fix(utils/detect-mimetype): add support for detecting id3 tags

[haydenbleasel]

Background

While testing the new Fal transcription functionality, I noticed that we weren't able to correctly detect the mimetype of an mp3 file. Some console logging showed that the headers didn't match. So after a bit of a deep dive, I learned that mp3 files can sometimes contain id3 tags, essentially metadata.

This PR strips that metadata if it exists, allowing the signature checks to function as intended.

Summary

This pull request includes significant changes to the detect-mimetype.ts file to enhance the detection of MIME types by handling ID3 tags in audio files. The most important changes include the addition of functions to strip ID3 tags from binary and base64 data and modifications to the detectMimeType function to utilize these new functions.

Enhancements to MIME type detection:

• Added getID3v2TagSize function to calculate the size of the ID3v2 tag in an audio file.
• Added stripID3 function to remove ID3 tags from a Uint8Array.
• Added isBase64ID3v2 function to check if a base64 string starts with an ID3v2 header.
• Added base64ToBytes function to convert base64 encoded data to a Uint8Array.
• Modified detectMimeType function to use stripID3TagsIfPresent to process data before checking MIME type signatures.

Tasks

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• If required, a patch changeset for relevant packages has been added
• You've run pnpm prettier-fix to fix any formatting issues

Future Work

None.

[Copilot]

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

[lgrammel]

Please add a test suite that covers the id3 behavior.

[lgrammel]

This leads to unnecessary conversion of potentially large data entries. Can the edit in the base64 case happen w/o converting to UInt8Array?

[haydenbleasel]

I did spend quite a while on this today, I couldn't get raw base64 stripping working. You can detect the existence of id3 tags by the prefix SURz but I think the remaining data between the prefix and the start of the raw mp3 frames are variable. You could strip out the data by removing everything before the known mp3 prefix e.g. //s= but I think you run the risk of cutting at the wrong point.

I'd love to know whether it's possible but yeah I couldn't get it working without conversion.

[lgrammel]

Please add a changeset (e.g. fix (core): support mimetypes with id3 tags) bc it changes the behavior.