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Technical Article | TA-20220210-CS-01 VDG Sense | Tutorials | Video Streaming  | PDF Download |
Introduction
This article explains how VDG Sense can be used and configured to stream video over a narrow bandwidth connection between server and client. For instance when video needs to be streamed via an ADSL internet connection. This technique is called ‘transcoding’ where VDG Sense will convert the video to a format which has a lower quality and framerate before it is send to the client. The image is a simplified schematic of the video-flow from camera to client.
How does it work
VDG Sense uses two settings to determine the quality and size of the videostream: the maximum bandwidth usage and the quality of the transcoded video. Transcoding can be enabled or disabled per client. The bandwidth usage is also configured per client and the transcode quality is configured per server and is the same for all clients using transcoding. This means multiple clients can use different bandwidth settings where the quality of the video remains the same.
Using the bandwidth, quality and the size of the panel in which the video is displayed, VDG Sense will transcode the video to achieve the highest possible quality and framerate. The schematic below shows 2 clients, each with different bandwidth settings and using the same quality video. However, client 1 is displaying a videostream in a small panel and client 2 shows it in a bigger panel (e.a. fullscreen). This affects the resolution and framerate of the videostream. In a smaller panel a lower resolution is needed so the framerate increases. In a bigger panel the resolution of the videostream is higher which lowers the framerate. This is an automatic process in VDG Sense.
Configuration
Configuration of transcoding is done in the Servers tab. It can be enabled in the subtab ‘Client Settings’ of the Servers tab. How to set the value is explained here.
Within the server settings tab, the tab ‘Advanced’ has the ‘Transcoding Quality’ setting. How to set the value is explained /wiki/spaces/KB/pages/933069368.
Quality examples
The effect of the Transcoding Quality is shown in the pictures below. First the original picture and below that examples of different quality settings.
On the left side the original FullHd image. The images on the right side of the orignal image the effect of 90, 50 and 10% quality setting:Quality setting with 10, 50 and 90% quality:
Bandwidth examples
The effect of the Bandwidth settings shown in the tables below. Bandwidth and the resolution of the panel are the two main factors which determine the framerate of the video. The tables below show the effect these parameters have. The results below are based on a FullHD camera at 25 frames per second with a bandwidth usage of 4Mbit.
Framerate if video is displayed in 4×4 layout (FullHD screen):
Quality | 128KBit | 256KBit | 512KBit | 1024KBit |
|---|---|---|---|---|
10% | 2 fps | 4 fps | 8 fps | 16 fps |
50% | 1 fps | 2 fps | 4 fps | 8 fps |
90% | 0.5 fps | 1 fps | 2 fps | 4 fps |
Framerate if video is displayed in full-screen (FullHD screen):
Quality | 128KBit | 256KBit | 512KBit | 1024KBit |
|---|---|---|---|---|
10% | 1 fps | 2 fps | 4 fps | 8 fps |
50% | 0.5 fps | 1 fps | 2 fps | 4 fps |
90% | 0.25 fps | 0.5 fps | 1 fps | 2 fps |