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• How can combine two separate scripts being piped together to make one script instead of two ?

  27 mars 2016, par user556068

  For the past couple hours I’ve been banging my head against the wall trying to figure out something I thought would be simple. Maybe it is but it’s beyond me at the moment. So I have now two scripts. Originallly they were part of the same but I could never make it work how it should. So the first part uses curl to download a file from a site. Then using grep and sedto filter out the text I need which is then put into a plain text file as a long list of website urls ; one per line. The last part of the 1st script calls on youtube -dl to read the batch file in order to obtain the web addresses where the actual content is located. I hope that makes sense.

  youtube-dl reads the batch file and outputs a new list urls into the terminal. This second list is not saved to file because it doesn’t need to be. These urls change from day to day or hour to hour. Using the read command, these urls are then passed to ffmpeg using a predetermined set of arguments for the input and output. Ffmpeg is executed on every url it receives and runs quietly in the background.

  The first paragraph describes script1.sh and paragraph 2 obviously describes script2.sh. When I pipe them together like script1.sh | script2.sh it works better than I ever thought possible. Maybe i’m nitpicking at this point but the idea is to have 1 unified script. For the moment I have simplified it by adding an alias to my .bash_profile.

  Here are the last two commands of script1.

  sed 's/\"\,/\//g' > "$HOME/file2.txt";
  
  cat $HOME/file2.txt | youtube-dl --ignore-config -iga -

  The trailing - allows youtube-dl to read from stdin.

  The second part of the script ; what I’m calling script2 at this point begins with

  while read -r input
  
  do
  
  ffmpeg [arg] [input] [arg2] [output]

  What am i not seeing that is causing the script to hang when the two halves are combined yet work perfectly if one is piped into the other ?

• ffmpeg, stretch audio to x seconds

  9 mai 2016, par Max Doumit

  I am trying to make an audio file be exactly x second.

  So far i tried using the atempo filter by doing the following calculation

  Audio length / desired length = atempo.

  But this is not accurate, and I am having to tweak the tempo manually to get it to an exact fit.

  Are there any other solutions to get this work ? Or am I doing this incorrectly ?

  My original file is a wav file, and my output in an mp3

  Here is a sample command

  ffmpeg -i input.wav -codec:a libmp3lame -filter:a "atempo=0.9992323" -b:a 320K output.mp3

  UPDATE.

  I was able to correctly calculate the tempo by changing the way I am receiving the audio length.

  I am now calculating the current audio length using the actual file size and the sample rate.

  Audio Length = file size / (sample rate * 2)

  Sample rate is something like 16000 Hz. You can get that by using ffprob or ffmpeg.

  EDIT - Solved

  Figured it out.
  I was calculating the tempo incorrectly.

  Audio length / desired length = atempo

  Should be

  desired length / Audio length = atempo

  I had to do a bit more reading on what the tempo actually does. Hope this helps someone.

• NReco ffmpeg library error

  19 janvier 2016, par agurodriguez

  I’m using NReco.VideoConverter for a video converting application. Now I’m trying to replace the audio in the source video for an mp3 track. I’m using this snippet from the official site : http://www.nrecosite.com/video_converter_net.aspx but I receiving this error :

  audio.mp3 : Invalid data found when processing input (exit code : 1)

  var ffmpeg = new NReco.VideoConverter.FFMpegConverter();
  
  ffmpeg.ConvertMedia("video.mp4", null, "output_video.mp4", null, new ConvertSettings() {
  
    AudioCodec = "copy", VideoCodec = "copy",
  
    CustomInputArgs = String.Format(" -i \"{0}\" ", "audio.mp3"),
  
    CustomOutputArgs = " -map 0 -map 1",
  
  });

  I tried with different audio files but still the same scenario.

  Hope you can help me !
  Regards