What happens to my 1080p source?

Discussion in 'Desktop & Laptop Computers Forum' started by JorisS, Aug 27, 2006.

  1. JorisS

    JorisS
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    Hi guys,

    I have a question:

    I'm running a setup with my PC functioning as HTPC through the secondary output (I use it for everything, don't have the cash to invest in a dedicated HTPC). I've hooked it to my projector through component (using a DVI-component dongle), which supports 720p and 1080i. The native resolution of the pj is 1366x768, so that 720p is accepted as is, but 1080i/p is somehow downscaled I guess.

    I wonder how this downscaling occurs when I play the source 1080p movie through the pc, on the secondary output, which is configured for 720p. Does the pc do the downscaling, or does the projector?

    What would be the best possible way to get an optimal image?

    I've been playing around with theatertek and ffdshow before, but then mostly to 'upscale'.

    *edit*

    What I wonder is: does a 1080p source give me similar image quality as using a 720p source? Or would I actually get better quality if I get 720p material only?
     
  2. MikeK

    MikeK
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    Hi guys,

    I have a question:

    I'm running a setup with my PC functioning as HTPC through the secondary output (I use it for everything, don't have the cash to invest in a dedicated HTPC). I've hooked it to my projector through component (using a DVI-component dongle), which supports 720p and 1080i. The native resolution of the pj is 1366x768, so that 720p is accepted as is, but 1080i/p is somehow downscaled I guess

    I wonder how this downscaling occurs when I play the source 1080p movie through the pc, on the secondary output, which is configured for 720p. Does the pc do the downscaling, or does the projector?.


    It sounds like the graphics card is doing all the upscaling of 720p and the downscaling of 1080i/p.

    What would be the best possible way to get an optimal image?
    I've been playing around with theatertek and ffdshow before, but then mostly to 'upscale'.


    The million dollar question :) :)

    There are many ways to do this and each will have it's own merits/drawbacks.
    You need a powerful PC to playback 1080 material while simultaneously post-processing it with ffdshow - but if you have such a PC, then this is probably the best way to do it IMHO. A Lanczos resize to 1366x768 in ffdshow might yield better results than letting your gfx card do the scaling (but you'd have to fiddle around to get the best settings to allow for overscan etc - you need to get it pixel-mapped if poss)


    What I wonder is: does a 1080p source give me similar image quality as using a 720p source? Or would I actually get better quality if I get 720p material only?
    Theoretically, the 1080p source should give you better results, but in practice you may notice little difference.
    Much of the "stuff" out there is processed/converted 1080i, so isn't true 1080p (or even 720p).
     
  3. JorisS

    JorisS
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    Thanks for the reply!

    Now in follow-up, I don't know if this is the right place for it though (if there is any ;) ):

    One of the HD files is an mpeg file, with two soundtracks. I think they're both AC3, one is German :)eek: ) the other English. Using an mpeg splitter I googled I managed to split the file into three parts, which would fit 2 DVD-DL and one regular DVD. But to my dismay I found that only the German audiotrack has been taken along :/

    I've considered some options:

    * convert mpeg -> avi, THEN split (as I've succesfully managed to split an AVI with dual sound track, using avi splitter program)

    * somehow split mpeg keeping both soundtracks (different program? suggestions?)

    * remove one soundtrack first, then split (have a program which can do this for avi, not sure about mpeg)


    Any ideas?
    There's a jungle of programs out there, most got a trial but aren't fully functional as such, and I would really like to avoid spending loads of money on buying licenses, only to find out that the program can't do what I want it to.

    After all, these are somewhat special files, with the high quality video and large size.
     
  4. MikeK

    MikeK
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    DGindex is free, and will demux the streams for you.

    Sorry, but I've got no idea how to remux again if it isn't an AVI file - never needed to do that.
     
  5. JorisS

    JorisS
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    I used it and split out two ac3 soundtracks. But have no clue what good that does me, really :D

    Basically what I have is a 18Gb MPEG file, I think it's MPEG 2. It's in 1080p with two ac3 tracks. And what I want is to cut it up into 3 parts, fitting on two dual layer dvd's and the last part perhaps on a regular.

    With one program I can split properly, but one of the soundtracks is gone (the english one!).

    With another program the audio remains in two tracks and the splitting seems to work, yet the time is somehow messed up and I'm not sure if somehow frames are lost...


    argh!
     
  6. MikeK

    MikeK
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    Are they .ts files?

    If so, you could use HDTV2MPEG - it's free too!
     
  7. fusion7

    fusion7
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    where did u get this dongle?
     
  8. JorisS

    JorisS
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    hope it's allowed to post links like these, but here's where I got mine:


    Might have been another seller, but same item/price.


    *edit*
    MikeK no it is one huge .mpg file
     
  9. dannyg81

    dannyg81
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    From I can remember, you can use .mpg files in HDTV2Mpeg, there's a drop down box to switch between the 2. If that doesn't work just change the extension to .ts and you'll be able to use it, as a .ts file is just a container for an mpeg2 stream anyway!
     

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