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• sh : ffmpeg : command not found when run command through php

  9 avril 2015, par Ashok

  I have installed successfully installed FFMpeg on root of my Centos 6 machine (https://trac.ffmpeg.org/wiki/CompilationGuide/Centos).

  My workplace of apache/php is /var/www/html

  Now I’m running below command successfully on /var/www/html directory to capture frame from the video file. It’s capturing a frame.

  [root@localhost html]# ffmpeg -i video.mpg -an -ss 30  -t 00:00:01 -r 1 -y -vcodec mjpeg -f mjpeg -s 160x100 frame8  2>&1

  I want to run this command through php and using shell_exec() or exec() php functions. My php code for running the command is :

  $cmd = "/root/bin/ffmpeg -i /project/app/webroot/videos/video.mpg -ss 00:00:14.435 -f image2 -vframes 1 /project/app/webroot/videothumbnails/example-thumb.jpg";
  
  $locale = 'en_IN.UTF-8';
  
  setlocale(LC_ALL, $locale);
  
  putenv('LC_ALL='.$locale);
  
  echo shell_exec($cmd);

  When I’m trying to run command through above php code, I’m getting below error :

  sh: ffmpeg: command not found

  Please help me to solve out this problem.

• Yes or no, will ffmpeg api do hardware decoding on iOS ?

  15 janvier 2019, par Fattie

  There seems to be conflicting information on this.

  https://trac.ffmpeg.org/wiki/HWAccelIntro

  notice the first diagram, it firmly marks iOS as “Y” on VideoToolbox

  

  however in the comments down the bottom it says

  VideoToolbox. ​VideoToolbox, only supported on macOS. H.264 decoding is available in FFmpeg/libavcodec.

  And in the confusing second diagram it says "Standalone" is not done for VideoToolbox.

  We have found that using ffmpeg compiled in to iOS .... it seems to not use hardware decoding, which is really a pain.

  1. With avcodec_get_hw_config() we get AV_PIX_FMT_VIDEOTOOLBOX, AV_HWDEVICE_TYPE_VIDEOTOOLBOX which is seemingly correct.

  2. But usage and framerates clearly shows everything is being done in CPU. The code is in ff_hevc_hls_residual_coding all the time. (That’s fffmpeg’s software decoder.)

  3. This very diff very long git.videolan.org URL here seems to suggest again it should all be working.

  4. Have tried every iPhone etc. of course

• Why are the colors transposed in my webm thumbnails ?

  9 décembre 2022, par Peter Chaplin

  I have been using ffmpeg to generate webm files from png frames, and the webm files run ok in my video player, but the thumbnail colours appear transposed - blue replacing red, purple replacing orange, brown replacing green. I've also encountered issue uploading the webm to an image hosting site (which normally does support webms), though this might be an issue on their end.
I'm on Ubuntu 22.04.1 LTS

  


  Does anyone know what might be causing this, and how to fix it ? Or how to check whether the webm files are ok or corrupted ?

  


  *Edit : ok, here's a side-by-side comparison of the thumbnails that appear in my file explorer - mp4 on the left and webm on the right.
Both were generated from the same set of pngs, using the same command except with the filename extension changed.

  


  

  


  Specifically,

  


  ffmpeg -framerate 24 -i Panel2Humanized/frame%04d.png panel2humanskin.webm


  


  and

  


  ffmpeg -framerate 24 -i Panel2Humanized/frame%04d.png panel2humanskin.mp4


  


  Both look the same when opened with a video player. It looks like the mp4 thumbnail grabbed the 1st frame while the webm grabbed the last, but the colors should be the same in each. (The text-bubble in the top-left is yellow in the mp4).

  


  *Follow-up : Apparently my WebMs are being generated in GBRP (Green-Blue-Red Planar) pixel format, the site I was trying to upload to requires YUV420P (Luma/Chroma 4:2:0 Planar) format, maybe that's the issue ? I'm still not sure exactly what that means or how to fix it.

  


  *Final follow-up : Looks like I needed to change the argument to :

  


  ffmpeg -framerate 24 -i Panel2Humanized/frame%04d.png -pix_fmt yuv420p paned2humanskin.webm