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TV System option (also called video output mode) defines a set of parameters for display video. Correct TV System value set on STB side makes possible to properly play back video on side of video receiver such as TV, computer monitor, etc. (hereinafter referred to as TV). TV System option defines two main parameters - Display resolution, and TV scan method (i-interlaced or p-progressive). In addition, for each value of TV system option, Aspect ratio and Framerate parameters are defined "by default". When STB works along with digital TV, Auto framerate mode can be activated on STB.
The list of TV System values is specified in Supported Video Output Modes section.

Graphic Resolution option determines display resolution to "draw" graphic objects (text, images, etc.) on the TV screen. The list of Graphic resolution values and specificity of displaying graphics on the TV screen, depending on Video output mode value, are considered in Graphic resolution section .

STB connecting to TV receiver

TV system , set on video outputs during and after STB booting

When STB boots (after power on or reset), one of Standard Definition (SD) mode is set at the STB video outputs: PAL(576i) or NTSC(480i) - the value is determined at the factory according to region where STB plan to be used (PAL region or NTSC region).
The SD video mode makes possible for all TV type (analog and digital) to display boot process on TV screen (logo and boot process messages). In addition, SD video mode is set when Bootloader menu (for MAG250/254/270) or System Recovery menu (MAG256/322 and all further STB models). During STB boot up, video signal is transferred simultaneously to digital (HDMI) and analog composite (AV) video outputs. After STB software loaded, STB switches to TV system value set in STB settings.
After STB is booted and STB software is loaded  HDMI output switches to TV system value that set in the STB settings.
Note. As an indicator of boot completion, can be considered start of media portal loading (Embedded or External) or Select a Portal for loading window displayed on the screen.

Problem of lack image on analog TV during STB boot (only for MAG250/254/270)

If during STB MAG250/254/270 boot up there is no image (black screen) on the analog TV, the cause may be a mismatch between STB TV system mode and video display resoluition suppotred by TV - PAL (480i) or NTSC (576i). To handle this issue user can change over TV system mode (PAL / NTSC) during boot up, using the remote control (RC).
If there is no image on the screen you need:

  • Unplug power of STB
  • Press and hold Menu on RC (direct your RC straight to STB front panel)
  • Plug power on STB with holding Menu
  • Hold on Menu button during 10 seconds.
  • Switch PAL - NTSC with single press on red button F1 on RC (Bootloader menu screen should appear).

Incorrect connection / setting of video output (only for MAG250/254/270)

If STB MAG250/254/270 TV system set as one of HD modes, an alarm message is sent to analog video (AV) output:

Image Documentation

If you see this warning then:

  • If you imply to use AV video output then video output mode selected on STB is wrong (change TV system to SD mode supported by your TV - PAL (480i) or NTSC (576i);
  • If you imply to use HDMI video output, you need to switch over your video output connection to HDMI. If you also use the HDMI connection in parallel with the CVBS (AV) connection, change source setting on TV (to HDMI input).

Information for developers. The warning text is located in the STB software image in file /home/default/SDmsg_en.

Screen resolution choice

Before first connecting STB to TV, user should carefully read operating instructions of TV. Make sure that TV system and Graphic Resolution values set in STB match your TV screen resolution. The factory settings of STB: Video output mode = Auto, Graphical resolution = Same as video.

The TV system parameters in the STB settings must be compatible with your TV. In case of incompatibility, image quality deterioration is possible, up to the complete lack of image on the TV screen.

As a rule, on TV devices there is marking of supported modes like:

If instructions or markings are not available, required information can be obtained on the website of TV manufacturer.

Storing parameters of video output mode and graphical resolution

Video output mode and graphical resolution are stored in STB environment variables :

  • tvsystem - video output mode in STB software working mode;
  • graphicres - graphic resolution of the screen in STB software working mode.

These settings are applied in STB running mode (when software is loaded).

How to change STB settings of TV system and Graphic resolution

TV system and Graphics resolution values can be auto set (default setting value) or selected manually by user. An ordinary way to set these patameters is System Settings of Portal (Embedded or External). In some cases (for example, if there is no image on the TV screen after STB software loaded), user may change these settings at the boot stage - from Bootloader menu (for MAG250/254/270) or System Recovery Utility menu (for other models).

Embedded portal settings

  • Enter System settings;
  • Go to Video;
  • Set desired value of Video output mode;
  • Set desired value of Graphic resolution;
  • Save data with Save (OK);
  • Confirm with OK - STB will automatically reboot.

Bootloader menu MAG250/254/270

  • Launch the Bootloader menu;
  • Upgrade Menu press Right on RC. If there is no such step then go to next one (this step can be absent if second Bootloader turned off or not installed);
  • Section TV System - by pressing Right set requiered value;
  • Section Graphic Res. - by pressing Right set required value;
  • Go to Exit&Save;
  • Section Exit & Save press the Right, confirm with OK.

System Recovery Utylity menu MAG256/3xx and higher

  • Bring up System Recovery Utility menu;
  • Come in TV System section (ОК on RC), select the appropriate setting and confirm (ОК on RC). Exit to top level of menu;
  • Come in Graphic Resolution section (ОК on RC), select the appropriate setting and confirm (ОК on RC). Exit to top level of menu;
  • Select and confirm Exit and Reboot (ОК on RC).

