Advanced display settings

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This page is related to Display page.

Contents

Introduction

  • The Advanced tab of Display Settings page from Control Center lets you configure less-common video output modes for the HMP, other than those available on the Display tab.
  • There are two configurations available, Advanced and Custom, the latter allowing you to set custom resolutions for non-standard screens. You can switch between these two modes using the "Configuration type" option.

Advanced configuration

The list of video modes is comprised of a set of "Standard video modes" built into the player, plus all video modes returned by the currently connected screen(s) which are supported by the HMP.

Control Center, Display Settings, Advanced tab

Options:

  • Resolution - selects the output resolution.
  • Force vertical refresh - selects the vertical refresh frequency. Maximum is 60Hz.
  • Force standard video modes - enables / disables forcing a standard video mode. (enabled by default)
    • When using a non-standard video mode, this option needs to be disabled. Note that changing screens to one which no longer supports the specified mode will result in the player dropping to 640x480 resolution for safety reasons.
    • Remember that a mode includes a resolution and a refresh rate. For example, 720x576 is a PAL HDMI resolution, thus will work with 50Hz, but not with 60Hz. See the Standard video modes page for a full list.
  • Restrict video mode to - selects the standard for the video mode being used: GTF, VESA or HDMI.
    • Choose blank if you do not know the mode and the HMP will select the best available.
  • Default aspect ratio - sets the aspect ratio from 4:3, 16:9 or 16:10.
  • HDMI display supports underscan - enables / disables the underscan feature for HDMI connections.
    • Since firmware 2.2.1, "HDMI display supports underscan" option is enabled by default.
  • VGA display supports DC offset - enables / disables the DC offset.
  • Overscan percentage - sets the overscan percentage (values from 0 to 5).
  • Screen orientation - selects the screen orientation between horizontal, vertical, rotated or flipped.
  • Enable audio output - enables / disables the audio output.

Once a combination of video resolution and vertical refresh rate has been chosen, press the "Check" button to see if the combination can be generated by the HMP. If so, press the OK button to apply the settings.

Underscan

The HMP supports underscan for HDMI connection, meaning that all pixels of the image are displayed by the screen, which is standard behavior for computer monitors as opposed to consumer televisions. This feature does not affect connections using VGA or DVI.

Overscan percentage allows you to choose the size of the black frame added by the player to compensate for the overscan of your screen (connected via HDMI).

  • If the screen supports underscan, then this setting is ignored.
  • The HMP tries to compensate overscan and expect your screen overscan to be around 3%. To change the default overscan settings, modify the Overscan percentage option. Increasing the value to 4% or 5% will reduce the amount of content not displayed by your screen. You may also need to disable the "HDMI display supports underscan" option.

DC offset

Starting with firmware version 2.2.4, the VGA output in all HMP models has a DC voltage offset in the RGB signals by default. This improves the quality of the black levels and is compatible with the vast majority of displays. If a display or repeater does not support this voltage offset (i.e. the image appears as overexposed), the feature can be disabled by deselecting the "VGA display supports DC offset" option.

Custom configuration

Control Center, Display Settings, Advanced tab, Custom resolution

In case your screen is using a non-standard resolution, you can set the HMP to output a custom video mode:

  1. Set the "Configuration type" option to "Custom".
  2. Set the "Custom video mode" field to your custom video mode (video timings), either as a CVT Mode or as a Fixed Mode.
    • Note that when setting a custom mode, some limits apply.
  3. Click the "Check" button to verify the validity of the custom video mode.
  4. If the custom video mode valid, click the "Apply" button.

CVT Mode

For CVT modes (VESA Coordinated Video Timings), use the following format:
<width> <height> <refresh> <type> <interlace>
  • <width>, <height> = the number of pixels (e.g. 1920, 1280, 1080, 720 etc.).
  • <refresh> = the vertical refresh rate (24, 25, 30, 50, 60)
  • For <type>, use one of the following:
    • "cvt-R" for CVT with "reduced blanking", normally OK with LCD or plasma displays
    • "cvt" for CVT compatible with CRT displays, which need longer blanking intervals
    • "cvt-Rm" is like "cvt-R" but with extra margin on the blanking intervals, to try if "cvt-R" does not work well
    • "cvt-m" is like "cvt" but with extra margin on the blanking intervals
  • For the <interlace> attribute, always write "p" since the video output of the HMP is always progressive.

