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Bi-Directional Looping - is it possible? Or alt?

PostPosted: Sat Sep 22, 2007 11:47 pm
by ratana
Hi, sorry if this has been asked before, but I did a search for it and did not see anything. On many Akai samplers, and the Emulator 2 and 3, you can loop a sample bidirectionally, that is it will play forwards, and then play backwards, and then forwards, etc etc.

Is it possible to do this on the EMU 64/6400/etc series at all? It does not appear to be an option in any of the obvious places. If there is a workaround would really appreciate the knowledge..... thanks,

Adam + Shawn

PostPosted: Sun Sep 23, 2007 6:29 am
by sampleandhold
What kind of loop are we talking about? Are we talking like a loop of a break? A loop of a wave form. If it is the first bit, then easy to work around. I have come up with three solutions just a moment ago. If it's the second bit, then, well... that's kind of a waste of time given that wave forms typically sound the same going forward or backwards. Even a saw going backwards typically sounds the same going forward.... I just need a bit more information.

snh

PostPosted: Sun Sep 23, 2007 11:01 pm
by Adam-V
Bi-directional looping of a sample s not supported in EOS machines. You need to manually reverse the sample and tack it on the end of the original to achieve this. It is a most annoying omittance of functionality in my opinion.

For samples that are difficult to loop, the manaul suggest using the auto-correlate function of crossfade looping. (See page 210 of the EOS 4 manual for more info on looping)

Cheers,
Adam-V

PostPosted: Mon Sep 24, 2007 3:43 am
by sampleandhold
that is what bi directional looping is? One going forward and one going backwards? Why not just have the loop, one version going forward and the other going backwards and just alternate... Or am I missing something. I feel that I am.

snh

PostPosted: Mon Sep 24, 2007 4:43 am
by Adam-V
Bi-directional looping supposedly overcomes some of the issues that can occur when sampling ensemble or pulse width modulated sounds where, due to chorusing effects you just cannot find an appropriate loop point without sampling many seconds worth of audio or ending up with a pulsing sound rather than a smooth natural sound. By having the looped section of a sample first play forward then in reverse rather than just forward, the theory is that the effect is not so noticeable as the start and end points always match up nicely.

Some samplers (Earlier E-Mu samplers included) allow you to specify this mode of looping as standard functionality allowing you to pick your loop points without having to actually destructively edit the sample. If you want to achieve this in modern E-Mu's, you need to edit the sample and somehow find the appropriate loop reversal points manually. Shame really, I reckon the amount of time I've spent on some samples trying to get the loop points right could have been drastically reduced if this function was available.

I guess the need for keeping loops as small as possible just diminished and E-mu obviously decided it was no longer even necessary once RAM started to become relatively cheap and samplers could be typically expanded to 128M.

Cheers,
Adam-V

PostPosted: Mon Sep 24, 2007 11:37 pm
by sampleandhold
I understand... that is actually brillant. Why not figure out the pitch of the note, and then just split the sample in half and reverse the later half? Or Cut and past the first half, but have the pasted version backwards. Might take some time but it should be possible. I have to do this with editing breaks in the emu. Sometimes the hit falls so far off the grid that by reversing the hit and then reversing the entire sample I found I can move samples around quite readily and tighten up a break with out having gaps and such. I might play with this to night. I will make some noisey sound and sample it at a known frequency and split it in half and see what happens. Very interesting technic. I wonder if that would work with snares and trying to make those strange long gated snare sounds that seen to never decay. You got some juices going.

snh