#1589 - RedboX - Mon Jan 20, 2003 4:24 pm
I noticed that Lik-Sang have started to sell the Kotobuki Systems Music Recorder MP3 for GBA, heres some information on it:
"
The Music Player MP3 incorporates an MP3 encoder and decoder, clips onto your the back of the GBA to play back MP3s which are loaded into the player via a CompactFlash card -- an 8MB one is included in the pack -- and you can use Kemco's widget to record music too at 64, 96 and 128 kbps, thanks to an external input. You can even use it away from your GBA with headphones and there are five different equalizer settings for the Normal, Jazz, Pops, Classic and Rock playback modes when you do. Best of all, there's a Karaoke mode, whereby the original vocals are canceled so you can croon along to the music yourself and record the results ready to send off to Sony Music to secure your contract.
Kemco's MP3 player comes in black or purple casings and will give you up to 10 hours of music while you walk, jog, pretend to work or whatever on three regular alkaline batteries.
http://www.kemco-games.com/kiki/mp3/music.html
"
Anyway, I'm just wondering where Datel's MP3 player for the GBA is, they were makinga lot of noise about it last summer, but theres no sign of it since, They claimed they could do it all with a GBA sized cart... I guess if they kept the MP3 playback all software on the GBA size, and shoved some flash memory into a GBA cart it's possible they could do it.....
#1650 - atari - Tue Jan 21, 2003 2:20 am
They'd need some kind of hardware to aid MP3 decoding since the GB isn't powerful enough on its own. I know it's obvious, just seems unlikely they'd be able to stuff it into a cartridge.
#1661 - tepples - Tue Jan 21, 2003 4:47 am
| atari wrote: |
| They'd need some kind of hardware to aid MP3 decoding since the GB isn't powerful enough on its own. I know it's obvious, just seems unlikely they'd be able to stuff it into a cartridge. |
"You can even use it away from your GBA with headphones"
But it's still possible to get high-quality audio reproduction in a format the GBA can handle, just not in MP3 format. There exist simpler formats that a 16 MHz ARM7 processor could probably decode in real-time, such as linear-predictive codecs (simple ADPCM or complicated CELP) and sub-band codecs (such as MP2). If you have experience with audio codecs on slow integer hardware, I'd like to read about it; please respond in the "Audio" forum.
_________________
-- Where is he?
-- Who?
-- You know, the human.
-- I think he moved to Tilwick.
#1680 - Splam - Tue Jan 21, 2003 3:39 pm
Very true, not sure what it is with peoples love of MP3 and always wanting files in that format, people don't seem to want to convert their files (like why should I? they work on everything else) but the files have to be put in a rom image somehow so a conversion to a more sensible gba format could be done then. MP3 is a streaming format (ie it has to handle only having small blocks of data available at any one time) the gba has all the data easily available at all times and therefore different compression methods can be used.
#1733 - eephltn - Wed Jan 22, 2003 6:19 am
That's true. But MP3 still has very good quality vs compression ratio for music. ADPCM has good quality but the compression rate is terrible. CELP is "Code-book Excited" so it will be good for voice but not for music. SBC is just dividing the source by multiple band-pass filters, then encoded by, say, ADPCM. I don't like MP3 either but there is not much choice for good music compression. If we wanna implement the decoder on a 16MHz ARM7TDMI, the choice is even less..... :(
#1737 - ampz - Wed Jan 22, 2003 10:03 am
eephltn: don't forget ogg vorbis
#1744 - Splam - Wed Jan 22, 2003 1:38 pm
@eephltn
I think you're missing my point or confusing the difference between "music" encoding and Compression. MP3 IS good for music and there's OGG and others too BUT they're all still streaming formats. Imagine how badly RAR would work if it only compressed your files in blocks of 20k and not on the whole file ;)
#1750 - col - Wed Jan 22, 2003 4:01 pm
| Splam wrote: |
@eephltn
I think you're missing my point or confusing the difference between "music" encoding and Compression. MP3 IS good for music and there's OGG and others too BUT they're all still streaming formats. Imagine how badly RAR would work if it only compressed your files in blocks of 20k and not on the whole file ;) |
Thats a very good point splam. Do you have any suggestions for a good solution using non-streaming compression.
Although for music, we' still have to deal in chunks due to ram constraints:
eg. would it be better speed wise using a 10k buffer in iwram or a 100k buffer in ewram?
cheers
col
#1769 - Splam - Wed Jan 22, 2003 10:05 pm
I've got a few ideas ;) I've done a couple of little tests but I need some time free from working on all the other stuff I'm doing to code an app to do the encoding then write the gba side player code. I'm basically thinking of an ADPCM based thing but doing some clever stuff to it so that there are more repeated areas and so more compression.
Buffer sizes, well you won't get "exact" playback buffers from decompression of this type but I don't think anything too mad would be needed, if you take a 1k buffer as being easily enough to play a mono sample at a pretty good playback rate x2 for stereo then add another k or so for overrun from the decompression :)
#1809 - RedboX - Thu Jan 23, 2003 1:59 pm
I cant rember the way Datel's player worked now, but I think the idea was you put MP3's on a flash card and then the flash card into the Player..
So at some point the GBA whould have to deal with mp3 format files.... I guess there could be a 4 minute "PLEASE WAIT LOADING..." while the GBA converts the MP3s to some other format...
I'll dig out the artical tonight and see what I can find out.