Search found 303 matches

by tryphon
Thu May 02, 2019 4:40 pm
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

Your formula is an approximation of mine (with a division by 3 rather than 6, unless I missed something, like efficace value or something like that, which is quite possible).

10^(db/10) = (2^1/log(2))^(db/10) = 2^(db/(10log(2))

and 10log(2) = 3.0103...

Unless the true formula is 10^(db/20) ?
by tryphon
Thu May 02, 2019 4:03 pm
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

Another question : when I translate decibel coordinates to linear ones (whatever they are), I did : attenuation_in_dB = 10*log(I_max/I) where I is my linear amplitude and I_max the maximum amplitude (since I use 16 bits integer, I_max = 32767), which led to : I = I_max*10^(-attenuation_in_dB/10) = I...
by tryphon
Wed May 01, 2019 9:50 am
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

Stupid me. Of course it makes sense ! Thanks :)
by tryphon
Wed May 01, 2019 8:35 am
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

Something I can't find in the above thread (but it may have overlooked it) : In the Envelop Generator, how is the attenuation initialized in the attack phase ? is it 1023 ? if so it means that if TL isn't 0 dB (maximal volume), then operator will remain silent for some time ? or is it initialized at...
by tryphon
Mon Apr 29, 2019 8:53 am
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

THANK YOU ! I knew this thread, but since it's very technical (and, as I said before, I have absolutely no knowledge in music nor FM synthesis - and generally speaking very few when it comes to hardware), I progressed slowly in reading it and hadn't come to this post. I have to digest all the inform...
by tryphon
Sun Apr 28, 2019 9:37 pm
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

Attack is done with reverse logarithmic slope while other things are done with normal logarithmic slopes. Thanks, it makes perfect sense ! The way envelopes progress is tied to couple LUTs, after every certain amount of samples according to one LUT and ADSR settings, a value from another LUT is add...
by tryphon
Sat Apr 27, 2019 8:32 pm
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

I tried another approach : I created a very simple VGM file, only one note, with variable AR (1 to 8) and TL (0 or 64), played it in various decoders (winamp with vgm reader plugin, Gens) and looked the resulting wav file in Audacity. Some strange things : 1) the results are not exactly the same (ev...
by tryphon
Thu Apr 25, 2019 7:01 am
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

The limit for AR is 31 tho. It's also instantaneous in that case anyway (since it's the maximum value). This isn't the case that cause me headaches :mrgreen: Also AR/DR/SR/RR all represent slopes (i.e. the angles). Angles, or derivates (i.e. tangent of angles) ? That's more the meaning of "rate" fo...
by tryphon
Thu Apr 25, 2019 6:56 am
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

AR is the attack rate, telling you at which speed we raise the Total Level (TL). 63 is a special value so envelop immediately reach the Total Level. The best way to find those information is to analyze sources of YM2612 emulator. I looked into an old (and quite ugly) version of MAME driver (from a ...
by tryphon
Wed Apr 24, 2019 9:49 am
Forum: Exodus
Topic: Load roms externally?
Replies: 6
Views: 1043

Re: Load roms externally?

A simple key-shortcut to load the last loaded ROM would be nice ;)
by tryphon
Tue Apr 23, 2019 10:53 pm
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

Nope, there's something fundamental I missed. I don't understand how to determine the delay between two update of the envelope generator. For example, if AR = 63 (Attack Rate), how long does it take to reach the maximum amplitude ? I don't even understant if AR is supposed to be a delay (in which un...
by tryphon
Tue Apr 23, 2019 5:19 pm
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

1) Ok, seems a misconception of the word "tone" here. They indeed are half-tones (or semi-tones). 2, 3) Thanks for clarifying. 4) Thanks. I've just discovered the translation of the japanese manual posted by Nemesis years ago, it explained where these figures came from. I'm looking into it for answe...
by tryphon
Tue Apr 23, 2019 9:25 am
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

And another one : Concerning frequency, the document at smspower linked above says a typical 12 tones sequence is : Low High 617 653 692 733 777 823 872 924 979 1037 1099 1164 635 372 392 755 800 847 898 951 1008 1131 1199 (36) (39) (41) (44) (46) (49) (52) (55) (58) (62) (70) That leads to several ...
by tryphon
Tue Apr 23, 2019 7:04 am
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Re: Some beginner questions concerning YM2612

Not much success, but I have more questions 8) Concerning volume envelope, what are the resolution of both time and amplitude ? For the 1st part of the envelope, I understand that I must "add" AR to the amplitude, but how often ? Also, I read that one unit in AR was equivalent to a gain of 0.75 dB, ...
by tryphon
Sun Apr 21, 2019 8:43 pm
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 3259

Some beginner questions concerning YM2612

Sorry for the naive questions, but I'm totally new to these things... Since it's a technical question about something I don't master, I'll ask in English and in French, in case my English would be a little broken. Also, if your French is better than your English, please answer in French, it'll be ea...