MOD playing on Atari and Amiga

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MOD playing on Atari and Amiga

Postby Zamuel_a » Wed Nov 11, 2009 9:20 pm

Every Amiga owners always says that the Amiga is best on playing tracker music and ok, it got 4 channels, BUT the Atari has a higher processor speed so I wonder how much the difference are? The Amiga can only play in 28kHz to, while the STE can do it in 50.
I know the Lance tracker can play 50kHz mods in about 30% processor time, so shouldn't a 25kHz (which is similar to Amigas 28kHz) be able to run in maybe 20% processor time? And the Atari is about 13% faster so maybe it can compensate for the lack of 4 channel output? Atleast it sounds to me that the difference isn't so big as many people thinks, and I prefer to listen to 50khz mods if I can choose :)

A Amiga mod player routine must take some time to? There is alot more than just output audio data in a mod player so it must take some time there to.
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Re: MOD playing on Atari and Amiga

Postby Frank B » Thu Nov 12, 2009 9:28 am

Zamuel_a wrote:Every Amiga owners always says that the Amiga is best on playing tracker music and ok, it got 4 channels, BUT the Atari has a higher processor speed so I wonder how much the difference are? The Amiga can only play in 28kHz to, while the STE can do it in 50.
I know the Lance tracker can play 50kHz mods in about 30% processor time, so shouldn't a 25kHz (which is similar to Amigas 28kHz) be able to run in maybe 20% processor time? And the Atari is about 13% faster so maybe it can compensate for the lack of 4 channel output? Atleast it sounds to me that the difference isn't so big as many people thinks, and I prefer to listen to 50khz mods if I can choose :)

A Amiga mod player routine must take some time to? There is alot more than just output audio data in a mod player so it must take some time there to.


The STe always sounded just as good to me as the Amiga when playing modules. One interesting thing about the Amiga is that on a VGA screen the max output frequency of paula is doubled. It's a bug in the chipset. So depending on the screen mode the max sample rate on the Amiga is 56 khz and not 28.

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Re: MOD playing on Atari and Amiga

Postby Zamuel_a » Thu Nov 12, 2009 1:52 pm

I think the STE sounds better than Amiga since it can run in 50kHz :)

Didn't know that about the Paula chip, but if it's then you have a VGA resolution I guess you need a Amiga 1200 or higher? I was just comparing a standard Amiga 500 and a standard STE, or else we can compare a A1200 to a Falcon and see who is best :wink:

It's the same thing with Amigas Cooper. Raster effects are easily done on the Atari to with Timer B interrupts and I think the higher clockspeed can compensate for gain you get from the Cooper.
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Re: MOD playing on Atari and Amiga

Postby coze » Thu Nov 12, 2009 2:16 pm

Zamuel_a wrote:Didn't know that about the Paula chip, but if it's then you have a VGA resolution I guess you need a Amiga 1200 or higher? I was just comparing a standard Amiga 500 and a standard STE, or else we can compare a A1200 to a Falcon and see who is best :wink:


Amiga 500 with ECS chipset can run VGA resolutions (only 4 colors though)

Zamuel_a wrote:It's the same thing with Amigas Cooper. Raster effects are easily done on the Atari to with Timer B interrupts and I think the higher clockspeed can compensate for gain you get from the Cooper.


hell no, I've seen many 'copper wanna be' demos on ST, and they were all jerky or low frame rate ... one thing an Atari can not ever beat an Amiga is doing rasters ... it's just the hardware that is specially designed on the Amiga to do it, and on the Atari, 68000 just doesn't cut it ...

if you watch this on a real Amiga, you'll see what I mean.

http://www.youtube.com/watch?v=NMRUj5nDewI

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Re: MOD playing on Atari and Amiga

Postby Zamuel_a » Thu Nov 12, 2009 2:59 pm

Ok, maybe the Amiga can do better rasters, but I don't think it's much of a demo effect then you have hardware for doing it. I prefer a software routine instead. Then if you use hardware to make better games or so, then it's another thing.
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Re: MOD playing on Atari and Amiga

Postby Frank B » Thu Nov 12, 2009 5:46 pm

I'm not sure about that. Unless you're doing hpos stuff with the copper it doesn't really matter whether it's the CPU or the copper doing the colour move. A vertical raster colour change appears to be the same. Besides you can always use the blitter on the ST(e) to hammer $ff8240 if you want to do horizontal colour split stuff much quicker than the CPU. It's kinda cool to use skip with a nice mask to do repeating rasters on the Amiga though.

