Tracks don't line up properly

[torvon]

Hi all,

Using audacity on my macbook from 2016. I use Bose headphones (QC35) and a Samson Meteor mic.

Whenever I record a track, and after that a second track, they are not aligned properly, the second is too late (something like 200ms maybe).

I searched for a while but could only find cases where this happens to people with a weird sound card, or folks who use external mixers. I don't use either.

Any pointers appreciated, it defeats the purpose of recording sound when tracks don't line up :/

Thanks for your help and the awesome software
torvon

[kozikowski]

If you're listening to the first track while you're recording the second, that's called overdubbing and there is a process to "tune out" the time differences.

https://manual.audacityteam.org/man/tut ... rdubs.html

One of the techniques is to generate a click track for the first track and then record your headphones.



The two tracks will be off by exactly one error.



Write that error down and apply it to the overdubbing correction panel.

Koz

[torvon]

Thanks so much Koz !!

[torvon]

Hi. So I did this a few times around, and the difference is always different. What could cause this?

To explain, I generate a clicktrack, record a new track playing the clicktrack while holding my headphones to the mic. I calculate the difference (e.g. -250ms) so that both tracks perfectly overlap, edit it in the preferences, save.

Now I do the exact same again. Tracks don't align, because it's -230ms, not -250ms now. I do this over and over again, they never align.

Why? Thanks.

[torvon]

So every time I follow the procedure exactly, I get different results. Same microphone, same headset, same distance between microphone and headset. Sometimes 200 ms latency, sometimes 250 ms latency.

Here a screenshot of the results: https://eiko-fried.com/wp-content/uploa ... .48.01.png

Here: the upper track is the clicktrack.

The second is my first recording.

The third is my second recording. All with the same options, I changed nothing in the meantime.

This means I am unable to correct the recording in a meaningful way, making proper recording with audacity impossible because it's always misaligned. Help please.

[kozikowski]

every time I follow the procedure exactly, I get different results.

That means the recording latency of the machine is wandering. That usually means the machine is busy doing other stuff while you're trying to perform.

Make sure all other apps are turned off and not just napping. You should not have a forest of lights or indicators in the application dock (usually on the bottom of the desktop). Then disconnect the machine from the internet. Either unplug the network cable or use the fan symbol in the upper right to disconnect from the WiFi.

You should not have thousands of icons on your desktop. The machine has to deal with and manage each and every one of them. It's not relaxed and passive. I make a folder called "Desktops," gather everything up, dump it all in a dated folder and store it in there.

Screen Shot 2020-05-08 at 10.13.19.png (8.89 KiB) Viewed 252 times

Use Spotlight (magnifying glass, upper right) to find stuff. If your stuff has a series of trash labels, maybe this is a good time to fix that.

Then Apple > Shutdown > Shutdown. If you get a little spinning daisy, see how long it takes to vanish. That's the Mac struggling to clean out all the trash you had going.

Then Start. Don't let anything else start. You may get a complaint that the machine can't reach iCloud or other on-line system or licensing server. Audacity doesn't deal with on-line storage very well. You can have one or the other.

Run Audacity and do the latency adjustment. See if that helps.

Koz

[torvon]

Super helpful as always (but honestly a little high maintenance, other programs I use do not require you do spend hours juggling stuff like that)

[kozikowski]

Overdubbing requires your machine to set up real time recording and real time playback perfectly and at the exact same time. If your machine does anything wrong at all, this is going to fall apart.

Most notably, the chat programs, Skype, Zoom, etc, are also struggling for majority control of your sound pathways. And they will win.

Cloud storage has network delays and latencies and they change, no matter how much the services want you to think they don't. This is pretty much deadly if your goal is to adjust latency and delays.

Koz

[kozikowski]

You don't have to do it this way. You can use the Time Shift Tool (two sideways black arrows) to push your new track in line with the others. Remember to switch back to the normal cursor ("I" Beam) before you try to do anything else.

Koz