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Amiga computer related discussion => Amiga Software Issues and Discussion => Topic started by: SilverZguru on August 30, 2012, 06:21:48 PM

Title: OctaMED 8 channel mode REALLY bad sounding!
Post by: SilverZguru on August 30, 2012, 06:21:48 PM
Hi all!
I have Amiga 500 which has 1mb of ram. I'm using OctaMED 4 Pro, but 8 channel play mode sounds just terrible noise instead of music... Should I get more ram?
I heard that the 8 channel mode should also work on A500.
Thanks.
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: LoadWB on August 30, 2012, 08:09:13 PM
I'm not an expert on this, so someone correct me if need be and take this as you will.  My first thought is CPU power; what CPU are you running?
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: amiman99 on August 30, 2012, 08:50:01 PM
I played 8 ch mods on A1000 and A2000 with 68000 CPU and it worked fine, but the audio levels were lower then standard mods.
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: derringer3 on August 30, 2012, 09:01:15 PM
Quote from: SilverZguru;705899
Hi all!
I have Amiga 500 which has 1mb of ram. I'm using OctaMED 4 Pro, but 8 channel play mode sounds just terrible noise instead of music... Should I get more ram?
I heard that the 8 channel mode should also work on A500.
Thanks.


Forget octamed & 8 channel on a500. Even any amiga with paula. (sound custom chip you now) The situation is better AFAIK if you use octamed soundstudio, because you can use paula 14Bit, if you have AHI (OS 3.1, which requires v39 rom) but not expect much. Theoretycally 4ch 8bit@28KHz degraded to half on 8ch.

If you have soundcard (which  you need a tons of accelerator and other thing on an a500) the situation is different. Best amiga classic config for music: a1200+turbocard+mediator+sblive.

On an a500... In the 90' i have not so much money, so i tried a lot of things to break the 4ch barrier of a500 in music. Options:

Get a turbocard. Ebay have hordes of them. Even replacing the cpu to 68010 (exactly the same pinout of the 68000 cpu) and adding extra fast ram accelerator brings you a double processing speed. If you have a late a500, then you can solder extra rams to your motherboard (with expert), so if you have 512chip+512 slow ram, then you get total continously 1,5mb chipram.

Anyway on a500 the best 8ch performance is digibooster. In the 90' my a500 has 1,5mb chipram and 4mb fastram with 68010. Digibooster can play 6ch with that, without a noticable sound degrading. With my current a500 (68030 cpu) 8ch is ok.

Also try musicline . It is different from tracker, but unique. Its like nowadays vst plugins in the 90's.
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: XDelusion on August 30, 2012, 09:25:26 PM
YOu may also want to check into getting your 500 re-capped.
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: SilverZguru on August 31, 2012, 05:10:03 AM
Or then I just focus doing music on my pc with Cubase 5 and midi keyboard ;)
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: Bamiga2002 on August 31, 2012, 05:54:20 AM
Chicken! :rolleyes:
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: klx300r on August 31, 2012, 06:56:20 AM
Quote from: XDelusion;705915
YOu may also want to check into getting your 500 re-capped.

+ 1 get her re-capped as I had the same sound problem in my 1200 3 years ago and caps solved the sound problem. Do a search and you'll see it's a common problem with 20+ year old miggies
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: Karlos on August 31, 2012, 08:45:02 AM
Guys, let's not overlook the basics.

First of all, if your machine sounds fine in 4 channel mode, but attempting to use 8 channels sounds awful, then it's not down to bad capacitors. Though having a 20-odd year old machine re-capped is not in itself a bad idea.

If, like me, you use OctaMED SS for many years, you may have forgotten that legacy 5-8 channel mode has some severe restrictions:

1) The channels are not independent and share hardware volume controls. That means that any volume changes in channel 1 also affect channel 5 and vice versa.

2) The legacy mixing routine used to play 2 samples in one channel runs at ~14kHz or so (I can't remember, but later versions of OctaMED had a "high quality" mode that ran at 28kHz but needed more CPU power). This will add lots of aliasing noise to samples that otherwise sound OK when played in 4 channel mode.

3) Sample loop lengths are heavily quantized. Instead of being able to define loops that are as short as 2 sample points, you are restricted to something like 200. This affects both the starting position and the loop length.

4) The biggest killer of all. The instantaneous amplitude of summing any two samples together on a channel may overflow the 8-bit range, resulting in heavy distortion. The mixing routines don't clip the result of adding the two sample values together, it simply overflows, often with sign inversion. It doesn't matter what you set the hardware channel volume to. The only way to properly cope with this is to alter the sample volume in the sample editor. Typically, you'd halve the volume of all your samples in 8 channel mode so that any combination of any pair of samples at once would never exceed an 8-bit result. This effectively means you are now dealing with 7-bit samples.

So, if 8 channel mode sounds awful, there are plenty of things to check. Making an 8 channel MED module sound good is not a trivial task and requires a good understanding of how it all works.

Often, your best bet is to use 6 channels. Not only does this reduce CPU load, but it gives you 2 regular channels on which you can play sounds that are just too distorted by being played by the old mixer.
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: SilverZguru on August 31, 2012, 12:17:20 PM
Hi Karlos! Yes, it sounds distorted. Even if I use 5 channel mode, its distorted! Does it really need that much power?!
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: Karlos on August 31, 2012, 12:46:38 PM
Quote from: SilverZguru;706005
Hi Karlos! Yes, it sounds distorted. Even if I use 5 channel mode, its distorted! Does it really need that much power?!


Please re-read my previous post. The distortion is probably nothing to do with lack of CPU power, I could play 8 channel MED modules on my A600.
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: SilverZguru on August 31, 2012, 02:40:27 PM
Now its working! Just needed to make samples more silent. ;)
Thanks to all!
Btw. OctaMED 4 pro can set volumes for every single channel. Even on A500
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: Karlos on August 31, 2012, 08:18:55 PM
Quote from: SilverZguru;706018

Btw. OctaMED 4 pro can set volumes for every single channel. Even on A500


You can set the volume for every single channel in any version of OctaMED, it's just that changing the volume of a split channel would always affect the channel it was split with. That is to say, changing the volume on either channel 1 or channel 5 would affect both.
Title: Re: OctaMED 8 channel mode REALLY bad sounding!
Post by: vox on September 01, 2012, 03:33:41 PM
Quote from: SilverZguru;705899
Hi all!
I have Amiga 500 which has 1mb of ram. I'm using OctaMED 4 Pro, but 8 channel play mode sounds just terrible noise instead of music... Should I get more ram?
I heard that the 8 channel mode should also work on A500.
Thanks.


Its a soft emulation mode using CPU.
Get 020 card at least or attach sound card to clock port.
Faster CPU and RAM is always a must, as well as at least Workbench 2.0