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Terminology Assistance

May 16, 2013 3:48 AM

Hi,

 

Just a quick one, I am re-reading the BBC SPec sheet as I feel I need to get to grips with it 100%, as we are about to go into shooting proper, and I still dont really know what Time Code is all about!!

 

Once of the sections mentions that Electronically generated moving graphics and effects (such as rollers, DVE moves, Wipes, fades and dissloves) must be generated and added as interlaced to avoid unacceptable judder.

 

Ok, I get wipes, fades and dissolves, but what are rollers and DVE moves? and since we are shooting and editing in 25p, is this still neccesary?

 

Thanks

 

Pierre

 
Replies
  • Currently Being Moderated
    May 16, 2013 4:45 AM   in reply to Pierre Devereux

    You'll have a hard job cutting on the wrong field with 25P material so you can ignore that one. In fact it is hard on any NLE to cut on the 'wrong' field. (Sometimes material comes in from a studio where the vision mixer is set to switch on 'either' field - where 50% of the cuts are wrong - but that hasn't happened to me for a few years now.)

     

    A roller is an end credit roller, a DVE move is really any sort of 'Digital Video Effect' (e.g. slides, pushes, zooms etc).

     

    If you render with fields enabled (Upper first) then you'll get field based motion.

     

    You can see the difference if you export a small animation - one with fields off, one with fields on.

     

    Reimport and put in a 50fps composition... step frame by frame and you'll see animation every frame on the 'fields' rendered, but only every other frame for the 'frame' rendered default.

     

    (I think 50fps comp is only way of stepping by fields in AE?)


    But then are you really 'editing' in AE?

     
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  • Currently Being Moderated
    May 16, 2013 5:55 AM   in reply to Pierre Devereux

    The FAQ on this site have two sections that will help you avoid "judder" or Flicker. I also wrote an article on judder that you'll find here.

     

    You must be aware of and check for these problems in every stage of production. You must also watch for judder with camera moves. Shooting at 25P you will also run into problems with Critical Panning speeds that cause the same problem with video and film. Since a lot of your work involves miniatures you'll have to be especially careful about this.

     

    The only way to really check your footage for these problems is to view the footage on a broadcast monitor. Refresh rates on computer displays can hide problems or show problems that don't exist in a broadcast situation. It's also important that you watch your finished footage from a proper viewing distance. Too close or too far away and your eyes can start to play tricks on you.

     

    If you get everything to work and your picture and sound are great then prepping for compression for final delivery is just a matter of using the right settings in your compressor. Every network has their own standards. If your production master is perfect simply loading up a standard and approved preset for delivery is all that it takes to perfectly match the delivery standards.

     

    I hope this helps. I hope you realize how lucky you are to have a long term paying gig that gives you the chance to ask these questions.

     
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  • Currently Being Moderated
    May 16, 2013 5:59 AM   in reply to Pierre Devereux

    I'm an editor, mainly Avid, not an AE guru so apologies if my explanations are a bit off. Your exports are frame based animations.

     

    The render settings I adjusted were in the AE render queue (i.e. AE needs to know it is rendering fields). I exported from AE then reimported into AE and added to a 50 fps comp in AE.

     

    Pr I don't have installed currently, but if that can jog by fields that saves the 50fps comp workaround.

     

    I think you can probably work in 25P to your hearts content without an issue, after all anything film originated is 25P (including the end rollers). Almost everything that I've seen that has gone through AE is rendered as frames.

     

    If you have an end roller I would ensure that has 50 fields per second movement though.

     

    Your retiming might well be a little funky if you were to render fields as it wouldn't match the temporal movement of other aspects of your scene (which would be frame based if not retimed).

     

    Harding machines are expensive... many facilities will do a full tech check for a price, including Harding. There are also online services you can upload files to. Factor in some time to make fixes if it fails for any reason. 

     

    In Pr I think it's 'file - new hd bars & tone' to generate colour bars - I suspect they are US spec rather than EBU though.

     

    http://www.belle-nuit.com/test-chart is a good source of bars for use within your project to keep an eye on levels as it is full range (0-255 in 8bit) and you can see any shifts that occur between apps but I don't think the Beeb will accept it on final output, they'll need 16-235 bars and -18dB tone matching their specs.

     
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    May 16, 2013 7:58 AM   in reply to Pierre Devereux

    If your're working in 4K and deliver in a smaller broadcast format (HD, SD) I'd rather worry about the downscaling quality as this can introduce serious flicker issues. As for interlaced, you are going to lose some detail but are on the safe side with fast transitions. If you are not obligated to deliver as interlaced and your transitions, VFX, etc. are guaranteed judder-free, I would render progressive for some more detail.

