Extremely Strange Problem....

[droog85]

OK I am running on a pretty powerful Windowx XP machine first of all, and my input device is a M-Audio USB Duo. Here is my problem:

When trying to make multitrack recordings with Audacity, my tracks never match up correctly in sync, and this is not the normal sync problem, let me explain. Even if i go in and match up the tracks exactly, another part of the song is out of sync. For example, if I line up the beginning of the song, by the end the 2 tracks are totally out of sync, and if I line up the end of the song, the beginning of the tracks are way out of sync.

So the first thing i tried was to record using a guitar plugged directly into my soundcar, by passing the USB input box. This didn't fix the problem, the same thing was happening.

Then I got a 4 track tape recorder with the idea of recording on there, and then sending it to the computer in 2 tracks, left and right, this I know is recorded perfectly well and in sync on the tape player so it isnt just crap playing (hah.) Anyway, I do that, send in a signal for left, and then record right, and then match them up manually again. STILL this happens, a part of the 2 tracks will be in sync but by the end the 2 stray away from each other drastically, it's like somewhere in the song its either speeding up the track or cutting it down during a silence or something. Anyway, I know this is long but this has been driving me absolutely insane. If there is anyone out there who could in any way help me, it would be so greatly appreciated. Thank you for your time.

[steve]

Try recording at a different sample rate.

[droog85]

Thanks, I tried it but it didnt help. This is so bizarre.

[steve]

We hear of this problem quite frequently, but it is usually with cheap or on-board sound cards.
The cause of the problem is that the sound card uses a clock signal so that it can divide up the incoming and outgoing audio data according to the selected sample rate. That clock signal must be steady and accurate to ensure that audio records and plays back at the correct speed. If the clock signal drifts (speeds up or slows down) then the audio will gradually change speed causing sync problems like you are experiencing. Unfortunately there is nothing that Audacity can do about it - if the sound card says that the sample rate is 44100Hz, then Audacity has no choice but to believe that the sample rate actually is 44100Hz, even if it is really starting at 44089Hz, then speeding up to 44103Hz, then slowing down again to 44097Hz (made up figures for illustration purposes).

It looks from the M-Audio USB Duo specification, that the sound card is optimised for ASIO, which unfortunately Audacity does not support. You may find that it records better with a program that can use ASIO drivers, such as Wavosaur, Krystal or Reaper (some other free/inexpensive recording programs).