Efficiently Reading ID3v2 Tags Over HTTP?

Paul Crowley asks: "Given an HTTP URL for an MP3 file, what's the best way to read its ID3 tags on a GNU/Linux system? It shouldn't be necessary to fetch the whole file: HTTP byteranges should make it possible to fetch only the tiny fraction that's needed, for a big saving in network bandwidth. However, existing ID3v2 libraries are designed to read local files. Extending these libraries for this purpose, or implementing a new one, would be a big job. What's the clean solution - is FUSE the best way, or is there a simpler way that doesn't require root privs? Can I do it using the existing id3lib binary?"

Comments

ID3v2 Sucks

[DeadSea]

As somebody who has tried to write libraries that read ID3v2 tags, I'd have to say I hate them. The standard is clear and well documented, but the chosen format is horrible. It is very hard to write a parser correctly. It would have been so much better to embed an XML document at the front of the MP3 file. Instead they decided to make each field in a special binary format prepended by a length field.

The number of checks you have to do is phenominal. The biggest worry is buffer overflow where the length given is greater than the actual length of the tag and you read more than is in the file. There are just hundreds of such edge cases. Libraries for ID3v2 are likely to be buggy, crashy, and just no fun.