Originally Posted by bitflipper  Pops, clicks and dropouts are the audible manifestation of interruptions to the data stream.
When recording, the audio interface is filling a buffer with data that's pouring in at a rate of at least 44,100 values every second, faster if you're recording multiple tracks and/or at higher sample rates. That's a lot of data, and it's important that it not be interrupted, even briefly.
As soon as the buffer has been filled with data, the interface switches to another buffer and starts filling it. SONAR (or Cubase, or Logic, or Pro Tools or GarageBand) then begins to process the data dropped in there by the interface.
By the time the interface has filled the second buffer, SONAR must be ready to start draining it immediately. But if it still hasn't finished with the first buffer, then whatever unprocessed data remains in the buffer is tossed. The data stream is interrupted, and you get a click (if it's a small amount of data), a pop (if it's a larger amount) or the dreaded DROPOUT message indicating the problem is so bad that SONAR's not even going to try. (In the latter case, a "dropout" as notified by SONAR happens after 4 consecutive buffers are missed.)
So it all revolves around the CPU having sufficient time to process a buffer-full of data before the next buffer fills up. That's a finite amount of time, depending on the size of the buffer and the data rate (sample rate * number of channels). You can get a clue as to how the CPU is keeping up from the CPU meter in the status bar. If it reads 50%, that means the CPU required 50% of the allotted time to process the data (recording + playback). (The CPU meter is not an indicator of how much CPU SONAR is using, which is why it never agrees with Task Manager.)
So there is really only one reason for pops 'n clicks: the CPU has too much to do in between buffer pump cycles. You have to figure out why that is, and alleviate the load on the CPU so that it can keep up.
The easiest thing to do is increase the buffer size. That alone may give the CPU enough headroom. Sometimes, though, it's not enough.
The next-easiest thing is to think about the tasks you're making the CPU perform during recording and (more importantly) playback.
If you've got three vocal tracks and each one has an instance of Perfect Space on it, that's a lot of overhead that can be reduced by using a single instance of PS on a bus.
Any audio tracks that have effects on them are candidates for freezing. Freezing eliminates all the effects from the CPU load. Freezing soft synths gives an even better bang:buck ratio. Using a drum sampler like EZDrummer, Superior, BFD or Jamstix? Freeze those guys and chop your CPU usage waay down.
Bypass any mastering effects while tracking. Most mastering effects, including all of the bundled LP-64 effects, are serious CPU-eaters. Save these for after tracking, when you can freeze tracks and raise your buffers.
Sometimes, people do all these things and STILL have pops and clicks. At that point, you have to suspect something's amiss in your computer. Do not blame it on your DAW, do not blame it on your audio interface - they are rarely to blame. More likely suspects are your network adapter or your video adaptor.
Aarg, I didn't mean to write a book on the subject (Hmm, maybe I should...) and supper is calling my name. Hope this helps. |