Sound gliches found on capture

[Bogdan Vaglarov]

To be honest I didn't know where to post this - here, in audio or Pana section?

I captured DV.avi for the first more serious project since my new PC is set up. And it's really the first work I'm doing with NLE (jsut have been experimenting before).

So while I was using my headphones to monitor the sound I noticed stranged 'scramble' sounds (like glich or click, don't know how to call it). It's on aproximately same interval. Also doesn't happens on all the lenth of the captured video.
Older tape recorded on different cam had even more harsh problems like that.
I came up checking the sound right out from the cam and actually I can hear it but not so 'pronounced'.
What is it - cam playback or recording problem? I noticed when the volume recorded were low there were virtually no such gliches.

In the same time while capturing I can see the counter stoping every 2.5 seconds or saw. Is it normal? Aproximately matches the glitch frequency.

Any advice or idea?

[Lars Siden]

Hello Bogdan,

Without any further knowledge of your setup, my guess is that you have a driver problem with your soundcard.

Still guessing: You probably have a builtin soundcard on the MB - make sure that you have the latest chipset-drivers for your motherboard and of course the latest drivers for the soundcard.

Second guess:

If you have a PCI soundcard - and a builtin soundcard, make sure that the builtin one is disabled in BIOS.

Good luck!

// Lazze

[Bogdan Vaglarov]

Hmm...
Well I have both onboard AC97 sound (Realtek) and USB external (Onkyo - very clean sound with analog and digital in/outs).

What you say would be valid for playback during preview or if I capture using the sound device. Generally the NLE wouldn't show this on print to tape or DVD authoring and I have them transfered too.

It seems cam/tape/playback problem.
Have to borow my mother in law's cam to check capturing from it.

[Lars Siden]

Hello B,

Generally I'd agree with you! But we've had several computers with the internal AC97 soundcard that has developed glitches during capture.

When you capture, then the sound is played through the soundcard, if there is an IRQ/Driver problem - then the firewireport will be affected too. Of course I can't be 100% sure that this is your problem!

// Lazze

[Bogdan Vaglarov]

Thanks for the last one.
Could you trouble shoot it after all?
I'll check the IRQ settings.

Also how about the small stops of the time code. It heppans every few seconds but there are no droped frames. Is it possible to be due to the ruller set to NTSC drop frame?

[Mike Rehmus]

<<<-- Originally posted by Bogdan Vaglarov : To be honest I didn't know where to post this - here, in audio or Pana section?
snip

"I came up checking the sound right out from the cam and actually I can hear it but not so 'pronounced'."


snip
Any advice or idea? -->>>

If you are playing the tape in the camera and monitoring the audio as you play the tape, then the sound card won't effect the audio directly from the camera. It perhaps is a slightly dirty head or a broken camcorder.

If you listen to the audio as you transfer into the computer, it will frequently have clicks and pops that do not show up on the timeline.

Does the audio exhibit the clicks when you play directly from the timeline?

[Bogdan Vaglarov]

I didn't examine the timeline very closely but the click waves are masked in the other sounds. I had one-two other harsher noises (probably bump from the operator) which were well visible and I removed easyly.

I have this after capture. During capture I use my LCD monitor speakers just to know what's going on.

I listened the sound again this evening straight from the cam on monitor headphones. I still can hear this noises but they sound slightly different from whats captured. Strange is that they are only in the left chanell. I can't confirm yet if they are matching the places on the captured material.
I have also very quite (almost undestinguishable) clicks in the right chanel which sound exactly as on the captured one.

I have to clean the heads and try also with other cam.
Is it possible just from dirty head to have such a problem. I expect if the heads are dirty to have visual porblems first.

[Lars Siden]

>Could you trouble shoot it after all?

On the machines running windows xp we solved it by using the builtin win xp driver for AC97 from microsoft.

>Also how about the small stops of the time code. It heppans >every few seconds but there are no droped frames. Is it >possible to be due to the ruller set to NTSC drop frame? -->>>

I really don't know - my heart says "can't be the dropframe"... I have some tapes on which the timecode is "damaged" - and when I capture them using scenedetection I have to use "optical"-scene detection and not rely on the timecode...

Hope you get it sorted out!

// Lazze

[Mike Rehmus]

Guys, if the tapes have the artifacts recorded on them, then the fault is either in the tape or the camera, not in his system unless he is saying that there are more artifacts heard on the timeline than when playing the tape in the camera and listening to the tape on the camera audio system.

Drop-Frame doesn't have any different number of frames than non-drop-frame. The counting rules are just different. The only thing that changes in the camera or in the NLE is the ruler changes.