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Re: MOD playing on Atari and Amiga

Postby Frank B » Thu Nov 12, 2009 5:49 pm

The AGA bank switched palette ain't very nice either. Commodore should have been shot for that :/

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Re: MOD playing on Atari and Amiga

Postby dlfrsilver » Thu Nov 12, 2009 8:06 pm

Zamuel_a wrote:I think the STE sounds better than Amiga since it can run in 50kHz :)


The Khz rate on the STE YM2192 chip is not compliant with the CD audio norm (44100 khz). Add to this that in reality the power needed to make some real 50Khz is far greater to what an STE can give. There is no STE game hitting 50Khz nor even 25khz. The amiga Paula's audio chip is on its side compliant with the Digital audio standard (44100khz), that means that 28khz sound quality is applicable
to the digital standard. By the way, 28 khz is even higher than the maximum frequency limit the human ear can hear. 50 khz is a nonsense since the human can't make any difference between a music at 20 khz and 44,1khz.

More is not always better :(

to playback an 8 bits 44,1Khz, you need an A1200 with a 68040+FPU. This gives an idea about the 50Khz on STE.

Also, with a tool called megalosound from Microdeal on amiga that i own, you can sample on a simple A500 in mono up to 70Khz and 39 khz in stereo ! (but well what's the point and use of this ? :?: )
Last edited by dlfrsilver on Thu Nov 12, 2009 8:11 pm, edited 1 time in total.
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Re: MOD playing on Atari and Amiga

Postby Zamuel_a » Thu Nov 12, 2009 8:50 pm

By the way, 28 khz is even higher than the maximum frequency limit the human ear can hear. 50 khz is a nonsense since the human can't make any difference between a music at 20 khz and 44,1khz


That is actually not true. It's true the ear can't hear a sound higher than about 20khz, BUT sampling frequence is NOT the frequency of the sound you put out. For example a square wave is made of a ground frequency (the frequency you hear) which is a sinus wave and then you have overtones that add up to that sine wave to create a square wave. It's what's make different instruments sounds different, so the higher frequency you can output, the more overtones can be combined to create the sound. One rule is that you MUST have TWICE the sampling speed to be able to read a wave correctly. Since a wave is made of two parts (high and low if you think of it in a simple way), then you need to get atlest two samples for every frequency span you want to read or else you can't read both the high and low part. so to be able to sample a 20kHz audio wave you need at a minimun 40khz sample rate, but that would mean you get one sample at the low part and one at the high part, so you would ONLY get a triangle wave even if you had a square wave to begin with. This is very easy to see on a oscilloscope.

One common rule is to use 10 times oversampling to get something that looks like the original wave, so if you want to sample a squarewave (which is the hardest one since it's so sharp edges) who is 20khz, then you need to have a sample rate of 200khz!

So even a CD at 44100Hz isn't so great. compare it with a audio DVD at 96khz and you will hear a big difference. It has ofcourse to do with the frequency of the instrument you listen to. A high frequency instrument sounds worse on a CD than a low frequence instrument.

If you listen at a sample on the STE at 25khz and 50khz you will hear a big difference and sample rate is just sample rate so there isn't any difference between an amiga and an atari then you compare the rates. They are both 8 bits to, so it will sound the same (if you forget about filters and such stuff)

From what I have read, the Lance tracker should output true 50khz mods in just 30% sample rate.

