recording out-of-sync with playback (v1.2.4)

[oldsinger765]

After using Audacity 1.2.4 for several years, I'm just trying recording my singing while playing back an accompaniment. I'm using a Shure SM58 mic thru a Behringer MIC200 preamp into the Line In of my RealTek sound card. After playing with volume level controls in Audacity and Control Panel, I've finally got good levels of both the voice and accompaniment. In Preferences>Audio I/O, I checked "Play other tracks while recording new one", and listen to the playback in headphones while recording my voice. So far, so good. But...

I have these questions:

1. I have found that in the composite tracks that include both voice and accompaniment, my voice actually comes earlier (not later) as the song progresses, as if the tempo is slightly higher on the voice, since it becomes more and more noticeable with time. That seems to be opposite or at least different from the delay/latency problem you discus in the docs and forum. Do you have a recommendation to prevent or correct this?

2. I thought the voice recording would be in a separate track, since you suggest zooming in and using the "time shift" tool to help with out-of-sync problems, but when I record, the voice seems to overlay the accompaniment tracks (although I don't see any change in the audio waveform). During the recording, I see the accompaniment volume in green in the left mixer window and the voice volume in red in the right mixer window. Is there something I should do so there will be a separate track for the voice being recorded?

3. I know my version of Audacity (1.2.4)is pretty old, but it's been working fine for me (except for the above), so I've been reluctant to upgrade to a later release. Should I download the latest alpha version, and will the old Audacity files I've created still work in the new version? I'm not sure what to do.

Audacity is a great package, and I'll appreciate any help you can offer. Thanks.

[steve]

3. I know my version of Audacity (1.2.4)is pretty old, but it's been working fine for me (except for the above), so I've been reluctant to upgrade to a later release. Should I download the latest alpha version, and will the old Audacity files I've created still work in the new version? I'm not sure what to do.

I'd recommend downloading the latest beta version (currently 1.3.13 beta - download from here: http://audacityteam.org/download/ )

If you install Audacity 1.3.13 into the default location it will not overwrite your 1.2.4 version, so you can have both versions installed at the same time.

Audacity 1.3.13 can usually open projects that have been saved by 1.2.x, but Audacity 1.2.4 cannot open projects save by Audacity 1.3.x.
There is a bug in at least some versions of Audacity 1.2.x that can make some projects open incorrectly in Audacity 1.3. This only appears to affect a small number of projects, but because of this I would recommend not overwriting the original 1.2.4 project. Open the project in Audacity 1.3.13 and then use "File > Save Project As..." and give the project a new, unique name before you start working on the project.

1. I have found that in the composite tracks that include both voice and accompaniment, my voice actually comes earlier (not later) as the song progresses, as if the tempo is slightly higher on the voice, since it becomes more and more noticeable with time. That seems to be opposite or at least different from the delay/latency problem you discus in the docs and forum. Do you have a recommendation to prevent or correct this?

There are two separate issues here:

1) "my voice actually comes earlier (not later)"
Audacity 1.2.x has automatic (not adjustable) latency correction. After recording the second track, the track will automatically be moved a little to the left to compensate for the recording delay (recording latency). The exact amount of latency depends on the sound card, the audio format, the sound card drivers and other factors. Audacity 1.2.x automatically adjusts for this delay by assuming a typical amount of latency. If the latency on your machine is less than this typical amount, then Audacity 1.2.x will over compensate and make the second track start a little early.
In Audacity 1.3.x the latency correction can be adjusted to match the actual recording latency for your computer. Instructions for how to do this are in the manual here: http://manual.audacityteam.org/man/Latency_Test

2) "it becomes more and more noticeable with time"
This is a different problem and indicates that the clock signal on your sound card is not constant but drifting slightly. Unfortunately there is no way that Audacity can control this - Audacity just records the data that it receives. I assume that you just have one sound card connected to your machine?
There are some possibilities for how to improve this, but rather than get too complicated now, lets look at your other issue first.

2. I thought the voice recording would be in a separate track,

Yes. If you already have one track in Audacity and you press the Record button, a new track will be created below the original track. Can you not see a second track? Do you have a very small screen on your computer? If so it may be that you need to scroll vertically to see the two tracks. Tracks may be resized so as to fit vertically - to do this "View > Fit Vertically".

[oldsinger765]

Steve, I usually have iTunes and Audacity open, one above the other, and I did not notice the vertical scroll bar in Audacity. When I re-sized the Audacity window, I can now see the voice tracks (I split the mic signal to stereo) as well as the accompaniment tracks above. Thanks for cluing me in.

I'll download the newer version shortly - I did read about how to determine the latency for my PC in the docs. I'll try using that.

Re/ the faster tempo on the voice recording, I'm not sure the sound card clock drifting is a good explanation, unless it always drifts in the same direction (faster) and at about the same rate, since I've seen the same effect on several recordings I've made. The voice and accompaniment tracks start out exactly in sync, but as the voice recording progresses, the voice gets more and more ahead of the accompaniment. In a 3-minute recording, the voice finishes about 1-2 seconds before the accompaniment - not much, but more than enough to be unacceptable.

Since this (rather than a constant time offset from latency) is my real problem for now, let's "get too complicated" and see if I can learn how to fix this "faster tempo" problem - when you have a few minutes to provide me with things to try.

I really appreciate any help on this. Thanks so much.

[oldsinger765]

Steve, duh! Now that I can see and work on the voice track, separate from the accompaniment tracks, I can change the tempo of either to match the other. I tried that, and with a little trial-and-error, I got the two in sync.

I think I'm OK on this for now, and I appreciate your help.

Brian

[steve]

Re/ the faster tempo on the voice recording, I'm not sure the sound card clock drifting is a good explanation, unless it always drifts in the same direction (faster) and at about the same rate, since I've seen the same effect on several recordings I've made.

Your sound card is using a slightly faster clock speed when playing back than it is when recording. I don't know why the clock speed can be different for recording and playback - it should of course be exactly the same, but it is not uncommon for there to be a difference on cheaper sound cards.

I can change the tempo of either to match the other.

Yes, as long as the speed remains wrong by a constant amount then the speed can be corrected, though you should use the "Change Speed" effect rather than the "Change Tempo" because the pitch will need correcting as well as the tempo.

[oldsinger765]

Steve, thanks so much for helping me fix my recording problem. I will follow your advice, and I should be fine.
Thanks again. Hopefully I won't have too many questions in the future. I think Audacity is a great tool -
it has been a great help to me.