YM2413 - MSX-MUSIC write timing.

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By Huey

Prophet (2694)

Huey's picture

11-04-2014, 10:15

Is there any timing or order needed when writing the YM registers?

I am experiencing some unexpected behaviour (pop's) when writing new (hw)voices and playing notes at the same time.

I am obeying the standard delay between adress (12 cycles) and data (84 cycles) writes. Just was wondering if there are other restrictions when writing (hw)voices.

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By WORP3

Paladin (864)

WORP3's picture

11-04-2014, 12:40

As you are mentioning, you only need to obey the standard delay between data and address writes.

It's probably a good idea to turn of the note/channel before changing it's voice.

By Huey

Prophet (2694)

Huey's picture

11-04-2014, 14:02

WORP3 wrote:

It's probably a good idea to turn of the note/channel before changing it's voice.

The issue is that it is sometimes wanted to NOT turn of the note so that is not an option. Sad
This to support the voice-linking trick to create custom voices with only HW voices.

By syn

Prophet (2113)

syn's picture

11-04-2014, 14:27

Arent the pops just caused by the change of sound itself and not coding related? (like if you just randomly put 2 wave-files together in an editor you are bound to hear some pop at the transition point). Sorry I don't know the exact terminology for this but if you don't understand what I mean I can just try again Wink

By Huey

Prophet (2694)

Huey's picture

11-04-2014, 14:50

Maybe. But I am using Moonblaster as a reference (using the audition in the voice selection menu) and there is no 'pop'.

Anyway the update order I use is:
- SW voice registers (if any)
- Volume+voice register update
- Tone register updates
- Drum register updates.

By Manuel

Ascended (19270)

Manuel's picture

11-04-2014, 15:02

So, what does MB do? (The code is available...)

By sd_snatcher

Prophet (3642)

sd_snatcher's picture

12-04-2014, 05:23

What kind of 'pop' are you hearing? Can you post an example?

By JohnHassink

Ambassador (5655)

JohnHassink's picture

12-04-2014, 06:12

sd_snatcher wrote:

What kind of 'pop' are you hearing? Can you post an example?

https://www.youtube.com/watch?v=1cwGZNclTf8

By Huey

Prophet (2694)

Huey's picture

12-04-2014, 10:16

Manuel wrote:

So, what does MB do? (The code is available...)

Well MB does things WAY different. It's not really comparable.

By WORP3

Paladin (864)

WORP3's picture

12-04-2014, 10:19

That's not a normal pop, sounds more like a rythm instrument got hit, are you sure that you are not writing to register 15 ?
I've you are having a MIDI-PAC lying around you could use it to see what is producing this sound.

By Huey

Prophet (2694)

Huey's picture

12-04-2014, 23:14

No it's not a rythm instrument.

Ik think there 2 two different case;
- a 'pop' which seem to occur at volume drop.
- a 'noise' which occurs at voice change.

[EDIT]Affirmative. Alternating the volume between 1 and 15 makes a 'pop'. Syn was right.
[EDIT2]Check. Moonblaster has same pops when alternating volumes.

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