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HDMI. What is it?!

Discussion in 'Projectors, Screens & Video Processors' started by Budville, Dec 5, 2003.

  1. Budville

    Budville
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    Hi guys and gals

    I was looking at the spec for the Sony VPL-HS20 and noticed it can accept HDMI. What is this? Is this a new connection format?

    From what I could work out, it is digital but thats all I know about it.

    Anyone come across this before?

    Thanks :clap:
     
  2. Adam M

    Adam M
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    I would do an google search on it personally.

    there is plenty info out there, but basically it is going to be a new industry standard connector for high end digital image and sound.

    From what I have read it allows individual connection of sound and picture between source and display.

    Eventually I would expect it to be used for connecting via amplification.

    it is a bidirectional cable so components can talk to eachother and thus select the best display output.

    It also is entirely digital which allows handshaking between components and does away with multiple analogue leads for both picture and sound. There are therefore fewer conversion stages and the cables are far less susceptible to noise over long runs.

    This leads on to a question I wanted to ask.

    If I connect a pioneer 868 to a HS20 via the 5m hdmi cable that I have just ordered, will it automatically switch the 868 output resolution to the best available.

    If so, does anyone know what that is?

    any idea what the best progressive output scan the machine has at its disposal?
     
  3. Budville

    Budville
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    Cheers Adam M.

    I will look on Google now.
     
  4. Kane D Williams

    Kane D Williams
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    A guy on AVS claims that when the HS20 is switched to video GBR rather than computer, that the picture is overscanned even when in thru mode!!!

    The DVI socket can be switched between the two modes, but I'm not sure about the HDMI (conflicting reports)? It may be that the HDMI will be fixed to video GBR and thus suffer overscan!?
     
  5. Adam M

    Adam M
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    Kane,

    I am new to allt his, can you explain what you mean by overscan?

    I don't use a an external computer scaler.

    My HS10 currently is connected via component to the DVD player.

    I have just bought an 868 so that I will have HDMI output, and thought it might be worth getting a PJ to match to take advantage of what I hope willbe an improvement.
     
  6. Kane D Williams

    Kane D Williams
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    Adam

    I'm sure the HDMI connection from the 868 will be a big improvement over component.

    In terms of overscan, this is something that bothers some people a lot (like me) and others not at all!

    Basically, I want to see every pixel of information that is contained in the image, but unfortunately this can be hard to achieve as displays (TV, Projector etc) and/or source (DVD player, Cable Box, TV tuner etc) can overscan and thus cut off some of the picture - I find displays are usually the worst culprit!

    There are technical reasons for the displays (and sources) to do this and it can vary from 1cm from the sides or top and bottom to 5cm (or more)! I find that most TV's seem to cut more off one side than the other and I got into the factory settings menu of my TV to regain most of my overscanned image.

    I work as a film editor and anyone who does anything TV/graphics based will no about 'TV safe' areas. Basically, you have a marker showing you where a TV will overscan too and thus you have to place any titles etc within that boundary, even though there is a fair bit of picture outside that area. Broadcast monitors have an underscan button, so you can see the full frame if you like.

    If TV channel idents that appear in the top left or right corners of the picture are being cropped, then this is a good indicator of overscan.

    Sending a digital signal via DVI or HDMI, it should be possible for 100% 1:1 mapping with no overscan (VGA/RGBHV signals work too).

    However, it has been suggested that overscan still occurs with the HDMI input of the HS20 (even in thru mode) and I can only assume this is because HDMI is still a 'video' standard rather than for computer use (like DVI)? Apparently though, the overscan is only 20 pixels all around, so not too bad anyway. If concerned, get a test disc and look for the overscan amount. With my current set up, I use the zoom out function on my Tosh SD900E and thus can see the whole picture. I'd guess that my TV used to cut off about 20% of the picture before I got into the factory settings and now about 5%. My PJ was cropping about 10%.

    I hope this is of some help? I'm sure others can explain better than me?

    Cheers
     
  7. Adam M

    Adam M
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    doubt they can.

    Brilliant answer and all that I needed.

    since you seem to know your stuff, can you explain about the progressive output from the 868 too?

    I have just checked the online manual and when connecting via hdmi cable you are given a choice of output resolutions.

    These include the native pal and ntsc resolutions in progressive format, but there is a further option of 1280x720 progressive video output, but this is not allocated to pal or ntsc.

    Would the lower progressive resolutions be headed ntsc and pal because they refer to their native resolutions, and this higher resolution is therefore the product of an internal scaler?

    If so, which is likely to yield the best quality.

    Obviously I could wait and just plug them in, but I am a big fan of the placebo effect, and even though I have never been great at spotting the differences between projectors, I would like to know that I at least think I am using the equipment to the best of its abilities.
     
  8. ailean

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    Think you got the right idea Adam. You can do scaling at either end and the HD res should only change by it's refresh rate between Pal(50hz) and NTSC(60Hz).

    Does seem to be alot of scope in these modes as I've read of some Pj that will only take say 1280x720 at 60Hz but can take native PAL at 50Hz and scale it internally to 1280x720.

    Most ideas I've seen think it's best to scale in the player but I think this is based on the quality of the scaler in different models of DVD vs different models on Pj. End of the day you'll have to try it and see as I've not spotted any other folks with a 868/HS20 combo (I'm interested in the results thou as I might end up with this combo if I can't get over my DLP nausier ;) ).
     
  9. William

    William
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  10. Kane D Williams

    Kane D Williams
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    Yeah, you seem to have the jist! 720p and 1080i are HD standards and so neither classed as PAL nor NTSC. However, as these are not true HD signals, but upscaled from PAL and NTSC sources (DVD's), then keeping the original refresh rates is desirable.

    If you want to use the entire 1386x788 resolution of the HS20, from what I gather the scaler works better down scaling from an up-scaled 1080i signal, rather than upscaling an already up-scaled (in DVD player) 720p or native 480p/576p signal.

    However, the best picture seems to be delivered when the HS20 passes a signal up-scaled to 720p without further scaling (in thru mode). I have not tested any of this BTW and I'm only going on what I've been reading and screen shots etc.

    I would like to know if there is a way of getting round the HDMI overscan issue. Is it possible to set the HDMI for computer input rather than GBR? This has nothing to do with the black level (1 or 16) thing BTW.
     
  11. Kane D Williams

    Kane D Williams
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    BTW, if you can get a DVD player or HCPC to output a 1366x768 signal, the Sony will take it but only at 56Hz (may be 57Hz). The Sony will not accept a 1386x788 signal.
     

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