Need help RE: "stuttering" audio on older DV tapes during capture

[seaoharewhy]

Hoping someone can point me in the right direction. I'm rather new to this, and am learning as I go.

I want to transfer my old DV tapes to DVD. These are the "digital 8" tapes, not mini-DV, so theyre the same size as the older hi-8s, if that matters. I'm using premiere pro cs3 to capture and i'm firewired 6 pin to 6 pin from camcorder directly into computer. Normally, I have no problems, and I know the problem is the tapes themselves, as the video is blocky and pixelated in sections, but the main problem is the audio. Its horrible and stutter-y throughout. The strange thing is that this stutter effect is only present when running it through computer, and NOT when i just playback directly on the camera. The video pixelation is present on both, but its mininmal enough so I dont mind. Also, my newer tapes capture perfectly. Its just the older ones that are bad...

What I want to know is, do I need to have these professionally restored/cleaned, or can someone recommend a particular setting that miight boost an audio signal or speed up the transfer rate of the data? I've got over 30 tapes, so I would rather not have to spend all that money for pro restoration. I've submitted a sample of the proble. Any help, greatly appreciated. Thanks

bad%20audio%20sample_.wmv

[edDV]

Looks to me like dirty heads. Have you used a cleaning tape or had the camcorder cleaned in a service shop?

For Digital8, Hi8 tapes can be used but old ones that are recorded over tend to get sticky. I've even had good results recording to new Video8 tapes but these need to be dubbed since the signal to noise margin is minimal for archiving.

[seaoharewhy]

Looks to me like dirty heads. Have you used a cleaning tape or had the camcorder cleaned in a service shop?

For Digital8, Hi8 tapes can be used but old ones that are recorded over tend to get sticky. I've even had good results recording to new Video8 tapes but these need to be dubbed since the signal to noise margin is minimal for archiving.

no, i havent had the heads cleaned, but thats because the camcorder itself works fine when it plays tapes that are newer. its literally a situation of the older the tapes, the worse the quality... the newer ones are pretty much fine. and again, its just the audio thats the issue. thanks for your help -- but i dont think cleaning the heads will do it..

[edDV]

Clean playback from digital video tape is mainly a signal to noise issue. Data is recovered so long as signal to noise is adequate. As noise builds, data begins to show errors. DV error correction is good but when the noise wins, pixels, lines or frames are corrupted. Audio is affected since it is interleaved.

Unlike analog, rusty bearing flutter and wow don't become an issue until data timing is lost.

Different tapes have different signal to noise performance. Newer formulations are better than older. More important is tape tracking. If the playback camcorder is different than the recording camcorder, tracking misalignment may affect signal to noise and cause data loss.

If the camcorder is well used, it probably needs cleaning as a first step.

[2Bdecided]

Did you change the recording mode at some point?

LP will play back less reliably than SP (nothing you can do about that now!)

More usefully, some software spits out 32kHz 12-bit audio, while handling 48kHz 16-bit audio just fine. What do you have?


If you're using the same camcorder that you recorded with, then the issue could be that the heads are worn. The old tapes are "correct" but don't play - the newer tapes match the worn heads so play.

This is very dangerous - it implies that when this camcorder dies, you may not be able to play back those newer tapes properly on any other machine, because they weren't recorded properly in the first place.

Cheers,
David.

[seaoharewhy]

hi --

no, i always use sp, never lp. and i am capturing with adobe premiere. the thing is, the sound is messed up even when its just being played through the system, regardless of whether i'm actually capturing or not

[JohnnyMalaria]

I don't agree with the heads being the problem. That usually shows up as banding.

Not only is the audio a problem but the video also shows signs of problems. If you look closely you will see that when there is movement (e.g., the man moves his head) then you get blockiness. This is because of the DV specification's way of dealing with corrupt data. When the data are very corrupt, the camcorder (on playback) will replace the corrupt data with the data from the previous frame from the same part of the image.

Given the audio and video issues, it has all the hallmarks of excessive dropouts. In short, your tapes are most likely deteriorating

[edDV]

hi --

no, i always use sp, never lp. and i am capturing with adobe premiere. the thing is, the sound is messed up even when its just being played through the system, regardless of whether i'm actually capturing or not

Is the sound "messed up" when playing from the camcorder audio out jacks?

[2Bdecided]

John,

I didn't download the sample.

Is it common for DV tapes to deteriorate like this? I haven't seen it on my ten year old tapes (yet!) (I don't have any Digital8).

Cheers,
David.

[JohnnyMalaria]

I haven't first-hand experience (thankfully) but the appearance of the blockiness in the sample is exactly what would happen if the camcorder is using the error concealment methods defined in the DV spec, i.e., corrupt macroblocks in one frame are replaced by those from the previous frame.

It would be interesting to recapture the same portion of the tape and see if the errors are the same.

As edDV suggests, it would be wise to see what the analog outputs are like (audio and video) in order to rule out FireWire/PC issues.