[fpc-pascal] where to find materials about MP3 file format

[José Mejuto]

El 14/08/2019 a las 22:23, Mgr. Janusz Chmiel escribió:

> I have A very big and non easy dream.
> Making similar MP3 editor like MP3 direct cut for Windows is. But sure! 
[...]
> operations to assign beginning of block and its end. And mainly, I want 
> to use remove block command, which will hae immediate effect. So MP3 
[...]
> Who of us would have some tip how to find MP3 file format technical 
> specifications?

Hello,

There are several documents about the MP3 format, but you only need for 
sure ID3V1, ID3V2 and MP3 frame format. You need ID3V1 and ID3V2 in 
order to skip this information (if you will not use it, as it is 
metadata only) and the MP3 frame format if you want to fast scan MP3 
time duration and scan for stream errors.

https://www.mp3-tech.org/programmer/frame_header.html

All other operations should be done with decompressed audio and in this 
situation nothing is different from MP3, WAV, AAC, OGG, etc.

There are only a few operations that you can apply to a MP3 stream 
without decompressing it, mainly volume change, as you can not, in 
example, remove a block directly from the MP3 stream even if the block 
is an MP3 frame because each frame is dependent of previous frames and 
if you remove one an audible "bleep" can happen (high chance).

So you only need something to decompress MP3 (and maybe other formats).

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