do the Secondary Sub channels take up as much space as the -1?

[newsposter]

I ask because I use suggestions to monitor space and have marked stuff like tube tv on my 17-2 station as 3 thumbs up. It's a 4 hour block so I used to think it's 4 hours of HD, which is about 4 pages of normal NP stuff or at least 4 other HD programs (approx). But now I read that the sub sub channels may actually use less so my estimates may be wrong.

Yes i'm that low on space at times :)

[litzdog911]

Yes, the sub-channels are typically much lower data rates than the primary HD channel, so they'll use less hard drive space.

[phox_mulder]

Keep in mind that the -1 is not always the primary HD channel.

We have one here, channel 5, NBC.

5-1 is a digital 4:3 SD upconvert.

5-2 is the 16:9 HD channel.

5-3 is a 24 hour weather channel.

5-2 would be the biggest recording space, 5-1 the 2nd biggest, 5-3 would be the smallest of the lot.
No idea where the channel 5 via DirecTV SD Locals would fit in as far as hard drive space though,
but if I had to guess, smaller than 5-2, but bigger than 5-3.


phox

[TyroneShoes]

TV stations typically allocate 10-14 mb/s to the main HD channel, which is usually the ".1" channel. They also typically allocate 3-4 mb/s to SD sub channels, so they will take about a third of the space on the HDD. Oddly enough, FOX network squeezes their prime programming to 9-12 mb/s, but non-network stuff from most FOX affils is more on the order of 12-14, so prime shows actually end up taking somewhat less space than upconverted SD.

Someone posted that they put 3 thumbs on "Law & Order" targeted to TNTHD and no thumbs or thumbs down on everything else, so that suggestions that it adds will give a regular accounting of normal HD hours. The theory is that L&O airs some 35 times a week, making it easy to weed out suggestions that are not an hour long, and that way the number of eps recorded quicky approximates the amount of hours available. Not a bad approach, I've kind of been doing the same thing with "The X-Files" on TNTHD (still need that regular Scully fix).

[Lee L]

So, do they go in and "de-thumb" the thumbs up that comes from setting a season pass for a show or simply recording one episode?

[TyroneShoes]

Who knows? I just reset the thumbs regularly, which puts everything at zero. If at that point you go 3 up to what you want recorded and occasionally 3 down to stuff that Tivo seems to fall in love with all on its own, the system works pretty good.

[cheer]

The secondary subchannels, on the whole, definitely use less space. As TyroneShoes points out, it's all a question of the bandwidth allocated.

For example, here in Chicago WCIU (analog 26) carries its main DTV signal on 26.1. Now WCIU isn't a major network affiliate, but they do carry some HD stuff, including Cubs and Sox games.

On the 26.2 subchannel, they carry the DTV feed for analog 23 (WWME), a sister station. This station is running the new "enhanced" Star Treks, and a 1-hr recording of these (not HD; 720x480 interlaced) is running about 1.2 gigabytes. (For comparison, a satellite-based 1-hr SD show runs me anywhere from 800 megabytes to 1 gigabyte.) On the other hand, my wife records stuff off of "PBS Create" which is on 11.3 (11.1 being the national PBS feed and 11.2 being our local WTTW feed), and a half hour is only 400 megabytes (and at 720x480 looks like crap).

They're all different, so it's hard to be sure. The "Law & Order" recommendation is a pretty good one (just because, as TyroneShoes said, it's on all the freaking time) but remember that it'll be in DirecTV's "HDLite" and so won't be the same as an OTA 1920x1080i recording in terms of space used.

[SpankyInChicago]

If your TV has an OTA tuner, you might be able to get a better grasp on the bandwidth required because your TV will tell you if the signal is 1080i, 720p, 480p, 480i or something else. I don't think you can't get your HR10-250 to do this unless you hack it.

Sticking with the WTTW example that cheer gave above, WTTW brodcasts 11-1, 11-2, and 11-3 on UHF frequency 47. They break out like this:

- 11-1 National 1080i PBS feed downconverted and broadcast as 720p

- 11-2 Simulcast of WTTW analog channel 11 broadcast in digital 480i (no, not 480p)

- 11-3 Broadcast of national "Create" channel content in digital 480i

The bandwidth allocated for 480i can clearly be much lower than the bandwidth allocated for 720p or 1080i.

[newsposter]

i dont have an ota connection directly to the tv but if i found a splitter that wouldnt degrade the already split lines (2 hdtivos stacked), i'd do it

[TyroneShoes]

...They're all different, so it's hard to be sure. The "Law & Order" recommendation is a pretty good one (just because, as TyroneShoes said, it's on all the freaking time) but remember that it'll be in DirecTV's "HDLite" and so won't be the same as an OTA 1920x1080i recording in terms of space used.
Which is exactly why I referred to it as an "approximation" (it was actually some other poster's idea, BTW).

What Spanky says about 1080i being a bit larger than 720p, and both being much larger than 480i is also an approximation. There is no technical reason that a station could not allocate just as much or even more bits to a 1080i stream as they might to a 480i sub, because the setting is an arbitrary choice on the part of the engineers for each stream. Of course doing that would be foolish if not bad engineering, so generally that guideline will indeed apply. But quite often, ironically enough, upconverted SD on one station can take up more space than true HD on another, because the station maintains the same bit rate for all content in a lot of cases. Or not...FOX local upconversion is typically higher than their network HD because FOX statmuxes their feeds.

[cheer]

Rightright...the most compelling use for TivoWebPlus, IMO, is the Info screen which shows used/free space in GB. :)