The Matrox Maevex 6150 gives you extensive controls. E.g. routing audio independently from video, making layouts (PiP) and configuring the DisplayPort preview output.
But perhaps the encoding settings are a better example. You have control over things like “Quantization Parameters” and setting up the “GOP structure”. But don’t worry. If you don’t want to play with these you don’t have to. Matrox chooses excellent default setting.
In the settings menu show above, you also see the pixel format. H.264 can have different flavors of chroma subsampling in the YUV colorspace. This is a way to reduce the bandwidth by discarding color information. You can select 4:2:0, 4:2:2 and 4:4:4. The latter setting disables chroma subsampling for the best image quality. However, your decoder needs to be able to handle this. A quick test showed that both 4:2:0 and 4:2:2 works in VLC, but 4:4:4 did not. But you might get it working tweaking other Maevex encoding parameters.
Of course, having control does not necessarily mean you have good quality. I haven’t done any objective quality measurements in the review. But looking at the quality of the streams, both in VLC (software) and with a BrightSign hardware decoder, I am impressed by the quality. The video looks crisp and is playing smoothly.
It’s not only the quality of the encoding that matters, but also the quality of the scaling. To get a sense of the scaling quality, I decoded a Matrox Maevex (Quad View encoded) RTSP stream with a BrightSigh LS424 player.
All sources are 1080p60, and the RTSP stream is 1080p60. This means that there’s a lot of scaling going on the Maevex.
To compare, I have created a similar quad view with a budget Multi-Viewer. No streaming, just 4x HDMI (1080p60) in and 1x HDMI (1080p60) out. Let’s compare the two by zooming in on a part of the quadrant containing the desktop of a Raspberry Pi (lower right).
Please note that there aren’t many pixels left for the zoomed-in part of the screen. So it’s physically impossible to get picture. But do you see the difference?
And keep in mind that the Multi-Viewer outputs an uncompressed 4:4:4 HDMI signal while the Maevex outputs a compressed 4:2:0 (reduced color resolution) H.264 stream and still looks better….