For instance, the string to select 1024x768 @ 60 Hz for LCD panels with automatic aspect ratio is: 1024 768 60 cvt-R p.

Fixed Mode

For a fixed mode, completely specified by the user, use the following format:
<width> <height> <refresh> <LM> <RM> <UM> <BM> <HS> <VS> <HP><VP> <interlace>
  • <width>, <height>, <refresh> and <interlace> are the same as above.
  • LM = left-margin, number of pixel clocks between the horizontal sync end and the first active pixel, decimal integer; in VESA standards this is known as the horizontal back porch.
  • RM = right-margin, number of pixel clocks between the last active pixel and the end of the video line; decimal integer; in VESA standard this is known as the horizontal front porch.
  • UM = upper-margin, number of video lines between the vertical sync end and the first active line; decimal integer; in VESA standard this is known as the vertical back porch.
  • BM = lower-margin, number of video lines between the last active line and the end of the video frame; decimal integer; in VESA standard this is known as the vertical front porch.
  • HS = horizontal sync duration in pixel clocks.
  • VS = vertical sync duration in video lines.
  • HP = horizontal sync polarity, either the + or - character (ie high or low active, respectively).
  • VP = Vertical sync polarity, either the + or - character (ie high or low active, respectively).
    • Note that there is no space between the HP and VP characters used for the sync.

For instance, the string for the standard VGA 640x480 is: 640 480 60 48 16 33 10 96 2 -- p

Limits

Not any custom video mode is supported by the HMP. The limits of the HMP are as following:

  1. The Pixel Clock Frequency (PCF) can be between 13.5 MHz and 150 MHz for HMP200, respectively 13.5 MHz and 75 MHz for HMP130 / HMP100.
    • To calculate the pixel clock frequency (PCF) of a custom video mode, use the following formula:
      PCF = <refresh> * ( <width> + <LM> + <RM> + <HS> ) * ( <height> + <UM> + <BM> + <VS> ) / 1000000
    • You can also use the cvt linux command to calculate the PCF when having only <width>, <height> and <refresh>.
  2. The maximum values for active width (e.g. <width>), horizontal blanking (e.g. <LM> + <RM>) and total height (e.g. <height> + <UM> + <BM>) are 2047.
  3. For HMP200, there is an additional limit of active pixels (e.g. <width> * <height>) of 2 073 600 pixels.

Low resolution

In case of low resolutions, the first thing to try is to use a standard resolution (for instance 640x480) and see if the screen accepts that resolution and displays just a part of the entire image (i.e. the image is trimmed). If so, you can create a regular project and simply put your content only in a small area (with a size equal to the size of the resolution) positioned on the top-left corner.

Otherwise, the corresponding small resolution needs to be set on the HMP, which is not a straightforward process since very often the minimum PCF limit is not reached in such cases. The solution is to artificially increase the PCF past 13.5 MHz limit by increasing the blanking intervals (we recommend increasing only <RM>, <BM> and <HS>). Note that the display may or may not support such artificially large blanking intervals. Here are some examples of such custom video modes:

  • 480 160 60 56 384 3 72 80 10 -+ p (for 480 x 160 at 60Hz)
  • 320 160 60 40 320 3 120 96 10 -+ p (for 320 x 160 at 60Hz)
  • 768 48 60 96 576 3 72 288 10 -+ p (for 768 x 48 at 60Hz)
  • 192 96 60 24 480 3 180 128 10 -+ p (for 192 x 96 at 60Hz)
  • 192 288 60 24 192 6 287 48 10 -+ p (for 192 x 288 at 60Hz)

Troubleshooting

  • When setting a resolution of 1920x1080 on the HMP100/HMP130, you need to manually set the "Force vertical refresh" option to 24, 25 or 30Hz; depending on your screen one of these could look better. Otherwise you get an error like: "The selected settings do not result in a video mode supported by the HMP100(HMP130) [...]".
    • Note that this does not refer to the video decoding capabilities of the player. To display a Full HD video, an HMP200 must be used.
  • If the content displayed on the screen is partially truncated, then it's a problem of overscan.
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