audio "channels-combine" sound error

Jim Hoare wrote on 3/6/2009, 8:57 PM

Vegas Pro 8.1 Vista 64 Intel i7 920
I have some right channel only audio tracks digitized from old video tapes. When 'combining' the channels and playing back the sound I get a sharp sound like gun fire then very muted or not audio. I have tried putting the audio on two tracks and swapping one track giving a left and right track with the same results. If I move either track slightly out of phase the sound plays normal. I have done this combining many times with 32 bit Vegas with no problems. FYI this is a new computer but with the old sound card. Thanks

Comments

TGS wrote on 3/7/2009, 11:42 AM

Try choosing 'Right Channel Only' instead of combine. it will still come out of both channels.
If worse comes to worse, you can Choose Right Channel Only, then copy it to another channel. Use a Pan Envelope and pan one to the left and the other one to the right and then right click on the "Record Arm" button and choose "Switches" on only one of the two tracks and choose "Invert Phase"
I've always only used just one audio track (Right or Left Channel Only) when the other audio track is bad It seems to playback fine in mono. (I don't even make a copy of the track, I just choose Right or Left Only) I've never combined both tracks into one unless they were recorded like a multitrack, with 2 sources completely separated. If it's a weak stereo recording, I'll boost the weaker channels volume to match the other. But when using one channel only, I've never had phase cancellation on playback from 2 speakers ......... Yet. Try a short test to a DVD RW.
My biggest problems and how I discovered this was because quite a few of my old VHS tapes seem to have some kind of noise, like a click or static or a hum on one track, every so often. If the soundtrack didn't sound like stereo, or didn't matter, I'd get rid of the track with problems by choosing the better track only. An easy fix.
(If you combine these new channels into mono, maybe you'll get phase cancellation.)

Jim Hoare wrote on 3/7/2009, 9:17 PM

Thanks TGS,
I have learned a lot from your response.
Choosing "Right Channel Only" and Pan at Center, produced the same gun shot sound followed by no audio. However, if I pan left or right (even slightly) the audio is normal. I have had success by using 2 audio tracks and panning 50% L and 50% R. (leaving each track as "both"). It doesn't make sense. I think it's a bug. I will load 8.0c on my 32bit computer and test the same file.

John_Cline wrote on 3/7/2009, 9:37 PM

Based on your description, it sound to me like there is an open ground in your audio playback system. Any sound you have been hearing is the difference between the two audio channels. Check your connections from the output of the computer to your speakers.