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• Android FFmpeg cant set quality of image

  24 octobre 2017, par TheOtherguyz4kj

  I am working with FFmpeg on Android, I am trying to extract frames from a video every second. I made this command that works well :

  final String cmd[] = {
  
  
  
              "-i",
  
              videoPath,
  
              "-vf",
  
              "fps=1",
  
              mediaStorageDir.getAbsolutePath() +
  
              "out%d.png"
  
      };

  Now I want to reduce the quality of the extracted frames so I tried this but get the error :

  final String cmd[] = {
  
  
  
              "-i",
  
              videoPath,
  
              "-vf",
  
              "fps=1",
  
              "-qscale:v 12",
  
              mediaStorageDir.getAbsolutePath() +
  
              "out%d.png"
  
      };

  At least one output file must be specified

  What is the problem ? I have searched online a lot and cant find a solution to the problem, also is there a better way to reduce the quality of my extracted frames ?

  thanks

• Trouble concatenating with ffmpeg (threads)

  4 janvier 2014, par mistypants

  I'm writing a batch script to automate one of my video editing processes. I've gotten everything done up to the final step, when I concatenate the video intro (1080.avi) with the video itself, then output. Here's the concatenate part of the script :

  ffmpeg -i 1080.avi -i %input%-lossless.avi ^
  
  -filter_complex "[0:0] [0:1] [1:0] [1:1] concat=n=2:v=1:a=1 [v] [a]" ^
  
  -map "[v]" -map "[a]" ^
  
  -c:v libx264 -preset veryslow -pix_fmt yuv420p ^
  
  -b:a 160k ^
  
  -threads 2 %input%-final.mp4

  It seems to work fine, but my computer overheats (it's a laptop) while it runs. I had this problem with just simple conversions and ffmpeg, so I added the -threads 2 part which eliminated the problem. It's back now.

  Did I mess up something in the script, or does concatenating just use more of the CPU ? If the latter, could I just decrease it to 1 thread ?

• Why does ffmpeg error on the last image in this avi -> jpg conversion ?

  13 avril 2018, par purple_arrows

  I want to make jpeg snapshots of every tenth frame of some avi files. I also want to skip some boring initial content that’s always the same in every avi.

  I’m using the following command :

  ffmpeg -ss SECONDS-TO-SKIP -i video.avi -vf framestep=step=10 images-%03.jpg

  For some files this works fine, but for others I get the following error (where THE-FINAL-NUMBER means I only get this error on what should be the last output image) :

  [image2 @ 0x16fa6c0] Could not open file : images-THE-FINAL-NUMBER.jpg
  
  av_interleaved_write_frame(): Input/output error

  What’s up ? Am I missing some important command line flag ? And how do I fix this ?

  ffmpeg version 2.8.14-0ubuntu0.16.04.1 built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.9) 20160609