[Bug]: Covers not loading for m4b audiobooks

[sandreas]

What happened?

I have a library of many m4b's and after upgrading audiobookshelf to a newer version, the covers of newly added m4b files don't show up, although I ensured that the files contain a valid cover.

What did you expect to happen?

I would have expected the covers to show up as normal.

Steps to reproduce the issue

Add the attached file to your audio book folder and wait for it to be scanned.
input.zip

This problem might be related to #1063 and #2885 - but is very specific to m4b files with embedded cover. I found out that the problem is possibly a wrong ffmpeg extraction command in:

audiobookshelf/server/utils/ffmpegHelpers.js

Line 56 in 190a100

/** @type {import('../libs/fluentFfmpeg/index').FfmpegCommand} */

    var ffmpeg = Ffmpeg(filepath)
    ffmpeg.addOption(['-map 0:v:0', '-frames:v 1'])
    ffmpeg.output(outputpath)

which results in

ffmpeg -i input.m4b -map 0:v:0 -frames:v 1 cover.jpg

This command extracts a FULLY BLACK cover for m4b files.

Possible solution
The corrected command that works and extracts the cover as expected would be:

ffmpeg -i input.m4b -map 0:v -map -0:V -c copy -frames:v 1 cover.jpg

or in code

    var ffmpeg = Ffmpeg(filepath)
    ffmpeg.addOption(['-map 0:v', '-map 0:V', '-c copy', '-frames:v 1'])
    ffmpeg.output(outputpath)

but I'm not sure, that this is the place the problem occurs.

Audiobookshelf version

2.17.4

How are you running audiobookshelf?

Docker

What OS is your Audiobookshelf server hosted from?

Linux

If the issue is being seen in the UI, what browsers are you seeing the problem on?

Chrome

Logs

No errors in log files

Additional Notes

Suggested solution should fix the problem.