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Horizontal Shift during long playback
Hello –
I’m having the following problem at a facility I occasionally work at.
Nobody else there has been able to resolve this issue, so I thought I’d give it a shot.First, the set-up:
Dual 2.7 GHz Power PC G5/2.5 GB DDR SDRAM
Mac OS X 10.4.2
FCP 5.0.2
AJA IO model: 0x1
ATTO ExpressPCI UL4D
Medea 613 GB RTV RAID drive
ATI Radeon 9650/VRAM: 256 MB
Sony BVW-75And now, the problem:
On longer outputs (typically a 26 minute show)via “Edit To Tape” there will be random, intermittent Very noticeable Horizontal shifts. The shift is about 1 frame. In subsequent attempts to output, the shift will not occur at the same location but it will occur. It will occur as often as every 1 -3 minutes, or with less frequency, again, seemingly randomly.
The audio outputs flawlessly to the tape.In shorter outputs this shift will not occur.
The captured media on the drive is fine and does not display any shifts.
I’m pretty sure that the shift does not occur on the desktop window, only on the output to tape. An engineer has checked the deck & heads and declared them to be fine.Any insight or advice is greatly appreciated.
– Jesse Gordon
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14 Replies
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Are you feeding blackburst to the AJA and the BVW-75?
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I am pretty sure that they do not have an external blackburst generator hooked up in there. I believe they have connected sync between the IO and the deck.
However if that was the issue shouldn’t I see the horizontal shift during the shorter ouputs as well?– Jesse
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>However if that was the issue shouldn’t I see the horizontal shift during the shorter ouputs as well?
Not necessarily. As you said, in longer transfers it is random and sometimes happens further apart than others, so in therory shorter pieces may be fine. Blackburst is a composite signal with a horizontal sync pulse. So from your description of the horizontal shift, it would appear that the lack of a refernce between your equipment could be the cause of the problem. Then again it may not be, but I would at least hook up a blackburst generator to see if it solves it.
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Jesse writes –
I am pretty sure that they do not have an external blackburst generator hooked up in there. I believe they have connected sync between the IO and the deck.
However if that was the issue shouldn’t I see the horizontal shift during the shorter ouputs as well?Hi BOYS – are you ready ?
Jesse, we will have to kill you. I have ranted like a maniac on this forum, and other forums over and over again – HOOK UP A G#$ DAMN BLACK GEN TO YOUR CAPTURE BOARD – I don’t care if its an AJA IO, and AJA LS, LH, Kona 2, Blackmagic, etc. Don’t complain to me about jitter, shifting, instability, shakey picture, etc. if you don’t have a common house black between your VTR and your editing system. AND once you have a BB gen hooked up, go into the AJA I/O control panel, click on Control, and make sure that it is in REF VIDEO, to make sure the AJA I/O uses the genlock input. When you say “they have connected sync between the IO and the deck” – this means NOTHING (imagine me screaming when I say NOTHING). NOW, once you hook up a GOOD QUALITY BLACK GENERATOR (including the cheap Horita BSG-50 not BG-50), do your tests again, and if you STILL have a shifting problem, then we can proceed. SO LET ME ASK YOU – the person who said that there is nothing wrong with your VTR, and has checked the deck and the heads – what kind of qualifications does he/she have, if they don’t understand the most basic hookup questions.Jesse – I am not saying that you can’t get shifting once you hook up a common black reference to the AJA and the VTR, but we can’t diagnose anything until you do.
Thanks –
Bob Zelin -
Note the TC where the shift occurs and check it at playback. If the shift is still there then it is not an external reference issue. While annoying, the external H shift in Sony Betacam machines does not affect the recording.
lee
http://www.leebergermedia.com -
Hi Lee – I respectfully disagree. If this gentlemen is doing insert edits, and he did not black his tape in 4 field to record the color framing info, he has the potential AT INSERT EDIT POINTS to get a color frame h shift. But it appears (and I could be wrong) that he is getting random shifting from simply playing back his material. Now certainly, he should not have this issue (even with no black generator) if he has selected FREE RUN in the AJA IO control panel, but becuase he is having this issue, we must eliminate as many possibilities as possible.
