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What are the max audio sampling rates+polyphony of old gaming consoles, of retro 8-bit sounds [moved from Scientific Discussion]
WAZAAAAA
post Apr 29 2013, 06:17
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Google didn't help me much on these.

Is there a way to know how much 'sampling rate' expressed in Hz and 'polyphony' did the old gaming consoles such as the NES and Gameboy support on their sound hardwares? This may or may not be a dumb question, as I'm not too much into this stuff, so please bear with me.

I've found on Wikipedia a fine chart showing examples of what kind of devices uses certain sampling rates, but in the list there's not what I'm searching for. Does anyone know?
I've also recently stumbled upon this strange thing called "polyphony" which I didn't fully understand. I have a program that has an option to change the maximum polyphony of it, with numbers that range from 32 to 512. Were 8-bit consoles even capable of playing multiple sounds at once in the first place?

I basically want to know how to make sounds as similar as possible to original retro gaming consoles.
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db1989
post Apr 29 2013, 08:47
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QUOTE (WAZAAAAA @ Apr 29 2013, 06:17) *
I've also recently stumbled upon this strange thing called "polyphony" which I didn't fully understand.
Sorry, but the quickest of searches would reveal that it denotes the number of notes (or patches, but that’s technically multitimbrality) that a device can play at once.

QUOTE
I have a program that has an option to change the maximum polyphony of it, with numbers that range from 32 to 512. Were 8-bit consoles even capable of playing multiple sounds at once in the first place?
…Have you actually listened to any 8-bit consoles? I’m not being sarcastic for its own sake, but you seem to be interested in these consoles, so I would think you would have more familiarity with how they sound. Yes, plenty of old devices were polyphonic and/or multitimbral. The GB, for instance, has two channels of pulse waves, one channel for arbitrary 4-bit waveforms, and one channel of noise. The C64 had, IIRC, three channels with selectable waveforms. The Mega Drive had 6 notes/timbres of 4-operator FM synthesis, one of which could be mapped to noise or samples, and 3 channels of pulse waves.

Specifications on other consoles will either be available readily online by searching or are not really relevant, e.g. some may not use systems that lend themselves to familiar measurements of quality. Perhaps that explains some of your lack of info, or perhaps you need to search harder; unfortunately, that’s often how it goes with relatively esoteric information like this. I have my doubts that this site will be any better than dedicated gaming/music sites that can be found via Google as it only rarely sees topics about such systems.

To make the sounds themselves, there are plenty of VST instruments and suchlike that emulate old hardware, or purists would recommend getting the actual hardware and playing from that. Certainly there is no one ‘retro game sound’ for which a single catch-all solution exists.

This also isn’t really “Scientific Discussion”.
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knutinh
post Apr 29 2013, 10:03
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QUOTE (WAZAAAAA @ Apr 29 2013, 06:17) *
I basically want to know how to make sounds as similar as possible to original retro gaming consoles.

You want to have a "superset" sound-generator that contains all of the flexibility of all retro gaming consoles? Or do you want to model one or more specific sound-generators?

I believe that retro consoles used a wide range of sound-generating methods - from early analog sound generation (simple analog synthesizers), FM-synthsis, samples etc. Low samplerates, few number of bits, etc may be a common theme, but a detailed model would contain specific aliasing behaviour etc.

The Commodore SID chip seems to be widely documented? Perhaps it can serve as a starting-point.

-k
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Arnold B. Kruege...
post Apr 29 2013, 13:00
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QUOTE (WAZAAAAA @ Apr 29 2013, 01:17) *
Google didn't help me much on these.

Is there a way to know how much 'sampling rate' expressed in Hz and 'polyphony' did the old gaming consoles such as the NES and Gameboy support on their sound hardwares? This may or may not be a dumb question, as I'm not too much into this stuff, so please bear with me.

