Audio Chriping during capture, not in headphones jack?

Matt Grunau

Matt Grunau

Adobe Demigod
Hi all. I have a whopping total of 15 hours on my DVXa. Though I have owned it for many months, I only shoot with it, and rarely use it as a deck. When I have used it as a deck, it was only for tapes recorded on it. I have only used MQ and PQ Panisonic tapes. Sometimes when I capture I get strange audio chriping and cliping sounds. But, I can as yet find no constant. All drivers for computer gear are up to date, neither computer has ever held a game or touched the internet.

Ok, here goes:


The chirping does not occur in the same places on the tape. It does not come through the headphones jack, so I don't think it is on the tape. It chirps on both of my 2 computer's different capture cards. Sometimes (like tonight) the chriping was very bad at first, but after a few tries, it goes mostly away. The tapes can sometimes be played back on other cameras (GL1&2GL2s) and are fine, other times there is audio chopping, not the chirping as much as audio skips and what sounds like clipping. It happens with ALC on or off, from the onboard mics & from the mic inputs set to mic or line. It usually happens when the audio is reached more than -12dbs (or so), though it is not clipping. It happens more often in 60i then 24p. Tonight, I somehow managed a whopping 59 dropped frames in under 3 minutes (3 clips in a row, capturing constantly with scene detect enabled during capture), on a seperate, defragged hard drive, and on another computer I got dropped frames on a defragmented C drive. Older footage usually plays with less chirping than newer, but I recently captured over 15 minutes of footage in 24p without a single problem, with multiple takes. It happens when captured with Vegas as well as Premiere.

Here are some mp3s. These are the same tape, same camera (though I did capture the tape with a GL1 and the audio chirped a little, and then went clean), different computers, 10 minutes apart.

http://www.paramm.com/smp.mp3
http://www.paramm.com/smp1.mp3

You will hear the chirping sounds in the music clearly.

I can't for the life of me figure out what this is. A loose or faulty firewire jack? Timecode problems? Cold camera? Dirty heads?

I treat this camera very very well, it has never been bumped, dropped, jostled, been in a dirty environment, gotten wet, hot, cold, or anything else which could cause damage. And again, it doesnt play through the headphones jack, and only 15 hours on the heads.

Someone please take a listen and any help/suggestions/ideas are very welcome.

EDIT: The DVX is the only camera to have these audio problems. I have captured from 4 other cameras and never a problem.
 
I here complete drop-out of audio signal. Am I hearing the right thing? Mabye I need to download them.

Andrew Hoffman
 
Never mind. I just downloaded the files and listened to them. I heard the chirping sound that was described. It sounds like dirty heads, Dirty tape path, or mis-aligned tape path. It could also be PG-SHIFTER. If it's giving you dropped frames and causing strange noises, it really sounds like something mechanical. I can't tell without looking at it though.

Best regards,

Andrew Hoffman
Senior Operations Manager
Specialized Communications Corp.
20940 Twin Springs Dr.
Smithsburg, MD 21783-1510 USA
800-359-1858
Fax: 301-790-0173
andrewh@spec-comm.com
www.spec-comm.com

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I played the files in QT and it just did audio dropout, so I don't know exactly what you're referring to here.

However, in the early days of DV editing we used to be plagued with a BEEP that would occasionally happen. Never in the headphones, only on captured footage. The beep turned out to be a minor audio dropout; the camcorder's playback system included error correction that took care of it, but the capture applications didn't, so the horrible beep would get passed straight through.

To get around it, we'd have to either mute a couple of frames here and there, or sometimes we'd actually go back and capture the whole audio track analog and sync it up.

That said, I haven't heard a beep from a DV camera in years. I don't know what software you're using, but it should have been sorted out long ago.
 
Spec-Comm said:
Never mind. I just downloaded the files and listened to them. I heard the chirping sound that was described. It sounds like dirty heads, Dirty tape path, or mis-aligned tape path. It could also be PG-SHIFTER. If it's giving you dropped frames and causing strange noises, it really sounds like something mechanical. I can't tell without looking at it though.
Click to expand...

Thanks. Only sometimes are there dropped frames. Usually, there are no dropped frames when the chirping happens. The video is always perfect.

Is there any way I can send you or post a picture of the inside where you could tell?


