Tape mechanisim problem at DVinfo.net

Pete Cofrancesco · November 11th, 2012, 10:50 AM

I was importing from a wedding and one of the cameras had a tape drive problem. Every few seconds the camera stops or skips over 3 seconds of footage. The end result was 600 tiny clips for an hour of footage. I don't understand it, I use the camera on a regular basis without issue, I had the entire tape mechanism replaced 6 months ago. I used new tapes same brand in both cameras. I even tried recording at the end of the tape that was at issue and it filmed and imported without issue.

When I was filming the wedding there were no warning messages. I discovered that the footage is all there it just can't be played back properly. When I play/fast forward on the camera I could see all the footage, which gave me the idea to import the footage via analog in slow frame by frame mode. Which worked but its SD and no audio.

It was a rainy day but the wedding was filmed indoors and there were no condensation error warnings. Thankfully I filmed with backup camera even though the client paid for only 1 camera. Of all the times something could go wrong why then?

Chris Soucy · November 11th, 2012, 01:35 PM

Hi, Peter............

You may have just been on the recieving end of what I've termed BSOD (Blue Screen Of Death) syndrome, though without it's trademark blue screen.

It is possible, either through operator error in fitting the tape or a tape fault itself, for the tape to misload and then mistrack during the write.

There is no warning, no error message, nada untill you come to play the tape back after rewinding it.

In a typical BSOD situation, the mistracking during the write means that data required to re - assemble I frames from the data stream simply isn't there on the tape, so no data can be retrieved.

Usually, the master frames can be seen during FF or Rew, though corrupt, they are at least mostly full frames.

When I said earlier about "operator error", this seems to be particularly prevalent during long shoots, where tapes are being swapped in/ out as fast as possible, and I suspect, not being fully pushed home in the carrier as a result of undue haste.

(That said, I've never been able to recreate this problem no matter how I've mishandled the tape!).

If it is a partial BSOD, the data simply wasn't written to the tape, as the tape wasn't where it was supposed to be in relation to the write heads.

Depending on the degree of mistracking, there will be more or less data loss, beyond a certain point HDV simply cannot recover the missing information, despite it having an exceedingly robust error recovery algorithm.

In those few cases where I've heard back from anyone suffering from this, the tape has always subsequently worked (recorded/ played) just fine, it's just the original recording that is toast.

If the next 2 or 3 tapes you run through the camera work just fine, I'd say it was a partial BSOD.

CS

Pete Cofrancesco · November 11th, 2012, 09:00 PM

the strange part is all the video data is on the tape. I proved this when I captured it in slow motion. I flipped open the tape door and look at the tape and doesn't look physically damaged in anyway.

November 11th, 2012, 10:50 AM	#1
Pete Cofrancesco Inner Circle Join Date: May 2004 Location: USA Posts: 3,005	Tape mechanisim problem I was importing from a wedding and one of the cameras had a tape drive problem. Every few seconds the camera stops or skips over 3 seconds of footage. The end result was 600 tiny clips for an hour of footage. I don't understand it, I use the camera on a regular basis without issue, I had the entire tape mechanism replaced 6 months ago. I used new tapes same brand in both cameras. I even tried recording at the end of the tape that was at issue and it filmed and imported without issue. When I was filming the wedding there were no warning messages. I discovered that the footage is all there it just can't be played back properly. When I play/fast forward on the camera I could see all the footage, which gave me the idea to import the footage via analog in slow frame by frame mode. Which worked but its SD and no audio. It was a rainy day but the wedding was filmed indoors and there were no condensation error warnings. Thankfully I filmed with backup camera even though the client paid for only 1 camera. Of all the times something could go wrong why then?

November 11th, 2012, 01:35 PM	#2
Chris Soucy Inner Circle Join Date: Feb 2007 Location: Fairfield, Dunedin, New Zealand Posts: 3,691 Images: 18	Re: Tape mechanisim problem Hi, Peter............ You may have just been on the recieving end of what I've termed BSOD (Blue Screen Of Death) syndrome, though without it's trademark blue screen. It is possible, either through operator error in fitting the tape or a tape fault itself, for the tape to misload and then mistrack during the write. There is no warning, no error message, nada untill you come to play the tape back after rewinding it. In a typical BSOD situation, the mistracking during the write means that data required to re - assemble I frames from the data stream simply isn't there on the tape, so no data can be retrieved. Usually, the master frames can be seen during FF or Rew, though corrupt, they are at least mostly full frames. When I said earlier about "operator error", this seems to be particularly prevalent during long shoots, where tapes are being swapped in/ out as fast as possible, and I suspect, not being fully pushed home in the carrier as a result of undue haste. (That said, I've never been able to recreate this problem no matter how I've mishandled the tape!). If it is a partial BSOD, the data simply wasn't written to the tape, as the tape wasn't where it was supposed to be in relation to the write heads. Depending on the degree of mistracking, there will be more or less data loss, beyond a certain point HDV simply cannot recover the missing information, despite it having an exceedingly robust error recovery algorithm. In those few cases where I've heard back from anyone suffering from this, the tape has always subsequently worked (recorded/ played) just fine, it's just the original recording that is toast. If the next 2 or 3 tapes you run through the camera work just fine, I'd say it was a partial BSOD. CS

November 11th, 2012, 09:00 PM	#3
Pete Cofrancesco Inner Circle Join Date: May 2004 Location: USA Posts: 3,005	Re: Tape mechanisim problem the strange part is all the video data is on the tape. I proved this when I captured it in slow motion. I flipped open the tape door and look at the tape and doesn't look physically damaged in anyway.