# Disk Capacity Poll



## SimpleSimon (Jan 15, 2004)

*PLEASE READ INSTRUCTIONS HERE!!!*

Because of another bug I've found ([thread=23912]0 second HD recordings[/thread]), I have concerns that we may be losing disk capacity due to lost file fragments of some type.

This poll is to get some real-world info on just what the box can contain, and whether it relates to that bug.

Note that "NO 0 second recordings" means that you've NEVER had one, not that there's one in the box at the moment.

To participate, just add up the total minutes of each recording - keep SD separate from HD. Multiply the HD number by 7 to get equivalent SD minutes and add that to the SD number. Then add the SD "Record Time Left". Then make your response including whether you've experienced any 0 second recordings or not.

Please be careful with the math - it's easy to confuse SD, HD and hours/minutes, and I really want this to be as accurate as possible.


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## Mark Lamutt (Mar 24, 2002)

I understand what you're trying to do with this poll, Simon, but I think it may be flawed. Every SD program will take up a different amount of disk space because the compression rates are different for each channel, and sometimes for individual programs on each channel. Same for HD programs - satellite HD programs transmitted at 14.2 MB/s take less disk space than OTA programs transmitted at 19.2 MB/s. So, I'm not sure how you can get an apples to apples comparison here.

Taken from my review:

I did 60 minute long test recordings on four different OTA channels: A 1080i channel broadcasting at 19.0 MB/s video bit rate, a 720p channel broadcasting at 12.752 MB/s VBR, a 480p channel broadcasting at 11.93 MB/s VBR, and a 480i channel broadcasting at 4.513 MB/s VBR.

The 60 minute 1080i 19.0 MB/s recording took 65 minutes of HD recording space.
The 60 minute 720p 12.752 MB/s recording took 47 minutes of HD recording space.
The 60 minute 480p 11.93 MB/s recording took 45 minutes of HD recording space.
The 60 minute 480i 4.513 MB/s recording took 18 minutes of HD recording space.

So, from this I draw this conclusion: The OTA recording capability of the 921 is much better than any of the current recording computer cards on the market today. With those cards, every OTA digital channel, no matter the resolution of the VBR record exactly the same size - around 8.2 GB/hr. The 921 obviously processes the transport stream, stripping out all of the wasted space to record smaller files while maintaining the necessary program information.


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## jsanders (Jan 21, 2004)

I think SimpleSimon's poll is actually okay because he is using the DVR menu to calculate *available* space by some set bit/rate that is determined by the 921, whatever that is. It would be different if he was asking how much was used, as that would have to take into consideration all of the different bit rates that you mentioned.

As far as my case goes, I really don't know, I haven't looked at it as far as SD space goes. I generally have anywhere between 6 and 14 hours of HD recording space left (according to whatever the 921 considers its HD bit rate for that calculation).


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## SimpleSimon (Jan 15, 2004)

Very good points, Mark, and appreciated.

However, with a large enough sample size, my primary objective will still be met. That is, is there a difference between people who experience the 0 second recording problem and those that don't?

Plus, again, with enough samples, we'll still get a better feel for the real-world capacity of the box.

I have hopes we'll get enough participation to show a pattern. 

In my case, I have 105 SD recordings and 4 HD ones. 22 of the recordings are TechTV
ScreenSavers + TechLive. Most of the rest are DISC, HIST, TLC. In other words, fairly standard stuff, totalling 116.6 hours. The 4 HD shows total 117 minutes. Doing the math gives me less than 138 hours.


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## SimpleSimon (Jan 15, 2004)

jsanders said:


> I think SimpleSimon's poll is actually okay because he is using the DVR menu to calculate *available* space by some set bit/rate that is determined by the 921, whatever that is. It would be different if he was asking how much was used, as that would have to take into consideration all of the different bit rates that you mentioned.


I'm asking for the total of used and available space, so Mark's comments do apply. If we had a display of the "equivalent free space" for each recording, then Mark's concern wouldn't matter - we'd have the apples-to-apples numbers.

I'm just hoping we get enough responses to minimize Mark's point. Averages would apply.


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## SimpleSimon (Jan 15, 2004)

I just erased an episode of Monster Garage. It was a 60 minute recording, but returned 1:24 of free space. That's a significant difference. Maybe there's enough of those to make up my "missing" capacity.

Edit: An episode of Charmed was even-up at 1:03.

Sure wish this poll could handle more - to REALLY know what's going on, we need more variables than can be gathered here.


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## jsanders (Jan 21, 2004)

SimpleSimon said:


> I'm asking for the total of used and available space, so Mark's comments do apply. If we had a display of the "equivalent free space" for each recording, then Mark's concern wouldn't matter - we'd have the apples-to-apples numbers.


Okay, that does change things... How are you asking for both though? Your question in the poll is, "How much SD free space do you have?"


