Originally posted by NikeMan
Boy, and I was thinking that 5 hours of HD recording was great. I thought HD was about 10 megs/second, that adds up to 180 gigs in 5 hours.
Not quite HD bitrates peak at 19.363 megabits
per second (within ATSC spec), which is a little less than 2½ megabytes
per second, but averages are usually lower than that. Assuming that what Mark recorded ran pretty close to that bitrate, that would be approximately 8 gigs per hour (perhaps a bit more), or 5 hours on a 40 gig hard drive (or less, since 40 billion bytes, formatted, would be closer to 37.2 real
gigs). Considering that hard drives get a lot bigger, for relatively little additional money, this would be an unacceptable compromise.
I would have thought if it could do 5 hours of HD it could do 50 hours of SD.
That depends upon the bitrate of the SD material being recorded. It also depends upon whether this material was pre-compressed (recorded from a digital cable channel) or encoded by the box (from an analog channel). Whereas a digital cable channel has a fixed (well, variable, but always within the confines of whatever the cable company and/or content provider has set) bitrate, an analog channel's compression can be set within the box to varying levels, depending upon the user's quality and space preferences. At its highest quality setting, the bitrate is likely higher than any digital cable channel at it's lowest, it's probably less. If one hour of analog-encoded SD was 6% of capacity, that would mean it could hold 16½ hours comfortably at that bitrate (which, assuming it's a 37.2 gig drive, would be approximately 5.2 megabits per second, considerably higher than most pre-compressed content). That's still an obscenely low figure these days.
Of course we don't know how accurate the % of capacity is.
It should be a helluva lot more accurate that "# of hours remaining" figures, seeing as how the box can't be sure of the bitrate that the user will record, but it knows exactly how much space is taken and how much is available. Unless there's a significant flaw in the software, I'm going to take this figure as the Word of God.
One last thing, what you record could make a big difference. One hour for Nascar with all the movement and colors would take up alot more space that one hour of 'Sunrise Earth' where the camera holds one frame of the sun coming up for about 10 minutes at a time(it's pretty but to slow for me that early in the morning :-) )
It's not as big a difference as you'd think. Talking specifically HD here, both Discovery HD Theater and TNT-HD broadcast at a fixed bitrate (or so I've read, maybe average), both ~19mbps (maybe a little less). Regardless of what content they're broadcasting, it'll always be approximately the same size, just looking better or worse depending upon the material. Even HBO and Showtime broadcast at 14.2mbps, and while I'm not certain if that's fixed or variable, it's still the "average" bitrate, so should always measure up to that in the end.
One other thing we've not mentioned yet is how much of the hard drive may be reserved
for push content (which would seem unnecessary with VOD, but still). We've known they were going to do it, this may be a sign that they have (it would also explain why 5 hours of near-full-bitrate HD adds up to almost exactly 40 gigs, instead of 37.2). If these do have larger than 40-gig hard drives, it would likely be an 80-gigger (one of the original specs). If they're cutting off half the hard drive for their own purposes, they're severely overstepping their boundaries. I want to record what I want to watch, not what you want me to watch.
Originally posted by markemery
I am in SW Portland, near the crossroads of Portland, Beaverton, Tigard.
Great, now I know where I need to move.
I'm going to look into the capacity issue today and I'll let you know what I come up with.
Thanks, Mark. That still doesn't answer the question, though what's your role in this, and how might I getno no noearn