I've found on Wikipedia a fine chart showing examples of what kind of devices uses certain sampling rates, but in the list there's not what I'm searching for. Does anyone know?
I've also recently stumbled upon this strange thing called "polyphony" which I didn't fully understand. I have a program that has an option to change the maximum polyphony of it, with numbers that range from 32 to 512. Were 8-bit consoles even capable of playing multiple sounds at once in the first place?


I'm under the impression that in the beginning, games only had analog synths. So, PCM concepts did not apply.

QUOTE
I basically want to know how to make sounds as similar as possible to original retro gaming consoles.


Wave tables are your friend.
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db1989
post Apr 29 2013, 13:11
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QUOTE (Arnold B. Krueger @ Apr 29 2013, 13:00) *
I'm under the impression that in the beginning, games only had analog synths. So, PCM concepts did not apply.

Is this impression based upon anything? I always pictured early computers/games as having primitive DCOs, probably coloured due to downstream processing, but nonetheless based upon an IC outputting a square/pulse wave in response to clocks/latches specified by an external input.

QUOTE (Arnold B. Krueger @ Apr 29 2013, 13:00) *
Wave tables are your friend.

I assume that by wavetables you’re following Creative’s ever-misleading logic of using that term to describe the sample-based synthesis (if that can really be called synthesis wink.gif) from ROM used by their Sound Blaster and its clones, rather than the original definition of wavetable synthesis as the method pioneered by the PPG and its descendents. Certainly the latter has not been involved in any consoles. As for the sample-based synthesis used by Creative et al., that’s characteristic of sound cards from the 90s for DOS- and early Windows-based computers, not standalone consoles.

In contrast, early gaming systems, which more typically define the term ‘retro’, used predominantly square/pulse waves only, numbering a small number of channels. As hardware advanced, then came a progression through additional types of oscillator, filters, FM, samples, and eventually direct playback of finished tracks from disk (compact or hard) in place of synthesis. Nowadays, as disk space and processing time are many orders of magnitude more plentiful, most systems seem to just play back pre-recorded songs.

As for the general character of the early oscillator-based synths, there isn’t really one. Whichever types and arrangements of components were used in whichever particular machine, all the way from the duty cycle to the analogue output, probably influenced the quality of the resulting sound. Going a bit further forward in time, just look at the YM2612 from the Mega Drive: ostensibly just another 4-operator FM synth, but implemented and connected in such a way that many models of the MD have particularly distinctive colourations (desirable or not, depending on taste) imparted to their sound. No doubt similar considerations apply to all system based on older and/or cost-cutting components.

Again, if you’re trying to emulate particular sounds, you can either settle for an approximation from a generic synth VSTi that probably outputs ‘excessively’ clean waveforms, or you can look for more specialised virtual instruments that claim to emulate particular characteristics of specific systems, or you can use the original hardware in combination with a tracker or suchlike. There’s no one-size-fits-all ‘retro sound’ and certainly no instrument that can accurately emulate all the old consoles with their various components and methods of synthesis.

Having said all that, if your target audience automatically associates any square/pulse wave, FM instrument, etc. with old consoles, you might be able to take the shortcut of using (insert generic synth of the chosen type) rather than hunting for someone else’s attempt at recreating any specific system. Then perhaps similarly generic downsampling and/or bit-reducing effects might get you a bit closer to the mythical ‘retro sound’, generally rather than faithfully to any one system.

This post has been edited by db1989: Apr 29 2013, 13:32
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2Bdecided
post Apr 29 2013, 17:47
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Just because a given console used X sample rate with Y bits doesn't mean that using X sample rate with Y bits on a modern sound card is going to give you "that" sound. Old sound chips had all kinds of distortion that modern sound cards will avoid - and that distortion is part of the vintage "sound".

It also does not mean that X sample rate with Y bits is sufficient to capture the sound coming out of a vintage system which happens to use those parameters.

Not that anybody claimed either of these things - I'm just anticipating where the discussion might have gone!