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## SimpleSimon (Jan 15, 2004)

jsanders said:


> Okay, that does change things... How are you asking for both though? Your question in the poll is, "How much SD free space do you have?"


Yeah - I screwed up the Poll title (Mark, can you fix? Remove "free").
I just edited the top post to help encourage people to read the destructions.

The free space display uses a 7:1 factor for SD:HD. To make the poll work, convert everything to SD equivalents (per the thread's first post). Do NOT count the displayed free space twice (SD & HD). They're actually the same number displayed in two different factors.


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## Mark Lamutt (Mar 24, 2002)

Poll title fixed, Simon. Let me know what other options you want in your poll, and I'll add them. I can add as many as you want (the joy of being an admin...unlimited poll options )


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## SimpleSimon (Jan 15, 2004)

Thanks Mark!

Note the 3 responses of less than 110 hours. I think those are folks that responded to the incorrect question. I've messaged them. Hopefully, they'll post a reply and then it'd be nice if you can correct their poll answers.


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## Mark Lamutt (Mar 24, 2002)

In my case, I have 13 HD events recorded totalling 14 hrs 34 min of recorded time. My display says I have 11 hrs 33 min remaining HD space, for a total of 26 hrs, 7 min.

Converting that at a 7:1 ratio, that would "equate" to (in quotes because I don't believe the 7:1 ratio is exactly right) 101 hrs 58 min of SD recorded events and my SD remaining is displayed at 80 hrs 51 min, for a total available SD recording space of 182 hrs 49 min.

I have had exactly one zero minute recording event in the life of my 921. It happened under L142. Haven't had one since.


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## Mark Lamutt (Mar 24, 2002)

There's no way that those 3 can correct their poll answers, but hopefully they will at least post their results here.


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## SimpleSimon (Jan 15, 2004)

Mark Lamutt said:


> In my case, I have 13 HD events recorded totalling 14 hrs 34 min of recorded time. My display says I have 11 hrs 33 min remaining HD space, for a total of 26 hrs, 7 min.
> 
> Converting that at a 7:1 ratio, that would "equate" to (in quotes because I don't believe the 7:1 ratio is exactly right) 101 hrs 58 min of SD recorded events and my SD remaining is displayed at 80 hrs 51 min, for a total available SD recording space of 182 hrs 49 min.
> 
> I have had exactly one zero minute recording event in the life of my 921. It happened under L142. Haven't had one since.


Unh. Bad math. You only add ONE of HD or SD free space - they represent the same disk area.

As for the 7:1 ratio, I agree that it's not exact, but it IS what the 921 uses. 11:33HD * 7 == 80:51SD - exactly.

That means that you have less than 110 total hours of space - just like the other 3 responses. But with only ONE 0 second recording. My theory doesn't hold up - unless it was a REALLY big HD recording that farkled.


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## Mark Lamutt (Mar 24, 2002)

I don't believe I added the space twice, except that I calculated it for both HD space and SD space - the 80:51 (reported space remanining) was added to the 101:58 (SD equivalent of space used for recordings) giving the total of 182:49.


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## Slordak (Dec 17, 2003)

Please note also that other things use space on the HD as well, such as the 9-day extended programming guide. Depending on the status of the guide (and whether one has extra channels such as locals), this can use varying amounts of disk space. Hence, it may not be possible to derive a meaningful count from the activity proposed in this thread.


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## SimpleSimon (Jan 15, 2004)

Slordak said:


> Please note also that other things use space on the HD as well, such as the 9-day extended programming guide. Depending on the status of the guide (and whether one has extra channels such as locals), this can use varying amounts of disk space. Hence, it may not be possible to derive a meaningful count from the activity proposed in this thread.


Good point, although in the grand scheme of things, I don't think the EPG can take up much space. Let's guess out an estimate here: 500 items (10 days @ 1/2 hour per item) * 200 channels (more than average) * 250 characters per item (a guess) = about 25MB. Even if that's wrong by an order of magnitude and is 250MB (someone would have to really convince me of that), that's still only 0.1% of the hard drive. Put another way, 250MB is roughly 10-15 minutes of SD time.


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## SimpleSimon (Jan 15, 2004)

Mark Lamutt said:


> I don't believe I added the space twice, except that I calculated it for both HD space and SD space - the 80:51 (reported space remanining) was added to the 101:58 (SD equivalent of space used for recordings) giving the total of 182:49.


Mark: You're absolutely right - I misread the numbers as written. I followed your 26:07HD as 101:58SD instead of the correct 14:34HD=101:58SD.

Count yourself lucky sir! Even if large chunks of your recordings are HD-light (and therefore mis-reported) that's still a lot more usable space than what I appear to have.

Maybe my SD recordings tend to the 'heavy' side as shown by "Monster Garage" (60 minutes) releasing 1:24 of space. Could that account for the roughly 33% discrepency I'm seeing? I hope so! That would be a lot better than the file system errors I'm suspecting!

In other words, I'll be very happy to have my theory proven wrong!


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