Path: chuka.playstation.co.uk!tjs From: tjs@cs.monash.edu.au (Toby Sargeant) Newsgroups: scee.yaroze.programming.sound Subject: Re: mp3 on yaroze.... Date: 27 Oct 1999 23:50:30 GMT Organization: PlayStation Net Yaroze (SCEE) Lines: 57 Message-ID: References: <7v2toh$6s1@chuka.playstation.co.uk> <7v4171$6kf1@chuka.playstation.co.uk> <7v7481$f4p1@chuka.playstation.co.uk> <38197cd9.204929122@news.playstation.co.uk> NNTP-Posting-Host: longford.cs.monash.edu.au X-Newsreader: slrn (0.9.4.3 UNIX) On Wed, 27 Oct 1999 22:32:30 GMT, Steven Osman wrote: >I agree... I'm not sure it's THAT impossible... but then again, I >really don't know enough about mp3. What I do know is that the >resulting data (post processed) needs to sustain only 150k/second (I >doubt that the output of mp3 exceeds that of a CD). That doesn't seem >like an impossible task. > >But then again, I really DON'T know enough about mp3. A 486dx2-66 (twice the clock speed of the playstation CPU) can _just_ play a mono 128k mp3, at pretty much full CPU utilisation. mp3 playing also relies on floating point operations, and seeing as the PSX CPU has no FPU, this has to be emulated. The playstation plays ADPCM samples only. Thus, there's the added overhead of converting from raw sample data to ADPCM format (which, I might add, is a SONY proprietary format, information on which is not available to yaroze members). All of this adds up to a very slow mp3 player. That being said, there's a *possibility* that if you could write an integer based mp3 player that used the GTE for matrix operations in order to parallelise the decoding of the mp3, there's a chance that you could play mp3's in realtime. In order to do it, however, you'd need to be very familiar with mp3 decoding and very familiar with the PSX at a hardware level. Anyone who's programming a yaroze has access to a PC anyway, so I don't see why having the playstation play mp3s is so interesting to people (apart, I guess, from the obvious geek factor). If you want a component unit that will play mp3s, ripping the guts out of an old vcr, and sticking an old pentium motherboard with a soundcard, ethernet and a serial port driven LCD display in their place would be a much cooler option. Alternatively, there's apparently a hardware addon like an Action Replay that will allow the psx to play mp3s. I don't know anything more than that, though. >Steven > >On Wed, 27 Oct 1999 23:05:33 +0800, "Stanley Lim" > wrote: > >>Issit possible to code in Assembly in Yaroze? Do you have any idea? Definitely, but this won't help you write an mp3 player. If you want to learn more, get a MIPS programmers manual, and have a look at as.exe (I'm assuming that the dos compiler has an accessible version of as), which is the assembler backend for gcc. if you compile a .c file with -S (note, capital s, not lowercase) the output will be the assembler conversion of the .c file. That's as good a place as any to start learning about the input format that as accepts. Toby.