[mma] - Overdrive - Oversampling broken
-
- Posts: 192
- Joined: Tue Apr 17, 2007 9:45 am
[mma] - Overdrive - Oversampling broken
in case the new overdrive effect is oversampled it is clearly faulty. This simple test (project samplerate 44 kHz) shows no oversampling is going on. A sine sweeps up to 22 Khz and processed through overdrive:
http://www.torpedotrickser.de/live8beta ... broken.zip
Once the highest generated harmonic hits nyquist (22050 Hz) it is instantly mirrored back into the audible spectrum without being attenuated.
/edit: removed suggestion/feature wish
http://www.torpedotrickser.de/live8beta ... broken.zip
Once the highest generated harmonic hits nyquist (22050 Hz) it is instantly mirrored back into the audible spectrum without being attenuated.
/edit: removed suggestion/feature wish
Last edited by Bunky Freaks on Thu Feb 05, 2009 4:05 pm, edited 1 time in total.
The key point in relation to this issue is that the current implementation is not working as the manufacturer intended.
Advice on what you would prefer (in terms of oversampling amount) should probably be kept separate from a thread alerting them to the existing oversampling being broken. Otherwise your report will get misclassified.
Just my POV, probably wrong.
Advice on what you would prefer (in terms of oversampling amount) should probably be kept separate from a thread alerting them to the existing oversampling being broken. Otherwise your report will get misclassified.
Just my POV, probably wrong.
-
- Posts: 192
- Joined: Tue Apr 17, 2007 9:45 am
oversampling within the devices in realtime audio works at multiplications of the soundcard operating frequency, not the sampling frequency of the recorded waves.ilia wrote:the project's sample rate was >44.1, right?
Try the example file - with your soundcard at 44.1, and see if the device created harmonics reflect back down when they hit 22khz.
they will
the recorded wave in this instance is not the issue - the additional realtime harmonics generated should be able to rise invisibly (inaudibly) above 22khz. They do not.
correctAngstrom wrote:oversampling within the devices in realtime audio works at multiplications of the soundcard operating frequency, not the sampling frequency of the recorded waves.
yes, but it could -- and in fact does, as I just checked -- happen when the project's sampling rate is higher, so this is not an oversampling issue per se (if it is indeed oversampled). And -- any practical oversampling of an overdrive will probably still result in harmonics reflecting back, since the overdrive algorithm will likely generate harmonic content above half the oversampling rate. Anyway, it's for Ableton to decide whether they want to filter those -- I personally am happy with the sound of aliasing...Try the example file - with your soundcard at 44.1, and see if the device created harmonics reflect back down when they hit 22khz.
they will
-
- Posts: 192
- Joined: Tue Apr 17, 2007 9:45 am
that might be due to the resampling of the audio file. For a clean sine sweep at any project sample rate use the test tone plugin from this freeware effects bundle:ilia wrote:Also -- I just listened to (and looked at) the swept sine sample without overdrive played back at 192kHz, and there is a whole lot of aliased lower frequency content added that wasn't there at 44.1. Not sure what this means, but it's kind of more disturbing than the original overdrive issue...
http://mda.smartelectronix.com/
-
- Posts: 192
- Joined: Tue Apr 17, 2007 9:45 am
true, but what's the expected behavior? I didn't even find any mention of it being oversampled...Bunky Freaks wrote:well, this is about a potentially broken implementation of oversampling in overdrive. if it does not work as expected (which i think i found prove for) it should be fixed.ilia wrote: I personally am happy with the sound of aliasing...
if resampling audio at higher rate in Live produces so many artifacts, that's worrisome. I rarely record at >44.1, so never noticed this before.Bunky Freaks wrote:that might be due to the resampling of the audio file.
thanks for the link. just tried it with a tone fixed at 18k (can still hear it -- just barely!), sampling rate 192K, applying overdrive with a high drive and/or high dynamics produces a lot of low frequency content.For a clean sine sweep at any project sample rate use the test tone plugin from this freeware effects bundle:
http://mda.smartelectronix.com/
-
- Posts: 192
- Joined: Tue Apr 17, 2007 9:45 am
@bunky
the thread prefix [MMA] has appeared. That means Matthias Mayrock is investigating it.
Once it gets identified as a bug it will usually get assigned a bug ID number, hence the threads with [number] prefixing the user's title.
It may be that Matthias will just fix this issue if he sees a problem, as the Overdrive was written by him, I think.
the thread prefix [MMA] has appeared. That means Matthias Mayrock is investigating it.
Once it gets identified as a bug it will usually get assigned a bug ID number, hence the threads with [number] prefixing the user's title.
It may be that Matthias will just fix this issue if he sees a problem, as the Overdrive was written by him, I think.