Information about id3v2 tags in mp3

[shanmugavel]

i am now working on designing an mp3 encoder. in that i have seen about id3v2 tags. i have the following questions in my mind abt that:
1. what is the anatomy of an mp3 file with an id3 tag.
2. how can an id3 tag be added to an mp3 file. can i add that directly in bitstream..
3. is it mandatory to use all the id3 tag frames. if not what are the things mandatory.
4. can anyone provide me with an mp3 encoder reference code(in C) which has the features of id3v2 tagging.

thanks in advance,.
regards,
shanmugavel

 

[M!k]

Re: id3v2 tags in mp3.

you'll find everything here:
http://id3lib.sourceforge.net/

 

[amraldo]

Re: id3v2 tags in mp3.

I think it is straight forward to handle the id3 tag with all of its version.
I did it once with id3tag v1.
I added a structure to for the tag.
I made a function that reads the tag if present:
1- seek from the file end b a distance of the tag
2- check if the tag is present & its v2.
3- read data of ssize = size of ur definded structure.
4- seek to the start of the file after reading the tag.

I made some assumptions that tag checking is the first thing done with the file before rerading it.

Regards,
Amraldo

 

[shanmugavel]

Re: id3v2 tags in mp3.

Hi Amraldo,
thanks for your reply.
i need a clarification about a frame type. what is the frame - unique file identifier (UFID) used for. how is it different from others.

 

[amraldo]

Re: id3v2 tags in mp3.

What do u mean by the fram?
Is it the MP3 frame??
Regards,
Amraldo.

 

[shanmugavel]

Re: id3v2 tags in mp3.

the frame is the frame of the id3v2 tag.
what happens if there is an error in the id3v2 tag. should it neglect the error without stopping the mp3 decoding.
if one of the id3v2 frame is replaced with all zeros what will happen.

Added after 2 hours:

how is the end of the id3v2 frame known. is it indicated by a null.(if it is so, i have seen the null immediately after the id3v2 frame id in the bitstream and then comes the text information abt the frame).
for eg, if the id3v2 frame id is TIT2. can anyone help me with an example how this frame looks like in the bitstream.

 

[amraldo]

Re: id3v2 tags in mp3.

I actually worked with ID3tagv1.
As I remember tag fields & lengths are previously known. You should use these lengthes when reading tag fields.

Regards,
Amraldo.