Before I even read the OP, I was going to point out that the amount of space taken up by programs on my DVR does not increase arithmetically. A 2 hour program takes more than twice as much space as a 1 hour program, and a four hour program takes more than twice as much space as a 2 hour program. During the Olympics, I set the DVR to record in 2 hour blocks, since that allowed for more recording than if I just set it to record the entire 4 or 5 hours of primetime coverage at once. I don’t know the reason for the discrepancy, but I don’t think it’s about HD vs. non-HD. Is it possible that larger blocks of recording are compressed at a different rate?
Over-the-air high definition programming is much less compressed than stuff that comes through a cable or satellite signal. OTA broadcasters don’t need to compress much, because they don’t have to worry about bandwidth limitations of cramming multiple signals through one wire. So, an OTA program can take up four times as much data space as a satellite program, or even more. As in, I find that satellite programs usually take up 1.5GB-2GB of space per hour of programming, while an OTA program can take up 6GB-8GB of space per hour, easily.
As a side effect, OTA shows almost always look way nicer than satellite shows. More data per second = more information per frame = better picture.
you can see blades of grass and nose hairs. it is good.
Are you on cable? Mine has low def versions of everything, and I can set recordings to use low def to save space.
As a TiVo owner for 10+ years now:
All TV content is digital now, SD or HD, cable or broadcast. So any ‘quality’ settings on a DVR are now redundant. All DVRs have always recorded all programming in digital format, they are essentially hard drives and hard drives do not do analog. Early SD TiVos (and all other DVRs) had analog-to-digital conversion hardware. The analog signal came in thru the coax, was converted to ones & zeros, and written onto the hard drive. Then it did the reverse when you played it back.
When cable companies started offering digital cable, not HD mind you but just digital cable (more channels, PPV, and eventually cable boxes w/DVRs in them) their DVRs could then eliminate the initial analog to digital conversion process, but only for the digital channels (in the early days only the cable channels above 100 were digital, the lower ones were still analog). And a non-cable company DVR (i.e. a TiVo) still always had to do the analog/digital thing because even with digital cable the standard definition signal coming out of the back of the cable box and going into the TiVo was analog.
Then High Definition TVs started appearing. HD was always 100% digital. Then, a couple years ago the govt mandated all TV broadcasts switch to digital (again, not necessarily HD but an all digital signal, even in SD) which they’ve done. So like I said above DVR ‘quality’ settings, even if they still have them, do nothing.
The key issue regarding different but same length shows seemingly taking up different amounts of space on a DVR’s hard drive is completely due to the MPEG compression used (initially only by the DVR itself) by broadcasters. Like others mentioned, sporting events like racing or football, things with a lot of constant motion throughout them, don’t compress as much as say a sitcom or anything more static in nature. This is true whether it’s SD or HD, but HD will always use about 5 to 10 times the space as the exact same show in SD.
Because of the variable nature of MPEG compression, TiVo did not put any kind of ‘Record Space Used/Remaining’ indicator anywhere in their software. Their reason was simple- Because every show takes up different amounts of hard disk space regardless of its length any such meter would never be accurate. Cable companies only put a ‘Percent of Free Space Remaining’ to give their customers some indication, but again there’s no accurate way to convert that into HH:MM:SS and there never will be.
i have a DVR with 6 recording mode selections, i can get 33 hours at the highest quality and 190 hours at the lowest quality on the hard drive.
FWIW, in the extreme case I cited, the 2½ hour program that took up ten percent (normally that’s ten hours) of space was “Slumdog Millionaire” carried on BBC America.
Have verified this is actually the case with actual recordings? Because my current TiVo, a Series 3 HD, still has a ‘quality’ setting too, but with the disclaimer: “Note: This setting has no effect on digital channels”.
that is the case with your TiVo.
the quality difference is very real on my nonTiVo machine.
When I copy from the Uverse cable box DVR to my Magnavox DVR, the signal is analog so that the receiver can see it. This analog signal goes to the Magnavox, where I can select a record “speed” which I presume is essentially a sample rate selection. Slower speeds take up less romm on the Magnavox DVR.
Signals cannot be dubbed within the Magnavox from hard disk to DVD at a faster speed than they were recorded. I presume this is also a sample rate issue.
Despite what others have said [ahem] the FCC has not mandated that low power broadcasters (aka LPTV) broadcast in digital. Check the following for details.
Anytime you use a cablebox’s coax output it’s going to be an analog signal. The HDMI output is the only one that’s digital. My TiVo isn’t connected to an external cablebox, I rent a CableCard for it instead, which slides directly into the TiVo via a PCMCIA slot.
There’s no reason a DVR/DVD-R set-top combo box couldn’t be designed to burn a DVD at high speed. I can transfer most of the stuff on my TiVo to my PC, then burn them at high speed to disc.***** Only being able to record at 1x speed makes the decks cheaper to make, quieter, more reliable, and less confusing for consumers to use. Makes the MPAA happy by discouraging mass duplication.
- Thing is, for HD stuff the files are so huge that the transfer rate is slower than the program play rate. IOW it takes longer to transfer the file than it would to just play it on the TiVo and record it on a component DVD recorder!
Thanks for the responses. Oddly, it seems that it’s mostly the (USA) “broadcast” channels that take up so much room. Just about all of the cable channels are one hour = 1%. I recorded a little over three hours of broadcast a couple of nights ago, and it was about 10%.
That’s not odd at all. It’s routine and normal that the cable companies compress the broadcast channels the least. It would be more odd (at least in the context of US cable companies) if they were compressing your the locals more than the cable channels.