hdhomerun Re: tv tuners

[dieterbsd%engineer.com@localhost]

> SiliconDust HDHomeRun Network-based Single Digital HDTV Tuner 
HDHR-T1-US
> Ethernet Interface <- streams upnp so recording video should be 
os-independent.

Yes, the HDHR is OS independent.  I have recorded video with NetBSD, 
FreeBSD,
and Linux.  They supply C source code for a CLI program.  I use at(1) 
to schedule
recordings.

The other big advantage of the HDHR is that it doesn't require a slot.
I never have enough slots.  It does require Ethernet, 100Mbps or faster.
10 Mbps is too slow for HD.  It has the feature where the Ethernet port
figures out which wire is which, so you don't need a crossover cable.
Any computer on your network can access the HDHR.

Recording doesn't require much CPU, you're just copying bits from 
Ethernet to
disk.  Playback requires either significant CPU, or hardware assist 
from GPU,
or Broadcom's "Crystal HD" chip, or perhaps a media streamer box, ...

You can locate the HDHR near where the antenna coax enters the house,
eliminating losses from a long coax run.  I suggest locating it in 
conditioned
space, attics get very hot in the summer.

The HDHR provides more debug info than most tuners.  You get seperate
signal strength and signal quality numbers.  You get the number of 
packets
that failed to be corrected by the forward error correction.  When this
number is 0, you have an exact copy of the bits transmitted by the 
station.

The HDHR can provide the entire data stream, or it can filter by PID.
This feature can save a fair bit of disk space.

Now the bad news: your Ethernet had better be perfect, dropping a single
packet can cause a glitch.  The current models transfer the video data 
via
UDP. (Older units allowed the option of using TCP.)  Control commands 
are
via TCP.

The consumer models require dhcp.  IIRC the profe$$ional "TECH" model 
allows
setting a static IP address.  Many customers have asked for the ability 
to
set a static IP address, but they refuse to consider it, citing worries
about supporting people who forget what address they set.

The firmware is buggy, and it is closed so we can't fix the bugs.

If you complain about a problem, they might delete the feature rather 
than
fixing the problem. (example: transferring the video data via TCP)  If
they do fix a problem, the new firmware and/or utilities are available
from their website.  Firmware can be updated over the Ethernet.  Note
that if the new firmware is worse, you might not be allowed to go
back.

The silicondust web site has a somewhat useful forum, but they censor 
it.
They also expire postings.  http://www.avsforum.com/ is an alternative.

It cannot do anything with analog signals (NTSC, PAL, SECAM).

The biggest problem is the reception.  I spent a fair amount of
time/effort/money improving my antenna system.  High gain antennas
in the attic, quad-shield coax, filtering out non-TV frequencies,
ferrite, etc.  After all this my analog signals were *beautiful*.
No snow, no ghosts, no interference.  But the HDHR frequently
has reception problems.

On the web you can find various reports that other tuners get better
reception than the HDHR.

Interesting thread starting with #10875 on:
http://www.avsforum.com/avs-vb/showthread.php?t=381623&pp=30&page=363

"VSWR of SEVEN!!!!! That's the worst I've ever seen in ANYTHING!!!!!"

"I have one of these newer HDHRs, and it is the worst tuner I've used
in years. I have a bunch of LGDT3303 based PC tuners, some as old as
5 years, and they all outperform the HDHR by a wide margin. But I
really, really like the concept of an HDHR and I want to make it work.
Is there anything I can do to compensate for its bad specs?"

"Pretty solid evidence that these (HDHomeRun) tuners are susceptible
to the "Image Frequency" problem."

Silicondust recommends locating the unit away from computers to
reduce interference.  The RF tuner is in the usual sheet metal
enclosure, but that is not enough.

To sum up, it is a real love/hate thing.  Having it connect via
Ethernet is great, but the problems are significant.