[mythtv-users] remote viewing/UPnP question

[Ross Boylan]

Raymond, than you for the information, which helps a lot.  I do have
some follow up questions/comments.
On Sun, 2012-09-30 at 19:20 -0400, Raymond Wagner wrote:
> On 9/30/2012 16:20, Ross Boylan wrote:
> > I've taken a couple of runs at accessing myth remotely, but have yet to
> > succeed.  Some of the docs I read confused me.  In particular,
> > http://www.mythtv.org/wiki/UPnP says "Make sure you have a route for
> > 239.0.0.0/8 out your lan nic BEFORE mythbackend starts (route add -net
> > 239.0.0.0/8 eth0). It seems it won't work if you add the route later."
> 
> That really depends on the system configuration. Some claim having such 
> a route configured is necessary for things function. I never recall 
> having to do such on my systems, on either Linux or FreeBSD. Whether 
> modern versions of the Linux kernel simply assume those routes and don't 
> bother displaying them, or that is controlled by some sysctl, I don't 
> know for certain.
Given that I have 2 NIC's, I probably need to tell the routing table
where to go, particularly since my default route is to the  outside
world.
> 
> > But other material suggests that isn't the only IP range that needs
> > special handling.  http://en.wikipedia.org/wiki/Universal_Plug_and_Play
> > says that version 1.1 references http://tools.ietf.org/html/rfc3927
> > which in turn refers to 169.254.*.*.  And the discussion of multicast at
> > http://tldp.org/HOWTO/Multicast-HOWTO-2.html says 224.0.0.* is for
> > management of the multicast 239.*.*.* addresses.
> 
> The whole 224/4 block is allocated for use by multicast. That includes 
> everything from 224.0.0.1 to 239.255.255.255. The UPnP autodetection 
> mechanism in particular only actually uses the address 239.255.255.250. 
> When you want to announce yourself or perform a search, you multicast a 
> datagram out on that address to anything that is listening. Technically, 
> very little consumer networking gear is actually cable of multicast, so 
> it all behaves like a broadcast. Inside that datagram is an address and 
> port upon which you are available for unicast access. The other machines 
> listening on the UPnP address then reply back directly to that address 
> and port with whatever information was requested.
Does this mean myth does not use the 224/4 block, apart from the
239.255.255.250 IP?
> 
> In order for that to work, you must exist somewhere on the network to be 
> reached. Normally, your DHCP server hands your system an address. 
> Sometimes, you define a static address. If you don't get anything from 
> anywhere, your system automatically comes up with its own arbitrary 
> address to use in the 169.254/16 range. In a fully configured network, 
> you have no use for this range. 
Good.  So that's all irrelevant to me, since I have a DHCP server.
> If you are trying to run a network 
> without having to configure anything, such that your systems are coming 
> up with their own addresses to use in this space, you need access to 
> that space, meaning you need an IP address in it and a route defined for it.
> 
> > My server connects to the laptop through a wireless router.
> 
> Likely not a cause of your basic problems, but something you will likely 
> end up dealing with later, wireless networks suck. For high latency 
> traffic such as viewing web pages, it's fine. For low latency, high 
> throughput traffic like streaming video, it really doesn't cut it. 
> Wireless networks will periodically drop out, even in the best of 
> environments, and MythTV is designed to operate on stable, reliable 
> networks.
Usually it connects via a cable; the wireless router does double duty as
an access point and a router for cables.
> 
> > I tried using Vista's Media Center (WMC) and Media Player (WMP) to
> > access the recordings.  I think they do UPnP, though the information
> > I've found is sketchy.  Does anyone know if they work?
> 
> I've only ever used it for occasional testing, but it's always seemed to 
> work well for me.
Do you mean testing UPnP in particular?
> 
> > (there is a setup screen that asks you to pick music/video/recordings
> > for UPnP--I'm not sure why it's only one, but I set if for recordings).
> 
> As I understand it, that is some workaround for screwy Microsoft UPnP 
> implementations. Normally, MythTV presents a directory structure to UPnP 
> clients, while Microsoft clients ignore that structure, and try to 
> resort all the content into its own categorization. That selector is to 
> only present one set, so everything doesn't get clumped together in one 
> unusable list.
> 
> > Some material indicates I need to set up a video directory, which I
> > have not done.  It would be empty anyway.  Some of that material says
> > I need to configure the external machine name in the folder location,
> > and I see no way to do that.
> 
> All of MythTV's recording and video library (and soon music and 
> photograph) storage is managed by the backend. You define the paths in 
> the "Storage Directories" section of mythtv-setup.
I saw that, but I don't see how the host name or IP is supposed to go in
where the directory name is.
> 
> > WMC and WMP do not detect any media servers as far as I can tell.
> > avahi-discover running on my linux box also does not report any sign of
> > myth.
> 
> If you left the configured defaults in mythtv-setup for MythTV to only 
> listen on 127.0.0.1, all those autodetection services will be disabled.
I've set it up to use the 192.168.40.2; at least I set that in 2 places
in mythtv-setup.
> 
> > The recordings are directly accessible from the laptop via samba.  Aside
> > from the browsing situation being bad because there are a ton of files
> > with names that do not reveal their content
> 
> If you want to access the files directly from the filesystem, and have 
> human-readable names, use mythlink.pl. 
Thank you  for the tip.  For some reason I thought converting the names
was a one-way process that caused other myth operations not to work so
well.
> It will produce one or more 
> secondary directories filled with symlinks back to the original 
> recording, with filenames formatted using the recording metadata and a 
> user-supplied formatting string.
> 
> > Finally, some of the TV's I might get say they do DLNA.  Does that mean
> > they will work with UPnP, or is something more required?  I realize that
> > even if they work the experience won't be great.
> 
> DLNA is a subset, and attempt at tighter standardization, of the UPnP AV 
> interface. DLNA capable TVs should work with MythTV using varying 
> degrees of success. MythTV records content using the original MPEG2/AC3 
> compression and TS container it comes in from the broadcaster, and then 
> pushes that unaltered to the UPnP client, so any sanely written TV 
> client should be capable of handling it. It's exactly the same thing the 
> TV should be getting from its own tuner.
I typically do lossless transcode to get rid of commercials.  I'm in the
US, which I believe means mpeg.  Will such transcoding interefere with
the ability of clients to play the material?   Does it matter if they
access the file directly via a share or through UPnP?

Thanks.
Ross