Gapless switching and CPU

T

Thenewexhibit

Power User
How much CPU does one have to stay under to have gapless switching? I know it's said to generally stay below 80%. If you're close to 80%, does it still work, or do you need to be much lower?

I just wonder because I feel like there was a time gapless worked better, but then again, I was mostly using one amp and changing drive channels. Now I'm using different amps, but I feel like sometimes gapless is working, and other times it sounds similar to gapless being off. This is with the editor not plugged in. I'm including the preset, but you'll have to import a cab into it. If you have the York M65 212, it's mix 5.

Curious if you're getting gapless between scene changes. If you hold down one of the scene buttons, it should take you to the Per Preset page (where I live most of the time) where you can change amp channels. I feel like that's where I notice it too. But maybe I'm just buggin'. CPU seems to be around 72%. Also, I'm on firmware 8.02 public beta 3, but I feel like I've noticed this with official releases as of lately too.
 

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One of my presets is around 72% and I’m changing scenes with different amp blocks seamlessly. I can’t seem to get a seamless transition from preset to preset. I’m getting a delay between the time I press the footswitch to the time the sound changes . No gap or loss of sound but I have to compensate by switching early to land on the next sound at the right time. I’ve been left wondering if gapless and seamless are considered to be 2 different things, regarding the claim of gapless in the FM9.
 
Does the switch you're using to change presets have a hold function? If so, it won't take effect immediately, because it has to wait to figure out if it's a hold action.
 
Dave Merrill said:
Does the switch you're using to change presets have a hold function? If so, it won't take effect immediately, because it has to wait to figure out if it's a hold action.
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No, checked and double checked, plus sent my presets to support to confirm. But this is exactly the behaviour I’m getting. I was over the moon happy when I thought I could switch from preset to preset. Now I’m back to paring down and removing blocks so I can switch scene to scene in a single preset.
 
I know stupid question
But have you checked to see gaplesss switching in settings is switched to All and it’s did not get turned off by one of the resets or updates
 
Do you have a lot of modifiers set up in that preset by chance? Modifiers and controllers can sometimes cause spikes in CPU when you change things.
 
Darrin66 said:
One of my presets is around 72% and I’m changing scenes with different amp blocks seamlessly. I can’t seem to get a seamless transition from preset to preset. I’m getting a delay between the time I press the footswitch to the time the sound changes . No gap or loss of sound but I have to compensate by switching early to land on the next sound at the right time. I’ve been left wondering if gapless and seamless are considered to be 2 different things, regarding the claim of gapless in the FM9.
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Unless the delay seems longer between those presets than others, that's expected. The gapless switching system works by playing back a slightly delayed signal of the last sound while the new preset is loaded, not doing anything to make the new preset output sound any faster. So you do need to switch somewhere around 50-100 ms early to hear the new preset exactly on your next note/chord.
 
That’s what I thought. That’s why I said it’s gapless, but not seamless. At least scene to scene is seamless, better than nothing.
 
Darrin66 said:
That’s what I thought. That’s why I said it’s gapless, but not seamless. At least scene to scene is seamless, better than nothing.
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Have you tried the preset I posted? I’d like to see if the scenes are gapless for you. Maybe I’m misunderstanding gapless a bit, but I feel like it sometimes sounds the same as if gapless was turned off. I only have 4 scenes I think, but I’d be curious your thoughts and experience.
 
Dave Merrill said:
Does the switch you're using to change presets have a hold function? If so, it won't take effect immediately, because it has to wait to figure out if it's a hold action.
Click to expand...
Would this have an effect on scene switching too? The preset I posted above has a Layout Link from Preset to Scenes, but, every Scene button has a hold function to take me to my Per Preset “pedalboard” layout. Is that potentially causing issues with gapless for me?

I notice it when changing amp channels too in the Per Preset (pedalboard) layout, where the top right button changes the amp channel or hold does a solo boost, or the button to the left of top right changes the amp channel or hold changes it to another amp channel.
 
Scene changes are only completely seamless if you're not changing block channels via scenes.

Hold functions will not affect gapless switching. The switch will simply fire on release (up stroke) instead of tap (down stroke) if a Hold function is present.
 
mr_fender said:
Scene changes are only completely seamless if you're not changing block channels via scenes.

Hold functions will not affect gapless switching. The switch will simply fire on release (up stroke) instead of tap (down stroke) if a Hold function is present.
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Oh, interesting! I thought that was the whole point of gapless switching in that changing scenes with different blocks was seamless? Am I misunderstanding something?
 
"Seamless" is kind of vague because gaplessly switching between two sounds could be thought of as creating a seam (boundary of 2 clearly different things) between the two sounds.

If a block which introduces a gap in its output when changing channels changes channels, the 'gapless' delay playback is triggered (if gapless changes are enabled). Not every block does this, and the ones that don't don't trigger the gapless mechanism.
 
It's seamless only if those blocks aren't changing channels at the same time. Anytime the channel changes, the block is reloaded with the new model's algorithm. That's where the original gap came from. That load takes a split second so the audio stream can't continue seamlessly unless something else fills that gap (i.e. gapless switching). The same thing happens on preset change, except all of the blocks are loading.

If you're switching between blocks that aren't changing channels then the audio stream switches from one block's output directly to the other and it is seamless (in reality I believe there is very fast crossfade to avoid pops and such but you hear no audible gap in the audio stream). Same is true if you are bypassing or enabling a block. It's switching between the block's bypassed and processed output signals. That too can be seamless.
 
Thenewexhibit said:
Have you tried the preset I posted? I’d like to see if the scenes are gapless for you. Maybe I’m misunderstanding gapless a bit, but I feel like it sometimes sounds the same as if gapless was turned off. I only have 4 scenes I think, but I’d be curious your thoughts and experience.
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No, I won’t be back home for a bit. I’ll try it next week and let you know.
 
I don't think there are any preconditions on gapless switching. I would say it like this: the extrapolation mechanism that covers up the gap is only triggered when it's needed.

I'll also say for anybody for whom a nice smooth transition is important: you might get better results if you use a single preset with a mix block to do a cross fade.
 
md1234 said:
I haven't heard before of those extra preconditions for gapless switching. Afaik you should be able to switch gapless between presets without paying attention to what blocks and channels you use.
When gapless switching was introduced: Thread 'FM9 Firmware Version 6.00 public beta (1)' https://forum.fractalaudio.com/threads/fm9-firmware-version-6-00-public-beta-1.201261/
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Also thought it works like this but it doesn‘t. I think some guidelines in the manual would help here. Especially switching amp channels brings out that gap in my case
 
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