If you want to hear a STE game with mod music, just play Obsession :)

to playback an 8 bits 44,1Khz, you need an A1200 with a 68040+FPU. This gives an idea about the 50Khz on STE.


This has to do with the Paula chip that needs a VGA resolution to play at that rate. It has nothing to do with the amiga itself. you need an Amiga with ECS chipset and then you can have 56khz samples, even on a Amiga 500
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Re: MOD playing on Atari and Amiga

Postby dlfrsilver » Thu Nov 12, 2009 10:15 pm

I own a boosted 1040 STE. The sound has nothing spectacular, It sounds OK that's all.
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Re: MOD playing on Atari and Amiga

Postby Frank B » Thu Nov 12, 2009 10:55 pm

Paula is basically a hardware soundtracker. You say I want channel 0-3 to play a sample at address x with a given volume at a sample rate up to 28 khz. The frequency, volume and sample address can be set per channel. The STE needs the CPU to mix samples and vary their frequency/volume.

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Re: MOD playing on Atari and Amiga

Postby Zamuel_a » Thu Nov 12, 2009 11:40 pm

I was thinking about playing a normal stereo sample on the STE, then it's no problem with sound quality. I think the 50khz mod routines works fine to with better sound than a standard Amiga 500.

I know all about the mixing of samples to create 4 channel mods on the STE, but I was just thinking about how much more processor time it takes compared to the Amiga if you calculate with the 13% higher clock rate.
Ofcourse you don't have to do any mixing on the Amiga, but the mod routine must take a few percent anyway?
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Re: MOD playing on Atari and Amiga

Postby leonard » Fri Nov 13, 2009 12:16 am

Hi,

Agree with samuel, sampling frequency for digital signal is not related to the theorical "20khz" human hear. 44100Hz is not enough for today "hifi" (CD is a twenty year standard :-)).

To main the main difference for quality in playing module is that STE has only a STE 8bits dac, so you have to mix 4 voices in 8bits (it means 6bits per sample). AMIGA has really 4 voices so all voices really use 8 bits of the samples. You can do things better on STE by mixing only 2 voices on right channel, and 2 on left, the quality is better.
And finally, for module playing, the quality of original sound insruments is far more important that the replay frequency (play an old amiga module with noisy instrument at 50khz, it still sounds bad :-))
Finally, Falcon is a cool machine to play amiga modules because you have a real 16bits DAC output so you can mix many 8bit voices without loosing any depth. (depth is almost as important as frequency for music quality, that's why 16bits CD quality is not enough today to play high dynamic instrument such as raw piano in concert. I guess DVD audio is 24bit am I right?

To finish you can test the STE amiga-music like quality with this demo :-)

http://pouet.net/prod.php?which=52336
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Re: MOD playing on Atari and Amiga

Postby dlfrsilver » Fri Nov 13, 2009 12:17 am

Hardware Soundtracker = no CPU charge and on STE = CPU charge.

Just look at the jamma boards using Yamaha YM2XXX chips. They all need to be driven by a CPU.
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Re: MOD playing on Atari and Amiga

Postby coze » Fri Nov 13, 2009 1:37 am

Zamuel_a wrote: or else we can compare a A1200 to a Falcon and see who is best :wink:


I don't want to bring this a Amiga vs Atari flame war but :D I have to add that comparing 1200 to falcon is not fair. Falcons retail price more than twice the 1200 I think. They were designed for different markets, if commodore wanted to produce a high end machine, they could have put a DSP and 030 to a1200 too, and they would be selling a similar prices then. :coffe:

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Re: MOD playing on Atari and Amiga

Postby Zamuel_a » Fri Nov 13, 2009 7:04 am

To main the main difference for quality in playing module is that STE has only a STE 8bits dac, so you have to mix 4 voices in 8bits (it means 6bits per sample). AMIGA has really 4 voices so all voices really use 8 bits of the samples. You can do things better on STE by mixing only 2 voices on right channel, and 2 on left, the quality is better.


