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Forums Broadcasting Headswitching

  • Headswitching

     Tom Matthies updated 9 years, 6 months ago 6 Members · 17 Posts
  • Maria

    March 12, 2011 at 5:41 pm

    We are about to go to master tape for our hour-long documentary which incorporates a number of different footage sources. We have already converted all of our non-23.98fps footage to our 23.98 ProRes timeline and color corrected; but we are just realizing that in our Quicktime movie there is a small amount of headswitching visible in footage that was shot HDV Pal 25fps. We did not notice this after the conversion at the quality control session.

    We are prepared to blow this up 2-3% if necessary, but it’s not ideal since this footage is HDV. We are wondering if it’s possible that this is an underscanning issue: that we are seeing a part of the frame that no one will see through any form of projection or broadcast. Does anyone have any experience with this issue? Do you know if broadcasters will reject footage with this problem?

    Many thanks.

    Maria Luisa Gambale
    Brooklyn, NY

  • Chad Brewer

    March 13, 2011 at 12:47 am

    Head switching was sometimes visible in old analog recording like VHS and U-Matic. Whatever you’re seeing is not head switching as you say it’s only on footage from 25fps HDV (PAL refers to SD).

    It is possible that whatever you’re seeing will not be displayed in correctly broadcasted/projected overscan situations, but I don’t know exactly what you’re seeing.

    It’s possible that these HDV clips have not been converted or scaled correctly to the rest of your project which I’m assuming is not HDV frame size.

    Have you had the chance to view what you’re seeing as problematic on a broadcast monitor yet? If not, what program are you viewing this through that is creating the worry? – that could make a difference as different software viewers have different aperture settings. It’s most likely something that will not come through in proper scan, but I can’t say for sure. Posting a screen shot of what you are seeing would be most helpful.

    Chad Brewer
    Senior Broadcast Videotape Operator
    TeleVersions, LLC

  • Rafael Amador

    March 13, 2011 at 2:02 am

    I agree with Chad; have a look again to that footage.
    HDV should perfectly fit the HD frame.

  • Maria

    March 13, 2011 at 3:21 pm

    I’ve attached the image. Apologies for the terminology confusion; our Executive Producer threw the name in the ring, and we all just adopted it.

    Updated information:

    The footage is actually old DV material, still PAL. We are working in a 1920×1080 timeline.

    It seems like these problem parts of the 1920×1080 image would show in projection and on HD flatscreen TV’s.

    So, some people here in NYC have actually recommended that we crop the whole movie. Our editor is trying 0.5 crop in FCP for the bottom and 0.2 for the top. But we want to confirm that this is an acceptable fix for broadcast and for theatrical projection. Otherwise, we’d have to blow up just those shots (DV, approx. 5-6 minutes in a 57-minute movie) 2-3%.

    I’ve attached an image, but it’s really hard to tell from a still image. At the bottom of the image, you can see the width of the stripe in the white wall where the bad part is slightly brighter. It’s also happening on the top, and you can tell at the right of her head scarf.

    Thank you all for your advice so far!

    Maria Luisa Gambale
    Brooklyn, NY

  • Bob Zelin

    March 13, 2011 at 9:01 pm

    I am so happy that you posted this, because now I have
    an opportunity to yell at you, and your company.

    Guess what – you have technical problems. Guess what, you live
    in NYC, where there are COUNTLESS qualified video engineers, countless
    qualified professional post houses, and countless places to buy or rent
    a waveform monitor for you to analyze what is going on.

    to figure out what is going on. Your crap at the bottom of the screen can be
    anything – “head switching noise” (which was prevalent from older VTR’s with TBC’s in them),
    or blanking errors, or something else. Even I could not diagnose what is going on
    unless I saw it on a waveform monitor to see if it was legal.

    This is exactly what broadcasting is about, and this is exactly what standards are about
    and using professional people with professional equipment is about.

    Will your stuff get rejected – ABSOLUTELY. Do you need to figure out what is going on –
    ABSOLUTELY. This is done by all of what I have mentioned before –

    1) Hire a freelancer that knows broadcast spec, or a freelance engineer
    2) Rent or buy a waveform monitor (no, not the one built into FCP or your AVID)
    3) go to one of the 1000 post houses in NY that have the staff and equipment that can
    analyze this for you.

