[mythtv-users] Raspberry Pi as a slave backend server

[Dave MythTV]

On Sun, Mar 22, 2015 at 3:20 PM, Jay Harbeston <jharbestonus at gmail.com>
wrote:

>
> On Mar 22, 2015 4:06 PM, "Dave MythTV" <dave.mythtv at gmail.com> wrote:
> >
> >
> >
> > On Sat, Mar 21, 2015 at 3:09 PM, jrh <jharbestonus at gmail.com> wrote:
> >>
> >>
> >>> On Mar 21, 2015, at 12:56 PM, Dave MythTV <dave.mythtv at gmail.com>
> wrote:
> >>>
> >>>
> >>> On Fri, Mar 6, 2015 at 8:22 PM, jrh <jharbestonus at gmail.com> wrote:
> >>>>
> >>>> I have experimented some using the raspberry pi as a slave backend
> server and have had generally good results with caveats.
> >>>>
> >>>> Configuration:
> >>>> Raspberry Pi Slave backends running v 27.4(dated in November)
> >>>> NFS mount to the Master backend for the mythtv directories.
> >>>> Hauppauge USB HVR-950Q tuner(1 only ) (configured only 1 virtual
> tuner so only 1 recording)
> >>>> I did not configure the analog side of the tuner, only the digital
> part.
> >>>>
> >>>> Using a Raspberry Pi model B and B+:
> >>>>
> >>>> Able to record Standard Definition mpg video stream.
> >>>> When attempting to record 720p or 1080i streams, there would
> consistently be TFW taking to long errors.
> >>>>
> >>>> Using a Raspberry Pi 2 model B: (the quad core version)
> >>>>
> >>>> Able to record Standard Definition mpg video stream
> >>>> Able to record both 720p and 1080i streams up to 15mbps!
> >>>>
> >>>> In summary, for 1 stream and a USB TV stick The RPi 2 is a viable
> masterbackend with the above conditions. I didn’t try multiple streams off
> the same real channel, but I suspicion the Pi 2 would be able to handle it.
> >>>>
> >>>> Note that I did not try analog recording as there are no analog NTSC
> Over the air broadcast stations in the area and so I didn’t even try to
> configure the analog side.
> >>>
> >>>
> >>> Thanks for sharing this information!
> >>>
> >>> A few quick questions for you:
> >>> 1) Which Linux distribution are you using?
> >>> 2) I'm assuming this testing was with a wired network (and not a USB
> wireless adapter)?
> >>> 3) Do you have any thoughts on the source of the TFW errors on the Pi
> 1?  Such as, whether the TFW errors with the Pi 1 were related to the CPU
> loading, pushing the data out across the network, or a limitation of the
> USB system?  (Since it kept up OK with standard definition streams, I'm
> wondering if the Pi 1 might be sufficient as a high-definition slave
> backend if it recorded directly to a small local USB hard drive, or even to
> its own SD card, and then did a non-realtime NFS data transfer back to the
> master backend when the tuner was idle?)
> >>>
> >>>
> >>> Keep us posted on how things go if you try multiple streams or
> multiple tuners on the Pi 2!
> >>>
> >>> Thanks
> >>> - Dave
> >>
> >>
> >> I am using raspbian off the noobs image.
> >>
> >> You are correct, I just used wired network. I didn’t even want to try
> going wireless.
> >>
> >> I didn’t even try experimenting using a local usb drive as that
> wouldn’t fit my usage scenario, so are still all good questions.
> >>
> >> I will be staying with a single USB tuner for my needs, and Since I
> started using the RPi 2 configured as above, I have had no TFW errors since
> starting to use it!
> >>
> >> I have no plans whatsoever to try to use an RPi of any kind as a
> frontend, however, they are very insteresting as a remote backend like I am
> using. The pi 2 plus the hauppauge USB tuner are only using around 7 watts
> while recording!
> >>
> >> By the Way, I noticed I goofed above when I said it was a viable master
> backend. I meant to say it is a viable SLAVE backend.
> >>
> >> An experiment I might try sometime in the future is to have an RPi as a
> masterbackend ONLY with no tuners(just define a dummy recorder). No
> immediate plans to try that tho yet.
> >>
> >> Regards
> >>
> >
> >
> > Thanks for the reply.
> >
> > Remind me again what your usage scenario is?
> >
>
> I needed a remote tuner as you spoke about however I do have wired network
> available. I don't think wireless will work very well.
> >
> > I'm considering a possible usage for myself with a remote slave backend
> up in the attic, on a wi-fi connection, to allow for separate tuners
> directly connected to separate directional antennas aimed at some of our
> fringe stations from nearby cities.   Being co-located up in the attic
> would allow the USB tuners to be directly connected to the antennas
> (effectively 6 inches or less of coax), minimizing the cable loss and
> removing the need for multiple additional long coax runs (and possibly
> pre-amps) to the master backend/frontend in the living room.
> >
> > The Raspberry Pi would seem to be a good candidate for this, but if I
> end up needing two or more Pi 2s to handle the separate tuners
> individually, I might as well just stick a single x86 ECS LIVA up there
> instead as the overall price and power consumption would be similar, and
> the setup would be much simpler.   If one of the Pi 1 models could do the
> task for a single HD stream, however, then even with multiples, the price
> and power figures swing into their favor.  :-)
>
> The pi 1 doesn't have enough 'grunt' to handle HD streams. When I tried it
> I had a lot of TFW errors.  The pi 2 was fine with HD stream. I didn't test
> was the multi tuners on the pi 2.
>
> Regarding your remote additional antenna, why not try the hdhr tuners?
>
> >
> > And it's all in that interesting scenario where it would be easy to test
> with experimentation, but if I try it and it doesn't work, the $$ "wasted"
> on the Pis could have just bought the LIVA.    Hence the interest in the
> details of what you've been testing!
> >
>
>
For my case, the fringe stations, the HDHR has a number of things against
it.    The older units had dual tuners with two independent RF inputs,
which is great, but they were known for having lower tuner sensitivity.
The newer units have better / more sensitive tuners, but have a single RF
input and an internal splitter which knocks down the signal.   For these
fringe stations, I'll need every last db of signal I can get - which means
two large directional antennas pointing two different directions and
nothing else but a low-noise preamp in the path.  Plus, the HDHomeRuns take
a lot more power and cost more (and I would need two), and I would have to
either run ethernet up to the attic, or set up a separate wifi bridge with
a local switch.   So.. not really practical.  :-)

I know you said the Pi 1 couldn't do a HD stream in your setup, but that
was pushing the data out over the network with NFS in real-time.   I'm
still thinking/wondering if it might be possible with local storage to the
SD card when recording, and a deferred non-real-time NFS transfer when the
tuner is idle.   That should halve the loading on the Pi's USB bus, and
significantly reduce the system processing load when recording.   I just
don't know if it would be enough...

Thanks
- Dave
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mythtv.org/pipermail/mythtv-users/attachments/20150322/937eb7d4/attachment.html>