posted 11 January 2010 20:37            

Im starting to build a personal wavetable/impulse-response/analysis files library, and have a couple of questions concerning the preparation of material.

a)what would be the simplest way of assureing that the wav and aif files are 4096 samples long (@ 16bit, 44.1) ? I still havent wrapped my head around the sound editor, not sure how to apply desired changes into effect, besides the generic trim ability discussed in the getting started manual.Any file I open there has 4096 samples, amp ranges and such already selected in the fields, whereas most of the time the actual sample is obviously totally different compared to the numbers on screen

b)I mainly work with rhythm material, so I have to be preety sovereign in timestrecth, beatmatching domain.Alot of times I have to recycle mismatched tempo loops into an ongoing project which has a fixed tempo. I always stumble upon the frequency field and the "rate" parameter of the generic source Protoypes.Most important is tempo scaling, meaning I can set different end tempos in relation to the samples source tempo (not big drops though, +/- 40 bpm), and tempo resolution (1/16, 1/32, 1/16t, etc.)
With my limited knowledge atm, is doing spectral analysis for each loop, and then do time and pitch (or both) manipulations, the only way, or is there another solution ? Also which analysis would suit best for non pitched material...GA, RE ??

thank you for any input!

regards from slovenia

posted 12 January 2010 12:04            

To change the length of a wav or aif file to 4096 samples:

1. Open the file in the Sample Editor.
2. Select all.
3. In the lower pane, select the template called "Interpolate Selection"
4. Set the desired number of samples (it defaults to 4096 so you can leave the default)
5. Click Insert

This will use 'perfect interpolation' to resize your file to exactly 4096 samples in length.

posted 12 January 2010 12:19            

Right, the !Rate control is the one to change. The !Rate should be replaced by a ratio of the desired tempo to the loop's original tempo.

For example, let's assume you have an 8-beat loop at an unknown tempo named 'rustdrum130' and that !BPM is the tempo you want to match. In the Frequency field of the GenericSource playing 'rustdrum130', you could use the following expression:

default * (!BPM / ('rustdrum130' closestBPMTo: !BPM forBeats: 8))

posted 12 January 2010 13:30            

You can do some interesting processing using spectral analysis/additive resynthesis, but bear in mind that, in order to identify the frequencies, the analysis has to look at a chunk of time so some of the micro events that occur during that time will be "blurred". The effect is often pleasant sounding but the time-smearing may not be appropriate for rhythmic loops.

Depending on the material, the Tau editor might be a useful approach.

posted 12 January 2010 14:36            

Edit : one thing I noticed, with the freq and bpm problem.Is it possible to strecth the loop in time only, without pitch correction....but thinking about it now, seems this cannot be done in frequency field alone right ?