Recording Quality

[jasel]

I'm a little confused about recording quality, and the space taken up by different formats.

I know if I record OTA HDTV it really sucks up disk space, but what about other formats (480i, 720p, etc.)? The recording quality screen says that the setting has no effect on recordings from digital channels.

I have digital cable service, or at least that's what it's called. So does that mean I'm recording at the same quality level all the time? In comparison, if I get 30 hours of HDTV, how much am I getting at 720p? At 480i? I've noticed that the box never asks me anymore if I want to record the whole show at best quality or the remaining portion at medium quality (that's what I set the quality at).

Now none of the recordings lists the resolution, but if I look at the info on live TV, they all are listed. All the cable shows are 480i, but the OTA shows can be 480i, 720p, 1080i, or HDTV. I only have listings for the .1 OTA channels which I assume are all digital. Is 1080i the same as HDTV (although it seems that HDTV is always full screen 16:9 and 1080i can be 4:3)? Are all 480i recordings the same? Is a digital cable show the same as 'best' quality for an analog show? Can I even record analog without removing a cable card? Lots of confusion here....

And what does 'Intercast' mean?

Thanks,

Jas.

[jasel]

bumping this to the top in the hopes that someone knows the answer...

[WK-JSP]

A Series 3 records digital channels in the digital format sent by your cable provider. There is no re-encoding going on, so no choice of encoding quality. That's a good thing. Generally your cable provider can squeeze more quality out of the same disk space than the TiVo encoders can for the analog channels. The reason is that they can encode "off line" and take as much time as they want, for example, using multipass algorithms. The tivo must encode analog channels in realtime.

The disk space consumed by a digital program depends on the bitrate your cable provider used. In my experience with Comcast, a HD 1080i program runs about 7.5GB/hour. A analog SD channel recording at "High Quality" runs about 2.5GB/hour. A digital SD channel runs 1.5GB/hour. Your mileage may vary, as this definitely depends on the provider and source material.

[pl1]

I've noticed that there is a folder for programs that the Series 3 deems to be a valid HD program. I may have 6 programs recorded from HD channels and only 4 show up in the HD folder. So, it's not like every program recorded from an HD channel will take up HD recording space. Which is a good thing.