Splasm Software Discussions

Failure in Audiobook Containers
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Author:  buro71a [ Fri Aug 30, 2019 2:54 pm ]
Post subject:  Failure in Audiobook Containers

Hi there!

I recently noticed a bug when the audiobook containers are written. No matter how you get audio data into ABB as soon as you write an audiobook (m4a or m4b, aac or aac-he) the book somehow is written as video container.

It plays fine in itunes and on iOS devices, but you can't use macOS' quicklook preview. I noticed the issue with the generated files when I tried to upload the files to the tonies.de cloud. They couldn't process the files.

As soon as you do the following with the files
ffmpeg -i generated.m4b -acodec copy -vcodec copy fixed.m4b

the files work just fine.

There must be an issue with container as the streams are fine (thus the copy option of ffmpeg works fine)


PS: I can't share sample files publicly (copyright!) but I'm fine with sending a sample file to the developers if needed :-)

Author:  keithg [ Sun Oct 27, 2019 5:35 pm ]
Post subject:  Re: Failure in Audiobook Containers

Just a note that we worked with Rico back at the end of August and determined the issue they're seeing is one Finder and Quick Look previews have had for some time - they just spin for audiobooks that have a chapter artwork track. As I recall, this began with PNG chapter artwork, which countered our intuition that PNG was the way to because it was the blessed image format on iOS, so we switched to JPEG. It spread to JPEG not long after. Chapter artwork has to be presented in a video track, so the files Rico found weren't working would look like video files to ffmpeg and running them through the ffmpeg binary you can download or install without building your own will strip the video track with the command Rico quoted. Thus, the files on Rico's end that got the ffmpeg treatment ended up without a video track for chapter artwork and worked in the Finder.

We reported the issue to Apple years ago and they declined to resolve it, so it's just something we - and our users - have had to live with. We did make a change in Audiobook Builder 2.1 that may help, though. Until 2.1, Audiobook Builder would take cover art and use it as chapter artwork until the first actual chapter artwork was encountered. If you added cover art, you got a video track with chapter artwork, like it or not. We flipped that off in 2.1, so you only get a video track with chapter artwork if you add artwork to a Chapter. So if you never add artwork to a Chapter, your audiobooks will work in Finder and Quick Look previews.

Hope that helps everyone who wonders what's the spin-dealio with their audiobooks in the Finder!

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