[All cameras][VAST] What is the workflow of the Seamless Recording function?

In this article, we'll be exploring in detail the seamless recording flow between a camera and the VAST software. Understanding this process is vital for optimizing your use of the system and troubleshooting potential issues.

 

Seamless Recording function:

Seamless recording refers to a continuous, uninterrupted process of capturing and storing video footage. Meaning that the camera and the VAST will work together to ensure there are no gaps in the recording timeline.

If there any gaps, the VAST server will simultaneously retrieve the time-tagged videos that were temporarily stored on SD/SDHC/SDXC cards.

 

VAST software behaviour:

• VAST retrieves lost recordings at 1X speed.
• Seamless recording demands twice the bandwidth as it involves simultaneous normal recording and retrieval.
• Seamless recording also necessitates twice the storage write speed.

For instance, if the recording stream bitrate is 2Mbps, during simultaneous normal recording and retrieval, VAST requires twice the bandwidth, amounting to 4Mbps in this scenario. This also means that a storage write speed of 4Mbps is required.

Seamless Recording Flow

 

On the camera side, the methods for identifying disconnecting and reconnecting differ.

• Disconnect:
  • TCP: If the camera does not receive a receiver report from VAST for 10 seconds, it will register as disconnected.
  • UDP: The camera sends a sender report every 7 seconds. If it does not receive a receiver report from VAST twice consecutively, it will register as disconnected.
• Connect:
  • VAST attempts to connect to the camera every 3 seconds using a GUID. If the GUID matches, the camera will register as connected.

Following this, lets see the following example. Suppose a camera is connected via TCP and UDP:

• For TCP: If the camera doesn't hear from VAST for 10 seconds, it assumes it's disconnected.
• For UDP: The camera sends a report every 7 seconds. If it doesn't get a response from VAST twice in a row (around 14 seconds), it assumes it's disconnected.

To reconnect, VAST tries every 3 seconds using a unique code (GUID). If the GUID is correct, the camera assumes it's reconnected. In short, the camera and VAST constantly check in with each other. If they lose contact, they realize quickly and try to reconnect.