Re: Reading and writing mp3 metadata

[Daurnimator <quae@...>]

On 30 April 2013 07:00, luciano de souza <luchyanus@gmail.com> wrote:
> Hello all,
> I am trying to create a small tool that reads and writes mp3 metadata.
> It's really easy. The last 128 bytes of a mp3 file stores the required
> information.
> In Pascal, the structure representing mp3 metadata is:
>
> type
> TID3 = record
> signature: array[0..2] of char;
> title, artist, album: array[0..29] of char;
> year: array[0..3] of char;
> comment: array[0..29] of char;
> genre: byte;
> end;
>
> My first difficult is: how to represent a Lua 128 bytes structure like that.
> And how can I read the last 128 bytes of a file and attibutes it to a
> structure, probably a table, with this fields, sized with the given
> values?
> In order words, I don't know what I should use to read and write a set
> of bytes in Lua and I don't know how to represent C or Pascal
> structures.
> Best regards,
> Luciano
>

Looks like you're trying to read ID3v1.
You may want to look to
https://github.com/daurnimator/lamt/blob/master/id3v1.lua#L53 for
inspiration.