[SDL] MP3 detection in SDL_Mixer (was Appending resources to .exe)

[Daniel K. O.]

Andre de Leiradella escreveu:
> I took a look at some MP3 files I have and all of them start with the same eight characters: ID3\3\0\0\0\0
>
> It is straight forward to add this test to music.c, but does anyone know if this is correct and how many characters should be tested (i.e. eight or just the first three...)?
>   

On my system, `file' identifies MP3 files with:

---
# MP3, M1A
0       beshort&0xFFFE  0xFFFA         MPEG ADTS, layer III, v1
---

and

---
# MP3, M2A
0       beshort&0xFFFE  0xFFF2         MPEG ADTS, layer III, v2
---

and

---
# MP3, M25A
0       beshort&0xFFFE  0xFFE2         MPEG ADTS, layer III,  v2.5
---

and

---
# ID3 version 2 tags <waschk at informatik.uni-rostock.de>
0       string          ID3     MP3 file with ID3 version 2.
---

For those file-magic-impaired:
 "0" means the offset being tested.
 "beshort" means to test 2 bytes, interpreting as a big-endian value
 "&0xhhhh" means to mask the value with 0xhhhh
 The value in the third column is the value that needs to be matched.

So if you want to support MP3 files without ID3 tags, you need to do
more tests.


---
Daniel K. O.