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  1. Member
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    Assuming to have a FullHD Tv (1920x1080p) and a Toshiba HD-A3 player.
    The max output resolution of this HD-DVD player is 1080i.
    But the HD-DVDs are encoded in 1080p, and the FullHD Tv also supports the 1080p.
    So my question is: will the outputted image be 1080i or 1080p?
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  2. Member edDV's Avatar
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    Originally Posted by arturo83
    Assuming to have a FullHD Tv (1920x1080p) and a Toshiba HD-A3 player.
    The max output resolution of this HD-DVD player is 1080i.
    But the HD-DVDs are encoded in 1080p, and the FullHD Tv also supports the 1080p.
    So my question is: will the outputted image be 1080i or 1080p?
    A 1080i connection can send the full 24fps 1080p picture but the method differs for NTSC or PAL frame rates.

    For PAL 25 frame rates, the 24p film frames are speeded to 25fps (with audio processing) and then split into fields. These fields are then sent as 1080i @ 25fps. The TV then combines the fields back into 25p frames, then repeats frames to 50 fps or 100 fps rates for display.

    For NTSC 29.97 frame rates, the 23.976p film frames are split into fields and then "telecined" (i.e. add pulldown pad fields) to 29.97 fps 1080i. 1080i is sent to the TV. The TV then "inverse telecines" (i.e. remove pulldown pad fields) and combines fields back to 23.976 fps progressive. These frames are then displayed in a 3 then 2 repeat pattern to 59.94 fps for display. The newest HDTV sets add an option to repeat these frames 5x to ~120Hz for display. Some of these HDTV sets interpolate intermediate frames instead of simple frame repeat.
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  3. Member
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    Thanks edDV, your explanation was very clear and detailed.
    Originally Posted by edDV
    A 1080i connection can send the full 24fps 1080p picture
    If I well understood, this is possible because the source is progressive; please correct me if I fail:
    for the PAL system for example, the 1080p/24 is sent as 1080i/25, but both interlaced fields are corresponding to a unique progressive frame, so the original 1080p can be perfectly recreated, with the unique difference of the frame rate's changing.
    At the contrary, if the source was a 1080i DVB transmission, for example, the two interlaced fields should correspond to different frames.

    So, assuming to have a FullHD Tv and a 1080p/24 encoded HD-DVD, there should be no differences between a player that can output a 1080p/50 signal and another one that can only output up to 1080i/25, right?
    (obviously I'm not speaking about the capability of some players to output a 1080p/24 signal)
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  4. Originally Posted by arturo83
    So, assuming to have a FullHD Tv and a 1080p/24 encoded HD-DVD, there should be no differences between a player that can output a 1080p/50 signal and another one that can only output up to 1080i/25, right?
    It depends on how well the HDTV converts the interlaced video to progressive. You may see occasional errors.
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  5. Member edDV's Avatar
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    Originally Posted by arturo83
    Thanks edDV, your explanation was very clear and detailed.
    Originally Posted by edDV
    A 1080i connection can send the full 24fps 1080p picture
    If I well understood, this is possible because the source is progressive; please correct me if I fail:
    for the PAL system for example, the 1080p/24 is sent as 1080i/25, but both interlaced fields are corresponding to a unique progressive frame, so the original 1080p can be perfectly recreated, with the unique difference of the frame rate's changing.
    At the contrary, if the source was a 1080i DVB transmission, for example, the two interlaced fields should correspond to different frames.

    So, assuming to have a FullHD Tv and a 1080p/24 encoded HD-DVD, there should be no differences between a player that can output a 1080p/50 signal and another one that can only output up to 1080i/25, right?
    (obviously I'm not speaking about the capability of some players to output a 1080p/24 signal)
    As Jagabo says, you are relying on the HDTV to properly combine the fields but recent and higher end models do this well. Movies on 1080i/25 broadcasts are sent in the same way. Sports and other live broadcasts are sent as 50 fields per second interlace. This gives smoother motion performance.

    It is possible for HD DVD and Bluray to be encoded as 1080i/25 (interlace) but most movies and TV series are encoded as progressive 1080p/24. Newer HDTV sets can receive 1080p/24 directly and perform frame repeats or frame interpolation to 96 or 120 frames per second without speed up.
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