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• IO.copy_stream performance in ruby

  19 juillet 2016, par stiller_leser

  I am trying to continously read a file in ruby (which is growing over time and needs to be processed in a separate process). Currently I am archiving this with the following bit of code :

  r,w = IO.pipe
  
  pid = Process.spawn('ffmpeg'+ffmpeg_args, {STDIN => r, STDERR => STDOUT})
  
  Process.detach pid
  
  while true do
  
    IO.copy_stream(open(@options['filename']), w)
  
    sleep 1
  
  end

  However - while working - I can’t imagine that this is the most performant way of doing it. An alternative would be to use the following variation :

  step = 1024*4
  
  copied = 0
  
  pid = Process.spawn('ffmpeg'+ffmpeg_args, {STDIN => r, STDERR => STDOUT})
  
  Process.detach pid
  
  while true do
  
    IO.copy_stream(open(@options['filename']), w, step, copied)
  
    copied += step
  
    sleep 1
  
  end

  which would only continously copy parts of the file (the issue here being if the step should ever overreach the end of the file). Other approaches such a simple read-file led to ffmpeg failing when there was no new data. With this solution the frames are dropped if no new data is available (which is what I need).

  Is there a better way (more performant) to archive something like that ?

  EDIT :

  Using the method proposed by @RaVeN I am now using the following code :

  open(@options['filename'], 'rb') do |stream|
  
    stream.seek(0, IO::SEEK_END)
  
    queue = INotify::Notifier.new
  
    queue.watch(@options['filename'], :modify) do
  
      w.write stream.read
  
    end
  
    queue.run
  
  end

  However now ffmpeg complaints about invalid data. Is there another method than read ?

• merging 2 editing videos without saving them using ffmpeg

  14 avril 2021, par Eswar T

  I want to combine 2 videos assume even they are edited among themselves

  


  How normally we do

  


  video 1 :

  


  ffmpeg -i 1.mp4 -filter:a "volume=0.0" test1.mp4


  


  video 2 :

  


  ffmpeg -i 2.mp4 -filter:a "volume=10.0" test2.mp4  


  


  now I can combine them using

  


  ffmpeg -i test1.mp4 -i test2.mp4 -filter_complex [0:v:0][0:a:0][1:v:0][1:a:0]concat=n=2:v=1:a=1[outv][outa] -map [outv] -map [outa] out.put.mp4


  


  So my question is, Is there a way to make this 3 steps process into 1 step and without saving files of step 1 and step 2

  


  I do know that we can combine into one using && but my main query is there a way to do without saving the files of video1 and video2 that edited files

  


  Hope I'm a bit clear with my query

  


  Question edited/added :

  


  ffmpeg -i test.mp4 -filter:a "volume=8.0,atempo=4.0" -vf "transpose=2,transpose=2,setpts=1/4*PTS" -s 640x480 test.mkv 


  


  can we do all these options also in the merge command(operations like change video Speed, resolution, rotation, framerate, and trim) ?

  


• Error while compile FFmpeg in Mac os

  24 septembre 2015, par Devganiya Hitesh

  I have downloaded Github projects ffmpeg-android.
  I have also followed all step given by him but in last step ./android_build.sh i’m facing following error in terminal.

  make: *** No rule to make target `clean'. Stop.
  
  make: *** No rule to make target `Makefile'.  Stop.
  
  ./libpng_build.sh: line 17: ./configure: No such file or directory