My attempt at 2ch Z80 mixer

TmEE co.(TM) · Post by **TmEE co.(TM)** » Sun Jun 24, 2007 8:51 pm

http://www.hot.ee/tmeeco/DWNLOADS/MSETEST.RAR

It can play 1ch @ 110KHz, and 2ch @ 52KHz.
This demo plays @ 22KHz or so.

2ch playback is little distorted because of extra jitter, and it sounds faster than 1ch on real HW (LDIR instruction executed faster ?) than on emulator where it sounds slower than 1ch.

A and B buttons make sound.

Thing is not finished though, need to work out sound effect stuff, and music part.

evildragon · Post by **evildragon** » Sun Jun 24, 2007 9:07 pm

this is awesome :p i never thought this was even possible...

TmEE co.(TM) · Post by **TmEE co.(TM)** » Sun Jun 24, 2007 9:12 pm

It is, and it sounds lot better on real HW, than on emulators (Fusion sounds nice though). 110KHz is achieved thanks to Stef's idea which he came quite some time ago (see the "How can I do music on MegaDrive" topic on MD stuff forum).

TmEE co.(TM) · Post by **TmEE co.(TM)** » Mon Jun 25, 2007 12:28 pm

Updated the thing, now it sounds much more nicer.

A=Snare drum (ch1)
B=Bass drum (ch0)
C=Crash cymbal(ch1)

There is a weird pop when 2ch are playing, I couldn't get rid of it... any ideas anyone ?

I was drumming whole night yesterday...

Shiru · Post by **Shiru** » Mon Jun 25, 2007 3:23 pm

TmEE co.(TM) wrote:There is a weird pop when 2ch are playing, I couldn't get rid of it... any ideas anyone ?

Record sound output from emulator to wav and look it in any sound editor, you understand this problem. It's a incorrect DC offset.

TmEE co.(TM) · Post by **TmEE co.(TM)** » Tue Jun 26, 2007 8:14 am

Yes it was... I lowered the volume of one channel playback (so it is as loud as 2ch) but I forgot to add 64 to get "silence" position (128), it was 64, and when 2ch played, jump from 64 to 128 caused a pop. Now it is fixed and works great !!!

Upadated again.

Stef · Post by **Stef** » Sun Jul 01, 2007 8:51 pm

It's awesome to see how we progressed from our first attempt

just need to continu in this way and we will do our 4 ch MOD player on Z80

Fonzie · Post by **Fonzie** » Mon Jul 02, 2007 6:22 am

yeah ^^ Very impressive dudes

May i recall that the official sega driver supported "delta compressed samples" (ADPCM?) in top of FM/PSG

Haha

I'm insane, I know

Anyway, nowadays, you may have 8Megabytes cartridges, so it is fine

Shiru · Post by **Shiru** » Mon Jul 02, 2007 6:59 am

DPCM and ADPCM is different things, DPCM is much simpler, it has fixed delta.

TmEE co.(TM) · Post by **TmEE co.(TM)** » Mon Jul 02, 2007 3:20 pm

For a while, I was thinking about creating my own brand of ADPCM, but as Fonz said, size is no problem today