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How do I change the quality settings in VMS Gateway?
How do I change the quality settings in VMS Gateway?
Updated over a week ago

VMS Gateway supports two different quality settings Low and High that you can assign to a virtual ONVIF device. Every output stream you add to that virtual ONVIF device will use the same quality settings, and you can switch a virtual ONVIF device between these presets at any time.

For each quality preset you can set the video resolution, frame rate, and H.264 bitrate.

The interface allows you complete flexibility on how you configure each setting in each preset, but we offer recommendations as there is a relationship between all three settings.

While the two presets are called Low and High there is no constraint on what you can set each preset to - it's up to you to be careful that you don't set confusing settings (e.g. having Low contain higher quality settings that High!)

What does 16:9 and 4:3 mean in the video resolution?

For the two lowest video resolutions there are two options that designate the aspect ration of the video:

  • 16:9 is widescreen

  • 4:3 is the older traditional TV standard used in standard definition

It is likely you should use 16:9, but if you have body worn devices, and configured your devices to a 4:3 resolution you should match the aspect ratio in VMS Gateway. If you do not you will see stretched video output.

EdgeVis encoders typically work with cameras set to 1080p or 720p and these are widescreen.

What video resolution / frame rate settings are recommended?

The complexity in this situation is that there are two different stages to getting video from your EdgeVis encoder to your VMS:

  • As part of your standard encoder setup, you set your encoder's quality and bandwidth settings to get the best compromise of quality vs cost vs reliability. Your encoder will then use variable resolution and frame rate depending on live network conditions.

  • VMS Gateway will pull down your encoder's video stream and convert it to H.264 using the preset settings you set above.

The aim is to try and lower the VMS Gateway quality settings to the point you can't see any video quality loss during typical use - this is where your EdgeVis encoder settings are close the configured VMS Gateway settings. This will minimise the size of the output video stream (lowering storage costs in your VMS) and allow VMS Gateway to transcode more encoders with the same hardware.

VMS Gateway will follow these rules:

  • Video resolution - will always be output at the configured settings.

    • If the current encoder video resolution is greater than the setting then the video will be resized down to fit.

    • If the current encoder video resolution is less than the VMS Gateway preset setting then the video will be resized up to fit.

  • Frame rate - will never exceed the configured setting, and if the EdgeVis encoder is outputting a higher frame rate the extra frames will be discarded. However if the EdgeVis frame rate is lower then VMS Gateway will also lower its output frame rate to match.

There is no perfect setting, and the best approach to optimising your settings can be:

  1. Open EdgeVis Client and watch a number of your streams - this will show you typical quality for your devices. The top right of the window will show your typical frame rate.

  2. Set your VMS Gateway preset to 1080p, and select the closest frame rate you observed in step 1. Set H.264 bit-rate to be 10 mbit/s. These settings are deliberately very high.

  3. Create a virtual ONVIF device, select your preset, and add the same EdgeVis encoders.

  4. View the video within your VMS, and compare with EdgeVis Client. The video quality should be comparable (as your preset is using very high quality settings).

  5. Reduce the video resolution down to 720p. Once ready, view the video again in your VMS. It is likely that the quality level is still comparable quality to EdgeVis client. Repeat this step again to 576p, and then 480p. If the quality unacceptably suffers with a new settings then raise the resolution to the previous step.

  6. The final step is to reduce the H.264 bitrate, again once step at a time. Observe the effect on video quality at each step and find a level where the quality is acceptable.

Body worn users can start these steps at 576p as the tend to stream at lower resolutions given the high level of movement in the EdgeVis stream.


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