Timestretching/Pitchshifting

[d.healey]

@Christoph-Hart Was it RubberBand 2 or 3 that you tried?

[Christoph Hart]

@d-healey Both. Rubberband v2 sounds completely off and Rubberband 3 sounds about as good as signalsmith (on some signal's it's better on some worse), but has 3x the CPU usage plus I couldn't get it to work correctly with the start of a sample (the API works a bit different so I would have to account for that).

There are a lot of parameters you can tweak in Rubberband so I might have just used the wrong ones, but I just wanted to slap it in and compare it to signalsmith and for my taste signalsmith is the clear winner here.

[johnmike]

so I have multiple drum loops loaded across multiple keys...Stretching works fine when I play a single key...but when I play multiple keys at the same time it plays back the loops at different BPMS..one key seems to hold the stretched tempo while the other is playing back at the original BPM that the loop was recorded at...

[johnmike]

as an addendum to the previous...seems as if the loops are the same bpm(originally before bringing in) then they play just fine when played together...but if they are different tempos(originally) they won't play back at the temposynced BPM....hopefully this makes sense....is there something I'm missing? or do all the loops I add in need to be at the same BPM for them to work together?

[Lindon]

@johnmike said in Timestretching/Pitchshifting:

as an addendum to the previous...seems as if the loops are the same bpm(originally before bringing in) then they play just fine when played together...but if they are different tempos(originally) they won't play back at the temposynced BPM....hopefully this makes sense....is there something I'm missing? or do all the loops I add in need to be at the same BPM for them to work together?

So my understanding is that the time/pitch stretching is applied to the sampler - and it is applied as a ratio - so yes if you want to play multiple loops together - everything in the sampler needs t start out at the same tempo - or you can set up sample maps with a single loop in it - and then use multiple samplers..

[johnmike]

@Lindon Gotcha...that's what started to make sense...not a problem...that means I just need to time stretch all the stuff that I want to time stretch into the same tempo lol...I'll mess about with that!

[d.healey]

@johnmike What about using multiple samplers, does that work?

[johnmike]

@d-healey I’m sure that would work…but for what I’m trying to do I’d need 88 samplers lol(a sampler for each loop on each key)…it would probably be way more efficient and less time consuming for me to just make everything a uniform BPM and then put them in one sampler…

[Christoph Hart]

no, the idea is that the tempo_sync mode will sync each sample to the BPM regardless of its source BPM, but this mode isn't working correctly yet. I'm totally undecided how to address the issue of detecting the bar length and getting the right multiplier so if anyone has ideas how to do this, let me know.

[johnmike]

@Christoph-Hart ahh gotcha…yea that would work…but as it stands this is still way ahead of where we were! I’ve been waiting for this!

[Lindon]

@Christoph-Hart said in Timestretching/Pitchshifting:

no, the idea is that the tempo_sync mode will sync each sample to the BPM regardless of its source BPM, but this mode isn't working correctly yet. I'm totally undecided how to address the issue of detecting the bar length and getting the right multiplier so if anyone has ideas how to do this, let me know.

Yep - you could do it like Kontakt(yew did I just say that?) - have a scripted call that lets the programmer/developer tell the process exactly how long in bars/beats each loop is and what tempo it is

[Christoph Hart]

@Lindon Why not just make a new sample property called NumQuarters that will be used to calculate the original BPM of the sample?

This will override the NumQuarters that you can set with the timestretch properties, which will override the default fallback behaviour of guessing how fast it is using the current tempo.

[Lindon]

@Christoph-Hart said in Timestretching/Pitchshifting:

@Lindon Why not just make a new sample property called NumQuarters that will be used to calculate the original BPM of the sample?

This will override the NumQuarters that you can set with the timestretch properties, which will override the default fallback behaviour of guessing how fast it is using the current tempo.

yep that works too...the only (slight) wrinkle is dealing with odd time signatures.. 6/8 for example - but even then all the developer need know is the number of bars and they can * 4 to get NumQuarters

[Christoph Hart]

@Lindon said in Timestretching/Pitchshifting:

6/8

=> 3 Quarters.

[Christoph Hart]

Alright, I've implemented the NumQuarters property. If this is non-zero, it will use the length of the sample with this information to calculate the source BPM, which should let you use different BPM values for every sample.

I've also fixed something in the engine and now it should play multiple voices with the correct time ratio in sync mode.

[d.healey]

@Christoph-Hart Nice!

[modularsamples]

In sampler it seems monophonic samples aren't summed when the stretch modes are enabled, everything comes out the left speaker.

[BWSounds]

@Christoph-Hart said in Timestretching/Pitchshifting:

I'm thinking about adding this to the AudioLooper too (it's pretty obvious that this might be useful there). Is anybody using the tempo synced mode in a real project? It previously changed the pitch to match the tempo but I guess that is so totally useless that I can replace the functionality and enable timestretching by default when the tempo syncing is activated.

is this a thing yet?
For some reason I cant build from the "feature_timestretch" commits...i'll figure out why on my own...
just asking

[Lindon]

@Christoph-Hart said in Timestretching/Pitchshifting:

Alright, I've implemented the NumQuarters property. If this is non-zero, it will use the length of the sample with this information to calculate the source BPM, which should let you use different BPM values for every sample.

I've also fixed something in the engine and now it should play multiple voices with the correct time ratio in sync mode.

Nice, but I still worry about doing this calc for those 13/7 time signatures, and you know there will be some...

[ulrik]

@Lindon said in Timestretching/Pitchshifting:

Nice, but I still worry about doing this calc for those 13/7 time signatures, and you know there will be some...

Hehe...