User’s Manual v.15
QVidium
®
H.264 HD Video Codecs
™
Copyright 2011-2014 QVidium
®
Technologies, Inc.
Page 61 of 71
13.2 Appendix B: Decoder Configuration Parameters
This section explains the parameters related to the setup and operation of the MPEG Decoder, the
error correction algorithms, and network transport configuration.
Input & Output Parameters
Input:
On the QVPRO and QVPRO-LITE, you can choose either
“Network”
or
“ASI”
as the input
source. Network selects the Ethernet port as the decoder input. ASI listens for an DVB-ASI stream
on the SDI BNC connector.
Warning:
Detect Video Break only works for Network input. If you use
ASI input, then the decoder may get into a bad state if there is an interruption in the input stream.
Network Parameters
The fields below relate to Ethernet/IP video transport settings.
IP Transport:
This selects the type of video IP packet decapsulation and error correction expected
by the codec in receiving a Video/IP stream. All packetized video transport mechanisms expect to
receive a multiplexed constant or variable bit rate MPEG-2 transport stream to decapsulate and
decode.
ARQ uses QVidium’s patented error correction mechanism for lost packet recovery. ARQ
encapsulates the video stream as a standard MPEG-2 Transport Stream as the payload of
UDP packets with an RTP packet header as per RFC2733. It relies upon an upstream
channel on UDP port 7020.
RTP mode decapsulates the MPEG-2 multiplexed data according to RFC2733. It will
process the data through the de-jitter buffer (if set to a non-zero value) and the reorder
buffer (also if set to a non-zero value), but will not send out ARQ retransmission requests.
Because RTP headers include a timestamp and sequence numbing, RTP protocol has the
advantage of providing lost packet and other network statistics.
UDP mode disables all error correction. It expects raw UDP packets without an RTP
header, and expects to receive an 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 Buffer:
The IP packets of incoming video streams may lose their ordering or suffer variable
delays during transport through an IP network. If the value of the Jitter Buffer is non-zero, the
QVidium QVPRO H.264IP Codec will process all incoming video/IP packets through a time-based
buffer that removes variations in packet arrival times, also known as packet jitter, and reorders
RTP encapsulated packets by their RTP sequence number. The Jitter Buffer parameter specifies
the size of this incoming packet buffer in milliseconds of delay, and holds incoming packets for this
amount of time before releasing them. You can specify zero (0) here to disable this additional
buffering when latency needs to be minimized. This buffer can only exist in ARQ and RTP modes.
Video Buffer Size:
This value, specified in milliseconds, adjusts a buffer in the video decoder that
helps prevent the decoder from running out of data and losing sync due to jitter or variability in the
delivery of data to the decoder. If you notice audio clicks or pauses, or if the decoded video
occasionally freezes or loses lip-sync, especially over long network distances, increasing this value