Bob Zelin
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Bob,
You may be right. The more I think about it the reference issue causes the video and blanking to shift vertically not horizontally. From his post it sounds as if the H shift is happening randomly during a full program edit to tape. Perhaps he should try a different deck if one is available. He could also try just recording the sequence without using the edit to tape feature.Lee
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Thanks for your responses guys.
Sorry if I didn’t do a good enough job of searching before posting: I scanned the last 3 months but should have looked back further.
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Bob:Hi BOYS – are you ready ?
Jesse, we will have to kill you. I have ranted like a maniac on this forum, and other forums over and over again – HOOK UP A G#$ DAMN BLACK GEN TO YOUR CAPTURE BOARD – I don’t care if its an AJA IO, and AJA LS, LH, Kona 2, Blackmagic, etc. Don’t complain to me about jitter, shifting, instability, shakey picture, etc. if you don’t have a common house black between your VTR and your editing system. AND once you have a BB gen hooked up, go into the AJA I/O control panel, click on Control, and make sure that it is in REF VIDEO, to make sure the AJA I/O uses the genlock input. When you say “they have connected sync between the IO and the deck” – this means NOTHING (imagine me screaming when I say NOTHING). NOW, once you hook up a GOOD QUALITY BLACK GENERATOR (including the cheap Horita BSG-50 not BG-50), do your tests again, and if you STILL have a shifting problem, then we can proceed.
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Jesse:
I’ll recommend that they get themselves a blackburst generator.
You’re saying Horita BG-50 = not adequate, BSG-50 = OK?
Still seems a little weird that there is no shift on shorter outputs, but a long output it will occur within the first few minutes.
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Bob:
SO LET ME ASK YOU – the person who said that there is nothing wrong with your VTR, and has checked the deck and the heads – what kind of qualifications does he/she have, if they don’t understand the most basic hookup questions.
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Jesse:
This particular suite is located in a Production Facility where multiple broadcast programs are produced. There is at least one engineer attached to the facility and I believe another attached to the show who comes in only on the days when they tape the show.Dunno which one OK’ed VTR this happened before I was called in. (Note that I was not involved with configuring this room.) The first 2 times I worked on the show, I only had to ouput the 2 – 3 minute tease, and so there was no problem. This only happens on longer outputs.
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Bob:
Jesse – I am not saying that you can’t get shifting once you hook up a common black reference to the AJA and the VTR, but we can’t diagnose anything until you do.Thanks –
Bob Zelin
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THANK YOU!
– Jesse -
The shift is present on the tape.
INSERT EDITS are clean.
Let me check the AJA IO control panel settings. Maybe it is not set to FREE RUN.
thx,
Jesse[Bob Zelin] “i Lee – I respectfully disagree. If this gentlemen is doing insert edits, and he did not black his tape in 4 field to record the color framing info, he has the potential AT INSERT EDIT POINTS to get a color frame h shift. But it appears (and I could be wrong) that he is getting random shifting from simply playing back his material. Now certainly, he should not have this issue (even with no black generator) if he has selected FREE RUN in the AJA IO control panel, but becuase he is having this issue, we must eliminate as many possibilities as possible.
Bob Zelin”
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Jesse:
This particular suite is located in a Production Facility where multiple broadcast programs are produced. There is at least one engineer attached to the facility and I believe another attached to the show who comes in only on the days when they tape the show.Wow! That is the first time I have heard of a facility producing multiple programs for broadcast that doesn’t have a house sync generator. What the hell are they thinking? Or not?
Horizontal shifts can also be attributed to incorrect timing callibration of the component video signals so if their engineers aren’t smart enough to have a blackburst generator in the faclilty they may not be smart enought to check the callibration of their machines. Tektronics website has a great downloadable booklet called NTSC video Measurements, that would be worthwhile taking a look at and maybe passing it on to their engineers.
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