Brett i think this should be directed to you,
There seems to be a bug in FMOD, as it will play an ID3v2 TAG in an mp3 file. The ID3v2 TAG is located at the start of the mp3 file and looks like the following in hex (incomplete):
00000000 4944 3303 0000 0000 020E 5758 5858 0000 0002 0000 0000 5443 4F50 0000 0001 0000 0054 4F50 ID3.......WXXX........TCOP.......TOP
00000024 4500 0000 0100 0000 5452 434B 0000 0002 0000 0033 5443 4F4E 0000 0001 0000 0057 434F 4D00 E.......TRCK.......3TCON.......WCOM.
Should FMOD perhaps ignore this data, because when it is played, i get squeals, pops, and blits from my speakers?
Let me know if you need any other info on this.
[quote="brett":2lnbqqdk]I could explain why but i wont because i think unless you’ve written an mp3 deocder before and have a firm knowledge of it you wouldnt understand anyway :)[/quote:2lnbqqdk]
That’s okay, even if I don’t understand it, I want you to explain anyway… it’s not as if I have anything better to do with my time. hehe
I tried it in Winamp, Coolplayer and Windows Media Player and it sounds perfect, no pop/blit/squeal, etc.
Just happens with fmod. This is using the FMOD example found in \samples\fmod.
I cropped the mp3 to about 10 seconds using mp3Trim, and verified that the file had valid frames. All is okay, and i have uploaded this snippet to http://www.r2.com.au/problem.mp3
If you play this file with FMOD, you will hear the squelch/pop/blit/squeal noise (whatever it is) as soon as you start playing it. It is ~84Kb in size to download, so let me know if it does it for you as well.
As I said it seems to work fine in the other media players i have tried, just not FMOD?
Damn, that noise scared me half to death when I first heard it!
Umm… Brett? It looks like we have a bug on our hands here… it’s not the ID3 tag either… I removed the tag from his file using winamp, and even after doing that it still made the noise when played with any FMOD app… I’d say it’s a corrupted MP3 file, but that certainly isn’t it, since it plays fine in any “commercial” player (Winamp, Windows Media Player, RealOne, etc.).
So if some frames are indeed filled with garbage, how can it be that commercial players manage to extract any audio at all from them? I mean, if you don’t believe it, play the file in Winamp, WMP, or something… it’s fine.
In actual fact its not just this one file, i’ve had it with quite a few other files that i have. I guess that you are not going to make the change, so i guess there is nothing i can do about it (except your suggested solution of starting at the said file position)
I do question you however, why do all the other decoders out there, that i have tried, have no problem with this? I know you said your decoder was written differently, but i thought there was a standard to follow?? (don’t take that the wrong way, i am just interested )
Just as an aside, were all the files you’ve experienced this problem with written out by the same encoder and, if so, which one?
FMOD tries to be very tolerant of corrupted files but the guys who write the encoders/taggers/etc. have to aim for compliance to the standards as well. If they put in as much effort to encode/tag them right as FMOD does to play them right then the world would be a better place I think 😀
Thanks for clearing that up, Brett and Andrew.
I can’t remember which encoder i used for the files, as they are in fact quite old.
I have been using CDex using the LAME encoder now for a quite a while and have had no problems, i just thought you would like to know about this possible bug.
Keep up the excellent work 😉
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