I have a DF Solutions product connected to a HDMI (or other format) switcher, which connects to multiple displays. However I don't get a picture on all displays. Why?

21 Nov 2009

Support Center » Knowledgebase » I have a DF Solutions product connected to a HDMI (or other format) switcher, which connects to multiple displays. However I don't get a picture on all displays. Why?

	I have a DF Solutions product connected to a HDMI (or other format) switcher, which connects to multiple displays. However I don't get a picture on all displays. Why?

Solution Video switchers are a great product for connecting a single source to multiple displays. They work really well for analogue video formats (composite / S-Video / Component) which typically distribute signals which are accepted by all TVs, since the video format is not particular to any one 'model' of TV.

HDMI and DVI is a different matter altogether. Modern LCD and plasma TVs are all built like computer monitors. Based on their size, pixel density, aspect-ratio and other factors, they accept a specific subset of all digital source formats, at specific resolutions/refresh-rates and other criteria.
When connecting a Video Source via HDMI to a single TV, both ends communicate over a protocol called EDID to work out what common formats are at their disposal, and each end adjusts to resolve a picture onto the screen.

However, this starts to fall apart when you have a Digital Video Source connected to multiple digital displays, via a splitter/matrix in the middle. When the Video Source is initializing, it will negotiate via EDID with the screen that the matrix is currently set to, and you will typically see a picture. However, not all displays connected to the splitter/matrix will support the same formats and resolutions, and the Video Source will have no way of knowing this.
The result is that when you switch from one display to another on the splitter/matrix, it is very possible that you will not see a picture, because the Video Source is outputting a format that is not handled by the TV.

With regards to DF Solutions products, we do not recommend the use of splitters or matrices unless:

1) All displays connected to the splitter/matrix are the same model and thus can handle the same resolution/format.
2) A product such as the Gefen HDMI Detective Plus is used to trick the video source into thinking it is only ever permanently connected to one display.

DF Solutions is unable to support the installation of video splitters and switchers unless the above points are adhered to.

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21 Sep 2009 10:10 AM