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• ClassX installation "codec not found" due to dependencies [migrated]

  25 mars 2014, par khateeb

  ClassX is an interactive lecture streaming system developed in the Electrical Engineering Department at Stanford University.
  Unlike conventional lecture capturing systems, ClassX requires very simple consumer-grade equipment and minimal human operation.

  I faced problems during installing it, I hope you have a solution.

  BTW : I successfully installed it 2 years ago, but now I think the problem as the dependencies and Ubuntu versions are different than the versions we used two years ago.

  Detailed description of the problem :

  • I’m using Ubuntu 12.04
  • I followed the instructions @ ClassX installation guide, and all steps till step 4 are successfully done (the encoder bin file generated).
  • When trying to encode the video using the classX web system, it shows the encoding completed after few seconds.However, there are no tiles generated.

  • I tried to execute the command at CX_log.txt, and the following error appears.

    mahmoud@Mahmoud-HP-Pavilion-dv5-Notebook-PC : $ sudo perl /var/www/ClassXWebSystem/system/publishers/web/actions/encode.pl "/var/www/ClassXWebSystem/content/encoding/FALL_2013_2014/CS106A_FALL_2013_2014/lecSEven" "/var/www/ClassXWebSystem/content/encoding/FALL_2013_2014/CS106A_FALL_2013_2014/.encoding_1372706251" "/var/www/ClassXWebSystem/content/streaming/FALL_2013_2014/CS106A_FALL_2013_2014/lecSEven" "/var/www/ClassXWebSystem/system/publishers/bin" classx y n n
    [sudo] password for mahmoud :
    00068.jpg
    ..
    .
    00068.mp4
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from ’/var/www/ClassXWebSystem/content/encoding/FALL_2013_2014/CS106A_FALL_2013_2014/.encoding_1372706251/00068.mp4’ :
    Metadata :
    major_brand : isom
    minor_version : 512
    compatible_brands : isomiso2avc1mp41
    encoder : Lavf52.39.0
    Duration : 00:02:30.05, start : 0.000000, bitrate : 8141 kb/s
    Stream #0.0(und) : Video : h264, yuv420p, 1920x1080 [PAR 1:1 DAR 16:9], 8007 kb/s, 29.95 fps, 29.97 tbr, 2997 tbn, 59.94 tbc
    Stream #0.1(und) : Audio : aac, 44100 Hz, stereo, s16, 128 kb/s
    Output #0, mp4, to ’/var/www/ClassXWebSystem/content/encoding/FALL_2013_2014/CS106A_FALL_2013_2014/.encoding_1372706251/stream0.mp4’ :
    Stream #0.0 : Video : [0][0][0][0] / 0x0000, yuv420p, 640x360, q=32-36, 64 kb/s, 90k tbn, 14.99 tbc
    codec not found

• vdpau : add av_vdpau_bind_context()

  4 octobre 2014, par Rémi Denis-Courmont

  vdpau : add av_vdpau_bind_context()
  This function provides an explicit VDPAU device and VDPAU driver to
  
  libavcodec, so that the application is relieved from codec specifics
  
  and VdpDevice life cycle management.
  A stub flags parameter is added for future extension. For instance, it
  
  could be used to ignore codec level capabilities (if someone feels
  
  dangerous).
  Signed-off-by : Anton Khirnov <anton@khirnov.net>
  

  • [DBH] doc/APIchanges
  • [DBH] libavcodec/vdpau.c
  • [DBH] libavcodec/vdpau.h
  • [DBH] libavcodec/vdpau_internal.h
  • [DBH] libavcodec/version.h

• How to acurately trim audio and video with ffmpeg ? [closed]

  6 janvier 2024, par ws90

  I'm trying to automate the trimming and concatenation of video clips that also contain audio using ffmpeg.
The following commands are being used to trim clips and then concatenate the trimmed clips.

  


  .\ffmpeg -ss $startInSeconds -i $inputFile -t $partDurationInSeconds $outputFile


  


  This is done once per input file, the values of $startInSeconds and $partDurationInSeconds are different for different clips.

  


  .\ffmpeg -f concat -safe 0 -i .\list.txt -c copy $concatOutputFile


  


  list.txt is a list of $outputFile from the first trim command.

  


  The audio of the concat video file gradually de-syncs over time (slowing down compared to the trimmed clips), which is the problem I'm looking to fix.
It seems to slow down by about half a frame at each concat join.

  


  Why is the concat command causing this de-sync and what can I do about it ?

  


  I thought this was due to a mismatch in duration between the audio and video tracks of a trimmed clip (the audio would often be shorter than the video after trimming). I then tried padding the audio to match the video before concatenating but the problem persists.
I also found an example where the tracks were identical in length and the problem persists, so I think the concat command is the culprit, not the trim command.