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The death of 720p...

Discussion in 'General TV Discussions Forum' started by scumball, Oct 10, 2005.

  1. scumball

    scumball
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    It seems that Sonys broadcast machines for HDCAM do not playback 720p format HD (unless you get to the HDCAM SR range). The offered resolutions are 1080/50i, 1080/59.94i, 1080/25p, 1080/29.97p for record and all those plus 1080/23.98p and 1080/24p for playback.

    Do you think this spells the downfall of 720p as a format of the future?

    I'm guessing a lot of mastering houses may decide against the SR route (as the machines retail at nearly twice the price) and as such future formats such as HD-DVD & Blu-Ray may be restricted to up/cross converted 1080i or 1080p. What are your opinions?
     
  2. Jim_Fear

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    Correct me if i'm wrong but couldn't you just downscale it? Wouldn't the image be better bein shot at a higher res to then be downscaled in an editing program or the like?

    Again, if i'm wrong dont flame me :)
     
  3. scumball

    scumball
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    You could, but the machines that can record/playback 720p material are circa £60K whereas the 1080i/p machines are circa £35K...I'm just wondering if any authoring houses will invest in this format when Sony seem to be pushing 1080 so much more.
     
  4. Jim_Fear

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    Something to do with Blue-Ray perhaps?
     
  5. Quickbeam

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    Lack of 720p support isn't HDCAM's only flaw. The recorded 1080i resolution is only 1440 x 1080i, so there are compromises there as well.

    Any broadcaster interested in achieving high production standards will now be buying SR gear, much as Sky has done. Still no word yet on what HD format(s) they will use on their own channels though.
     
  6. AML

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    Im thinking that eventually everything will be 1920X1080p.
    So start saving for all the new upcoming 1080p panels. Sony just launched a new "Bravia" 46" LCD that does 1080p.

    The PS3 will also support 1080p, and so will Blu Ray. So its quite possible that they want all content to be 1080p.
     
  7. scumball

    scumball
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    So HDCAM SR records the 1080i at 1920x1080? Are all the 1080 modes 1440x1080 on HDCAM or just the interlaced resolutions?
     
  8. Quickbeam

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    SR does 1920. HDCAM is 1440 on all 1080 line modes. Attack of the Crones was shot 1440 x 1080p (HDCAM). Revenge of the Stiff was 1920 x 1080p (SR).
     
  9. Stephen Neal

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    The interlaced and progressive modes of HDCam are pretty near identical. It uses the same "on tape" format - and records the progressive frames as segmented frames, which occupy the same space as a field.

    All original HDCam VTRs operate at 1440x1080 (and lower than 720x1080 for the chroma AIUI) - there were no other resolutions, it is just the frame rate that changes.

    The HDCam SRs offer a higher resolution, and 720p compatibility. Anyone buying regular HDCam these days for most applications may not be making a great move.

    HD-D5 is more common in the US AIUI (as it is higher quality than non-SR HDCam) - and copes with 720p.

    At the lower end of the scale DVCProHD/100 and HDV both cope with 720p as well as 1080i - however DVCProHD subsamples 720p to 960x720, and 1080i to 1280x1080 I believe. (HDV runs at 1280x720 and 1440x1080)
     
  10. Stephen Neal

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    The limitation of HDCam to 1440x1080 only is a legacy issue more than anything. Sony have been involved with the 1125/60i (which is what 1080/60i is based on) system since the 80s at least - first with analogue VTRs, then digital uncompressed open-reel VTRs, then HDCam. 720p was never a standard in Japan - it was introduced in the US when they went HD in 1998.

    As Sony were firmly in the 1080 line camp - for a long time they made little gear that would operate at 720 lines. These days they are more pragmatic, and their latest cameras, and HDCam SR VTRs offer full 720p compatibility. (Their new cameras can run at 1080p and scale to 720p)

    If you are starting an HD operation now there is no problem with running 720p and using Sony gear - as Sky may well do (as they have bought kit that will work at 720p and 1080i)

    As for mastering - I'd have thought quite a lot of stuff was actually delivered on HD-D5 rather than HDCam?
     
