DLNA–what is it? First steps on a path to wisdom…

I am looking at DLNA to work out if I can use it as a sensible alternative to a HDMI matrix + HDMI extenders.

This article I found contained a nice overview of DLNA that I could understand.  There is of course the DLNA web site – but I have not found that site so useful to date.  I also found this article interesting from Sony.  This article (“why do I hate the DLNA protocol so much”) I personally found interesting from someone who has been implementing the DLNA standard in an open source project.  I have a programming background, so it was interesting to see that DLNA is implemented using HTTP, XML, SOAP, and streaming multimedia content over HTTP (with appropriate content types).  I had hoped to read the spec online – from that last post it looks like its $5,000 for a copy of the spec (!).  Hmmm – might be better to go look at the open source implementation instead!

So it appears that DLNA is a subset of UPnP (Universal Plug and Play) A/V, where only specific file formats are permitted.  Ok.

My hope for DLNA is that with a DLNA compatible TV, it might be an easy way to view multiple available sources (Foxtel, DVD, baby video monitor) easily, much like selecting between different A/V inputs on your TV.  The problem is the need to convert the different sources into a DLNA stream.  Examples of sources I want to convert include:

  • DVD output (although there are “DLNA compatible” DVD players on the market now – just have to work out if they can view a DLNA source or act as a DLNA source).
  • Foxtel pay TV
  • Baby video monitor

The trick here is how to convert the HDMI output of the Foxtel box, or the low quality composite video output of my baby monitor, into a DLNA stream.  Hopefully there is a box that can do this – but it does not sound trivial and I have not found such a box yet.  It might require a full PC in order to do it.  For example, it may be that the Foxtel output needs to be transcoded in real time to one of the DLNA supported video formats.  Doing it real time is the challenge.

Note: I may ditch my current baby monitor solution if I can find a DLNA compatible surveillance camera system.  The nice thing about DLNA is multiple TVs can watch the stream at the same time – so can check up on the baby from the nearest TV.  I got a blank look when I asked for a DLNA compatible from a local electronics shop (but it could have just been the salesperson I got).

Another thing I don’t understand yet is how to pause, change track etc when viewing a DVD.  I believe it is possible, but not sure how yet.  (Some hints are given here – play, pause, seek, volume, … basic stuff only?)  And what controls can be sent down the channel to the device?  For example, can you send an “eject DVD” command, more more usefully, all the commands to control my Foxtel (pay TV) IQ box (includes hard disk recorder)?  I don’t understand enough about DLNA yet to work out what is possible.  Some stuff I have read indicated that pause, play, change track was supported within DLNA.  It may be that sending IR signals back somehow (independent to DLNA) is still going to be required.

More investigation to come!

PS: Gosh, doing more Google searches you find forum posts such as this one that go on for pages.  Looks like there is lots of people around doing stuff in this area.

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