I just tried making a recording from a a couple of different vinyl records with a brand new stylus in Audacity and every few seconds the stereo image will suddenly alternate between (and it’s hard to explain) jumping the panning from left to right and vice versa. It’s not a hard pan (the other channel does not go silent) but the audio seems to suddenly move from the center to somewhere in the left to suddenly somewhere in the right with a loud click at these points (a digital click, not a vinyl click). I am recording into a Xonar U7.
You can hear it in this sample file - this is the raw audio; I have simply faded it in and out at each end. Check out the sudden shift in imaging around 8 seconds in and again at 12 seconds. What is causing this and how do I stop it? I tried centering the phase in Audition but it doesn’t help.
I’m not hearing the “image” problem (maybe because it’s a short clip or maybe because I didn’t listen carefully enough), but I can hear the click/pop and I can see it when I zoom-in. I’d guess you have buffer overflow.
Try increasing the [u]Audio to buffer latency[/u]. If that doesn’t help, make sure you are not running any other applications, and try to minimize stuff running in the background.
…Your operating system is always multitasking, even if you’re running only one application. When you record, the digital audio stream flows at a constant rate into a buffer (temporary storage) and when the operating system gets around to it, it reads the data from the buffer in a quick-burst and writes it to your hard disk. If the operating system doesn’t get back to reading the buffer on time, you get buffer overflow and a glitch (a discontinuity).
A “faster” CPU will help but the other task doesn’t have to be taking up a lot of CPU time, it just has to hog the CPU for a few milliseconds too long. (And, the root problem usually isn’t CPU speed.) A larger buffer (more latency) reduces the chances of a glitch by allowing more time between buffer-reads. (When you play-back the danger is buffer underflow.)
When I click the ASIO button on my Xonar U7 system tray icon, it tells me that the latency is 20ms. Do I increase it here or do I do it in Audacity’s settings? If the latter, what setting do you recommend? I am also getting microseconds of silence in the recordings where the recording is muted temporarily instead of being a continuous stream of audio.
It depends on a lots of unknown variables… Like everything in life, more is better!!! (Although a huge buffer may not solve your problem.) There will be several minutes of “latency” between the time you record and when you play back… Maybe hours, days, weeks, months… A few extra milliseconds don’t matter.
Latency is ONLY an issue when you are monitoring yourself on headphones through the computer while speaking/singing/playing an instrument. When digitizing vinyl, it’s just not an issue.
OK. So forgive me for being naive but does this mean I have to use a different recording input in Audiacity, is that related? I am using WASAPI at the minute. The jumping/panning thing is fixed but I am still getting microseconds of silence throughout the recording where the audio mutes for a millisecond or so.