Sound speed and pitch in as3

[raresn]

Hey guys! We have a new challenge ahead :)
We need to slow down/speed up a sound without changing it's pitch.
Does someone know how to do that? Or has any libraries/anes that might help?
We've been searching like crazy and nothing....

Thank you!

[VCone]

You could try:

http://iq12.com/old_blog/2009/08/25/real-time-pitch-shifting/

PS: Better to ask coding question on StackOverflow under the AS3 tag. Then showcase your result on this Github.

[raresn]

Good tip with StackOverflow - thanks.
And thank you for the project link. After running it it doesn't really do what i expected it to do - speed up the sound without changing the pitch.

[VCone]

My bad. After re-reading my own answer on S.O site I realise misread "whilst adjusting pitch" as saying "whilst keeping pitch". Don't ask how I missed it when it's there in bold letters for extra noticing.

PS: Is the code usable as a starting point? If yes maybe read up on the logic of keeping pitch then ask something on StackOverflow for further advice if stuck. (note: You need to have some code attempt before they can help to fix anything. Otherwise they'll downvote you instead).

[ajwfrost]

Presumably you'd need to combine the pitch-shifting with re-sampling? Or to put it another way: if you want to speed up a sound then you need to either play it back at a higher rate, or resample it to have fewer samples so that it plays more quickly. But doing that would affect the pitch; so then you can use that algorithm to shift the pitch back down again.

Don't know if there's any library to do both at once. I would suggest that a C (or similar) library could be used for this and then turned into a SWC library with the help of crossbridge - that's likely to be more efficient than trying to cross-compile/transcribe it manually.

[raresn]

@VCone - no worries. Yes i wrote the part where i can speed the sound up, but the pitch is super bad.
@ajwfrost - the last part with a C library is the conclusion i ended up with after talking with chatGPT till 3 am last night :))

[teotigraphix]

Rubber Band (Pitch/Time stretch algorithms) could easily be made into an ANE for Android/Windows etc.

https://breakfastquay.com/rubberband/why.html

[raresn]

This actually sounds very cool! If it's just C++ maybe i can turn it into a SWC with Crossbridge like ajwfrost suggested?

[teotigraphix]

Actually, I don't have that answer. I am knee deep in my own audio stuff atm but I was thinking about that down the road in AS3. :)

With an ANE you just need some AS3 API to access the very simple one class C++ API Rubber Band uses.

Caustic, an Android app uses this library for time/ptich stretching since around 2015 on Mac/Win/iOS/Android and it works well. Real time wasn't tried back then but it could probably work on most newer devices now.

[2jfw]

Not sure if this meets all your requirements but have a look at:
https://github.com/Adolio/Syrinx-Sound-Manager

I think its the most complete and up-to-date as3 project regarding sounds and effects etc..

[raresn]

Just might be it! I will try it and let you know! Thanks!

[raresn]

@2jfw
Here is what i found: I am trying to change the pitch independent from the speed.
Meaning, i am trying to speed up a sound but adjust the pitch so it doesn't sound like a cartoon :)
The example there, increases the speed, therefore increasing the pitch.