Couldn't we just use ffmpeg? This way i think we could even embed the metadata during the encoding process

Even ffmpeg uses AtomicParsley to embed metadata.

Looks like I misread, I thought you had said youtube-dl.

ffmpeg doesn't support metadata embedding into AAC containers which the mp4 format (.m4a) uses, so this doesn't work.

That's not entirely true. It supports all the tags currently used by freyr-js, for the exception of apID, purd, ©enc, rDNSatom and rtng, unless you specify a flag in ffmpeg which however messes with the other metadata. (*)

Also, metadata written with ffmpeg can't be read by AtomicParsley, and this makes me think that they are not readable by iTunes too. They can however be read by other players.

I don't know if you consider these metadata to be important, but if they aren't, I could make a PR in a few days implementing the use of ffmpeg to embed metadata. Otherwise I can't offer a solution, as I'm not experienced in rust nor wasm.

(*) the flag is -movflags use_metadata_tags. I don't know exactly how it works, given that I can't find proper documentation, but it renders metadata such as the track number not readable by vlc and others.

Also, metadata written with ffmpeg can't be read by AtomicParsley, and this makes me think that they are not readable by iTunes too.

That is a point of concern for this project.

I don't have much time these days, but this is worth investigating. I will if I ever find the time. Or if you do, and can submit a PR, I'd be happy to test and review it. Reusing the embedded ffmpeg wasm binary for this would save on third-party requirements and make freyr a "download only" solution.

The help would be very much appreciated.

Otherwise, I'm pretty happy with the state of things as it is.

Hi, I was working on using ffmpeg to add metadata, but then I noticed that some tags were not recognized correctly by other music players, so I abandoned the idea.

I wanted to develop a WASM version of lofty-rs, but due to university I didn't have much time. I think I can start working on it in a couple of days and I'll be happy to submit a PR once I get things to work.

That would be amazing, feel free to reach out if you need any help. Thank you!