     
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    May 16, 2013 1:24 PM   in reply to Pierre Devereux
    I need to think of investing in a colour correction program. At the moment, I use RedCineX - its all we have.

    Do not underestimate Color Finesse, which is included with After Effects. If you managed to read up the Color Correction Handbook, you find that Color Finesse is a nice start to implement your brand new theoretical knowledge.

     

    And I think SpeedGrade is also at your disposal. Check out, for example, some new features introduced in upcoming SpeedGrade CC:

     
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    May 17, 2013 1:02 AM   in reply to Pierre Devereux

    Well it depends how your editing software handles the downscaling. In case you run into issues I can recommend this workflow: http://www.bellunevideo.com/tutdetail.php?tutid=12

    It's for HD to SD conversion but can be easily applied to any other format.

     
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    May 17, 2013 5:48 AM   in reply to Pierre Devereux

    If the full 4K frame is required, I will make it a 3D Layer and push it back in Z-Space.

    That's still scaling the shot. You're re-sampling the images. AE does a better job scaling down than scaling up but sometimes, just like in Photoshop you will want to add a bit of sharpening to the layer at this point. Most of the time nothing is required and over sharpening can lead to other problems when the shot is played back at full frame rate.

     

    Once again, this points out the importance of a broadcast monitor for final quality judgements. Nothing can beat a well setup production environment. Even though I do most of my work on a MacBook Pro Retina, my critical judgements for critical projects are always checked for final quality on a fully calibrated broadcast quality monitor in a color neutral room from an optimal viewing distance.

     
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    May 20, 2013 12:41 PM   in reply to Pierre Devereux

    All SD broadcast material sent over cable or broadcast is interlaced. It has to be. If field one and field two are identical then you have "progressive" footage because you have pairs of identical fields. If field one and field 2 are different then you have interlaced footage.

     

    HD and digital content is a different matter. Depending on the network you can send out or broadcast all kinds of different formats.

     
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    May 21, 2013 4:22 AM   in reply to Pierre Devereux

    If your underlying content is 25 distinct images per second (i.e. frame based motion) and you are modifying parts of the frame (e.g. mouth movements) then trying to do that with 50 distinct images per second (i.e. field based motion) then you would never be able to get it to match. This animation must be progressive if the underlying plates are progressive.

     

    If you have transitions between scenes that are (for example) 'push' effects where one scene moves off and is replaced by one that moves on then, strictly speaking, that movement should be field based. I'm sure you could get a dispensation for it not being field based, provided you ensured the movement was not too 'juddery' (subjective).

     

    If you have an end credit roller then that should be field based. Again you might get a dispensation if you thought you needed it artistically.

     

    Best to do some tests and get some clearance from your commissioning body for anything you are unsure of (which will be much more definitive than the Internet's guesswork).

     

    Or do a deal with a facility or post-production supervisor to act as your technical guides... They have many years experience of this (which is why it is more expensive than dry-hiring equipment).

     
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    May 23, 2013 6:06 AM   in reply to Pierre Devereux

    Interlacing lessens the chance of judders but increases the chance of dancing edges especially in type for things like credit rolls. If you render your footage progressive and then re render it interlaced you have pairs of identical fields so it looks exactly the same as it would if it were not interlaced. You change nothing about the way the shot looks. If you render a composition with movement as interlaced then you change the look of the motion.

     

    I would choose one. Interlaced footage will look smoother than progressive with camera movement. Progressive will have a more pronounced motion blur but if you are filming stop motion then the motion blur is a mute point because you'll either have to fake it with something like Force Motion Blur or live without it. The point is that taking some already progressive footage and re-encoding it as interlaced will not change the look of the footage at all.

     
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    May 27, 2013 6:47 AM   in reply to Pierre Devereux

    1. As far as I understand, BBC doesn't currently accept file delivery: they're still under testing with selective acceptance and plan to make a special announcements about delivery by file. So, make sure you'll be allowed to deliver by file from the very beginning. Otherwise you'll have to start your delivery on HDCamSR tape.

     

    2. Currently you have to either save a look and apply it in AE or render an intermediate of your choice out of SpeedGrade. With Lumetri Deep Color Engine in upcoming CC 'SpeedGrade <---> PrPro' workflow will definitely become easier.

     

    Regard to preferred intermediate codec, it's, as always, about finding optimal 'quality / file size / render time' ratio.

     
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    May 27, 2013 7:44 AM   in reply to Pierre Devereux

    Since your AE comps are a complex compositing work, you need to render an intermediate in either case, 'cos it's unwise to rely on Dynamic Link under these circumstances, and you can't send dynamically linked comps to SpeedGrade from both AE and PrPro. Hence, you have to render DIs.

     

    I also humbly remind you about Color Finesse: it's a nice colour grading tool, and it may appear Color Finesse is all you currently need...

     
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