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    Understanding Basic Video/HDMI Concepts

    Hi

    I am new to concept of Video Display Protocols and currently trying to absorb Basic Concepts. I would be grateful if somebody can point be towards right resources/directions for same.

    1. I believe i understood concept of resolution like 640X480i means . 640 rows X 480 columns of Pixels
    -> i/p means whether frame is interlaced/progressive type.

    a.) Is 640X480 complete depiction of frame size (esp in case of HDMI 1.4/2.0 ) or it means only active part ?
    b.) What does 640X480 @ 60 HZ means ? What frequency is 60 Hz denoting?
    c.) What is concept of Blanking Lines -: Horizontal or Vertical ?
    d.) Is it different to Blanking Interval ?
    e.) What is concept of HBLANK, VBLANK, HSYNC, VSYNC, HTOTAL, VTOTAL, Data Enable and Polarity of a Frame? How is each of them calculated ?
    f.) What is TMDS Clock ? How it is different to Serial Clock?
    g.) Are Serial Clock and Pixel Clock Same Thing ?


    I would be grateful for answers and if somebody can point me towards any material i would be even more grateful

    Thanks
    NuBee

    •   Alt17th April 2016, 18:10

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    re: Understanding Basic Video/HDMI Concepts

    Quote Originally Posted by nubee_hdmi View Post
    a.) Is 640X480 complete depiction of frame size (esp in case of HDMI 1.4/2.0 ) or it means only active part ?
    I download videos from Youtube. By hovering the mouse over a file (in Win 7), I can examine its properties. Frame size comes in many combinations of specs. This is the frame size it will open in Windows Media Player. If I choose Full screen, then it fills to the edge of my display. My computer display is 1280 x 800.

    Sometimes I hook up my computer to my digital tv so I can play videos which are 1080 pixels high. The patch cable is HDMI. The tv does something strange. I have to fiddle with the Zoom settings before I can settle on a satisfactory picture. Unavoidably the tv enlarges the size coming from the computer, so that a small border around the edges is lost. This is similar to old-style analog tv behavior.

    I didn't expect a modern digital tv to do the same thing. I cannot see icons around the extreme edges of the screen, therefore I need to remember where they are, or else I click the wrong spot.

    b.) What does 640X480 @ 60 HZ means ? What frequency is 60 Hz denoting?
    Frame rate. You can see this spec by hovering the mouse over a video file. Lately I see Youtube has the capability to transmit at frame rates up to 60 frames per second, 720 pixels high. (There are 1080 pixel and greater resolution, but I'm not sure those are also 60 fps capable.)

    If you right-click in a video window, and select 'stats for nerds', you see specs for the video you're watching.

    I only had a ready answer for the above questions.



    •   Alt17th April 2016, 18:49

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    Re: Understanding Basic Video/HDMI Concepts

    a.) Is 640X480 complete depiction of frame size (esp in case of HDMI 1.4/2.0 ) or it means only active part ? Only the active part.
    b.) What does 640X480 @ 60 HZ means ? What frequency is 60 Hz denoting? The number of 640x480 pixel frames per second
    c.) What is concept of Blanking Lines -: Horizontal or Vertical ? Dead time where no actual picture data is being transmitted.
    d.) Is it different to Blanking Interval ? No.
    e.) What is concept of HBLANK, VBLANK, HSYNC, VSYNC, HTOTAL, VTOTAL, Data Enable and Polarity of a Frame? How is each of them calculated ?
    f.) What is TMDS Clock ? How it is different to Serial Clock? The TMDS clock is the pixel clock. The actual data rate is much higher then this clock.
    g.) Are Serial Clock and Pixel Clock Same Thing ? As mentioned in 'f' - the pixel clock is rate at which a pixel at every channel arrives. The actual "data rate" clock is extracted from this pixel clock



    •   Alt17th April 2016, 22:50

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    Re: Understanding Basic Video/HDMI Concepts

    Quote Originally Posted by shaiko View Post
    a.) Is 640X480 complete depiction of frame size (esp in case of HDMI 1.4/2.0 ) or it means only active part ? Only the active part.
    b.) What does 640X480 @ 60 HZ means ? What frequency is 60 Hz denoting? The number of 640x480 pixel frames per second
    c.) What is concept of Blanking Lines -: Horizontal or Vertical ? Dead time where no actual picture data is being transmitted.
    d.) Is it different to Blanking Interval ? No.
    e.) What is concept of HBLANK, VBLANK, HSYNC, VSYNC, HTOTAL, VTOTAL, Data Enable and Polarity of a Frame? How is each of them calculated ?
    f.) What is TMDS Clock ? How it is different to Serial Clock? The TMDS clock is the pixel clock. The actual data rate is much higher then this clock.
    g.) Are Serial Clock and Pixel Clock Same Thing ? As mentioned in 'f' - the pixel clock is rate at which a pixel at every channel arrives. The actual "data rate" clock is extracted from this pixel clock
    Thank You very much, Can you please explain with explain with example what do you mean by actual data rate ?



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    Re: Understanding Basic Video/HDMI Concepts

    Quote Originally Posted by nubee_hdmi View Post
    e.) What is concept of HBLANK, VBLANK, HSYNC, VSYNC, HTOTAL, VTOTAL, Data Enable and Polarity of a Frame? How is each of them calculated ?
    They are used to specify specific intervals of time in the video signal.

    HBLANK the horizontal blanking interval, i.e. the end of a row of pixels (in analog this was for the time it takes to set the electron beam back to the beginning of the row.
    VBLANK the vertical blanking interval, i.e. the time given for the beam to be moved from the bottom row back to the top row.
    HSYNC sync signal for the start of a row
    VSYNC sync signal for the start of a new picture frame

    Don't know about HTOTAL or VTOTAL or the others

    Each of these is based on the number of pixels in the image and the frame rate, the duration of the blanking intervals.



    •   Alt18th April 2016, 15:58

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    Re: Understanding Basic Video/HDMI Concepts

    Thank You very much, Can you please explain with explain with example what do you mean by actual data rate ?
    Consider an HDMI channel that consists of 4 lanes - Clock, Red, Green, Blue.
    Per every clock edge a single pixel of Red, Green and Blue is transmitted.
    But each of the pixels is consists of 8 bits of data. So if the pixel clock is X - the rate of the bits that builds each pixel is 8*X
    I.E - the bit rate is 8*X then the pixel clock frequency.



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