Page 1 of 2 12 LastLast
Results 1 to 10 of 12
  1. #1

    video calibration

    hiii there....
    actually i want to ask some technical questions about video sync. calibration which i have read in the link below:

    http://www.mediacollege.com/video/ca...iming/nzrb.pdf

    my questions are:
    1. it is mentioned in this link document that while calibrating ccu cameras,a pst key of the mixer should be used...why not pgm key?

    2. i have a basic grass-vally vision mixer (analog) and there is a difference in subcarrier phase between pst and pgm key about 25 degrees for the same ccu camera sourse input although all the ccu cameras are synced together,how can i fix this problem?(difference in phase between pst and pgm)??

    3. while transition from a source to another (mix), there is a flash slightely appears in the video....does this relate to the s.c. phase difference mentioned in question no.2???

    thanx in advance

  2. #2
    still waiting

  3. #3
    Administrator Dave's Avatar
    Join Date
    Sep 2004
    Location
    Te Awamutu, New Zealand
    Posts
    3,959
    Blog Entries
    79
    If you can wait a little longer, I'm pretty sure my brother wrote that document so I'll ask him about it (I only had a quick scan - I'll have a closer look ASAP). Unfortunately I'm heading away for a few days so I can't make any promises about when I can answer.

    Just quickly, I used to work in the same OB truck referred to in that document, but before it was written (which was a few years ago now). If necessary I'll try my best to recall how it all worked
    Dave Owen
    MediaCollege.com

  4. #4
    thank you dave, i think i can wait.

  5. #5
    Hi there,
    1) Its been a few years now, but it had something to do with the mixer stripping the sync pulse and re-inserting it at the pgm stage. It was most likely just the procedure we devised for our particular configuration - and not the only way to do it.

    2) From memory, the SCH phase discrepancy you have between pst & pgm busses can be rectified by adjusting the sch pot on the middle board of the switcher frame (on a GVG110 at least - not sure of your model sorry). I can look it up in the manual if you have a GVG110.

    3) Yes it is possible this is related to the above, I would suggest sorting the SCH error and seeing if it helps.

    You could also try contacing Grass Valley directly - (http://www.grassvalley.com). I'm sure they would be glad to help.

    Cheers,
    Scratch.

  6. #6
    Administrator Dave's Avatar
    Join Date
    Sep 2004
    Location
    Te Awamutu, New Zealand
    Posts
    3,959
    Blog Entries
    79
    For those of you who haven't been introduced, meet my brother Scratch
    Dave Owen
    MediaCollege.com

  7. #7
    Senior Member SC358's Avatar
    Join Date
    May 2005
    Location
    NYC
    Posts
    608
    Blog Entries
    2
    From what I can recall, PGM has a processing amplifier while PST does not at it's output. There is a timing difference between the 2 banks but that's not an issue because the 2 banks serve 2 different purposes.

    Depending on which model you have, it's either a jumper or a switch to deactivate/
    activate the Proc Amp. All your timing adjustments to Color Black should be on the PGM bank with the Proc Amp off.

    If your timing is very far off, then you will see a sort of flash or jump.
    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

  8. #8
    Administrator Dave's Avatar
    Join Date
    Sep 2004
    Location
    Te Awamutu, New Zealand
    Posts
    3,959
    Blog Entries
    79
    IIRC, we were once instructed to stop timing cameras online because our program feed was permenantly routed to the master control room, and every time we put an unsynched source online it set off alarms down there. So some manager figured the easiest solution was to stop us timing via the program feed. It's not hard to think of a better solution but that's how it goes - just an example of how/why different production situations have different rules.
    Dave Owen
    MediaCollege.com

  9. #9
    first of all i want to thank dave,scratch,and sc358

    mr.sc358, i tried to make the adjustments and to be perfectly similar to each other but flash is still running while mixing!!!!

    scratch, i will show you the picture of that mixer coz i really tried to know its model number but i didn't find it.

    now another question:
    can the lever arm-if its movement is not smooth or let us say(non-linear)-couse the flash???

    actually i tried also to control the lever arm movement by some potentiometers related to lever arm limit,the result was a smooth and perfect mixing but it didn't lock to the another source and hence the red-light didn't work normally!!!!! so i have been disappointed and normalized the lever arm limit to its previous position.

    any conclutions???

  10. #10
    Senior Member SC358's Avatar
    Join Date
    May 2005
    Location
    NYC
    Posts
    608
    Blog Entries
    2
    While checking on your waveform and vectorscope - can you confirm they are both set to EXT Ref? And as a precaution, they should be pre-calibrated to a known reference (Color Bars) as well, prior to systems adjustments.

    Can you also confirm which you are using, PST or PGM (with the Proc AMP off) to do your timing?

    And definitely use the lever arm for transition (either fade or wipe) to see any mis-timing such as jumps or flashes. Does the flash occur just at the end of the transition? Does the flash occur with all certain sources to Color Black?

    Do you use Color Bars? If so, how is the timing between Color Black and Color Bars?
    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Subscribe to us on YouTube