Re: working with mp3 files

[Siard <shiems@mailbox.org>]

Celejar:
> mick crane:
> > hello,
> > I am totally clueless about audio files.
> > Have for example librivox recordings of "1984" split into a dozen files.
> > Would like to combine them together into one file with
> > ffmpeg join_together "files" some_options) out_file
> > presumably each file has meta data that I only need once ?
> > Anybody point to a book or resource for a numpty to discover how it 
> > works?
> 
> https://trac.ffmpeg.org/wiki/Concatenate
> 
> I concatenate mp4 video files (produced by my smartphone video
> recording app, which starts a new file every 4GB) by putting them
> (making sure they are named sequentially, e.g. "1.mp4", "2.mp4", etc.)
> into an otherwise empty directory and running the following command
> (taken from the above page):
> 
> ffmpeg -f concat -safe 0 -i <(for f in ./*.mp4; do echo "file '$PWD/$f'"; done) -c copy output.mp4

The method that I know is slightly different. I once took it from
https://medium.com/abraia/basic-video-editing-for-social-media-with-ffmpeg-commands-1e873801659
but that site has apparently been simplified now and concatenation has been
removed.
I found that it works fine for mp3's as well.

Create join.txt file that contains the exact paths of the files that you
want to join. All files should be same format (same codec). The path name
of all files should be mentioned one by one like below.
  file /home/xx/myvideos/part1.mp4
  file /home/xx/myvideos/part2.mp4
  file /home/xx/myvideos/part3.mp4
  file /home/xx/myvideos/part4.mp4
Now, join all files using command:
$ ffmpeg -f concat -i join.txt -c copy output.mp4
If you get an error something like below;
  [concat @ 0x555fed174cc0] Unsafe file name '/path/to/mp4'
  join.txt: Operation not permitted
add "-safe 0":
$ ffmpeg -f concat -safe 0 -i join.txt -c copy output.mp4