[Windows 10 Pro x64 (10.0.19041)]
[MOTU 24io audio interface - ASIO 2048 buffer size]
When applying ‘fast’ volume automation to either incease or decrease volume of a part to zero, say, (-inf dB to 0 dB, or 0 dB to -inf dB), and the automation line between the two points is linear, the transition sounds smooth. It sounds AND exports the same way.
However, upon applying any form of ‘curve’ to the fast volume increase or decrease, there is a noticeable glitch where the volume jumps up and down before the automated transitions end.
EDIT: I’ve tracked down the issue and it appears to occur when using 1024 sample ASIO buffer or higher (at 48kHz sampling rate).
Steps to repeat:
- Create an empty project at 48kHz and set the ASIO buffer to 2048.
- Create an audio track and put some whitenoise audio onto the track.
- Apply varying lengths of volume automation up and down. Try from -inf dB to 0dB and vice versa.
- Try different timing - long, medium, short, ultra-short duration between automation points.
- Now, apply ‘curves’ to the volume automation.
You will notice that the increase or decrease in volume sounds fairly smooth for longer times between the two automation points where a curve is used, but more and more ‘glitchy’ the shorter the duration between the two points. Cubase also exports the same glitches.
Here is a downloadable project demonstrating the issue:
The demo project also contains two audio tracks with exports I conducted one after another using exactly the same settings as in the project, to check. These can be unmuted using the tool to hear what they sound like. The glitches are consistent no matter how many exports are conducted.
P.S. Here’s a video demonstrating how I found the bug. This is a project I’m working on. I wanted a quicker fade, so tried using a curve to speed things up and give a smoother transition. The ‘stutter’ sound is what I am demonstrating. Please ignore the occasional “BEEP” sounds. This is something to do with the capture software (AAC 192 audio codec issue).