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

  • You should find out what the actual ffmpeg command is and also provide the complete ffmpeg console output. Then properly format it by highlighting it and pressing ctrl+k or by using the code button.
    – llogan
    Mar 23, 2014 at 17:47

1 Answer 1


Did you install ffmpeg exactly as stated in the guide, by compiling it from source with the required options?

  • This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post.
    – hichris123
    Mar 25, 2014 at 1:02

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