Ableton SRC weirdness/bug

Discuss music production with Ableton Live.
Post Reply
just_in
Posts: 71
Joined: Thu Sep 09, 2010 3:55 pm

Ableton SRC weirdness/bug

Post by just_in » Thu Jul 29, 2021 9:04 pm

I noticed that if a 192kHz recording has noise in the very high inaudible range (above 50kHz), Live's resampling dumps this noise into the audible range, when playing back or rendering at 44.1/48kHz. Whether High Quality sample rate conversion is enabled or not makes no difference.
Example file: https://filepost.io/d/eVm88um7jY

I thought Ableton used SoX for resampling, but SoX doesn't have this problem and neither do other apps/DAWs that I tried.

Tarekith
Posts: 19065
Joined: Fri Jan 07, 2005 11:46 pm
Location: Ableton Forum Administrator
Contact:

Re: Ableton SRC weirdness/bug

Post by Tarekith » Fri Jul 30, 2021 2:05 pm

Just out of curiosity what interface were you using to record 192kHz at?
Tarekith
Ableton Forum Administrator
https://tarekith.com

siliconarc
Posts: 2836
Joined: Mon Jul 16, 2007 12:27 pm
Location: UK
Contact:

Re: Ableton SRC weirdness/bug

Post by siliconarc » Fri Jul 30, 2021 4:38 pm

tried your file playing at 44.1 and 48 and i hear the same - the high freq dithering noise gets pushed into audible range.

out of curiosity i made a 192 khz test tone file in izotope rx (constant sine tone at 80 khz)
playing this file back in Live at 44.1 khz plays the tone at a very audible 8 khz :|

file is here if interested: https://filepost.io/d/B7xUormuHz

just_in
Posts: 71
Joined: Thu Sep 09, 2010 3:55 pm

Re: Ableton SRC weirdness/bug

Post by just_in » Fri Jul 30, 2021 9:49 pm

Tarekith wrote:
Fri Jul 30, 2021 2:05 pm
Just out of curiosity what interface were you using to record 192kHz at?
That was with an onboard Realtek line input, but I've seen some similar stuff with other gear.

High frequency noise is not that uncommon, whether it's from dithering or something else. Here's Amir from ASR rambling about it, for instance: https://www.youtube.com/watch?v=THjusVQpPMA

garyboozy wrote:
Fri Jul 30, 2021 4:38 pm
tried your file playing at 44.1 and 48 and i hear the same - the high freq dithering noise gets pushed into audible range.

out of curiosity i made a 192 khz test tone file in izotope rx (constant sine tone at 80 khz)
playing this file back in Live at 44.1 khz plays the tone at a very audible 8 khz :|

file is here if interested: https://filepost.io/d/B7xUormuHz
Yep. At 192 kHz you can also get some audible tones with your file in Live if you change the pitch (like +21 semitones) or if you load it in Simpler and play with it.

jestermgee
Posts: 4500
Joined: Mon Apr 26, 2010 6:38 am

Re: Ableton SRC weirdness/bug

Post by jestermgee » Fri Jul 30, 2021 11:26 pm

Don’t record at 192k? Especially using the onboard audio interface.

just_in
Posts: 71
Joined: Thu Sep 09, 2010 3:55 pm

Re: Ableton SRC weirdness/bug

Post by just_in » Sat Jul 31, 2021 9:02 am

Heh, I don't think that's a good solution.
Some users are going to deal with 192 kHz and ultrasonic content nowadays, it is what it is. And if those users are not aware of these SRC issues, they might assume their audio clips are permanently damaged. Live should handle this better.
I tried these files in other apps (Reaper, Acoustica, Audacity, some media players...) and none of them produce audible tones. Well, Reaper does if you select a low quality SRC mode, but not by default.

siliconarc
Posts: 2836
Joined: Mon Jul 16, 2007 12:27 pm
Location: UK
Contact:

Re: Ableton SRC weirdness/bug

Post by siliconarc » Mon Aug 02, 2021 8:58 am

fwiw, Bitwig also plays back that 80khz tone as 8khz (with audio output set to 44.1)

just_in
Posts: 71
Joined: Thu Sep 09, 2010 3:55 pm

Re: Ableton SRC weirdness/bug

Post by just_in » Fri Aug 06, 2021 1:26 pm

just_in wrote:
Thu Jul 29, 2021 9:04 pm
I thought Ableton used SoX for resampling, but SoX doesn't have this problem and neither do other apps/DAWs that I tried.
Just to clear this up, because I think I know what's happening now. I was also confused by Live's excellent result on this SRC comparison website, since I was unable to reproduce that result by loading the 96k test file (sweep) in a 44k project.
Live does use a high quality (SoX) SRC, but only for downsampling the rendered audio, if it's needed when exporting. Otherwise, for playback and rendering, it uses a lower quality mode.
Also, from the manual:
If you export at a sample rate that is lower than your current project sample rate, Live will first export at the current project sample rate and then downsample the file in a second step using a high-quality process.

So, as long as you work at 44.1/48k in Live, those 192k samples will produce extra tones/noise, both during playback and in the rendered/exported files.
But if you work at 192k (aka if your audio device is set to 192k in Live) you can then play back those samples and export them to 44.1k without any issues, since in that case Live renders at 192k and then downsamples with a higher quality SRC. Well, at least if you're not doing any pitch changes and such—that uses its own SRC/interpolation, which can be noisy even at 192k.

Post Reply