  11. Calleva

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    So - to turn the argument on it's head..
    As the original HD-CAM did not support 720P, but the latest incarnations do - This must mean that 720P is becoming more popular and the format of the future, not facing it's death at all !!! :rotfl:



    In reality, of course, it's Sony realising they had a hole in their product range. 720P is an important format and 1440x1080 (3:1:1 sampling) was never going to be good enough for mastering - hence the widespread use of HD-D5.

    HD-CAM SR was specifically introduced to try and get that mastering business back into Sony's hands by being a 'universal' tape format and truly capable of un-compressed video (i.e. it is capable of 4:4:4 sampling, which is needed for Chroma-keying)

    Until the whole broadcast chain can support 1080P@60Hz (i.e. cameras, recorders, editing, Encoding, transmission, reception and display) 720P will remain an important format for sports, if nothing else.
     
  12. Stephen Neal

    Stephen Neal
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    Yep - that is a far more realistic way of looking at it!
    Yep - Sony originally had an uncompressed open-reel DVTR in the early 90s - though this may (as the BBC Quadriga 4xD1 system was) have been based on 1440 not 1920 sampling. (1440 is twice 720 - which is the universal SD sampling rate). 1920 sampling was introduced around the time the US looked at HD - as there was a strong push to go "square pixel" - especially from the computer industry, who have never coped with non-square pixels very well. In reality 1080i now has a very unbalanced resolution, as 1920x1080i delivers nearer 1920x800 resolution, 1440x800 would be a more balanced format... (And is used in Aus)

    Is HDCam SR uncompressed? I knew it allowed for 4:4:4, but although this removes chroma sub-sampling, I thought there was still a degree of intra-frame compression going on. I thought D6 (aka Digital Voodoo) was the only uncompressed HD cassette-based tape format.

    Yep - though many still use 1080/60i (or 50i in Europe) for sports, as the motion rendition is the same, though the resolution on movement is lower, and the quality of slow-motion replays is consequently reduced.

    It will be interesting to see which, if any, format dominates in Europe - 720/50p or 1080/50i. All current on-air services are 1080/50i based (Euro1080, Premiere, Pro7, Sat1, C-More HD, Canal Plus HD)

    Currently 1080/50p and 1080/60p cameras and VTRs exist, but the standard interconnect used for HD in broadcast applications - HD-SDI - doesn't support the data rate required. You either need to use two interconnects per source or destination (which doubles the cabling requirements, and halves the size of your vision mixer and reduces your router size to a quarter) or you have to lightly 2:1 compress (and no single standard exists for mezzanine compression yet)
     
  13. scumball

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    Thanks for all the great info....
     
  14. Calleva

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    OF course, you are correct there, it is mildly compressed, but is not sub-sampled which is what I was trying to say, but failing :oops:

    Scumball mentioned attack of the clones, which was shot HD-CAM to a large extent - but there was some recording directly to Digital Disk Recorders for some work - specifically the shots needing chroma-keying - It's not widely publicised (and was denied in the early days) due to political pressures from certain quarters.

    Ah, this takes me back! ;)

    R.
     
  15. loadsofleads

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    Are those star wars films, or are they some obscure blue movies you picked up off the internet :rolleyes:
     
  16. Pecker

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    Surely, 720p will be around as a format for quite some time, as it's currently the de facto format for almost every Hi-Def display you can currently buy in the UK.

    If word gets round that all the Hi-Def plasmas, LCDs & £20k 3 wheel DLP projectors are using a sub-standard format, there'll be hell to pay, and it'll impact on consumer confidence, just as the companies are trying to get people to upgrade to HD.

    Steve W
     
  17. dllord

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    Yeah whos going to buy a HDTV now if there is only about 2 1080i sets about
     

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