You mean for a 8 channel mod? I thought that normal 4 channel mods were just 2 voices on right and 2 on left channel.

I had liked to know what the processorspeed is on an amiga 500 then you play mods at 28khz. The time it takes to handle the mod format itself (must be a few percent).

I saw a documentery once about the CD format and why it got a so odd frequency as 44100Hz. Apparently they used Beta max video tapes for storing data in the beginning. There were no harddrives to store 650Mb of data in the early 80s! Atlest not cheap, so they used video tapes instead and the maximum frequency you could use on the tapes was 44100Hz :)
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Re: MOD playing on Atari and Amiga

Postby DarkLord » Fri Nov 13, 2009 8:38 am

coze wrote:
Zamuel_a wrote: or else we can compare a A1200 to a Falcon and see who is best :wink:


I don't want to bring this a Amiga vs Atari flame war but :D I have to add that comparing 1200 to falcon is not fair. Falcons retail price more than twice the 1200 I think. They were designed for different markets, if commodore wanted to produce a high end machine, they could have put a DSP and 030 to a1200 too, and they would be selling a similar prices then. :coffe:


Ditto about the flame war - seen and been involved in way too many... :)

I have to say though, when I bought my Falcon it was $799.00 for a base machine, and the
Amiga A1200 in my area was running almost the same price. Very little difference. Maybe
it was a regional thing? Dunno. But that's the way it was.
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Re: MOD playing on Atari and Amiga

Postby Zamuel_a » Fri Nov 13, 2009 11:33 am

$799 for a Falcon was cheap! :D Here in Sweden I think they cost something like 2-3 times that. It was real expensive, but the amiga 1200 was much cheaper.
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Re: MOD playing on Atari and Amiga

Postby dlfrsilver » Fri Nov 13, 2009 7:55 pm

The amiga 500 doesn't use main CPU, paula can be used independantly.

The amiga 1200 in France was way way cheaper (3490 francs which makes 607 euros in equivalent today) than the Falcon which was really expensive (6500 francs, which makes 1130 euros equivalently today).
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Re: MOD playing on Atari and Amiga

Postby bod/STAX » Fri Nov 13, 2009 8:31 pm

It is possible to have 16-bit 50khz replay on the STE (Truly better than a CD), but in mono only.

This was mentioned in the Audio Sculpture manual requiring some soldering modifications to the
DMA sound chip (Synchron Assembly said they could send out schematics for this).

Has anyone actually tried this and, if so, how does it compare to 8-bit 50khz output?
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Re: MOD playing on Atari and Amiga

Postby Frank B » Fri Nov 13, 2009 9:54 pm

Of course it uses the CPU on the Amiga. :) Maybe not for mixing the channels but it still has to interpret the tracker data to tell Paula what to do. From memory the raster time taken for the Protracker replayer on the Amiga is about 15-20 scanlines. Wouldn't be surprised if it has some interrupt overhead too.

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Re: MOD playing on Atari and Amiga

Postby leonard » Fri Nov 13, 2009 10:08 pm

Frank B wrote:Of course it uses the CPU on the Amiga. :) Maybe not for mixing the channels but it still has to interpret the tracker data to tell Paula what to do. From memory the raster time taken for the Protracker replayer on the Amiga is about 15-20 scanlines. Wouldn't be surprised if it has some interrupt overhead too.


Yes it use CPU, about the same CPU as a standard "chip" music driver on atari, so it's about between 8 and 12 raster line for protracker. The funny part is that amiga coder are not "CPU" expert :-) so if you look at the protracker original replay code, you will see tons of awfull things such as DIV, etc. Add to this some AMIGA music driver use wait-loop to setup the next loop sample adress. (so the CPU is waiting for nothing). Best player use timer to setup the loop adress few rasterline after without "hanging" the CPU. And some other good player just setup the loop adress on the next VBlank, so it does not need interrupt at all. The fastest MOD player on AMIGA 500 takes about 5 raster lines I guess.

