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• Normalizing audio of several wav snippets with ffmpeg

  17 mai 2023, par dick_kickem

  I searched the site and I figured that maybe ffmpeg-normalize could be part of my solution but I'm really not sure.

  


  In my free time me and my friends create quizzes for people to solve. One of these is a music quiz, where you hear audio snippets and have to guess the artist and song title. A few years back I did most of them using Audacity, which means recording snippets from existing videos, inserting fade in and fade out to every snippet, putting announcements like "Number x" before the x-th song and also making sure that all songs are fairly of equal loudeness (-6.0 dB).

  


  The result in Audacity looked like this.

  


  

  


  Lazy as I am, I learned about ffmpeg and wrote a script, which does all these steps for me. The script is mostly written in bash. I use some audio files where I extract the audio in wav-format, add a fade in and fade out and then I try to set the volume to -6.0 dB as with Audacity. The part where this happens looks like this :

  


  ...[some code before]...

# write the audio details of temmp.wav into the "info" file
ffmpeg -i temp.wav -filter:a volumedetect -f null - 2> info

#check out the max volume of temp.wav
max_vol=$(grep "max_volume" info | cut -d ' ' -f5)

# determine the difference between the max volume and -6
vol_diff=$(expr "-6-($max_vol)" | bc -l)

# change temp.wav loudness by the determined difference
ffmpeg -y -i temp.wav -filter:a "volume=$vol_diff$db" $count.wav

...[some code after]...


  


  I do this with all snippets, leaving me with usually ten snippets in the format 1.wav, 2.wav and so on. Lastly, I concatenate them all with announcements in the form nr1.wav, 1.wav, nr2.wav, 2.wav and so on. Overall this works really great for me. Yet, the loudness is not quite as equal as in Audacity. Here is a screenshot of a generated music quiz using the described script (not the same music snippets as the example before) :

  


  

  


  You can see some peaks pointing out. It's not bad and in fact, it works for me in most cases, but it's not like what I used to have with Audacity. Does anyone have any idea how to fix that to make it more equal ?

  


  Thank you in advance and kind regards

  


• Is there somewhere that I can get pre-compiled libraries for reading mp4 files (MinGW32, Windows, C++)

  25 juin 2023, par Gorlash

  I would like to find a simple library that I can link to a console-mode C++ utility, to display info about mp4 files (play length, width, height, maybe bit-rate)... I don't need to write or convert data, just read and display it.

  


  The library should come with the standard SDK components :
.lib, .dll, .h, examples.c or examples.cpp, api docs
I build with MinGW 32-bit, not with Visual C++.

  


  I am developing a console media-listing utility to display interesting data about various audio/video media files. It works for almost all formats that I could wish to examine, but mp4 has ended up being a real headache !! mp3 was challenging enough, but I was able eventually to find a short example program in C that would decode the various formats, and over a couple of years I weeded out a couple of bugs with that... but mp4 puts mp3 to shame !! There don't seem to be any single-source-file utilities that will handle parsing mp4 files successfully, so I'm falling back on looking for a library that will handle this for me, with a simple API...

  


  I've looked at a number of common libraries for this purpose (ffmpeg, libvlc, opencv, Bento4, some others) but none of them come as pre-compiled libraries, ready for use, and none of them are trivial to build, especially with MinGW...

  


• Revision 30149 : On ajoute un champs "extension" dans la table spip_spipmotion_attentes ...

  24 juillet 2009, par kent1@… — Log

  On ajoute un champs "extension" dans la table spip_spipmotion_attentes pour gérer l’encodage multiple
  On nécessite spip-bonux dorénavant