Sound pitch

GregBUG

it's possible to implement in sdk the option to control sound picth?

yes i can use different file for different tone (and i gidhelix i use this system) but... is resource consuming...

like: Sound:play(startTime, loops, pitch)

atilim

Currently not possible. Using different sounds is the only way.

GregBUG

ah ok.

thanks anyway.

keszegh

I noticed that pitching is now possible. But that changes the length of the sound too. Is there a way to change pitch while the length of the sound remains the same?
thanks

hgy29

Changing sound pitch is actually playing the sound faster (higher overall frequencies) or slower (lower frequencies), so indeed it changes the sound effective duration. Don't know how it could be done while preserving sound length. Perhaps by doing a fourrier transform, shifting frequencies, and reconstructing back the signal, but that would be highly cpu intensive.

keszegh

so in all music apps like simple piano apps etc. they always have all the sound files for every single key? it gets quite resource-wasting even if you have only one instrument.
at least e.g. caustic is not doing that and it's pretty fast.

keszegh

what i need apparently is changing tempo or time-stretch.
this library can do that, but i wanted to avoid writing plugins, as it always takes too much time for me:
http://www.surina.net/soundtouch/

keszegh

anybody willing to make a plugin for the cross-platform library soundtouch?

i know it's selfish to ask something like that but it seems to be fairly easy, in the download there is a sample java project etc.
http://www.surina.net/soundtouch/download.html
so i guess it is not so hard for those with more practice. with some luck somebody else might find useful to have this library available.

hgy29

As far as I know, digital pianos do exactly what gideros does: playing the sample tone at different frequency depending on the key you press, eventually looping over while the key is pressed. This is also the technique used in amiga/atari soundtrackers (the .mod file format and derivatives).
If you intend to make a piano like app, fire your sounds independantly each time a note needs to be played, depending on your tempo, and adjust the sound pitch to match the actual note, i.e. if your note is a 'C' and you want to play a 'C#', adjust the pitch to ~1.0595.

keszegh

@hgy29, i see, so the playback time also changes but it is not noticeable (btw, a real piano does the same?). perhaps i changed the pitches too radically then. can you link me a table with the notes corresponding to pitches (if my note is e.g. a 'C')?

Holonist

Sorry if I'm not really helpful here, but it definitely is possible to do this with a computer.

http://en.m.wikipedia.org/wiki/Audio_time-scale/pitch_modification

hgy29

Sorry @keszegh I don't have a table. When I do it, I use the fact that shifting by a full octave is a matter of doubling or dividing frequency by 2, and then since there are 12 half tones in standard note scales (C,C#,D,D#,E,F,F#,G,G#,A,A#,B for C major) I use a factor of 2^(1/12) to shift one halftone up.
Musicians would say that notes aren't actually equally spread in the octave, but it had worked not too bad for my purposes so far

hgy29

As a one point reference, I use the standard A4=440Hz (http://en.wikipedia.org/wiki/A440_(pitch_standard))

hgy29

This may be useful too:
http://en.wikipedia.org/wiki/Piano_key_frequencies

keszegh

thanks for all the info, i will do something like these.