Supported Video Output Modes (TV System)

Available TV Systems

In the STB software working mode the following video output modes are supported:

TV system

Screen resolution*

Scanning mode**

Frame rate, frame/sec

Aspect ratio


Auto-detecting TV System
STB sets TV System, depending on type of video output and TV device used.
PAL region (Europe, Australia, most of Asia and Africa, some countries in South America, etc.)
PAL (576i)
50 semi-frame/sec
Analog TV - 4:3
Digital TV - 16:9
Analog TV and digital SDTV standard. PAL color encoding system is used for analog TV.
HD / HD Ready
50 semi-frame/sec
Full HD
HD Ready 1080p / Full HD
4K Ultra HD
NTSC region (America, Japan, etc.)
NTSC (480i)
640 × 480
60 полукадров/c

Аналоговое TV - 4:3
Цифровое TV - 16:9
Analog TV and digital SDTV standard. NTSC color encoding system is used for analog TV.
HD / HD Ready
60 полукадров/c
Full HD
HD Ready 1080p / Full HD
4K Ultra HD
- Screen resolutions are specified for digital TV standard.
** - Scanning mode: i - interlaced, p - progressive. To display interlaced video on progressive scan displays (contemporary TV types), playback applies deinterlacing to the video signal.

Making choice of TV System

The choice of required TV system (video output mode) depends on various factors, like that:

  • type of the TV device - for analog devices, modes with interlaced scanning (interleasing) are usually used, for digital devices - with progressive are usually used;
  • region of use - broadcasting of television in different regions (in the table these regions are specified as NTSC and PAL) adapted to different frame rates (25/50 or 30/60 frames per second) and screen resolution (only in SD mode);
  • type of media content being played - depends on the TV platform used for broadcasting or the mode of creating the video;
  • etc.

Graphic Resolution (Graphic Res.)

Graphic Resolution options

In the STB software working mode the following graphics resolution options are supported:

Graphics resolution options Comment
TV System Resolution Autodetection of the graphics resolution, depending on TV system setting.

Graphic Resolution setting

If value of Graphic Res. option set in STB is greater than permissible resolution of video output then the most appropriate resolution of graphics window is selected by STB.

If value TV System Res. is selected then STB sets resolution value that is appropriate to current video output mode.

For example:

If you set TV System in 1080i-50 then video will be played with resolution 1920×1080, and graphics can be "drawn" with one of the values: 720×576, 1280×720, 1920×1080. That is, user may choose any resolution value for graphics menu. In this case, graphics resolution values lower than video resolution will be scaled up to TV System value. 
If Graphic Resolution set in TV System Res, then graphics resolution value will set appropriate to current TV system value, that is 1920×1080.

Typical variant: If user selects Video output mode (TV System) - 1080i-50 and Graphic resolution (Graphic Res) - 720×576 then video will be played at highest possible quality and graphics will be upscaled. In this case, the data traffic reduces and STB performance improves.

Possible variants:
TV System Video Resolution Graphic Resolution Type of graphics resolution
1080i/p-50/60 1920×1080 1920×1080, 1280×720, 720×576 HD
720p-50/60 1280×720 1280×720, 720×576 HD
576p-50/60 1024×576 720×576 ED
PAL (576i) 720×576 720×576 SD
NTSC (480i) 720×480 720×480 SD

Type of digital video output HDMI-DVI

Type of digital video output HDMI or DVI is chosen depending on type of digital port used on TV device. STB factory setting defines type of digital video output as HDMI. If you need to switch over type of digital video output:

  • Enter System settings Video More;
  • Set HDMI/DVI required value:
    • HDMI - for devices with HDMI port;
    • DVI - for devices with DVI port.
  • Confirm with Save (OK);
  • Message Successfully saved should appear on the screen.

When you connect STB to device with HDMI-input then HDMI option must be set. If option DVI is set then no audio signal is given on STB HDMI output!

Auto frame rate

Auto frame rate feature is intended to set required Frame rate value on HDMI video output, depending on video content being played. The required Frame rate value is selected from one of pre-indicated variants. Thus, STB sets on HDMI output that frame rate value at which played video was created initially. This provides the TV device ability to process video by itself, making "smoothing" the video displaying - i.e. adjusting display refresh rate to match video.

In the factory setting of STB, Auto frame rate feature disabled and Frame rate is set according to TV system setting.

To set Auto frame rate feature:

  • Enter System settings VideoMore;
  • Set Auto frame rate value:
    • Disabled - Auto frame rate feature is disabled (the frame rate will be set, depending on the TV system option value);
    • 50/60 - choice between frequency values of 50 Hz or 60 Hz;
    • 24/50/60 - choice between frequency values of 24 Hz, 50 Hz or 60 Hz;
    • 24/50 - choice between 24 Hz or 50 Hz;
    • 24/60 - choice between 24 Hz or 60 Hz;
  • Confirm with Save (OK);
  • Message Successfully saved should appear on the screen.

Use Auto frame rate feature carefully! When Auto frame rate is on, some video signal receivers may not display video signal:

1. Auto frame rate feature can be applied only with HD screen resolution (720p/1080i/1080p). Before enabling this function in the STB, make sure that the TV supports specified screen resolution values.
2. Auto frame rate feature must be supported by the video signal receiver. For example, some digital computer monitors do not support this function.

Need Help

Dave is an expert on the MAG STB and the author of this article.

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