Cheers,
David.

This post has been edited by 2Bdecided: Apr 29 2013, 17:47
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saratoga
post Apr 29 2013, 17:56
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http://multimedia.cx/eggs/sequencing-midi-from-a-chiptune/
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benski
post Apr 29 2013, 20:14
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QUOTE (knutinh @ Apr 29 2013, 04:03) *
The Commodore SID chip seems to be widely documented? Perhaps it can serve as a starting-point.


The SID chip is well documented, but it contains analog components . And the digital section of the synthesizer run at a very high sampling rate (1 MHz). These facts make it more difficult to emulate, at least without some knowledge about digital filter design, band-limited waveform generation, and real-time resampling techniques.
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stv014
post Apr 30 2013, 11:04
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For the SID chip, there is already good quality open source emulation code available.
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Arnold B. Kruege...
post Apr 30 2013, 15:11
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QUOTE (db1989 @ Apr 29 2013, 08:11) *
QUOTE (Arnold B. Krueger @ Apr 29 2013, 13:00) *
I'm under the impression that in the beginning, games only had analog synths. So, PCM concepts did not apply.

Is this impression based upon anything?


http://en.wikipedia.org/wiki/MOS_Technology_SID

QUOTE
In contrast, early gaming systems, which more typically define the term ‘retro’, used predominantly square/pulse waves only, numbering a small number of channels. As hardware advanced, then came a progression through additional types of oscillator, filters, FM, samples, and eventually direct playback of finished tracks from disk (compact or hard) in place of synthesis. Nowadays, as disk space and processing time are many orders of magnitude more plentiful, most systems seem to just play back pre-recorded songs.


That is characteristic of analog synthesis technology, with digital controls.

I think that you aren't really reading what I said because I'm saying one thing and you are saying "No" and then saying the same thing I said some other way.

This post has been edited by Arnold B. Krueger: Apr 30 2013, 15:12
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db1989
post Apr 30 2013, 17:49
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QUOTE (Arnold B. Krueger @ Apr 30 2013, 15:11) *
QUOTE (db1989 @ Apr 29 2013, 08:11) *
QUOTE (Arnold B. Krueger @ Apr 29 2013, 13:00) *
I'm under the impression that in the beginning, games only had analog synths. So, PCM concepts did not apply.
Is this impression based upon anything?
http://en.wikipedia.org/wiki/MOS_Technology_SID
Does one citation count as a general impression now? Anyway:
QUOTE
All control ports are digital, while the output ports are analog.
Becoming analogue at the output is for the subsequent filters; the generation of signal seems to be purely digital.

My interpretation is that if it uses a digital IC to generate a signal rather than a VCO, it’s not analogue. My presumption is that most, if not all(?), computer systems used digital ICs by virtue of their nature as digital systems. If that is false, feel free to explain with reasoning and examples; that’s what I was looking for, not brief restatements of the same general points without elaboration.

QUOTE (Arnold)
QUOTE (me)
In contrast, early gaming systems, which more typically define the term ‘retro’, used predominantly square/pulse waves only, numbering a small number of channels. As hardware advanced, then came a progression through additional types of oscillator, filters, FM, samples, and eventually direct playback of finished tracks from disk
That is characteristic of analog synthesis technology, with digital controls.
What is? All of it, or just the bit about “early gaming systems”? I highly doubt that, to name just two, my Amstrad CPC 464 or Game Boy had miniature analogue synthesisers in them. Most of the discussion about the circuitry in these systems are peppered with references to bit-depth and so forth, something that seems to go against your generalisation with quite some force.

