how can i do music on megadrive?

TmEE co.(TM) · Post by **TmEE co.(TM)** » Tue Feb 06, 2007 6:32 am

I'll keep it in mind. I was thinking of mixing stuff last night and I've come up with this: If the sounds are in the same 32K segment, mixing is not a problem, but if 1 sound is in 1 32K segment and other in another 32K segment it grows into a problem because changing banks is NOT very good idea when mixing is happening. I was thinking of copying some data from one bank to RAM and mix it later with data from one bank. I guess it is slow, but not slower than changing banks.

Stef · Post by **Stef** » Mon Feb 12, 2007 9:56 am

I should give you my code, it's able to mix 2 samples from different bank at 11 Khz. I guess it can up to 14/16 Khz with good optimisations.

I also past my week end to write a new Z80 driver to play simple sample. It can play a sample up to 41 Khz.
Features of this driver :
- capable of playing long sample (> 64 KB)
- stop/restart play at anytime
- keep a status "playing" flag bit
- capable of playing at variable sample rate (parameter of my playSampe function)

Post by **KanedaFr** » Mon Feb 12, 2007 10:01 am

wow!!!

ok, so I stop working on mine

it seems you're better at this than me, I'm at 9.3KHz max

I'm waiting for the driver !!

Fonzie · Post by **Fonzie** » Mon Feb 12, 2007 10:32 am

Hey kaneda

you are joking?
Sure the the KHz are more impressive but don't forget you're doing something more important at same time

Don't give up

8khz is perfect for most games

Stef · Post by **Stef** » Mon Feb 12, 2007 10:37 am

I'll post the source just when i'll be back at home

Pascal · Post by **Pascal** » Mon Feb 12, 2007 10:59 am

sweeet , 2 samples mixing is what i need for finishing one of my game

Stef · Post by **Stef** » Mon Feb 12, 2007 12:55 pm

Pascal wrote:sweeet , 2 samples mixing is what i need for finishing one of my game

My code need some tweaks and bit of rewrite as it's quite awful for now but at least it work

The sample needs to be 8 bits signed for faster mixing operation for now.

Pascal · Post by **Pascal** » Mon Feb 12, 2007 1:35 pm

only result prevail

TmEE co.(TM) · Post by **TmEE co.(TM)** » Mon Feb 12, 2007 6:20 pm

Stef wrote:I'll post the source just when i'll be back at home

When would it happen ? I hope I can understand it

Actually I haven't even started to write my mixer, I'm too busy with my new MD game, hint: A+B+C+Start+Down in GBMD.

Stef · Post by **Stef** » Mon Feb 12, 2007 7:32 pm

Sorry i was really long, here's the link :

Z80 basic driver for sample play (source)

The code is commented here and there, hope you understand it

have fun

Edit : i updated the archive to include C functions using the Z80 drivers. The startPlaySample function also does the "rate to wait state" conversion so it's important to have it

playSample2 is used for another driver, ignores it here.

I'll post my source of the 2 channels player later after some minors tweaks and changes.

TmEE co.(TM) · Post by **TmEE co.(TM)** » Tue Feb 13, 2007 6:24 am

I usually don't comment my code, but as long as I understand it... I spend quite some time commenting my WAVPLAY

Post by **KanedaFr** » Tue Feb 13, 2007 8:49 am

Ok, I now know why I'm unable to have your rate : I set the bank every time...
I need to do it since I also play PSG and FM
I so had 3 banks, need to set it before each read...

Stef, may I use some of your code since you optimize it a lot ?
perhaps I can optimize mine a little more...

TmEE co.(TM) · Post by **TmEE co.(TM)** » Tue Feb 13, 2007 1:09 pm

How many samples you play at the time ?

Stef · Post by **Stef** » Tue Feb 13, 2007 2:29 pm

KanedaFr wrote:Ok, I now know why I'm unable to have your rate : I set the bank every time...
I need to do it since I also play PSG and FM
I so had 3 banks, need to set it before each read...

Stef, may I use some of your code since you optimize it a lot ?
perhaps I can optimize mine a little more...

Of course you can

At first shot i also did set bank each time but that was a real waste when you're playing a single sample since you can do it only when needed (it's a part of optimisation :p). For 2 samples or more, you haven't anymore choice unfortunatly so the play rate is really reduced what even you do :-/

TmEE co.(TM) · Post by **TmEE co.(TM)** » Wed Feb 14, 2007 8:29 am

Stef wrote:Sorry i was really long, here's the link :

Z80 basic driver for sample play (source)

The code is commented here and there, hope you understand it
have fun

Your code is really understandable, your coding style is exactly like mine