[nmglug] ffmpeg guidance, please to convert m4b to mp3

LeRoy Diener leroy at choosetherightside.com
Wed Nov 30 09:06:10 PST 2022

To Wayne and all:

The .m4b file is not corrupted. The 11hr file plays flawlessly in VLC
and SMplayer. The first 1hr loads correctly in Audacity, but only as
the truncated portion of the larger file. I found that others had a
similar experience, as
at https://forum.audacityteam.org/viewtopic.php?t=79754

I'm guessing that the issue for Audacity is that the .m4b file includes
some encoding which points to a .cue file which has the timestamps for
the chapters. Here are snippets of the .cue file:
TITLE "Chapter 01"
INDEX 01 0:0:00
TITLE "Chapter 02"
INDEX 01 20:14:56
TITLE "Chapter 19"
INDEX 01 661:19:09

My end objective is to break the 11hr file into smaller files, ideally
the chapters of the audiobook.
I'm not sure what is the best workflow for this. Here's one idea. If I
can convert the .m4b file to a .mp3 file, then I can edit it in
Audacity. It might be even easier if I can use ffmpeg to split the file
into chapters.
I would be happy to have the chapter files in .m4b format
(unconverted). I just want to end up with files that are not so long.

Wayne, thanks for your ideas. I have not yet tried using the nitrag
script. I'm not sure how to do that, and I'm being cautious, asking for

I'm still unsure about how to proceed.
There is something glorious birthing within all of us.
I am the Love of God, no matter what.BSA
LeRoy Diener

On Tue, 2022-11-29 at 15:32 -0800, Wayne wrote:
> If it can't be opened correctly by Audacity, is it possible the file
> is corrupted somehow?
> Do you really want the results in separate chapters, or is a single
> non-chaptered file okay? ffmpeg would be a very simple command-line
> if you wish to write to a single file. If you need to separate by
> chapters, did you try using the nitrag script?
> BTW, most video/audio editors use ffmpeg or one of it's components as
> it's engine. It is extremely powerful.
> Wayne
> On 11/26/22 1:16 PM, LeRoy Diener wrote:
> > Hi NMGLUG folks,
> > 
> > I would like to convert an audiobook .m4b file (probably with
> > chapters in metadata) to .mp3 files split into chapters.
> > I'm trying to learn how to convert files.
> > I looked at https://ffmpeg.org/ffmpeg.html but it gets
> > overwhelming.
> > 
> > I'm not sure what the best approach will be.
> > I also found https://github.com/sandreas/m4b-tool where the author
> > references https://github.com/sandreas/tone
> > Additionally, I found this script from nitrag
> > https://gist.github.com/nitrag/a188b8969a539ce0f7a64deb56c00277
> > Other options appear in
> > https://www.videoproc.com/media-converter/m4b-to-mp3.htm
> > Indeed, my first idea was to import the .m4b file into Audacity to
> > do the conversion. Unfortunately, it doesn't import correctly into
> > Audacity.
> > I'm able to play .m4b file in VLC and SMplayer. It seems like it's
> > possible to use VLC to do the conversion with some help from
> > ffmpeg, though maybe not a great option.
> > 
> > Any thoughts?
> > 
> > Thanks,
> > LeRoy
> > 
> > -- 
> > 
> > There is something glorious birthing within all of us.
> > I am the Love of God, no matter what.
> > BSA
> > LeRoy Diener
> > 213-LEROYIZ
> > 213-537-6949
> > https://leroydiener.com <https://leroydiener.com/>
> > 
> > _______________________________________________
> > nmglug mailing list
> > nmglug at lists.nmglug.org
> > http://lists.nmglug.org/listinfo.cgi/nmglug-nmglug.org
> > 
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