Merge multiple m4b files without transcoding? about m4b-tool HOT 5 CLOSED

Thanks for reporting... There is not explicetely an option for this, since i thought, ffmpeg would skip it automatically. As you might know, ffmpeg is used for merging files and --audio-codec parameter is more or less directly converted to ffmpegs -acodec parameter, so you could try to use:

--audio-codec="copy"

This might fail, i'm not sure, if this has side-effects - especially because ffmpeg should detect, wether encoding is needed. I'm also not 100% sure, if there IS a merging capability in ffmpeg without re-encoding and whats the result, if you just copy the codec.

BUT: I'll treat this issue as a feature request and will check the docs, so that you won't have to provide any parameter for just merging files as they are in the next version of m4b-tool - default option should be to copy the codec and not to transcode / encode again, when it is not neccessary.

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The workaround I ended up using was CTRL-C after the first file was transcoded, then I just added the source files with the same file name structure (number-filename-finished.m4b) to the tmp folder.

When I ran m4b-tool again it merged them into a single m4b without any transcoding or issues.

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Haha this is a nice one ;) But good that you mentioned it, perhaps i can provde a quickfix that way... i'll override the target files with the existing files and it should work...

thx

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Fixed by adding --no-conversion flag... feedback welcome, here is a build :-)
m4b-tool.zip

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Is it worth creating a new issue to track causes of failures when using --no-conversion? ffmpeg notes there could be multiple causes though I haven't looked into it. Using the latest version, plus AtomicParsley to first remove covers (somewhere someone mentioned that as a cause), I was able to get merging as such to properly work with correct chapters, though in one case metadata wasn't preserved and chapters were named by number. I haven't tried to track down what made it work. Should m4b-tool perform some steps such as removing covers or other metadata before attempting a merge as such?

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