Barry_Green said:
I played the files in QT and it just did audio dropout, so I don't know exactly what you're referring to here.
Click to expand...


Thanks Barry. Did both files do the dropout? I played it on Quicktime 6.5 for PC and still head the chirps. They are somewhat subtle, very high end, and sound like mechanical crickets. They also bounce from left to right during play. Software is Vegas and Premiere.



I also seem to have this problem more with MQ tapes than PQ, though being both dry lube I would have figured them to be ok.



EDIT: Andrew, if the heads were misaligned, wouldn't the problem be on the same spot on the tapes if it was recorded that way, or wouldn't they play back with the chriping in the same places? Also, would misalgned tape heads also cause video artifacts which I could look for? I haven't seen any.

If misaligned or mechanical, what would cause the camera to play fine at some times at long durations from the get go? And if misaligned or mechanical, why is it clear through the headphones?
 
Chris_Mueller said:
Is this similar to what I'm experiencing in this thread?

http://www.dvxuser.com/V3/showthread.php?t=43955

Download the audio clip. For some reason I can't really detect anything in your samples.
Click to expand...

I am hearing something around the two second mark that is exactly what I am referring to.

The sample with mine on it is the smp.mp3 above, for those who are having trouble hearing it.




Here is the same sample, with the sound isolated more. It seems to be mainly in the 12k range:

htp://www.paramm.com/smp_iso.mp3

There is a lot of high end here, and each artifact peaks around -6db.
 
Hmm... For some reason I didn't hear it the first time around. I definitely hear it and it's exactly what I hear in my audio section. :(

Does anyone know what's going on?

I've put at least 75 hours on the heads from recording alone. Not once have I cleaned it. Does this sound like dirty heads? (Although I do NOT hear the dropouts on the camera's headphone-out port.)
 
Chris_Mueller said:
Hmm... For some reason I didn't hear it the first time around. I definitely hear it and it's exactly what I hear in my audio section. :(

Does anyone know what's going on?

I've put at least 75 hours on the heads from recording alone. Not once have I cleaned it. Does this sound like dirty heads? (Although I do NOT hear the dropouts on the camera's headphone-out port.)
Click to expand...


That's exactly the same thing I am having, but with only 15 hours on the heads.

Out of curiosity, have you tried the RCA outs to see if it is there as well? And what are you Mic switch settings set to? I just noticed mine were set with the phantom power on. I didn't put them on, so my cameraman on our last job must have. I wonder if that would affect Line In signals or maybe in your case, powered Mic signals.

Maybe this is a power or voltage issue, since both audio chrips during relatively loud sections of the file?

Anyone else have any ideas?
 
I'm having a simluar sounding issue. In the headphones their is no problem but on the tape no audio for a second then it's back. The weird part is some tapes it works fine.

Anyone have any ideas before I send this off to the panasonic repair shop?
 
I have the same problem. Video is fine, audio gives strange artifacts. I recorded with an external Mic using fantom power (both channels on input 2). Artfacts are high chirping digital sounding noise different on both channels. The problem is particularly disturbing in recorded music, not particularly in speech or silence. Only hearable trough firewire capture, not on analog outputs. Used the same tape on a different camcorder and there the audio was clean! I figure the problem must be in the DVX100 conversion to firewire, although this is the first time I have detected this problem, but I'm not using the external Mic for a long time.
I don't think it is dirty heads, that would give video dropouts as well.
 
I am having a similar problem with sound. When I playback the footage there is a drop in sound. I tried lowering my sound levels and upon playback it continued to cut off every six seconds. I have 62 hours of recording. Should I clean the heads? What should I do?
 
solproductions said:
I am having a similar problem with sound. When I playback the footage there is a drop in sound. I tried lowering my sound levels and upon playback it continued to cut off every six seconds. I have 62 hours of recording. Should I clean the heads? What should I do?
Click to expand...

can i check how long is your xlr cable?
did you cross your sound cable with power cable while recording?

best of all, is to send your camera back to servicing.
mine is a brand new 102ben ( pal model)
used in singapore for months for recording events and wedding.
so far, it prove itself well.

www.vocaremedia.com
call to inspire
 
My XLR cable is 30 cm long. However, that is not the problem. I just captured my tape using another camcorder and the sound was fine. I think the problem is in the firewire output from the DVX
Rob
 
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