QVidium QVMP2C-1011 - Manual (Page 38)

User’s Manual v.28 QVidium™ MPEG2+4 Codec
38 of 45 - Copyright 2007-2008 QVidium™ Technologies, Inc.
• UDP is similar to the RTP transport above, but expects raw UDP packets without
an RTP header. It expects to receive the MPEG-2 transport stream directly from
the UDP payload. Use this setting for interoperability with some Set-Top Boxes.
Multicast Address: This specifies the IP multicast address, if any, to listen to for the
Video/IP stream. For receiving a unicast video/IP stream, leave this field blank.
UDP Port: This specifies which UDP port number (P), base 10, to listen on for the
Video/IP stream. Be certain to open also your firewall to port P+2 and P+4 for ProMPEG
FEC. (P+2 for column parity and P+4 for row parity packets.)
Jitter: Packets in incoming IP packet streams may lose their ordering or suffer variable
delays during transport through an IP network. The QVidium MPEG2+4 IP Codec buffers
all incoming video/IP packets in a buffer and reorders RTP encapsulated packets by RTP
sequence number. This parameter specifies the size of this incoming packet buffer in
milliseconds of delay. Specify 0 here to disable this additional buffering when latency
needs to be minimize.
ARQ Parameters
The parameters below ONLY pertain to QVidium ARQ error correction. They will be
ignored unless ARQ is selected for IP Transport.
Target Latency: QVidium’s ARQ error correction operates through the addition of a
small additional buffering delay to provide enough time to request and receive
replacement for each lost packet. Target Latency gives the ARQ mechanism a target value
for determining the necessary ARQ delay. The ARQ divides the Target Latency, specified
in milliseconds, by the round-trip time to the video encoding source to determine the
number of request attempts. Unless Robust Mode is enabled, it sets a minimum ARQ
latency of one round-trip time. A larger Target Latency allows the system to increase the
number or repeat requests.
Max Burst Drop: Burst packet losses are common occurrences in many IP networks and
the Internet. IP networks may dynamically change paths in response to load balancing,
link failure avoidance, and for other reasons. During a re-route, a sequence of queued
packets on a discontinued path may be dropped. A burst of packets may be dropped when
higher priority packets stall a lower priority buffer. ARQ will notice a burst packet loss
when the first packet after the loss arrives at the codec. Setting the Max Burst Drop Delay
(in milliseconds) will delay the ARQ repeat request by this amount to handle packet burst
losses.
Robust Mode: Normally, the ARQ will only require that a minimum of one repeat request
is sent to the video encoding source device, regardless of the Target Latency. However,
enabling Robust Mode will increase the minimum number of repeat requests to a minimum
of two retries.
ARQ Port: By default, ARQ normally sends upstream retransmission request packets on
UDP port 7020. You can change this ARQ Port setting to any valid and non-conflicting