The links he gives at the very end of the video are also useful.
Next time someone pretends the oric (or whatever ym emulation program) plays the ST tunes identical i'll send him to sndhrecord.atari.org for a comparison :p
Btw. Does someone know if there is a site with oric tune recordings ? Having a good reference is always useful !
Oric's 8912 volume scale
-
- Squad Leader
- Posts: 757
- Joined: Sat May 21, 2011 7:21 pm
- Location: Between UK and France
- Contact:
Re: Oric's 8912 volume scale
I have a friend that could explain why emulation need some clever math for giving the correct sound, I haven't seen this video yet, I can ask him to make a simple text to explain why if some of you are interested!Dbug wrote:On the topic, there's some interesting details about sound on Gunstick's presentation: https://www.youtube.com/watch?v=yLDtiTS4JLg
Around the 34th minute there are some Audacity sample output of the three channels, and discussion of the shape on emulators vs real machine.
My Projects: Replic'Oric Project - StratoCumulus Project
- meynaf
- 1st Star Corporal
- Posts: 14
- Joined: Mon Jul 18, 2016 6:37 pm
- Location: Lyon (France)
- Contact:
Re: Oric's 8912 volume scale
I already know why emulation needs some clever math. What i don't know is what this clever math can be. If you friend knows, he's more than welcome to explain !Godzil wrote: I have a friend that could explain why emulation need some clever math for giving the correct sound, I haven't seen this video yet, I can ask him to make a simple text to explain why if some of you are interested!
Re: Oric's 8912 volume scale
I'm probably far too late and/or answering the wrong question, and I'm learning this stuff almost as I type, but as far as I can make out there are two segments of maths involved:meynaf wrote:I already know why emulation needs some clever math. What i don't know is what this clever math can be. If you friend knows, he's more than welcome to explain !Godzil wrote: I have a friend that could explain why emulation need some clever math for giving the correct sound, I haven't seen this video yet, I can ask him to make a simple text to explain why if some of you are interested!
- voltage decay;
- resampling.
The diagrams there are artificial but note how they match the measured waves given in the Youtube video linked earlier. So output voltage is a differential equation, a function of voltage and time since the voltage was set. The AY will hit the voltage it is supposed to, then decay until the next conscious change.Wherever a voltage (output) is artificially held away from zero, there will be leakage and the actual output will decay towards zero at a rate proportional to the offset from zero:
dV
-- = -kV
dt
where k is a constant.
Rampling is much more trite — see any of the windowing techniques, e.g. as per here. It's also not something the original hardware does, it's just how you squeeze what the original hardware does out of your speaker. So there's more leeway.
Who is online
Users browsing this forum: No registered users and 1 guest