feat: Adds Audio Channel Metadata - #1036

[mayanez]

First off awesome project! I'm looking to get familiar with the codebase to start adding a few missing features for classical music (#1036). I'm starting off small and figured this would be a good contribution although not in the linked issue since it is especially for those with multi-channel versions of the same track in their library.

I'm fairly new to Go as well so let me know if anything is off on that front. With regards to the current changes two things I wasn't able to piece together:

• the naming convention for the db/migration file
• the configuration for prettier. It looks like SongList.js needs to run it.

If I missed anything regarding the contributing conventions let me know.

Cheers!

[deluan]

Hey, thanks for this!

First off awesome project! I'm looking to get familiar with the codebase to start adding a few missing features for classical music (#1036). I'm starting off small and figured this would be a good contribution although not in the linked issue since it is especially for those with multi-channel versions of the same track in their library.

Is channels really that important? Can you send me an example of file with more than 2 channels?

I'm fairly new to Go as well so let me know if anything is off on that front. With regards to the current changes two things I wasn't able to piece together:

• the naming convention for the db/migration file

To create an empty migration skeleton, run make migration. Ex: make migration name=add_mediafile_channels

• the configuration for prettier. It looks like SongList.js needs to run it.

Yeah, it is breaking the build. Usually you install a prettier plugin in your IDE and enable autoformat with it. You can also run npm run prettier inside the /ui folder. To be sure you don't push broken code, setup your git hooks (make setup-git)

If I missed anything regarding the contributing conventions let me know.

I'll review the PR as soon as I can

[deluan]

Looks good, just missing the support for channels in the ffmpeg extractor. Can you please implement it?

[mayanez]

Thanks for the feedback. I'll try to address your comments as best I can and will circle around if I uncover any issues.

Is channels really that important? Can you send me an example of file with more than 2 channels?
Its more common for classical music and other live music recordings. The primary sources for this are SACD, Blu-ray, and DVD.

You can find sample tracks here: https://oppodigital.com/hra/dsd-by-davidelias.aspx

[mayanez]

While going over the ffmpeg scanner I found that using ffprobe, which is part of the ffmpeg, packages can significantly simplify parsing. I've chosen to make it output json so that it's easily parse-able and refactored the necessary parts. It should be more robust to any future ffmpeg version changes as well.

[deluan]

Thanks for taking a stab at the ffmpeg extractor. Unfortunately there's one important thing you overlooked: batching.

Originally I tried to use ffprobe for extracting metadata (you may find references to it in GitHub history), for the same reasons you pointed above, but it was too slow as it has to exec one ffprobe command for each track file. For a few hundred songs it will be slow, but may not have a huge impact. But for libraries over 50K songs (we have users with >1Mi songs), this is simply unacceptable.

The way I found to speed up this was to call ffmpeg passing all files in a directory in one command only, drastically reducing the time required to import all songs. Unfortunately ffprobe does not support multiple input files, nor ffmpeg outputs json or other more parseable formats...

Anyway, I'm afraid I won't be able to accept this change. If you are having trouble parsing ffmpeg's output with regex, please reach ou to me through Discord and I can help with that.

[deluan]

Thanks for the changes, and sorry, I didn't have time to work on the project the last couple of days. I'll take a look at this as soon as possible.

[deluan]

Hey, sorry for the delay. I already reviewed it and looks good. Will try it this weekend and if everything is fine, will merge this

[deluan]

LGTM. Thanks for the contribution!

[deluan]

Actually I just tried the ffmpeg extractor, and it is not able to get channels from some files (M4A and OGG). Here are some samples:

01-01 The Hollow.ogg.zip
02 I Get Around.m4a.zip

[mayanez]

Actually I just tried the ffmpeg extractor, and it is not able to get channels from some files (M4A and OGG). Here are some samples:

01-01 The Hollow.ogg.zip
02 I Get Around.m4a.zip

Looks like it's possible to have a language in the stream. I've updated the regex to account for it and added appropriate test cases.

[github-actions]

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