Bad video ruining Audio Only capture??

[Walter Biscardi]

[Mo] “Is this making sense to anyone? Is there some reason that the goofy video would cause FCP audio capture problems even though I do have consistent timecode?”

Yep, if the video levels in the feedback get up to around 120IRE or so, you’ll get some bleed into the audio track. That’s why you’ll occassionally hear audio breakup when watching local commercials because the whites are too high.

Walter Biscardi, Jr.
https://www.biscardicreative.com

Now editing “Good Eats” in HD for the Food Network

“I reject your reality and substitute my own!” – Adam Savage, Mythbusters

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[Walter Biscardi] “Yep, if the video levels in the feedback get up to around 120IRE or so, you’ll get some bleed into the audio track. That’s why you’ll occassionally hear audio breakup when watching local commercials because the whites are too high.”

Whoa, there. “Apples-to-oranges” comparison.

This explanation (“bleed into the audio”) is only applicable only if the material was being BROADCAST, for gosh sake.

With on-air and cable TV, the video and audio are MODULATED together in such a relationship (“RF offset”) that if the video gets overdriven it can cause artifacts in the audio when the TV receiver attempts to reconstruct the signals.

BUT, on analog video TAPE, if the audio is on the linear (Ch.1 & Ch.2) tracks, they have NO “CONNECTION” or interaction with the video tracks at all.

Especially because the video is a modulated RF signal recorded by the rotating heads, and the audio is standard “audio tape analog” recorded on one edge of the tape and played by separate stationary heads. (Yes, without video and control-track the audio would be unstable, but that’s a different matter.)

If this is BetaCam SP and you happened to be using the AFM (“Hi-Fi”) audio tracks (Ch.3 and Ch.4), those channels ARE recorded “ALONG WITH” the video by the rotating video heads.
But its still not likely that “over-driven” video would cause audio problems as the two portions of the signal are processed in different manners from each other.

And many times the AFM tracks of BetaSP are not even used.

I don’t know where the problems you have with your video tape are coming from, but unless this was recorded off-the-air (and/or the audio was “bad” EVERY TIME YOU PLAY IT) its not “colorful video” ruining the audio “directly” (see below).

[Mo] “I can just play the tape and all is well, but log and capture is a no go on quite a few of the clips.”

I assume you have the Beta connected to FCP via the AJA io.
The wild video MIGHT be causing some odd behavior in the AJA (similar to, but not the same as, my “broadcast” example).

Try this:
Disconnect the Beta’s video from the AJA (maybe send some other stable video source into the analog video input instead of the Beta’s video… just for this dub).
See if that clears this up.

[Walter Biscardi]

[Matte] “BUT, on analog video TAPE, if the audio is on the linear (Ch.1 & Ch.2) tracks, they have NO “CONNECTION” or interaction with the video tracks at all.”

All I can tell you is that when I was using BetaSP all the time for Capture, this issue would pop up at least once a year and it was always a result of completely blown out whites in the image.

Walter Biscardi, Jr.
https://www.biscardicreative.com

Now editing “Good Eats” in HD for the Food Network

“I reject your reality and substitute my own!” – Adam Savage, Mythbusters

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[Walter Biscardi] “All I can tell you is that when I was using BetaSP all the time for Capture, this issue would pop up at least once a year and it was always a result of completely blown out whites in the image.”

My comments where it direct response to what you said before:
[Walter Biscardi] “That’s why you’ll occasionally hear audio breakup when watching local commercials because the whites are too high.”

But in PRODUCTION (not broadcast or cable-cast) it is simply not possible to distort the linear audio track on a video tape from over-driven video.

They are not related.

Again, if you have audio problems related to video on CAPTURE, I would look to the CAPTURE SYSTEM as being the “link-in-the-chain” adversely affected by the hot video in these cases.

[Mo Gardner]

I am using the AJA Io, by the way.
Hey, thanks for the lively discussion gentlemen. I will try the “capture now” and if all else fails, dub it to another tape and add a stable video signal.

… ever forward

[Tom Matthies]

If you’re using an AJA for capture and the video seems to be causing problems, try feeding the AJA with a stable video source, such as black burst into the composite inputs rather than the component output from the beta deck. Then just capture the audio portion as you normally would. If the timecode or the control track is messed up on the Betacam tape, try using capture now and uncontrollable device settings.
should work.
Tom

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[Tom Matthies] “try feeding the AJA with a stable video source, such as black burst into the composite inputs rather than the component output from the beta deck. Then just capture the audio portion as you normally would.”

[Matte] “Try this:
Disconnect the Beta’s video from the AJA (maybe send some other stable video source into the analog video input instead of the Beta’s video… just for this dub).”

I detect a “trend” forming.

[Mo Gardner]

I took the tape and inserted black all the way through. Had no problems digitizing thereafter. It a miracle! But seriously, I find it odd that garbage video would cause audio digitizing problem despite the presence of consistent timecode??!!?