QUOTE
I think that you aren't really reading what I said because I'm saying one thing and you are saying "No" and then saying the same thing I said some other way.
All righty then. Notice now how your reply was just the same thing, but repeating yourself instead of me, even. Feel free to actually explain things this time around.
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saratoga
post Apr 30 2013, 21:25
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I don't really see the distinction between a digital function generator clocked off a vco and an analog generator composed of a vco controlled by a digital circuit. Its the same idea described differently.
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benski
post May 1 2013, 16:19
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QUOTE (saratoga @ Apr 30 2013, 15:25) *
I don't really see the distinction between a digital function generator clocked off a vco and an analog generator composed of a vco controlled by a digital circuit. Its the same idea described differently.


Except that the digital function generator necessarily aliases (unless extreme care is taken in the mathematics, which is unlikely).
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stv014
post May 1 2013, 19:03
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QUOTE (benski @ May 1 2013, 17:19) *
Except that the digital function generator necessarily aliases (unless extreme care is taken in the mathematics, which is unlikely).


The generators in early 8-bit machines were often limited to dividing the clock frequency by integer ratios. This avoids aliasing, but the pitch accuracy is not perfect, especially if the clock frequency is low. On the other hand, the SID (C64) allows for high pitch resolution at the expense of aliasing, but the high (~1 MHz) sample rate reduces the level of the aliasing.

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benski
post May 1 2013, 19:08
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QUOTE (stv014 @ May 1 2013, 13:03) *
QUOTE (benski @ May 1 2013, 17:19) *
Except that the digital function generator necessarily aliases (unless extreme care is taken in the mathematics, which is unlikely).


The generators in early 8-bit machines were often limited to dividing the clock frequency by integer ratios. This avoids aliasing, but the pitch accuracy is not perfect, especially if the clock frequency is low. On the other hand, the SID (C64) allows for high pitch resolution at the expense of aliasing, but the high (~1 MHz) sample rate reduces the level of the aliasing.


A frequency that is an integer divisor of the sample rate still aliases! Just that the aliased components are harmonically related to the signal so it does not sound as bad.

High sample rates do not change the level of aliasing error in the time-domain. This reason for this is because the discontinuity "width" (e.g. +1 to -1 transition in a square wave) is the same regardless of frequency: the width is theoretically infinitely small (in the analog domain). However, high sample rates cause the aliasing to fall below the hearing threshold within the audible frequency band. Which of course is good enough.

Sorry for being pedantic, I frequently see a lot of misinformation on the internet about digital waveform generation and aliasing, so I figured I would point it out here.

This post has been edited by benski: May 1 2013, 19:26
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stv014
post May 1 2013, 19:50
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QUOTE (benski @ May 1 2013, 20:08) *
A frequency that is an integer divisor of the sample rate still aliases! Just that the aliased components are harmonically related to the signal so it does not sound as bad.


In the case of a simple symmetrical square wave (which is what this type of generator is typically used for, by toggling the output every N samples), the aliasing does not produce components that were not already there in the signal, so the effect is basically just filtering at the highest frequency components. Also, since the sample rate is high (100-250 kHz), it does not really make an audible difference.

Edit: since there is actually no real "DAC" with a reconstruction filter, the above mentioned filtering effect does not apply either.

QUOTE
High sample rates do not change the level of aliasing error in the time-domain.


Which is not of much relevance for audibility (and audible aliasing is what matters in the context of the topic being discussed). The level does become lower in the frequency domain, and as RMS level relative to the signal.

This post has been edited by stv014: May 1 2013, 20:12
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saratoga
post May 1 2013, 19:51
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QUOTE (benski @ May 1 2013, 11:19) *
QUOTE (saratoga @ Apr 30 2013, 15:25) *
I don't really see the distinction between a digital function generator clocked off a vco and an analog generator composed of a vco controlled by a digital circuit. Its the same idea described differently.


Except that the digital function generator necessarily aliases (unless extreme care is taken in the mathematics, which is unlikely).


I assumed that by "digital" he meant a device that takes some constant square wave clock and multiplies it by a rational number to generate a tones. IIUC you're think more like a DDS system where there is an actual DAC inline with synthesis.
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