69
votes
Accepted
How did musicians acquire samples for tracker music (MOD, S3M, XM and the like)?
I composed a small number of Amiga tracker modules at around the turn of the 1990s, one of which even enjoyed some popularity. These songs were made, first and foremost, for my personal amusement — ...
- 2,012
60
votes
Accepted
Why do programmable sound generators like SID include a noise generator?
One basic distinction in acoustics is the one between sounds that oscillate with a pattern that is repeated over time and sounds that are chaotic in nature, and show no repetitive pattern.
Sounds ...
- 925
34
votes
Accepted
Why does MP3 audio decoding overwhelm retro CPU's?
What's lacking is mostly raw number-crunching ability. The MP3 format is relatively lightweight, and can be implemented using only fixed-point math (no FPU required), but it still takes a fair amount ...
- 8,550
32
votes
How did musicians acquire samples for tracker music (MOD, S3M, XM and the like)?
The four main ways were:
you knew someone with the sampling card or sampler (many of samplers had the capability to sample sound in CD quality and save it to floppy disk).
you bought some kind of &...
- 5,487
27
votes
Accepted
How was digital sound playback achieved on the Commodore 64?
No hardware revisions are necessary. The digitization playback is achieved by bit-banging the volume register of the SID chip to simulate a digital playback device. Essentially, the SID can be used ...
- 1,053
23
votes
Why do programmable sound generators like SID include a noise generator?
Many PSG's (Programmable Sound Generators) at the time (such as the popular AY-3-8910) were made for applications like doorbells, kiosk machines, etc. And, of course, arcade machines and computers.
...
- 8,441
20
votes
How did musicians acquire samples for tracker music (MOD, S3M, XM and the like)?
Did they really plug a synthesizer's audio output into a line input of a sound card and digitize the analog sound? But were audio cards of the early 90s at all capable of capturing analog audio at ...
- 10.7k
20
votes
Accepted
How was polyphony achieved on systems with only one audio channel?
I know of two ways of achieving polyphony in system with 1-bit audio systems:
The simple way: time-multiplex two or more frequencies. For example, if you want the system to produce a mix of two tones,...
- 18.6k
13
votes
How was polyphony achieved on systems with only one audio channel?
Just wanted to add a historical note (as this is retro computing). All Manchester computers from the earliest days generated sound by attaching a speaker to a single bit of a register (usually the ...
12
votes
How was polyphony achieved on systems with only one audio channel?
And these systems had not just a single audio channel, but a single-bit audio channel. There are no doubt many techniques, but a simple approach is to rapidly interleave the output of two or more ...
- 7,656
12
votes
Why does MP3 audio decoding overwhelm retro CPU's?
Mp3 is primarily a lossy compression format for audio. It must be decompressed, and the process needs a lot of CPU time (as for retro computers.)
Modern computers both have speeds good two orders of ...
- 7,075
11
votes
Why do programmable sound generators like SID include a noise generator?
In some systems, the noise channel could be used as a cheap source of pseudo-randomness, such as in the Atari POKEY (read address 0A). Here, cheap means that the CPU can do other things whilst the ...
- 18.5k
9
votes
How was digital sound playback achieved on the Commodore 64?
The best audio quality was obtained with pulse width modulation using the square wave voice. The oscillator was set to 0 and the pulse width was set by flipping the pulse width from 0 to maximum.
...
- 938
9
votes
Why does MP3 audio decoding overwhelm retro CPU's?
Like others already answered: old CPUs does not have enough MIPS, and/or they are lacking instructions that would helped in MP3 decoding algorithm (remember that MP3 is standardized in 1995.).
Nice ...
- 121
8
votes
Why does MP3 audio decoding overwhelm retro CPU's?
Early 68k processors implemented a multi-cycle multiply instruction (70 cycles per MULx), so the inverse MDCT would likely be the limiting factor in terms of raw CPU time.
- 8,125
8
votes
Is it possible to use a TI-99/4A cassette cable with Digital Audio devices?
Any cassette tape system which can utilize a standard cassette tape recorder can be plugged into any audio device, with sufficient quality, and will work.
You can record saved files with any audio ...
- 4,643
6
votes
How was digital sound playback achieved on the Commodore 64?
There were also some more recent creative alternatives taking advantage of filters and undocumented test bits as well. Check out the Cubase64 demo by Mahoney: http://www.livet.se/mahoney/cubase64 ...
- 77
6
votes
Accepted
ES688 AudioDrive 4-bit proprietary codec: Any way to decode?
With hints taken from this answer, your 4-bit ESPCM format is not that difficult to be decoded correctly. Your python decoder does a lot of things right. Out of 20 nibbles, only 19 nibbles contain ...
- 7,636
6
votes
ES688 AudioDrive 4-bit proprietary codec: Any way to decode?
I also created a lot of files using ESPCM compression in the 1990s. The ones I have were saved with an extension of AUD, but internally they are .wav files. ESPCM compression takes each sample and ...
6
votes
Accepted
ZX Spectrum: What is the "T" state value, with reference to sound?
In the Spectrum lexicon, a t-state is just a "time state" — a single cycle of the ~3.5Mhz clock.
For implied evidence of that, see e.g. this document of 128K ZX Spectrum Technical Information, which ...
- 36k
6
votes
Accepted
What bit depth and sampling frequency could the BBC micro play back sampled sounds?
Here's how the specific routine you posted works. It appears to be using the "4-bit linear" method mentioned on this page. The resulting samples are not truly linear, but it's easy to ...
- 16.7k
5
votes
How did musicians acquire samples for tracker music (MOD, S3M, XM and the like)?
But were audio cards of the early 90s at all capable of capturing analog audio at reasonable quality?
Kind of yes, but...
There is relatively little "information" in audio above 10kHz, and ...
- 1,994
5
votes
How to write directly to the Commodore 64 (or similar) DAC
DAC is a digital analog converter. There is no such periphery on C64, but the closest to it is the SID chip, for playing sound.
Also the SID chip was not designed for that. It can play ADSR (attack-...
- 1,749
5
votes
Why do programmable sound generators like SID include a noise generator?
There are many acoustic events - drum beats, steps, explosions, breath, abrasion, clicking... that are based on a lot of harmonically unrelated frequencies in relatively irregular patterns. Which is ...
- 5,660
5
votes
What bit depth and sampling frequency could the BBC micro play back sampled sounds?
The BBC Micro uses an SN76489, which provides three tone channels each with sixteen volume levels. For speech playback the standard approach is to set the channels in use to a very high frequency and ...
- 36k
5
votes
How to wrap 32 bits drivers on 64 bits based Windows or even vxd?
The difficulty seems to be that Windows Driver Model device drivers aren't stand-alone chunks of code. They consist of two layers: the bus driver, PCI in this example, which is provided with Windows, ...
- 12.4k
4
votes
How was digital sound playback achieved on the Commodore 64?
It seems that all the earlier posts only give partial answers to the question. The below extract of the relevant parts of my doc
https://bitbucket.org/wothke/websid/src/master/docs/digi-samples.txt
...
- 41
4
votes
ES688 AudioDrive 4-bit proprietary codec: Any way to decode?
While preparing a sample, I did the following:
Silenced error in Python wave module (sampwidth is arbitrary - should be 0.5, but it's hardly supported):
if wFormatTag == WAVE_FORMAT_PCM:
try:
...
- 221
3
votes
How did musicians acquire samples for tracker music (MOD, S3M, XM and the like)?
Mostly I stole them from other people's mods!
For original samples (like all the vocal stuff in Online Pizza), I asked my dad to buy a cheap microphone, then plugged it into the mic port of our PC's ...
- 161
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