Phase Inverssion -Sound Forge - PC - MAGIX Community Forums Archive

Subject:Phase Inverssion Posted by: Djpm05 Date:11/9/2003 3:55:39 PM I need to know if this is possible, and would work: in techno (especially) the sounds are all quantinized, and many of them are loops, and therefore easy to change. but many songs have one beat, and then add another, but never have just the other beat going. when trying to remix a song, being able to single out a specific sample is invaluable, and I found a way to do it (in theory) but I have no idea of a program that will do it, and if it would work. He're how i've proposed to do it. the samples are: A = Bass beat B = hi hat the samples you have are: A AB AB-A=B you can cancel out a by inverting it's phase and "adding" it to AB. this would make a pretty amazing sample, and with some work, you could easily just make the inverted waveform a little more accentuated, and cancel out parts that would otherwise still be there. i've done some tests using sound forge and just sine waves, but i am yet to get a good result. can anyone help me out? or tell me of a program that inverts the phase or a sample 180 degree's? Regards, David King (buy a clie)
Subject:RE: Phase Inverssion Reply by: Chienworks Date:11/9/2003 9:57:37 PM Sound Forge does a perfect inversion. However, this isn't enough. The inverted sample has to be sample accurate and perfectly in phase with the clip you're trying to remove it from. Unless your combined AB clip uses the A clip in sample phase, then it's not going to be the same sample anymore. More specifically, if the samples were combined in any fashion other than a digital paste/mix in some sort of software like Sound Forge (for example, played back from CDs or a sampling units and then mixed together), the samples may not be aligned perfectly anymore. The resulting value each 44100th of a second (or whatever sampling rate) will be recalculated from adjacent samples so it won't be an exact match to the original wave form. Even in a direct digital mixing environment, differences in sampling rates or an environment that doesn't quantize to samples will result in an altered waveform. Sorry, but the more i re-read the last paragraph the more i think i'm not explaining it well. If all i've done is confused you then i'll try again tomorrow when i'm awake ;) But, for now, keep in mind that there are many things that can prevent what you are attempting from working even when the software does do a 180° phase inversion perfectly.
Subject:RE: Phase Inverssion Reply by: Rednroll Date:11/10/2003 7:34:49 AM Go get some sleep Chien. :-) Your theory is correct and will work to accentuate the parts not subtracted out, even if the samples are not perfectly alligned. In otherwords something that is 175 degrees out of phase will still subtract out well enough to achieve what you are trying to do, although 180 degrees would be ideal. Could you tell me what "quantinized" means? Is that the new Everyready sample loops, which keep going..and going...and going?

Subject:Phase Inverssion

Posted by: Djpm05

Date:11/9/2003 3:55:39 PM

I need to know if this is possible, and would work:

in techno (especially) the sounds are all quantinized, and many of them are loops, and therefore easy to change. but many songs have one beat, and then add another, but never have just the other beat going. when trying to remix a song, being able to single out a specific sample is invaluable, and I found a way to do it (in theory) but I have no idea of a program that will do it, and if it would work. He're how i've proposed to do it.

the samples are:
A = Bass beat
B = hi hat

the samples you have are:
A
AB

AB-A=B

you can cancel out a by inverting it's phase and "adding" it to AB. this would make a pretty amazing sample, and with some work, you could easily just make the inverted waveform a little more accentuated, and cancel out parts that would otherwise still be there. i've done some tests using sound forge and just sine waves, but i am yet to get a good result. can anyone help me out? or tell me of a program that inverts the phase or a sample 180 degree's?

Regards,
David King

(buy a clie)

Subject:RE: Phase Inverssion

Reply by: Chienworks

Date:11/9/2003 9:57:37 PM

Sound Forge does a perfect inversion. However, this isn't enough. The inverted sample has to be sample accurate and perfectly in phase with the clip you're trying to remove it from. Unless your combined AB clip uses the A clip in sample phase, then it's not going to be the same sample anymore. More specifically, if the samples were combined in any fashion other than a digital paste/mix in some sort of software like Sound Forge (for example, played back from CDs or a sampling units and then mixed together), the samples may not be aligned perfectly anymore. The resulting value each 44100th of a second (or whatever sampling rate) will be recalculated from adjacent samples so it won't be an exact match to the original wave form. Even in a direct digital mixing environment, differences in sampling rates or an environment that doesn't quantize to samples will result in an altered waveform.

Sorry, but the more i re-read the last paragraph the more i think i'm not explaining it well. If all i've done is confused you then i'll try again tomorrow when i'm awake ;) But, for now, keep in mind that there are many things that can prevent what you are attempting from working even when the software does do a 180° phase inversion perfectly.

Subject:RE: Phase Inverssion

Reply by: Rednroll

Date:11/10/2003 7:34:49 AM

Go get some sleep Chien. :-)

Your theory is correct and will work to accentuate the parts not subtracted out, even if the samples are not perfectly alligned. In otherwords something that is 175 degrees out of phase will still subtract out well enough to achieve what you are trying to do, although 180 degrees would be ideal.

Could you tell me what "quantinized" means? Is that the new Everyready sample loops, which keep going..and going...and going?