Drucegrove DragonFly User Manual 1.4
Page 39
Supported Network Protocols for Video
Video and/or audio can only be sent over a network as packets inside a container. User Datagram Protocol (UDP) is
often used in live broadcasts because it supports multicasting (see Live Network Video section).
The following table shows current network protocol support:
Video Format
Software Demux (CPU)
UDP *
* UDP protocol only supports
MPEG-TS container
HTTP *
* UDP protocol only supports
MJPEG streams
MMS
RTSP
Live Network Video Overview
For a live network video source, a video streaming device should be present on the Ethernet network. The streaming
device could be anything from an IPTV DVB Gateway coupled with a Transceiver, to an IP Security Camera.
For IPTV, the video should be output as an MPEG Transport Stream via UDP to a
Port
on an
IP Address
. The IPTV
streamer can either send the video directly to a single DragonFly via its IP address (unicast), or to a virtual location
on the network where multiple DragonFly units can “tune in” and receive the video simultaneously (multicast).
The
Port
is a 16 bit value, can be any value between 0 and
65535. Certain ports are reserved under IPv4 (ie, port 80 for
HTTP). Drucegrove generally configure video to be sent to port 5000 by default.
Multicast streaming requires managed switches with IGMP (Internet Group Management Protocol) Querying, which
manages the video stream on the network and directs it to the units on the network that need to receive it. Only one
copy of the video stream exists on the network, regardless of the number of units receiving. This means minimum
bandwidth is required.
Unicast streaming does not require managed network switches (IGMP querying is not required, unlike multicast), but
for each DragonFly unit receiving a copy of the video, the streamer will have to send out a dedicated copy. This
means that for 10 units to receive unicast video, 10 times the network bandwidth is required compared to sending
out a single copy. Video streaming hardware will only be able to support a limited number of unicast streams; in
some cases only a single stream can be output at any one time. Multicast is therefore recommended if more than
one unit on the network is showing video.
IP Addresses
are made up of 32 bits. They are typically represented by four byte values (0-255) separated by a
decimal point. If the first four bits (4 most significant bits) of an IP Address are 1110, then this is a multicast IP
Address under the IPv4 standard. This means that multicast streams should be on IP Addresses between the range
224.x.x.x and 239.x.x.x. There does not have to be any hardware on the network configured to the multicast address,
it is just a virtual location, and when the streamer sends data to a valid multicast address the managed switches uses
IGMP Querying to route the video packets to the correct locations. When a DragonFly unit is configured to receive
multicast UDP video, it sends a command to the IGMP Querier, telling it to send it any multicast data destined for
the specified multicast IP Address. Drucegrove generally configure multicast video to be sent to 239.0.0.1 by default.
