Audacity slightly shortens a 2nd recording track...

[novicesinger]

I'm having a weird problem here...

I have a WinXP PC. a USB mic.

I use Audacity to make amateur singing covers.

I usually have one track that has the instrumental.

Then I record one or more vocal tracks, mixing from both.

The problem is, the vocal track. I will sing on time to the instrumental, but after it records, I can see the vocal track moving slightly to the left. That itself is not so bad because I can time shift it into position. But what happens is, the vocal track progressively gets faster slightly so that when I time shift the first note of the vocal to match the instrumental, 2 minutes later, the vocal still is not timed correctly though I had time shifted the entire track from the start!

It looks like Audacity progressively shortens or speeds up the vocal track!

To test this, I did a vocal track but instead of singing, I'd time my voice to the drum beat. And progressively, my voice sounds earlier and earlier, becoming off synch with the drum beats even though when I recorded myself, it was on beat.

This is a horrible glitch. How can I fix this?

[kozikowski]

That is almost always a data rate mismatch and that's almost always a crappy sound card.

Let's say you paid hundreds of dollars for your USB microphone. It's a pretty safe bet that your microphone is going to produce a 16-bit, 44100, Mono signal (for example) with pretty good accuracy. Nowhere is it written that your crappy sound card is going to play that segment back at 44100. Suppose it's a little slow because your card cost $3.87 USD and all the components are cheap. That means you will be constantly chasing yourself because there will always be a difference in time between record and playback. This usually shows up over a three minute song. It's usually not obvious right away. Sometimes it is.

You can get around this with a click track. Play a click track back and sing all the parts of the performance to the click track, not the music. All the voice parts will match each other and they will match any instruments you played to the click track. The music will not match the click track on playback, and it won't match anything you downloaded from the internet.

Not all computers can be forced into being a Digital Audio Workstation.

Koz

[novicesinger]

My notebook's soundcard is HD RealTek. Is that a bad soundcard?

[novicesinger]

Weird. I just recorded another take and this time it came out fine? Is it because I switched USB ports to my mic?

[whomper]

My notebook's soundcard is HD RealTek. Is that a bad soundcard?

sometimes realtek is poor (mine is kaput as in DOA not working). not always. depends on the pc maker. and which drivers you have. you did update the drivers didnt you ?

and yes, switching usb ports can make things seem different too.

notebooks tend to be harder to use for good audio than desktop pcs.