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• Concat gives flickering result

  4 avril 2016, par Robin Castlin

  I really don't get this; I use ffmpeg concat one 2 files and the audio is concated well, but the videos aren't. The second video causes freeze/flicker/green screen instead.

  'ffmpeg -y -f concat -i concat.txt -c:v libx264 -pix_fmt yuv420p -c:a copy output.mkv

  Comparing the files, I have made them as identical as possible:

  • input.mkv1
    Video: MPEG4 Video (H264) 1280x720 60fps [V: h264 main L4.1, yuv420p, 1280x720 [default]] Audio: AAC 48000Hz stereo [A: aac, 48000 Hz, stereo [default]]
  • input2.mkv
    Video: MPEG4 Video (H264) 1280x720 60fps [V: English [eng] (h264 main L4.1, yuv420p, 1280x720) [default]] Audio: AAC 48000Hz stereo [A: English [eng] (aac, 48000 Hz, stereo) [default]]

  What could cause this behavior?

  

• -bash : ./configure : Permission denied - libvpx

  4 avril 2016, par Prasad Revanaki

  I am installing ffmpeg on Linux 2.6.32-504.el6.x86_64 x86_64. As part of installation, i have to configure libvpx. While configuring libvpx, I am getting permission denied error.

  cd /opt
  cp /opt/ml-sp-tng/ffmpeg/libvpx-v1.3.0.tar.gz .
  tar xzfv libvpx-v1.3.0.tar.gz
  cd libvpx
  ./configure --prefix="$HOME/ffmpeg_build" --disable-examples
  
  -bash: ./configure: Permission denied
  

• How to Burn Subtitle (SRT) file and Timecode in FFMpeg

  4 avril 2016, par Rahul Prasad

  I am trying to burn (hardcode) an SRT file and a timecode value to a MP4 file, but to no avail.

  I am currently burning the srt and timecode using the below commands:

  Burn SRT

  ffmpeg -i input.mp4 -vf subtitles=subs.srt out.mp4
  

  Burn Timecode

  ffmpeg -i input.mp4  -filter_complex "drawtext=fontfile=/Windows/Fonts/arial.ttf:x=320:y=main_h-50:fontsize=32:fontcolor='white':timecode='00\:00\:00\:00':rate=29.97" -y output.mp4
  

  However, I am not able to combine the two into a single command as ffmpeg does not allow usage of -vf and -filter_complex together.

  Is there a workaround?

• OpenCV (C++) Load images sequentially with name containing X

  4 avril 2016, par Alec Gamble

  I was wanting to create a program which would take every image within a certain directory (preferably with a specific image prefix) and store them in an array of Mats.

  subquestion: I'm creating the images using ffmpeg previously in the same program.

  system(
         "ffmpeg "
         "-i ..." // input file
         "-r 10 " // rate in Hz
         "..." // output location
         );
  

  What is the best practice for the location to output the images to considering that they're to be temporary? I'm building in XCode and am currently making an OSX application but I would ideally like to be able to port it to iOS. should I use /tmp?

• ffmpeg only set width

  4 avril 2016, par flatworld

  I need to set width only, in ffmpeg.

  I used the code below:

  ffmpeg -i IMG_0361.mov -y -vcodec mpeg4 \
         -vf scale=480:-1 -r 15 \
         -b 64k -acodec libfaac -ac 1 -ar 8000 -ab 12200 \
         -flags bitexact IMG_0361.mp4
  

  But it shows an error:

  ffmpeg: unrecognized option '-vf'