Re: Bandwidth requirements for DVArchive client

At 05:41 AM 6/9/2004, Tom Spraggins wrote:
>I am just on the verge of buying an HD-1000 anyway, and a DVArchive client 
>would be great!  Is 802.11b fast enough?  I'm not anticipating upgrading 
>to 802.11g for a while.

Good question!

I have found that with multiple wireless links, 802.11b is *not* fast 
enough, and that 802.11g is fast enough if everything is working pretty 
much flawlessly.  (I am assuming that all of your devices are linked 
wirelessly, or nearly so.  In my configuration, my ReplayTV and DVArchive 
machine have 802.11g links to a common 802.11g access point, and the Roku 
HD1000 is wired to the AP via 100bTX.)

The issue here is that the video is streamed from the ReplayTV to the 
DVArchive PC, and then from the DVArchive PC to the Roku, meaning that the 
amount of wireless bandwidth is double or triple what would otherwise be 
required.  This is something that could (and definitely should) be fixed in 
later versions of the DVAClient, if I am understanding the underlying 
architecture correctly.  Note that this is not much of an issue if you 
download shows from the ReplayTV to the DVArchive PC first, then stream 
them from the PC to your Roku HD1000, and 802.11b might be enough bandwidth 
in that scenario.

I had to experiment with numerous different WiFi channels to find the one 
with the least interference, and even tinker a lot with antenna orientation 
(!), despite the fact that the WiFi devices are all within a 100' radius of 
the AP, albeit spread across different floors of the house with the AP in 
the middle.  The odds that you'll see 54 Mbps with 802.11g are very slim - 
it backs off to lower speeds quickly unless the devices are all very close 
to each other, at least with the commodity D-Link gear I am using.  With 
that said, it still beats 802.11b, and with some patience, you can get 
pretty solid 20-30 Mbps performance out of it.

I'd also remark that my best-case streaming video playback STILL has very 
occasional hiccups due (probably) to congestion on the wireless 
links.  When I replace the WiFi link between the AP and the DVArchive PC 
with a wired one, these hiccups disappear.  The hiccups occur consistently, 
at the same points in a given MPEG file, implying to me that they are due 
to a surge in traffic, perhaps due to variable bit rate encoding by the 
ReplayTV.  (Forgive me, I am not a streaming media expert.)

The worst-case performance is that the HD1000 will stutter and even crash 
if it becomes bandwidth starved.  CinemaSix does not seem to respond well 
to this scenario for some reason.  In fact, once this starts, it sometimes 
gets stuck in a death spiral of sorts - it will play a second or two of 
video, stop, play another second or two of video, etc.   I believe this is 
a correctable problem in CinemaSix - it should be more tolerant of 
bandwidth congestion and simply pause the video, refill its buffer, and 
restart the video playback at that point, or something like this.  (Again, 
forgive me if this is inaccurate, as I am guessing here!)

I've been experimenting with this for a few days now on and off.  Overall, 
it is an EXCELLENT start towards a 'killer app' for the HD1000 and a very 
nice compliment to my existing ReplayTV.  With that said, it's clearly an 
early version, and there is lots of room for improvement --  the least of 
which being direct streaming from the ReplayTV itself to the HD1000, 
bypassing the hair-pin through a DVArchive server.  (Making it possible to 
rewind/skip ahead would also be nice.  I miss the 30 second advance button!)

But with that said, it is still pretty damn impressive, and the quality of 
the video playback on the HD1000 when it works is really rather 
outstanding.  It's convinced me to keep my HD1000 instead of returning it, 
as I had planned to do, and has actually got me thinking about a lot of 
other possibilities for the product.

Anyone else doing this over WiFi, by chance?

-- Jared