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Author Topic: PS1 Pitch Modulation  (Read 633 times)

PresidentLeever

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PS1 Pitch Modulation
« on: October 22, 2020, 09:17:18 am »
So I recently learned that this is a thing on the PS1 (though some documentation refers to it as FM). I assume that it works like on SNES. Does anyone know of any examples of this? For music or sfx.

Here is the effect used on SNES:
https://www.youtube.com/watch?v=06zXa85tlU0

October 22, 2020, 01:03:16 pm - (Auto Merged - Double Posts are not allowed before 7 days.)
"FF7 used PMod extensively. Mostly for sound effects but sometimes for ambient sound. the song "J-E-N-O-V-A" uses pitch mod in its Horn Pad lead sample too if I recall correctly"
Youtube comment about pitch mod on ps1, an uploader of a video on the snes ditto responded.

« Last Edit: October 22, 2020, 01:03:16 pm by PresidentLeever »
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Bregalad

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Re: PS1 Pitch Modulation
« Reply #1 on: October 23, 2020, 12:12:35 pm »
It definitely works like on SNES. Both sound chips were made by Sony. For both consoles, Squaresoft is the main user of the feature, and mostly for sound effects.

Even though there is parallels between both effects, it's abusive to call pitch modulation FM because typical FM is more than that, and besides pitch modulation is more than FM in that it can use something other than sine waves.

It's not just FF7 but pretty much all Squaresoft game where the effect is widely used for sound effects, including FF8, FF9, Chocobo's Dungeon, Legend of Mana, Chrono Cross, Threads of Fate, and possibly other games.

I don't have any example where this is used for music, but the latter games uses dynamic-channel allocation so this wouldn't cope well with pitch modulation. Thus if this is used for music anywhere it would most likely be in either FF7, Front Mission 2 or Parasite Eve, all latter games uses dynamic channel allocation.

PresidentLeever

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Re: PS1 Pitch Modulation
« Reply #2 on: October 23, 2020, 12:49:06 pm »
When you say something other than sine waves, what do you mean? From what I read (also saw on a YT video about the SNES effect) it uses an lfo on an empty channel to affect the sampled soundwave on the modulated channel?

Also there are sine wave only-based FM chips, but there are also FM chips with other default soundwaves such as saw, camel, etc. OPL3 is one IIRC.

Dynamic channel allocation, you mean that the music switches channels for when sound effects play? Or just periodically to avoid getting cut off by sfx?
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Bregalad

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Re: PS1 Pitch Modulation
« Reply #3 on: October 23, 2020, 03:00:36 pm »
When you say something other than sine waves, what do you mean?
I mean BRR or VAG samples (for respectively SNES and PS1).

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From what I read (also saw on a YT video about the SNES effect) it uses an lfo on an empty channel to affect the sampled soundwave on the modulated channel?
Not necessairly an empty channel ! Channel N will affect pitch of channel N+1. And it's not LFO since the modulator will typically be in hearable range and as thus distort the affected channel and not just oscillate it's pitch (which is what LFO means).

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Also there are sine wave only-based FM chips, but there are also FM chips with other default soundwaves such as saw, camel, etc. OPL3 is one IIRC.
Sure, but the whole point of FM is to get rid of samples and synthesise complex sounds using math instead. Pitch modulations uses a sample to distort another sample, the goal is to make an effect on a sample. However it can do something a bit similar to FM in some cases but is much less limited as the pitch of the modulator is not necessarly correlated with the pitch of the modulated wave.

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Dynamic channel allocation, you mean that the music switches channels for when sound effects play? Or just periodically to avoid getting cut off by sfx?
It means that any musical track can be played with any hardware sound channel. As thus a hardwarare sound channel played in isolation will seem to play random notes from various instruments playing the song. This is typically used to allow a note to release while another is attacked, very useful for harp sounds for example. This is largely incompatible with pitch modultion which needs channel N to affect channel N+1; of course there might be workarounds.

Squaresoft's later games uses dynamic channel allocation for music but not for sound effects.

PresidentLeever

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Re: PS1 Pitch Modulation
« Reply #4 on: October 23, 2020, 05:40:00 pm »
Ok so the modulating channel does use a sample too.

The low frequency oscillator can also be used for vibrato or tremolo on MD for example, for a timbre changing effect on certain instruments, or for a different timbre-changing effect on the YM2151 chip (good for wind sfx or more complex snare drums).

Yeah it would be weird if they couldn't use that (either to make strings ring out or what I mentioned, which was done in MD and SNES games) while some voices were set to certain channels to do the PM effect, or just to make sure they're always playing a musical harmony.

Thanks for the info.
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Bregalad

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Re: PS1 Pitch Modulation
« Reply #5 on: October 25, 2020, 04:53:30 am »
Ok so the modulating channel does use a sample too.
White noise can also be used.
The modulating channel can also be silenced by setting the volume to 0 but still have effect on channel N+1 (I forgot to mention that in my previous reply)

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The low frequency oscillator can also be used for vibrato or tremolo on MD for example, for a timbre changing effect on certain instruments, or for a different timbre-changing effect on the YM2151 chip (good for wind sfx or more complex snare drums).
There's no hardware equivalent on SNES or PS1 you'd have to change the volume or pitch by software.

PresidentLeever

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Re: PS1 Pitch Modulation
« Reply #6 on: October 25, 2020, 09:29:04 am »
Ok, thanks for the info.

I know I'm just saying how it works on those FM chips.
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