    I used to hate all these standards, but I now realize, that this is what keeps hi end places
    in business.

    Bob Zelin

  • Chad Brewer

    March 14, 2011 at 12:41 am

    Bob is also from NYC, if you couldn’t tell, and now you’ve both met on the COW.

    It is very true that certain portions of all images should be under the view of a professional scope. In your case, I would not crop the entire film, only minimally crop the PAL DV shots to eliminate what appears to be how interlaced lines drawn in DV are “exposed” when uprezed to 1080. Nothing will be rejected by such a slight cropping before mastering to tape

    When you master to tape however, it will be up to the mastering house to make sure that your entire program is in spec based on scope measurements and other tape layout procedures when it goes to a professional VTR based on the requirements set by whomever will be receiving the program.

    Bob’s suggestions have credence.
    Hopefully this helps as well.

    Chad Brewer
    Senior Broadcast Videotape Operator
    TeleVersions, LLC

  • Bob Zelin

    March 14, 2011 at 9:17 pm

    answer me this Chad,
    how do you create a show for broadcast delivery with –
    1) no test equipment
    2) no professional trained personel
    3) no willingness to go to a “mastering” house or professional post production house”
    4) no willingness to rent the proper equipment to accomplish this

    tell me Chad – how do you make a broadcast show, without hiring the correct staff or equipment ? How do you do it with untrained unqualified personel, or without the right equipment ? Or the unwillingness to to out of house, to have it done for you ?
    Tell me Chad – how can the owner of this company keep all the profits for himself, without spending one penny to accomplish this ?

    bob Zelin

  • Sam Cole

    March 14, 2011 at 11:35 pm

    Bob – we deal with these types all the time. It is a real education to them when they see what we go thru to ‘legalise’ their product before it goes to tape.
    And then we send them the bill and they SCREAM!!!

    But creatives are just that and to edit a show without concern for the technicals is a weight off their shoulders and more money for my company.

    Sam Cole
    On line Mastering Facility
    FCP, Avid, Adobe
    Sydney, Australia

  • Chad Brewer

    March 15, 2011 at 12:14 am

    [Bob Zelin] “tell me Chad – how do you make a broadcast show, without hiring the correct staff or equipment ?”

    In my last post I mentioned going to a mastering house, did I not? Where did I come off saying professional equipment and professionals who know how to use the equipment are not necessary? One is EXTREMELY challenged and/or doomed for rejection in meeting broadcast specs without them. That’s one of the reasons companies like TeleVersions are still in business. Being one of, if not the Midwest’s highest-end broadcast/mastering facilities with all the necessary equipment, I’m so used to people in situations like this coming to a dedicated facility like ours to ensure their mastering is to whatever broadcast spec must be met.

    In offering my advice on the original post, I guess I was assuming they were prepping this to take to a mastering house. In no way was I insinuating that mastering for broadcast can be achieved without the proper equipment and personnel. If I was, the company I work for would be out of business and I would be unemployed.

    I don’t know why your post was directed towards me (instead of cheapskates out there who think they can do it all themselves without professionals like us). Why would I invalidate what I do every day to make a living?

    Chad Brewer
    Senior Broadcast Videotape Operator
    TeleVersions, LLC

  • Maria

    March 15, 2011 at 12:23 am

    This chain of messages is very funny. Just to clear up a few wrong assumptions (though I hate to break anyone’s stride here), we are taking it to a post house for mastering. They hardware-converted the offending footage for us originally and didn’t catch the problem. We discovered the issue over the weekend with a tape mastering session planned at the post house for Monday morning. Not being able to reach them, we were trying to figure out some possible answers over the weekend from anyone who was available, so that we could show up prepared with options, as our film is due to be sent to an international festival tomorrow.

    I did manage to consult off the forum with some editors and post-production professionals, and we got our answers. Notably not here.

    Maria Luisa Gambale
    Brooklyn, NY

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