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• Handling Unknown encoder with ffmpeg hardware acceleration

  23 septembre 2018, par Gabrielle

  I am having a heavy use of CPU from ffmpeg to record my screen.

  To solve this, I am trying to use hardware acceleration. The problem is that my program is intended to run in different platforms...

  I would like to know if there is a way to say "use any hardware acceleration available or none if none is available"...

  I tried to use -c:v h264_nvenc -allow-sw 1 in hope that, since I was testing on a Mac and I don’t have this encoding, the software encoding would be used instead, but this did not happened, instead, the entire command crashed.

• how to use ffmpeg to cache a stream

  17 septembre 2018, par Marcel

  i am using the following command to copy a live stream and restream it to a different endpoint. This works Ok , but the problem is that the stream breaks up/buffer occurs on client/stuttering and does not run smoothly or even fails.
  Here is the command i am using

  ffmpeg -loglevel fatal -fflags +igndts -re -i "$1" -acodec copy -vcodec copy -tune zerolatency -f mpegts pipe:1

  $1 is an mpegts http stream url

  what will be the correct command to use for ffmpeg to "cache" few seconds of the input stream (input is mpegts) before emitting the stream out as is ? I hope by caching i can get a smooth playback , no stuttering or buffering on the client side.

  thanks for help !!

• 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