The new QMODs have the ability to output the video stream as an RF channel, an IPTV stream, or both at the same time.
First, it may surprise you that a digital QAM channel has always been an MPEG2/MPEG4 video stream. The only difference from Video over Ethernet is that the stream is carried over RF instead of IP. So when we create the MPEG stream, it's automatically compatible with RF and IP. We just have to add data to the stream when you opt for Ethernet to allow Unicast or Multicast network operation.
What Are the Streaming Options?
Presently, the IPTV stream is essentially the same as the RF Transport Stream.
- If the QMOD is set to provide only one program (no video input assigned to Program B), the IPTV stream will be an MPEG single program transport stream (SPTS), either for multicast or unicast.
- f the QMOD is set to use two programs, the IPTV stream will be an MPEG multiple program transport stream (MPTS), either for Multicast or Unicast.
- There isn’t a way to create one MPTS stream for RF QAM, and also create two SPTS streams for IP. That would require 4 encoders.
To Stream or Not to Stream
Presently, we are broadcasting the same stream for RF and IPTV. That's a full-bore HD MPEG2 stream typically set to 18 Mpbs for a single-program stream, 38 Mbps for a dual-program stream. Common for RF, a really big stream for many networks. This can be reduced by lowering the bitrate on one or both channels.
If the QMOD is set for Ethernet only, you can set the QMOD to variable bitrate, which will reduce bandwidth for typical content.
When the QMOD is set for dual-channel operation, not all IPTV receivers can be set to receive 2 programs in one stream. Better IPTV receivers can, not for inexpensive receivers such as Amino.
In summary, the IPTV stream we produce now may not be usable for sites that have restricted bandwidth. However, we already have QMODs delivering ITPV streams in several installations, so there are valid applications today.
Many also like the ability to broadcast media over RF, giving them a pathway for facility-wide media that won't stress their current network.
This form of Video over Ethernet creates a link from the QMOD to a specific IP receiver. The pros are that this stream will operate over most current networks and routers. The takeback is that you can only stream to one receiver at a time, and you need to set up the link within the QMOD.
Multicasting is far easier to implement, as you just broadcast the stream with a multicast address, and the routers do the work of sending the stream to receivers that request it.
The usual catch for integration is that not all routers can handle multicasting. All the site's routers must have multicasting enabled, with requires either software updates or new routers. Of the sites where QMOD IPTV technology is used, we are doing multicasting over 1G networks. In addition, the routers are set up as a VLAN, separating the media streams from the standard traffic.
Multicast IP addresses range from 22.214.171.124 through 126.96.36.199, which are set aside for multicast streams. However, there are "reserved" combinations in that range that don't work efficiently, so you'll want to use addresses assigned by the IT department. Typical "non-reserved" addresses include: