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• How to split audio file into equal-length segments with ffmpeg ?

  11 mars, par GPWR

  I want to split an audio file into several equal-length segments using FFmpeg. I want to specify the general segment duration (no overlap), and I want FFmpeg to render as many segments as it takes to go over the whole audio file (in other words, the number of segments to be rendered is unspecified).
Also, since I am not very experienced with FFmpeg (I only use it to make simple file conversions with few arguments), I would like a description of the code you should use to do this, rather than just a piece of code that I won't necessarily understand, if possible.
Thank you in advance.

  


  P.S. Here's the context for why I'm trying to do this :
I would like to sample a song into single-bar loops automatically, instead of having to chop them manually using a DAW. All I want to do is align the first beat of the song to the beat grid in my DAW, and then export that audio file and use it to generate one-bar loops in FFmpeg.

  


  In the future, I will try to do something like a batch command in which one can specify the tempo and key signature, and it will generate the loops using FFmpeg automatically (as long as the loop is aligned to the beat grid, as I've mentioned earlier). 😀

  


• Normalize audio, then reduce the volume in ffmpeg

  27 octobre 2014, par Steve Sheldon

  I have a question relating to ffmpeg. First here is the scenario, I am working on a project where I need to have some audio with a presenter talking and then potentially some background music. I also have the requirement to normalize the audio. I would like to do this without presenting a bunch of options to the user.

  For normalization I use something similar to this post :

  How to normalize audio with ffmpeg.

  In short, I get a volume adjustment which I then apply to ffmpeg like this :

  ffmpeg -i <input /> -af "volume=xxxdB" <output>
  
  </output>

  So far so good. Now let’s consider the backing track, it doesn’t want to be the same volume as the presenters voice, this would be really distracting, so I want to lower that by some percentage. I can also do this with ffmpeg, I could do it like this (example would set volume to 50%) :

  ffmpeg -i <input /> -af "volume=0.5" <output>
  
  </output>

  Using these two commands back to back, I can get the desired result.

  My question has two parts :

  1. Is there a way to do this in one step ?
  2. Is there any benefit to doing it in one step ?

  Thanks for any help !

• FFMPEG audio filter/settings to crossfade but with only the first file becoming quiet

  24 janvier 2019, par howcountrywidefield

  I have two audio files that I want to concatenate, while crossfading between them at 3 seconds offset. But I do not want a traditional crossfade with the first file getting quiet while simultaniously the second file gets louder, which I know could be achieved with the acrossfade filter, but rather I want only the first file getting quieter, while the second file should start at 100% loudness right away.

  I have an idea for a step-by-step procedure where I would

  1. strip away the last 3 seconds of the first file into a temporary file

  2. strip away the first 3 seconds of the second file into a temporary file

  3. apply a afade=out filter to the first temporary file

  4. merge the two temporary files together

  5. concatenate the first file, the merged file, and the second file

  all using seperate ffmpeg commands

  I guess this would do the trick, but it would be very error-prone I guess, and I was wondering if there was a way to do all I want to achieve with just one command.