AS NZS 62676.1.2:2020 pdf free.Video surveillance systems for use in security applications Part 1.2: System requirements 一Perd formance requirements for video transmission (IEC 62676- 1-2:2013, MOD).
4.2 Network time services
4.2.1 General
The Video Transmission Device (VTD) will require network time services for a real-time clock, eventing, logging and for the video transport stream (TS).
The VTD shall never start streaming video for recording purposes, if the requirements below on the accuracy of the time stamping of the video frames cannot be granted. This shall especially be verified after start-up or re-initiation after power loss of the VTD. Otherwise the integrity of the stream recordings may be corrupted and may not allow the correct replay not only of the concerned frame sequences, but also of other recordings. This has even higher impact on images used for the evidential purposes.
4.2.2 Real-time clock
The real time clock in the Video Transmission device should be synchronized with a time normal using RFC 2030, Simple Network Time Protocol (SNTP) Version 4 for lPv4, lPv6 and OSI. The addresses of the SNTP servers should come from the Time Server DHCP option (4). The more accurate system time shall be used as default: the SNTP best accuracy is 0,25 p5, whereas the usage of the ‘Time Server’ according to RFC 868 offers only a best accuracy of
1 5.
4.2.3 Accurate time services for the transport stream
As an option, Network Time Protocol (NTP) (Version 3) as detailed in RFC 1305 should be implemented when time services with an accuracy of I ms to 50 ms according to the requirements of Table 1 are needed. The lP addresses of the time servers should come from the Network Time Server DHCP option (42). The Network Time Protocol should be tried first and only on failure shall Simple Network Time Protocol be used. A null Network Time Server DHCP option (42) means no server is available and Simple Network Time Protocol should be used.AS NZS 62676.1.2 pdf download.