power outage disaster
by Post Office Video
on
Jan 25, 2007 at 7:40:12 pm
I was shooting some interviews with my JVC GY-100A HDV camera with AC power. A breaker blew and I lost camera power. After restoring power I saw that timecode and white balance had been retained. We were pressed for time so we continued the interview. I checked the end of the tape & it was fine. Unfortunately, I later discovered that everything recorded before the power outage was unplayable. It had timecode and audio but no video. Every 2 or 3 seconds there is a glitch in the audio and video. I presume that the video does not work because the glitching is preventing complete GOP's. This has happened to me before when shooting beta but in that case the video was still playable.
If anyone has a suggestion I would love to hear it. If not, hopefully this will prevent someone else from suffering my fate.
Re: power outage disaster by santellavision on Jan 25, 2007 at 7:49:42 pm
The footage at the head of the tape (way before the power interuption) won't play? I don't understand how footage recorded minutes or hours before won't play. That's the craziest thing I have ever heard.
Re: power outage disaster by David Smith on Jan 25, 2007 at 8:32:10 pm
Wow, so sorry for your troubles. It does indeed seem an odd problem though. I don't know that camera but is it possible when you got it working again some format setting had been switched (fps, 50/60 cycles something like that)? Perhaps the subsequent footage was shot at the new settings and the camera won't play back the other footage because it's now in a different setting. Just a wild guess, but on the face of it it doesn't make sense that footage shot before the problem is no good.
Had you done a test record and playback before the interview started? We always do that, taking a look at bars, at pictures, and listening to audio playback. I hope you can resolve the problem!
Re: power outage disaster by Post Office Video on Jan 25, 2007 at 9:12:13 pm
I am sorry to say that I did not do a test record first. I tried your advice about inadvertently changing from 60 to 50- good idea but that wasn't it. I did not touch any settings after the power hit. I also got a suggestion that perhaps the tape had become twisted in the shell and was facing the wrong way out- also a good idea but that wasn't it either.
At this point my best guess is that there was something wrong with the camera that was reset by the power hit...
Re: power outage disaster by David Smith on Jan 25, 2007 at 10:34:52 pm
Ouch. So sorry Chris. Any chance it reset the frame rate, like into or out of 24fps? Interlaced to progressive? It's just so weird that you should have audio and timecode AND have some mysterious video anomaly that disappears when the camera takes a power hit.
Re: power outage disaster by epontius on Jan 25, 2007 at 11:24:21 pm
I'm thinking that it's probably still GOP related...The sudden power interruption most likely didn't allow the camera to gracefully finish up whatever it does when you press the record button again to stop recording. And starting and stopping the recording after the incident would have allow it to complete..
The million $ question would be to make sure that material that you recorded on other tapes previous to the incident still playback properly. If not that would point to there being something majorily out of whack with the recording mechanisms.
Re: power outage disaster by santellavision on Jan 25, 2007 at 11:29:16 pm
Chris,
Was the damaged footage before the power crash all one take? Or were there multiple starts and stops? If it was one long continuous take and it crashed before stopping, that might explain the GOP not being finished correctly.
Re: power outage disaster by David Smith on Jan 25, 2007 at 11:47:13 pm
[epontius]"The million $ question would be to make sure that material that you recorded on other tapes previous to the incident still playback properly. If not that would point to there being something majorily out of whack with the recording mechanisms."
That's an excellent point. I've seen it happen with head alignments. Recordings that could only be played back on the machine that created it. Another test would be to see if the second part of the interview plays back on another camera or deck. If not, it could point to the same kind of issue.
Re: power outage disaster by Post Office Video on Jan 26, 2007 at 1:02:04 am
I did start and stop the camera during the takes damaged by the outage. I was shooting in 720p. I will try playing back in the camera at 24fps- I usally use 30. My HDV deck usually changes over automatically when it detects that, however.
