(AVFormatContext *pFormatCtx, AVCodecContext *pCodecCtx, int videoStream, AVFrame *pFrame) { AVPacket packet; int frameFinished = 0; while( !frameFinished &amp;&amp; av_read_frame(pFormatCtx, &amp;packet) &gt;= 0 ) { // Is this a packet from the video stream? if( packet.stream_index == videoStream ) { // Decode video frame avcodec_decode_video2(pCodecCtx, pFrame, &amp;frameFinished, &amp;packet); } // Free the packet that was allocated by av_read_frame av_free_packet(&amp;packet); } return frameFinished!=0; } </code></pre> <p>I'm also getting lots of error messages in my log:</p> <pre><code>[h263 @ 0x7804c00] warning: first frame is no keyframe [h263 @ 0x7804c00] illegal ac vlc code at 6x1 [h263 @ 0x7804c00] Error at MB: 18 [h263 @ 0x7804c00] concealing 99 DC, 99 AC, 99 MV errors [h263 @ 0x7804c00] I cbpy damaged at 10 4 [h263 @ 0x7804c00] Error at MB: 58 [h263 @ 0x7804c00] concealing 99 DC, 99 AC, 99 MV errors [h263 @ 0x7804c00] I cbpy damaged at 6 6 [h263 @ 0x7804c00] Error at MB: 78 [h263 @ 0x7804c00] concealing 76 DC, 76 AC, 76 MV errors [h263 @ 0x7804c00] I cbpy damaged at 5 5 [h263 @ 0x7804c00] Error at MB: 65 [h263 @ 0x7804c00] concealing 88 DC, 88 AC, 88 MV errors [h263 @ 0x7804c00] illegal ac vlc code at 7x5 [h263 @ 0x7804c00] Error at MB: 67 [h263 @ 0x7804c00] concealing 86 DC, 86 AC, 86 MV errors </code></pre> <p>...and so on</p> <p>edit: this is 99.9% a UDP-TCP problem. I've found this link:</p> <blockquote> <p>rtsp://195.200.199.8/mpeg4/media.amp</p> </blockquote> <p>This is some test camera available online. It streams with artifacts. However if it has get parameter 'tcp' and if I use this </p> <blockquote> <p>rtsp://195.200.199.8/mpeg4/media.amp?tcp</p> </blockquote> <p>everything works without artifacts.</p> <p>So to correct my question: is there any way to force YouTube or ffmpeg to use TCP ?</p>
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    1. COWhat function are you using to open the connection to the url? Have you written your own URLContext?
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    2. CO@JConway I'm just using standard avformat_open_input with URL as path
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