[pvrusb2] HVR-1950 Schedule Information Source

[Roger]

On Wed, 2009-05-06 at 23:55 -0500, Mike Isely wrote:
> On Wed, 6 May 2009, Roger 
> > 
> > I've performed manual scheduling using MythWIKI for the past year.  It's
> > much easier with the wiki page, after the initial learning curve.
> > 
> > Feeling more comfortable the HVR-1950 should work here after acquiring
> > this missing info concerning EIT & finding XvMC works extremely well
> > (nullifying the system requirements. ;-)
> 
> You DO realize you're debating an issue that amounts to a trivial 
> $20/year, right?

Yes.  I also realize the *real* person bailing out the banks is me with
my interest payments.  Besides, I'm quite boring here in my old age &
only watch the nightly news & PBS shows. :-)

> 
> 
> > 
> > I was considering a HDHomeRun, but then would figure I would have to
> > upgrade my entire network to gigabit and then, as I run Gentoo syncing
> > to a local portage, would create hiccups on the local net causing frame
> > jitters during recordings.  Figure the pvrusb2/hvr-1950 will provide
> > better stable recordings.
> 
> You'll get the same quality of recording from either type of device.
> 
> Two errors in logic here.
> 
> First, you don't need a gigabit network to use an HDHomerun.  I ran here 
> using 100BaseT for quite a long time without any problem.  (I'm using 
> gigabit everywhere now but this wasn't the reason why.)  If you're 
> really worried about this, stick a second NIC in your backend system and 
> use a crossover cable to direct-connect it to the HDHomeRun.  With that 
> you'll have a private pipe to the tuner anyway.
> 
> Second, the data from an HDHomeRun - just like from an HVR-1950 or any 
> pvrusb2-driven device - is a digital bit stream consisting of mpeg2 
> data.  These are not raw video frames and are thus not sensitive to 
> relative timing.  This is an important difference because mpeg2 data is 
> internally self-timed.  Jitter / non-deterministic packet delivery will 
> not harm the quality of the video stream at all.  So long as the sending 
> side can buffer a second or two of data (should not be a problem) you 
> won't lose anything.  And since the receiving end is a MythTV backend, 
> it's going to buffer up a few seconds there anyway.  Hiccups should not 
> be a problem - unless your backend gets overloaded but that's the same 
> with a pvrusb2-driven device as well.
> 
> The behavior of the bit stream from an HDHomeRun will be functionally 
> identical to what you get from a pvrusb2-driven device, i.e. in the end 
> it's just an mpeg stream.  And a 100BaseT link should be fine.
> 
>   -Mike

Thanks for putting some holes into my apparently logical thinking
patterns. ;-)

Didn't realize the HDHomeRun buffered packet transmittal.  But I am
constantly maxing-out my 100TX home LAN with local Gentoo Portage syncs.

There's a good write-up in a forum on HDHomeRun packet transmittal
rates. ie. 100Mbps for 100TX LAN, and one HDHomeRun only uses 20Mbps.

I've also implemented nice & ionice into my Portage syncs to prevent
overloads. (ie. ionice -c2 -n7 nice -n19 rsync)

-- 
Roger
http://rogerx.freeshell.org