Again, for quality, saying that "STE is 50khz so it's better than CD" is just a mistake. There is tons of other stuff to consider for audio quality (raw sample instrument quality, 8bits depth MOD sample, original instrument sampling frequency, volume-table emulation, 8bits sound mixing, etc...). 50khz sounds a bit too "marketing" to me (ATARI could say "hey, 50khz is better than 44.1Khz").

AMIGA hardware is definitvely better than ATARI hardware to replay protracker module :-) But you can emulate it on STE quite well if you take care about quality and don't bother about your CPU (because it takes a huge amount of CPU to emulate PAULA with good quality).
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Re: MOD playing on Atari and Amiga

Postby dlfrsilver » Sat Nov 14, 2009 12:29 pm

leonard wrote:
Frank B wrote:Of course it uses the CPU on the Amiga. :) Maybe not for mixing the channels but it still has to interpret the tracker data to tell Paula what to do. From memory the raster time taken for the Protracker replayer on the Amiga is about 15-20 scanlines. Wouldn't be surprised if it has some interrupt overhead too.


what i meant was that the CPU get no charge. Of course it has to interpret data so that paula takes it next, but overall the 68000 on amiga doesn't take 30% or more CPU for this task.

Yes it use CPU, about the same CPU as a standard "chip" music driver on atari, so it's about between 8 and 12 raster line for protracker.

The funny part is that amiga coder are not "CPU" expert :-)


Mainly because of the difference between both machines :D Everything must be made in soft on atari, which led the coders to work out tight code, when on amiga coders just use the 68000 to drive the hardware.

Amiga coders thinks and breath "custom chips" programming when ST coders thinks "68000 coding".

so if you look at the protracker original replay code, you will see tons of awfull things such as DIV, etc. Add to this some AMIGA music driver use wait-loop to setup the next loop sample adress. (so the CPU is waiting for nothing). Best player use timer to setup the loop adress few rasterline after without "hanging" the CPU. And some other good player just setup the loop adress on the next VBlank, so it does not need interrupt at all. The fastest MOD player on AMIGA 500 takes about 5 raster lines I guess.


interesting :D

Again, for quality, saying that "STE is 50khz so it's better than CD" is just a mistake. There is tons of other stuff to consider for audio quality (raw sample instrument quality, 8bits depth MOD sample, original instrument sampling frequency, volume-table emulation, 8bits sound mixing, etc...). 50khz sounds a bit too "marketing" to me (ATARI could say "hey, 50khz is better than 44.1Khz").


Yes, 50 khz on STE is all relative.

AMIGA hardware is definitvely better than ATARI hardware to replay protracker module :-) But you can emulate it on STE quite well if you take care about quality and don't bother about your CPU (because it takes a huge amount of CPU to emulate PAULA with good quality).


Nothing beats hardware over software. Just check up coin-ops. Everything is hardwired and so simple..... If you want to do the same in software, things get a lot more difficult :( (and i don't even talk about RAM requirement and so on)
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Re: MOD playing on Atari and Amiga

Postby Zamuel_a » Sat Nov 14, 2009 2:41 pm

The amiga 500 doesn't use main CPU, paula can be used independantly


I know that. But that is same on the Atari to. The sample player doesn't use the CPU at all if you don't want to mix samples. But Paula doesn't have an mod player routine inside from what I know so that has to be done on the MPU.
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Re: MOD playing on Atari and Amiga

Postby Zamuel_a » Thu Nov 19, 2009 7:15 pm

I have never coded anything on the Amiga and wonder how easy the cooper is to use? I think it's rather easy to use Timer B to generate rasters and so on the Atari and it feels like it must be somewhat similar on the Amiga. Ok alittle more code on the Atari, but it feels more like "setup"
If you think about the 13% extra MPU time on the Atari, that gives you around 100 cycles for each visible line on the screen to use with Timer B to get down to the same speed as the Amiga. For just plain rasters you don't use many cycles every line so then the whole machine is still faster than an Amiga.
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