Datavideo BB-1, Instruction Manual

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Datavideo NVD-3X MK2 Decoders
Datavideo NVD-3X MK2 HDMI/SDI decoders connect seamlessly with dvCloud using just your username and
password.
Features:
• Control the NVD-30 MK2 settings from anywhere over the internet.
• Monitor the NVD-30 MK2 from anywhere over the internet.
• Easily link the NVD-30 MK2 to encoders via the cloud.
• Use SRT (secure reliable transport) for reliable low latency point to pint links over the internet.
Please see the NVD-3X MK2 manual for more information.
SRT Latency
You can add from 20 ms to 8000 ms of latency to the SRT stream. Increasing latency gives more time to buffer
packets and resend any that got lost in transit to the destination. If the latency value set for the stream is too low
and there is packet loss over the network, retransmission of lost packets will not be possible, and the stream quality
will suffer.
dvCloud provides several detailed statistics to ensure you set an appropriate SRT latency value:

Round Trip Time: The round-trip time between the encoder and dvCloud.

Packet Loss %: The total percentage of packets lost between the encoder and dvCloud NOTE: Most are
recovered by retransmission at the source and so do not necessarily result in any artifacts.

Receive Rate: The total received data rate (Audio + Video).

Total packets Received / Lost: This is the total number of SRT packets received and reported missing by the
dvCloud. For each “hole” detected in the packet sequence, a request to re-transmit the lost packet is sent to
the sender. This lost packet may (or may not) be re-covered by the re-transmit request. NOTE: This is the
raw number of packets dropped by the network. Most are recovered by retransmission at the source and so
do not necessarily result in any artifacts.

Total packets Dropped: This is the number of SRT packets reported dropped. NOTE: These are packets that
have arrived at the dvCloud too late, or that never arrive at all and have not been recovered. Some type of
video artifact may result (i.e., a replayed frame or video blocking artifacts). This statistic is very important as
it can indicate the SRT latency value is too low or video bitrate is too high.
As a general rule you should monitor the round trip times and set the SRT latency value to 4 * RTT or 2.5 * RTT if low
latency is required, if the ‘Total packets Dropped’ value is increasing the latency value is still too low and must be
increased.