211 w/EHD - HD/SD "Time Remaining" questions

[bhelms]

Hi all. I'm having good luck with the conversion so far (KoW!) but I did notice something interesting and wonder if anyone else sees the same thing and/or has an explanation? (I did "search" this topic but came up empty - sorry if it's a repeat topic.)

When I first activated the 1TB drive I took note that in the recordings list screen where it tells you how much time remained on the drive it said something like 98 hrs HD and 366 hrs SD. I don't pay much attention to the SD time even tho' I do have a number of SD recordings already. I do however look occasionally at the HD time remaining. I realize both figures are a function of total remaining empty HDD space and make some assumptions about resolution/bitrates and related factors. One could assume the HD/SD ratio would be constant in that calculation but I did not check that (?)

Yesterday I had HD recordings on there that totaled close to 20 hrs. if you added their individual times (plus some SD recordings). But yet that time remaining indication still said 90+ HD hrs.! As I began deleting the 1+ hr. HD programs I noted that the HD time remaining increased only about 15 mins. for each one deleted. When I got done deleting about 12 hrs. of HD programs I was back at ~93 hrs. HD capacity displayed. Most of the HD programs I deleted were recorded from one of the HD "cable" news channels. I realize that quite a few times what is being shown is actually SD content, but only occasionally in these prime time programs (certain segments and many commercials).

I am surprised that the calculation is that "far off"! Anyone have any explanation for that? Does this mean that for the type of program I'm actually recording I might have a considerably greater capacity than the ~98 hrs. originally displayed when the HDD was essentially empty?

TIA and BRgds...

 

[boavista]

I noticed the same thing a few days ago on my 211K. I record David letterman every day so i can watch the next day when i feel is convenient. The other day i noticed that after i erased the episode ( that is 1 hour long) it only took up about 8 minutes of HD space! I just found it interesting since i recorded this Via WIVB OTA siginal ( mpeg2). I found this odd but good because it says i have 55H 9Min of HD left and i know it will be actually more then that.

 

[BuddyBoy]

They can't predict how much space an HD recording is going to use. At max bitrate an hour of OTA could be as much as 8GB, while an hour of low-bitrate H.264 HD from Dish could be as little as 2GB. When the space consumed varies by up to a factor of 4 the time remaining is only going to be an approximation. 500GB of HD could be as little as 60 hours recording time, but as much as 250 hours.

 

[bhelms]

OK - Good information. All the shows I deleted were from Dish and I expect low bitrate. For an experiment I'll check the time before/after I record a 1-hr. OTA channel, then delete it and check again. I should be back where I started at that point. What you say pretty much confirms what I was thinking, that even as an approximation, the Dish shows I'm recording are probably closer to the 2GB size, and that would jive with the 15-mins. I saw consumed per program in that timer. So if I ever fill that HD it will probably exceed 200 hrs. of HD programs, at least as Dish sends them...!

 

[jpmarto]

I just connected a "Western Digital My Book Essential Edition 1 TB USB 2.0 External Hard Drive WDH1U10000N" to my 211 today. When all was configured it listed 98.7 hours of available HD recording.

For my 622s, for every one hour of HD programming I delete, I get about 20 minutes back on my available recording time. The "available" must be a very arbitrary estimate.

Buddyboy's explanation makes total sense -- not all HD is equal.

 

[bhelms]

I just connected a "Western Digital My Book Essential Edition 1 TB USB 2.0 External Hard Drive WDH1U10000N" to my 211 today. When all was configured it listed 98.7 hours of available HD recording.

For my 622s, for every one hour of HD programming I delete, I get about 20 minutes back on my available recording time. The "available" must be a very arbitrary estimate.

Buddyboy's explanation makes total sense -- not all HD is equal.

Same drive I have. (The "perfect storm" of the recent L524 SW spool allowing that increased capacity and a great sale at Staples!) And I had the same initial HD capacity indicated, 98+ hrs. (can't remember the decimal value). I never paid much attention to what my 622 was doing. There I record mostly archival uninterrupted HD movies and action sporting events and I can see that their bitrates might be on the high(er) side. With the 211 I am presently recording mostly 1-hr. shows that have some SD content including the commercials, and since I'm inclined to erase them after one view, that's when I took notice of this phenomena. I had guessed the answer and Buddyboy pretty much confirmed it.

Tks all and BRgds...

 

[Hall]

As I began deleting the 1+ hr. HD programs I noted that the HD time remaining increased only about 15 mins. for each one deleted.

For what it's worth, I see very similar numbers on my 622 with internal HDD. I was deleting 1-hour programs that were from Dish (HD, MPEG4) and it seemed like I was only gaining about 15 minutes or so for each 1-hour show I deleted. I didn't pay that much attention, but I do know it wasn't "giving back" anywhere near what I was expecting.

 

[KKlare]

With MPEG-2 there is essentially a constant ratio of space used and duration of recording.
With MPEG-4 there is substantial variation depending on the frame-to-frame changes.
For MPEG-2 SD, 800 to 900 MB/hr and HD, 4000 to 5000 MB/hr.
For MPEG-4 HD, 1600 to 3200 MB/hr with most nearer 2500.
The traditional ratio of SD to HD time of 6 to 7 was based on 480i and 1080i MPEG-2.
Adding commercials and other padding makes the ratio worse.
An average of 115 min and 1964 MB for 343 SD recordings, mostly movies for all.
An average of 122 min and 5576 MB for 530 HD recordings, MPEG-2 and MPEG-4.

-Ken

 

[BuddyBoy]

With MPEG-2 there is essentially a constant ratio of space used and duration of recording.
With MPEG-4 there is substantial variation depending on the frame-to-frame changes.

The variance in bitrates between the two encoding schemes has everything to do with bandwidth allocation decisions made by Dish, and almost nothing to do with any inherent property of the encoder. When Dish HD was MPEG-2 bitrates varied from 10 to 17Mbits/sec. I have some old recordings from HDNet that were topping out near 18Mbits/sec (also full 1920x1080i).

For MPEG-4 HD, 1600 to 3200 MB/hr with most nearer 2500.

An hour of CBS primetime from my Dish locals ranges between 4.6 and 5.8GB per hour. Fox is in the 2.5-3.2GB range, likely because it is only 720p, and being film source (primetime dramas), is 24p so it really does only have half as many pixels as 1080i, and thus Dish encodes at a lower bitrate.

 

[bhelms]

How do you check the program bitrates and/or total GB a program has placed onto the HDD?

 

[Hall]

Paid more attention this time... I deleted a few 1-hour programs, recorded from satellite (and likely MPEG4 though not necessarily "HD") and gained .... 9 minutes.

 

[BuddyBoy]

How do you check the program bitrates and/or total GB a program has placed onto the HDD?

I have an R5000-HD, but you also see the sizes when you select programs for transferring to an external hard drive.

 

[bhelms]

Tks for that. That will help me if/when I add an EHD to my 622 (likely - I already have the drive but am stalling at paying another $40 fee!) but does not help with my current 211/EHD deployment.

How are you and other folks getting the bitrate and/or resolution information for specific programs ??

 

[howie14]

I don't know if others will find this to be true, but I've noticed that although the change in time remaining is extremely small after I delete something-sometimes as little as 3 minutes having been saved-if I close and reopen the dvr screen the number will change showing a greater time remaining.

1 hour shows still always take up less than one hour of space, however.