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  1. What is resolution of broadcast TV signal and how it signal is ok on 16:9 & 4:3 TVs which have different resolution?
    Last edited by Mark22; 24th Sep 2016 at 04:19.
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  2. Dinosaur Supervisor KarMa's Avatar
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    North American Digital TV (ATSC) is usually broadcasted at either 1920x1080, 1280x720, or 720/704x480. 16:9 content on a 4:3 TV is usually cropped to 4:3 by the TV. 4:3 content on a 16:9 TV would be filled in by black bars on the left and right side.
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    Flags tell the TV or receiver what shape (4:3 or 16:9) the incoming broadcast is to handle it accordingly. The actual resolution of the broadcast stream is fixed. For standard definition broadcasts it can be up to 720x576i for PAL and 720x480i for NTSC, but it can be lower in the horizontal. The resolution does not change with aspect ratio – that's what the flags are for.

    High definition broadcasts are either 720p or 1080i.
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  4. Explorer Case's Avatar
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    The frame and thus the pixels get stretched to fit the desired aspect ratio, making the pixel-information a bit rectangular/non-square.

    (image from my 2006 archive, so ignore the ‘regular’ adjective ... )
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  5. Originally Posted by Mark22 View Post
    What is resolution of broadcast TV signal and how it signal is ok on 16:9 & 4:3 TVs which have different resolution?
    For legacy (SD) there is no resolution but bandwidth and in case of USA video luminance bandwidth is approx 4.2MHz - for DVD bandwidth is equal (theoretically) to 6.75MHz (digital 720 pixels in line) - legacy resolution in pixels will be somewhere around 448 pixels ((720:4.2)/6.75).

    For wide aspect ratio video size is compressed to fit in normal aspect video and TV expand video size back - bandwidth stay same so number of pixels is constant.
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    Originally Posted by KarMa View Post
    North American Digital TV (ATSC) is usually broadcasted at either 1920x1080, 1280x720, or 720/704x480. 16:9 content on a 4:3 TV is usually cropped to 4:3 by the TV. 4:3 content on a 16:9 TV would be filled in by black bars on the left and right side.
    I record TV with an ATSC tuner card. I've captured SD broadcast streams with the following resolutions: 528x480 (4:3), 640x480 (4:3), 704x480 (16:9 and 4:3) and 720x480 (16:9). [Edit] (All of these are 480i.)
    Last edited by usually_quiet; 24th Sep 2016 at 15:32. Reason: accuracy
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    Originally Posted by Skiller View Post
    For standard definition broadcasts it can be up to 720x576i for PAL and 720x480i for NTSC, but it can be lower in the horizontal.
    Standard definition in the digital ATSC system, which has almost completely replaced NTSC worldwide, also allows a 480 progressive signal.
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    Originally Posted by JVRaines View Post
    Originally Posted by Skiller View Post
    For standard definition broadcasts it can be up to 720x576i for PAL and 720x480i for NTSC, but it can be lower in the horizontal.
    Standard definition in the digital ATSC system, which has almost completely replaced NTSC worldwide, also allows a 480 progressive signal.
    Have you watched any ATSC channels currently using 480p? I'm wondering if this is another option allowed by the spec which broadcasters are not interested in using. I have only seen various 480i resolutions up to now.
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