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View Full Version : How much more space will HD and digital consumer on HD DVR vs. Series 2


CAG45
03-23-2009, 06:51 PM
I'm upgrading from a Series 2 to an HD DVR, because Comcast is converting many on my stations to digital-only.

I don't have an HDTV, so I don't really care about the HD part of the DVR. The reason I bought the HD DVR was so that I could use cable cards and bypass a cable box.

My Series 2 was rated as "180 hours".
The HD DVR is rated as "20 hours HD" and "180 hours ?regular?".

For my Series 2, we've settled into a "routine" where we know how many shows we can tape with the various quality levels - Best, High, Medium, ... - such that we always have enough disk space.

So am I going to be in for an "un-pleasant" surprise:
(1) because the HD DVR will store HD recordings in a way that takes up much more disk space than it did on my Series 2 (even if I can't watch them in HD)?
(2) When Comcast switches many of the stations to digital, suddenly recordings from these stations will take up much more disk space?

How does the recording of an HD program compare (in terms of disk space) to the recording of a program using Best, High, Medium?

How does the recording of a digital program compare (in terms of disk space) to the recording of a program using Best, High, Medium?

RonDawg
03-23-2009, 07:15 PM
Remember that with cable, almost all HD channels will have an SD equivalent. There are only a handful of "HD-only" channels such as HDNet. And if you don't even subscribe to your cable provider's HD tier, it's all moot anyway.

HD does take up a lot more space than even the "Best" analog SD recording. History Channel HD for example can use up to 8GB/broadcast hour.

Depending on channel provider and program, SD digital falls roughly between "High Quality" and "Best" for analog channels.

Stephen Tu
03-23-2009, 07:20 PM
The SD digital channels don't take much space at all. Comcast is cramming them into < 1.5 GB per hour, sometimes even < 1 Gb. So it's a bit more than "basic", less than "medium", with better quality (Comcast's encoders are a lot more expensive & higher quality than what Tivo can shove into a consumer priced box).

HD channels vary considerably between 4-7.5 Gb/hr in my area. Maybe average in the 6.25Gb/hr area. So it's roughly taking about twice the space as "best" on average.

If you find yourself running out of space, just slap in a bigger drive or get the external ESATA.

colagirl
08-12-2010, 06:29 PM
This discussion seems to dance all around my specific inquiry.

In my area (probably most), TW Cable delivers numerous channels at different levels. For example, I can view my NBC affiliate on channel 3, "Broadcast Cable"; 120, "Local Programming" and 1120, "HD Local Pgmg."

TiVo says "[adjusting] recording quality levels do[es] not apply to digital broadcast programs."

Sometimes, I'd rather sacrifice quality to minimize disk space used, so I record Program X on Ch. 3 at Basic quality.

Am I really changing the recording quality on Channel 3? Do these settings affect Channels 120 and 1120? Signal-wise, what's the difference between what I'm getting on Channels 3, 120 and 1120?

I'm on a home network, if that makes a difference, equipment- or otherwise. Also, what is the off-the-shelf hard drive size in the Series 3 HD?

Be gentle, I'm a newbie. Thanks for your help.
____________________________________________________________

TiVo HD, Cisco STA 1520 Tuner Adapter, Toshiba 26HLV66 TV/DVD, TiVo Wireless G Adapter, TWC Digital Rebuild (East)

steve614
08-12-2010, 06:40 PM
If the TivoHD (or original OLED series3) is letting you select a recording quality, then you're not recording a digital channel and selecting basic quality will give you the smallest file size.
You can't select quality for a digital channel, so you are stuck with what comes over the line.

kdmorse
08-12-2010, 06:41 PM
In my area (probably most), TW Cable delivers numerous channels at different levels. For example, I can view my NBC affiliate on channel 3, "Broadcast Cable"; 120, "Local Programming" and 1120, "HD Local Pgmg."


Well, to answer that question we have to make some assumptions based on the information given. I am going to start with the following:

3 - Broadcast Cable - SD Analog Signal.
120 - Local Programming - Digital SD version of same channel
1120 - HD Local Programming - Digital HD version of same channel

If that's true, the following will be the likely result:

Tivo Premier without cablecards

Record from Channel 3: You will get an analog signal, with the same analog quality choices. No actual change, for as long as the analog channel survives.
Record from Channel 120: Unsupported without a CableCard. If you do it (no guide data) - it will be digital, visibly better than Best quality. Consumes about the same space as Medium quality
Record from Channel 1120: Unsupported without a CableCard. If you do it (no guide data) - it will be Digital, HD Quality, and consume lots of disk space.


Tivo Premier with cablecards

Record from Channel 3: You will get mapped to a digital signal - visibly better than Best quality. Consumes about the same space as Medium quality.
Record from Channel 120: Same as Channel 3, as Channel 3 probably will map to channel 120 under the covers.
Record from Channel 1120: Digital, HD Quality, and consumes lots of disk space.

This of course makes several assumptions about your current setup, how they handle analog vs digital, how they map their channels (does anyone not use ADS these days?), etc.... Your Mileage May Vary...

-Ken

colagirl
08-12-2010, 07:09 PM
Steve614 -- Thanks. I went back through part of my To Do List and confirmed that some shows are slated to record at different qualities. Your answer suggests that whenever I am offered a choice, I really am making a choice. Excellent.

kdmorse -- Thanks to you, too. However, I'm not using Premier, rather, TiVo HD with a multi-stream cablecard. (Guess I shoulda mentioned that from the get-go.) Your answer suggests that I might as well delete channels such as our example 3 from the Guide, since it is merely a beard for 120.

So which is it? Duke it out, boys!

Also, what is the off-the-shelf hard drive size in the Series 3 HD?

cheers, y'all

colagirl
08-12-2010, 08:16 PM
Hey, Steve614 and kdmorse --

I hope my lame attempt at humor did not offend. If it did, I sincerely apologize.

Your prompt and knowledgeable answers were highly appreciated. The way I understood them, they seemed diametrically opposed, so I just wanted to clarify. My bad.

Thanks for your help.

cheers

colagirl
08-13-2010, 12:47 AM
Ken --

"(does anyone not use ADS these days?)" What does this mean?

Thanks again.

Ken, I ain't afraid of no Pope.

steve614
08-13-2010, 06:55 PM
Hey, Steve614 and kdmorse --

I hope my lame attempt at humor did not offend. If it did, I sincerely apologize.

Your prompt and knowledgeable answers were highly appreciated. The way I understood them, they seemed diametrically opposed, so I just wanted to clarify. My bad.

Thanks for your help.

cheers
No worries here.

I don't have cable, so I don't know how the Tivo deals with multiple tiered channels.
It sounds like Ken is saying if you select your channel 3, the cable card remaps the request to channel 120, but I don't think that happens in your case.
For example, if you select a show to record from the guide and you're able to select a recording quality, then it is an analog channel. The option does not appear for a digital channel.
To be sure if a channel is analog or not, you can tune to the channel in question and then go to DVR diagnostics under system information. If the channel is analog, it will say so next to the modulation line.