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• Getting artifacts when trying to read video stream from YouTube

  23 février 2012, par givi

  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 :

  rtsp ://v8.cache5.c.youtube.com/CiILENy73wIaGQkJlrXMiAG8BxMYDSANFEgGUgZ2aWRlb3MM/0/0/0/video.3gp

  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.

  Here is the function for reading a frame :

  bool nextFrame(AVFormatContext *pFormatCtx, AVCodecContext *pCodecCtx, int videoStream, AVFrame *pFrame) {  AVPacket packet;
  
      int frameFinished = 0;
  
  
  
      while( !frameFinished && av_read_frame(pFormatCtx, &packet) >= 0 ) {
  
          // Is this a packet from the video stream?
  
          if( packet.stream_index == videoStream ) {
  
              // Decode video frame
  
              avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
          }
  
  
  
          // Free the packet that was allocated by av_read_frame
  
          av_free_packet(&packet);    
  
         }    
  
         return frameFinished!=0;  
  
  }

  I'm also getting lots of error messages in my log :

  [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

  ...and so on

  edit : this is 99.9% a UDP-TCP problem. I've found this link :

  rtsp ://195.200.199.8/mpeg4/media.amp

  This is some test camera available online. It streams with artifacts. However if it has get parameter 'tcp' and if I use this

  rtsp ://195.200.199.8/mpeg4/media.amp ?tcp

  everything works without artifacts.

  So to correct my question : is there any way to force YouTube or ffmpeg to use TCP ?

• Use M4S2 as default video tag for MPEG-4 ASP in asf.

  5 octobre 2011, par Carl Eugen Hoyos

  Use M4S2 as default video tag for MPEG-4 ASP in asf.

• Transcoding a video from GoToMeeting WMV to MP4 using FFMPEG on Windows locks up dos window [migrated]

  22 août 2011, par Ryan

  I've been tasked with converting some pre-recorded GoToMeeting videos from wmv to mp4 format. I've got the GoToMeeting transcoder app available from Citrix (g2mtranscoder.exe) that takes the source wmv and makes it so that ffmpeg can work with the wmv. The problem I have is when I then try and take that wmv and transcode it to mp4.

  I'm using the latest pre-compiled static version of ffmpeg for Windows from here http://ffmpeg.zeranoe.com/builds/

  Here is the command line I'm using to begin the conversion :

  "C:\ffmpeg\ffmpeg.exe" -i "999_1366_768_g2m_transcoded.wmv" -f "mp4" -b "1000k" -r "30" -ab "128k" -ar "22050" -s "1366x768" -strict "experimental" -y "999.mp4"

  Here is FFMPEG's output. The last line is where the dos window seems to stop executing/locks up (when I say lock up I mean just the dos window is locked up, not the entire machine) :

  ffmpeg version N-31932-g41bf67d, Copyright (c) 2000-2011 the FFmpeg developers built on Aug 16 2011 18:54:12 with gcc 4.6.1
  
  configuration: --enable-gpl --enable-version3 --enable-memalign-hack --enable-runtime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libopenjpeg --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  
    libavutil    51. 12. 0 / 51. 12. 0
  
    libavcodec   53. 10. 0 / 53. 10. 0
  
    libavformat  53.  7. 0 / 53.  7. 0
  
    libavdevice  53.  3. 0 / 53.  3. 0
  
    libavfilter   2. 31. 1 /  2. 31. 1
  
    libswscale    2.  0. 0 /  2.  0. 0
  
    libpostproc  51.  2. 0 / 51.  2. 0
  
  [asf @ 01BBB600] max_analyze_duration 5000000 reached at 5194000
  
  
  
  Seems stream 1 codec frame rate differs from container frame rate: 1000.00 (1000/1) -> 59.92 (719/12)
  
  Input #0, asf, from 'D:\Inetpub\g2m\Transcoding\999_1366_768_g2m_transcoded.wmv':
  
    Metadata:
  
      WMFSDKVersion   : 10.00.00.4007
  
      WMFSDKNeeded    : 0.0.0.0000
  
      IsVBR           : 1
  
      VBR Peak        : 4403
  
      Buffer Average  : 1470
  
      WM/ToolVersion  : 4.8 Build 723
  
      WM/ToolName     : GoToMeeting
  
      BitRateFrom the writer: 1553
  
      Audio samples   : 6221
  
      Video samples   : 3455
  
      recording time  : Mon, 22 Aug 2011 11:48:42 Eastern Daylight Time
  
    Duration: 00:38:30.71, start: 0.000000, bitrate: 160 kb/s
  
      Stream #0.0: Audio: wmav2, 44100 Hz, 1 channels, s16, 48 kb/s
  
      Stream #0.1: Video: wmv3 (Main), yuv420p, 1366x768, 2154 kb/s, 59.92 tbr, 1k tbn, 1k tbc
  
  [buffer @ 01BBC120] w:1366 h:768 pixfmt:yuv420p tb:1/1000000 sar:0/1 sws_param:
  
  Output #0, mp4, to '\\nas4\FMS_APPLICATIONS\SVC\sk12\webinars\999.mp4':
  
    Metadata:
  
      WMFSDKVersion   : 10.00.00.4007
  
      WMFSDKNeeded    : 0.0.0.0000
  
      IsVBR           : 1
  
      VBR Peak        : 4403
  
      Buffer Average  : 1470
  
      WM/ToolVersion  : 4.8 Build 723
  
      WM/ToolName     : GoToMeeting
  
      BitRateFrom the writer: 1553
  
      Audio samples   : 6221
  
      Video samples   : 3455
  
      recording time  : Mon, 22 Aug 2011 11:48:42 Eastern Daylight Time
  
      encoder         : Lavf53.7.0
  
      Stream #0.0: Video: mpeg4, yuv420p, 1366x768, q=2-31, 1000 kb/s, 30 tbn, 30 tbc
  
      Stream #0.1: Audio: aac, 22050 Hz, 1 channels, s16, 128 kb/s
  
  Stream mapping:
  
    Stream #0.1 -> #0.0
  
    Stream #0.0 -> #0.1
  
  Press [q] to stop, [?] for help
  
  frame=  149 fps= 63 q=23.5 size=    1103kB time=00:00:04.96 bitrate=1818.6kbits/s dup=144 drop=0

  Does anyone have any idea why it's locking up the dos window and essentially failing to convert the file to mp4 ? I had a friend test it on a linux box and he was able to convert the video just fine.

  Thanks