*Reducing network and client load

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Technical Article | TA-20201002-TP-46 VDG Sense | Tutorials | Video Streaming Open

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Introduction

VDG Sense has several techniques to reduce network traffic between server and client and to reduce the (CPU) load on operator stations when viewing many cameras. VDG Senses uses the streaming capabilities of the cameras itself to achieve this. There are three ways to achieve a more efficient use of resources:

• Dual Streaming
  Sense recieves a high resolution and low resolution video stream from the camera. Depending on the size of the panel in which the camera is viewed, either the high or low resolution stream is displayed.

• Multicast
  Operator stations connect directly to the multicast address of the camera instead of requesting it from the server.

• Dual Streaming in combination with Multicast
  Operator stations connect directly to either the low or high resolution stream of the camera depending on the size of the panel in which the camera is viewed.

When to use Dual Streaming or Multicast

Dual streaming is best used in a system where multiple high resolution video streams should be displayed on the operator station at the same time. For example, in a situation where 16 Full HD with H.264 encoding should be displayed, there will be a significant impact on the CPU load of the operator station. By default the actual panel size in which the video is presented is not taken into account eventhough the video stream is displayed in a (much) smaller panel. This means there is a significent overhead in video processing. It would make sense to process a video stream which is more or less the same resolution of the video panel to reduce this overhead. Dual streaming can achieve this effect.

Multicast streaming is best used in a system where may operator clients are displaying the same video stream. By default SenseVideoManager is receiving video from the camera and depending on who is viewing the camera it is send to one or more clients. With many clients this could create a network-bottleneck on the server system. By using multicast the operator stations (SenseClient) can connect directly to the multicast address of the camera without causing extra network load on the server.

In designing the installation and when to use which streaming technique, common questions are:

• Operator want to view many cameras on a single operator station
  Dual Streaming could be used, this reduces system load (CPU and memory) of operator station and reduces network load between server and client

• Many operator stations displaying the same set of cameras
  Multicast could be used, this reduces network load from server to client

• Network traffic between servers and clients need to be reduced
  Either dual streaming or multicast can be used

• Two or more server (parks) need to record video from the same cameras (backup system)
  Multicast need to be used. To prevent hick-ups in the video stream, it is not advised to have more than 1 system access the unicast stream of a camera.

Configuring Dual Streaming

Dual streaming can only be enabled if the device supports it and if Sense supports it for that device. If this is the case, Sense will show the option “Dual Streaming” in the device’s advanced settings tab (Read more)

1. Select the camera device in the Devices tab

2. Open the Advanced settings subtab

3. Select the “Enable dual streaming” checkbox

4. Select ‘Stream 2’

Record
In version  2.4.1 or higher the stream which should be recorded can be selected, it is either stream 1 or stream 2.

Stream Profile
For some cameras it is required that the stream profile is entered here. See below for more explanation and for which camera types this applies.

Max panel width
The maximum video panel width in pixels in which stream 2 will be displayed. If the video panel exceeds this number, stream 1 will be displayed. Normally this value is sliglhy higher than the actual setting of the second stream videostream width. For instance if the second stream is 720/576, the max panel width could be 960. To check the dual streaming configuration enable famerate and resolution in the OSD style (Read more). This will show the resolution and framerate in the videopanel when in operator mode.

Configuring Multicast

Multicast can only be enabled if the device supports it and if Sense supports it for that device. There are also differences in the type of multicast streaming supported by Sense. Depending on the cameratype, Sense will show the option “Enable Multicast” in the device’s advanced settings tab (Read more). To enable multicast check “Enable Multicast” checkbox.

For cameras which only support direct streaming or passive multicast the following settings will be available (e.a. VDG):

Multicast Address
The multicast address of the camera

Multicast Port
The multicast port of the camera

For the VDG camera the settings to enable multicast should be like this:

For cameras which support both RTSP multicast and direct streaming or passive multicast the following settings will be available (e.a Siqura, ONVIF):

RTSP (auto)
Depending on the camera type this option is available or not. Using ‘RTSP (auto)’ the Multicat Address’ and ‘Multicast Port’ will be not available. Using this mode the actual multicast address is retrieved from the camera using RTSP negotiation. VDG Sense also does not change or configure any values in the camera itself.

RTSP (manual)
Depending on the camera type this option is available or not. Using  ‘RTSP (manual)’ the settings ‘Multicat Address’ and ‘Multicast Port’ will be available. They need to correspond to the multicast settings in the camera. There is no negotiation with the camera about which multicast address and port should be used. VDG Sense also does not change or configure any values in the camera itself.

Multicast Address
The multicast address of the camera

Multicast Port
The multicast port of the camera

Below is an example of a Siqura Eve device settings page where both options could be configured.

In VDG Sense ‘Direct Streaming’ corresponds  with ‘RTSP Manual’ mode and ‘RTSP (Multicast)’ corresponds with ‘RTSP (Auto)’. It is adivsed to disable ‘Direct Streaming’ if RTSP Multicast is used because it could conflict with each other.

Dual streaming & Multicasting

Dual streaming and multicasting can also be enabled simultaneously. In the ‘Stream 2’ settings the multicast checkbox and settings need to be configured: 

Camera compatibility

Some camera brands which support dual streaming, require an additional in-camera configuration or the ‘Stream Profile’ in VDG Sense needs to be configured.

Samsung Wisenet III
A stream profile called ‘DUAL’ needs to be configured in the camera configutation. It is not require to fill in the ‘Stream Profile’ setting in VDG Sense. The procedure to add the stream profile is this:

1. Open the device web configuration page

2. Click the ‘Setup’ tab

3. By default, the “Video profile” page should be opened

4. Create a new profile and name it ‘DUAL’ (case sensitive, without quotes)

5. Click ‘Apply’

Siqura 1000/1100 series
For Siqura 1000/1100 series the ‘Stream Profile’ for the second stream needs to be set to ‘subStream’ (without the quotes).

Grundig 1
For Grundig 1 series the ‘Stream Profile’ for the second stream needs to be set to ‘subStream’ (without the quotes).

Axis
For Axis cameras the ‘Stream Profile’ depends on which stream needs to be used by VDG Sense. Axis offers several pre-configured streams with the name ‘Mobile’ and ‘Balanced’, but new stream profiles can be added. The names of the stream profiles can be found in the webpage of the camera.

ONVIF
To use dual streaming with camera which are configured as ONVIF device in VDG Sense, the name of the stream profile is unknown. Camera suppliers use unique names for the available streams. To determine the name of the second stream a program called ‘Onvif Device Manager’ is needed and can be downloaded by following this link.

The Onvif Device Manager is able to find all ONVIF compliant cameras in the local network. Follow this procedure to find the name of the ‘Stream Profile’:

1. Type in the user credentials in the upper left corner of the window

2. Find and select the correct camera

3. Click on ‘Profiles’ in the configuration pane, the available profiles appear in the list on the left side

4. Use the name of the second (or third/fourth if applicable) in the ‘Stream Profile’ setting of the device in VDG Sense.