Strange multitrack sync problem ?
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Posted on Feb 14, 2009 10:33 am
velocetteman
Member Since: Feb 14, 2009
Hi .... I'm in the process of setting up a basic home recording set up using Cool Edit Pro 2.1 in conjunction with an external USB sound card (Creative SB Live USB). My problem is this ... I lay down piano on track 1 and accompany it by recording live on track 2. However when I play back both tracks, the second track gradually and noticeably starts creeping ahead of the first one. I can't see how this sync problem can happen if I'm using the same sound card to record and playback ... surely the same clock is being used in both cases. Or maybe I'm doing something really stupid!
Behaves exactly the same in Audacity, so it's not a Cool Edit problem.
Any advice appreciated, as I'm rather stumped at the moment
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olddogMember
Since: Jul 02, 2003
Feb 14, 2009 02:46 pm I'm not usually one to jump on the Creative cards are junk for recording, but I would say that particular one is probably going to be problamatic for any multi-track recording. You're best bet is to pick up an inexpensive USB interface from the likes of Line6 or M-Audio.
You could try using Asio4All, that helps for alot people trying to use interfaces such as that. You could also try setting the delay offset in CEP. To do so you'll need to have a short clip of something like a click track (something with easy to identify transients), place that in track 1, then route the output of the soundcard back into CEP and record on another track. Zoomin till you can see at the sample level, find the difference in # of samples the 2 tracks are apart and enter that in CEP's multi-track prefs. Then try recording something to see if it helps.
Dan
Feb 14, 2009 03:03 pm Thanks Dan .... I'll give the Asio4All drivers a go. With respect to your second suggestion, it does not appear to be a fixed latency problem. As I said, the second track gradually drifts ahead of the first, so that the longer the playback time, the bigger the discrepancy. I suspect you might be right about the Creative unit .. it looks as if it can't cope properly with full duplex mode during simultaneous record/playback, perhaps due to the increased USB bandwidth, although I've got it running on a separate USB2 card with nothing else attached.
If all else fails I'll try a Tascam unit that I can borrow for a while.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Feb 14, 2009 09:49 pm Funny thing is the older PCI units were a much more stable unit as far as the internal clock drifting goes. I actually used one in a test box years ago for authoring GM sequences and did a bit of recording with it for kicks. It locked up very well. But these days most of the Creative stuff is pretty much ultra low level parts, internal audio clock included.
What you are experiencing is drift. All you can do is make certain that your recording application's are marked to use the SB cards internal clock and not the motherboards clock for sync. That could be issue as most application's default to using the motherboards clock for audio sync purposes. So possibly check that first.
Feb 15, 2009 10:32 am I suppose the PCI units have more bandwidth to operate with compared to USB. Not sure it could be a clock drift problem ... surely the Analogue to Digital and Digital to Analogue converters within the USB unit share or are derived from a *common* clock.
Anyway, who knows what the inner gubbins of these units are
The good news is that Dan's suggestion of using ASIO4ALL drivers instead of the Creative ones appear to have solved the problem, although Cool Edit Pro does not support ASIO, and there's legal problems with Audacity, so I've had to use Reaper instead.
I'll probably end up getting a better sound interface eventually ... at the moment I'm just dipping my toes in the water to get a handle on the main concepts and techniques of multitrack digital home recording and editing.
Thanks to everyone for their prompt and helpful input ... much appreciated, guys.
KaiserMember
Since: Feb 15, 2009
Feb 15, 2009 03:14 pm I've been having the same problem, I'm using GarageBand in a 2.16 4GB Macbook Pro, with a Behringer UCA202
it's the same situation, when I lay down a software instrument on track 1 and accompany it by recording audio on track 2. when I play back both tracks, the second track moves a little to the right not playing in sync with the first track, metronome on while recording and playback.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Feb 15, 2009 03:41 pm It is as I stated above, one of two things. Either the internal clock of the interface is drifting, (which is more then possible in your case as the UCA202 is nothing but junk) or it is simply not be locked to by your recording software.
You need to go into the audio preferences and make sure that both the recording and playback timing master is set to use the UCA202 internal clock and not the system clock.
If it is set to use the system clock that will happen as it cannot lock up the interfaces clock which will in the end cause the drift issue you are experiencing.
olddogMember
Since: Jul 02, 2003
Feb 16, 2009 02:03 am Glad ASIO4All worked out for you, Reaper is probably a better app to be using any way these days, CEP is pretty old, though it still has a lot of useful tools for working on the stereo mix after you're done tracking and mixing.
Dan
Feb 16, 2009 04:53 am Kaiser, what you appear to be describing is a <fixed> latency problem, which is therefore a bit different from the problem I had. You say the second track moves a little bit to the right relative to the first, which sounds to me like you are talking about a fixed delay.
This means that when you are recording track 2 while listening to track 1, the conversion of the track 2 analogue input into digital form is taking a noticeable length of time, resulting in the offset you are experiencing.
As Dan says in his posting above, your editing software (which I am not familiar with) should be able to compensate for this by using a latency offset to align the two tracks during playback. Alternatively, try different audio drivers. (Don't know anything about Mac drivers to offer you any specific advice there.)
Also, you might have your buffer size set too large, if this is adjustable in the driver. Try reducing it and see what happens.
Stu
