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Now, that's interesting.
I counted tivo out, even after the new price
cuts.
I've got showshifter running perfectly
finally, and
I can watch dvd's divx listen to mp3's, browse the web, share the cable
modem
serve files timeshift and watch tv all from one box.
Wireless keyboard and mouse, IR control from
wintv
card to control NTL digibox with a RedRat2 which I got working just
yesterday
after about 2 years of trying on and off.
Had to train the RR 3 or 4 times, but finally
it
works! (I have to contact the maker and forward a very long delayed cheque,
along with a case of beer I think, for his patience)
As my house is a typical Berkshire 2.5 bedroom
job,
having less boxes is a good thing. I've killed the dvd player and a tivo
and a
router by my reckoning.
But I am building a security system, and it
suddenly sounds interesting.
I am very interested in how this goes Kevin,
so
please post up your progress.
Jason
----- Original Message -----
Sent: Friday, March 08, 2002 7:08
PM
Subject: [ukha_d] Tivo as a security
recorder (long ramble)
Following an offline chat with one of our members I just though I'd post
some
thoughts about using Tivo as a video security recorder in case others are
interested. It's something I'm playing with at the moment. In a dedicated
scenario like this you don't need a subscription to Tivo so you get a great
alternative to a Time-Lapse recorder for your £200, the big plus being you
have full speed/quality recordings.
Tivo per say doesn't have an 'AUX' video input that is easy to record
>from
's
standard aerial input and it has a Scart input capable of either composite
video or RGB recording. Normally your decoder box is connected in
here.
I had originally tried to convince Tivo Inc. to incorporate a
time
lapse type recording ability into the software allowing a low frame rate
and /
or poor quality. My idea was that on some sort of trigger condition (alarm)
the Tivo could step up to highest quality & full frame rate. That way
you
would have hundreds of hours of time lapse and still space for highest
quality
in alarm conditions. I had imagined the trigger to be either
(preferably) a serial input to Tivo or a remote IR keypress and that
the
buffer could be retained at full frame rate. But no luck and no one
else
seemed to want this feature. So a review of my options and I am thinking about
the
following....
My camera will be connected directly to the Scart input and just appears to
the Tivo as any channel that would have been on an external decoder. In a
multi camera situation then either you go through a multiplexer (optionally
with auto alarm triggered full screen selection at the mux) or you modulate
your cameras onto the aerial input on different channels and select
accordingly. The first is preferable for reasons that become
apparent*.
It would seem there are two options for recording depending on recording
history needs.
1) You
leave Tivo set to the channel and when an alarm condition is generated you
send an IR command forcing the recorder on (*at the right channel) -
unfortunately I suspect the buffer will not be recorded - this is
really because there is no program guide in Tivo (as you have no
subscription)
and although the buffer is now intelligently copied in v 2.5 of the
software
the problem is the intelligence goes back to the scheduled program
start which is not available. I have yet to try this as I need my
guide info to run out. *If a channel change occurred the buffer would be
cleared anyway. Using this method you probably lose a couple
of
seconds at the critical time which is vital so probably a better solution
is
....
2) You
set
up a series of manual recordings. The length of the recordings here is
dependent on a few things. How much activity you have that is
generating
an alarm condition, the size of the hard disks in your Tivo (recording time
available) and what quality you want to capture 'alarm' recordings at. I
have
upgraded to large disks and I have chosen to record at Medium
quality. There's also no point in recording at too high a quality if the
cameras are not up to it. So I have manually set up 48 recordings each
of
exactly 30 mins. in length. I might move to 96*15 mins.. I can record
about 1 weeks continuous video at this rate. The simple way now is to log
the
exact time of any intrusion on you home PC (from say a triggered PIR or
motion
detection software) and then cross reference to the recordings to pick out
the
segment that contains your video clip. Tivo by itself will purge oldest
recordings first to make way for the new ones so in my setup you have a
week before they get deleted.
There are better ways though that increase your ''weeks' recordings by
orders of magnitude ! Firstly you don't need to set up full
24hour recording if there are times when you are not monitoring for
alarm
conditions using your alarm triggers (e.g. PIR's in an office during office
hours or when the alarm isn't set). Secondly you only need to keep clips
that
have alarm conditions associated, so we can introduce some
intelligence.
Two solutions spring to mind.
You could
immediately delete a recorded clip if the next segment has started and no
alarm condition was logged during its recording. However Tivo will do this
eventually for you anyway so you may feel more comfortable having it left
there just in case it contains something that your sensors missed, or
perhaps delete it after an hour if no later alarms occurred. An
even better option seems to be to mark any recording that contains an
alarm condition as 'keep indefinitely, this way the required clips are
never
deleted and the adjacent clips if required stay around for at least a week.
Perhaps you should keep immediately adjacent clips as well just for good
measure.
The
control side for this is done through infra red - it would be nice to use
the
serial port but I haven't unearthed any information yet on this
protocol.
I use motion detection software over several cameras to select which to
record, supplemented by PIR's. These will probably go through a mux to
allow
single or split screen selection in multi trigger situations. The
alarm
trip signalling goes to Comfort &/or HomeVision which creates a log
file
of the times and to generate the various IR signals to update the Tivo. A
nice
feature is that the Tivo is 'fail safe' to a recording condition and so
should
something not work or be interfered with then recording is still
there. Also there is no time critical IR interaction as I am only altering
the
flagging on previously saved files.
I
haven't
actually done all this yet as I was waiting for my second dedicated Tivo to
arrive but now it has I shall be giving it a go. Food for thought
perhaps... if anyone else is interested get in touch with
me...
Kevin
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