Directv Tivo

[jaidev]

Just thinking out aloud here..
question regarding DirecTV Tivos im wondering about is..
would a Directv Tivo be expecting a NTSC signal from the Satellite Signal?

[ehintz]

Just a WAG here, but I don't think it will matter. It's just writing the sat signal straight to disk so it shouldn't matter in theory anyway-it's all just bits and bytes. But it might freak later when you attempt to play it and get PAL instead of NTSC. I guess the key here would be the dsp chip-is it the same as a standalone? If so, presumably the PAL mods would work and all would be hunky dory.

[number6]

Just a WAG here, but I don't think it will matter. It's just writing the sat signal straight to disk so it shouldn't matter in theory anyway-it's all just bits and bytes. But it might freak later when you attempt to play it and get PAL instead of NTSC. I guess the key here would be the dsp chip-is it the same as a standalone? If so, presumably the PAL mods would work and all would be hunky dory.

The Directivo only has the MPEG2 decoder chips (and related video encoder chips to output the decoded video stream to your analogue TV set).
The MPEG decoder works with either PAL or NTSC as its setup by the fpga module that gets loaded.
The SA Tivos we have have a MPEG encoder as well to take the analogue TV signals from the Video input sockets or vbia the Aerial socket/tuner) and turn it into a MPEG stream that can be recorded to disk forplayback later.

The DirecTivo is much cheaper to make and buy since it only does decoding of MPEG stream and never encoding.

You can only use a DirecTivo to play back digital signals that were encoded in MPEG2 (by the broadcaster before uplink to satellite) for the same TV system.
e.g. you can use it to watch NTSC signals from a DirectTv sat as these are broadcast as "NTSC" MPEG streams.
If you recieved a PAL encoded MPEG stream [e.g. from Sky NZ] then your DirectTivo would have to be in "PAL" mode for the mpeg decoder and video encoder chips to be able to output this signal correctly to your TV set.

What it can't do is receive NTSC signals and output as PAL [or v.v.].

However, most good TV's here are multi-standard anyway so will accept NTSC or PAL - or PAL-60 (which is NTSC signals shoe-horned into PAL format, with the PAL colour signalling added but with NTSC's frame rate of 60 fields/sec), which is what a lot of the cheap VCRs output that purport to have "NTSC playback" actually output.

Thus giving you the worst of both PAL and NTSC worlds, but allowing you to watch those NTSC videos in some sort of colour on your PAL TV.


As an aside, if you wonder at how "compatible" the Tivo software is between SA units a DirectTivo units, look in /etc/rc.d/rc.sysinit, you will find in this startup script lots of references to CAMs and other crypto related "hardware" which is not present in a SA Tivo, but is in the DirectTivo.

So, the whole Tivo software is designed to be "soft" configured to handle both SA Tivos and DirecTivos and configure itself accordingly and I think software wise the difference between a DirecTivo and SA Tivos release 3.0 softwares "DNA" is not as much as you might suppose.

The CAM that does the decryption of the NDS Videoguard used by DTV is a software module that gets downloaded into the "TS processor chip" on the DirectTivo mainboard when Tivo starts up and thats the chip that unscrambles the MPEG streams (on playback only) then feeds it out to the Tivo video subsystem that decodes this stream from MPEG 2 format and lets you watch it on your TV. The unscramble of streams is done during playback not during record so that the stream stays encrypted while on disk (a requirement that the movie studios insist on to protect their "IP").

In theory, if you had a CAM for Sky NZ's VideoGuard you could use a DirectTivo out of the box as an alternative to Skys decoder.

Of course you won't get the interactive features [like Skymail] but who cares.
And with the dual tuners in it and dual LNBs on your dish you could do what most Sky subscribers can't do now and thats record two sky channels at once with one decoder.

[buzbyau]

I am a newbie at this.. and was just wondering what you ment by.. SA Tivos, I would like to get a Tivo with a satellite receiver built in ie.. a DirecTV Tivo

However I am concerned that it will not be able to install a TurboNet card and PAL Tuner.

Do you have any advice for models etc..

Thanks in advance