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lmacmil

join:2001-01-26
South Bend, IN

[DVR] What determines how fast the guide is restored?

I have a Moto DCT-3416. It takes well over 24 hours for the guide contents to be fully restored after a power shut down. I was in Fla recently and the condo had a Cisco RCN-???. I had to shut it off when it hung and I'm sure the guide was fully restored in only 4 or 5 hours. Is it the DVR or something local that determines how fast the guide gets re-populated? Just curious.

As an aside, the Cisco box seemed to have way more capacity than my 160MB Moto.


gar187er
I do this for a living

join:2006-06-24
Dover, DE
kudos:4
processor speed, memory of the box......signal quality.....how slammed the DNCS...lots of factors.....
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I'm better than you!

Russ6

join:2011-03-17
Houston, TX
kudos:1
reply to lmacmil
said by lmacmil:

I have a Moto DCT-3416. It takes well over 24 hours for the guide contents to be fully restored after a power shut down. I was in Fla recently and the condo had a Cisco RCN-???. I had to shut it off when it hung and I'm sure the guide was fully restored in only 4 or 5 hours. Is it the DVR or something local that determines how fast the guide gets re-populated? Just curious.

As an aside, the Cisco box seemed to have way more capacity than my 160MB Moto.

Click the following link for how the guide data is repopulated:

»Re: [STB] Cisco thinking of getting out of the set-top box busin
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SA 8300 HD DVRs with Patched S25 Guide
Links:
'S25 Guide Blog' 'Schedule' 'Info' 'Patch Thread'

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
reply to lmacmil
Guide data is sent over the slow OOB channel. It's just a rolling datastream that the box has to listen in on. Given the number of channels now, there may only be one or two 'full' streams per day. There are also more frequent passes of other data, such as channel names and near-term (6-8 hours) data. The data is only held in memory, not on disk.

Also, the OOB channel is getting overloaded as it also is used for firmware downloads, network control, OnDemand menus, etc...

Basically, it may take several passes of the data to completely fill in. Also, at least with iGuide, there is not enough memory set aside to completely hold the guide. It start to fill up (about 720 slots, each 30-minutes, is the max), maxes out, does a triage to compact and dump data that is the furthest out, then keeps filling in and shrinking until it stabilizes.

Mine is hovering around 550 slots now.


Floppy

join:2002-07-03
reply to gar187er
said by gar187er:

processor speed, memory of the box......signal quality.....how slammed the DNCS...lots of factors.....

Moto boxes don't run on the DNCS. They're controlled by the DAC which is Moto's verison of the box driver. The DNCS is the box driver in a Cisco/SA area.

The guide populates slower on Moto vs SA however the DNCS micromanages everything compared to the DAC which isn't needed in some cases one such example is the VOD design.

GTFan

join:2004-12-03
I've never understood why Moto doesn't cache the data to the drive to avoid this annoying nonsense, can someone explain?


markofmayhem
Why not now?
Premium
join:2004-04-08
Pittsburgh, PA
kudos:5
Not all boxes have drives. These are not "mini computers" hooked up to an intranet, they are very simplistic, single-purposed consumer electronics. Having more versions than "the current one" is not feasible on the infrastructure. As built-in Docsis modems with "request-serve" communication models overtake the OOB "broadcast-listen" model, such differentiating modules, middle/firm/soft-ware layers, as well as "apps", "widgets", and other services per device, per account, will be not only possible, but an elegant and simplistic solution. Not today, not yet. The "guide" is a module in system space, Moto doesn't design/support much outside of kernel space (deep firmware, kernel compile).
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Show off that hardware: join Team Discovery and Team Helix

moes

join:2009-11-15
Cedar City, UT
reply to GTFan
Not all of us have rented dvr's from the cable company or we do not have them at all, so the logic is good with what you asked, but not always feasible

GTFan

join:2004-12-03
Flash storage has been cheap for a long time now, even if you don't have a drive. And you don't need much to store 7 days of guide data. Yeah I know, Moto has nothing to do with this, but this is yet another example of how cableCos pick the least common denominator junk for their customers. Which is understandable for the cableCo to maximize profit, of course.

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
Flash would not be a good choice for guide data due to the constant changes. Flash RAM literally 'wears out' over time. SSD drives have to use algorithms to vary where the data goes to keep the wear even.

One compromise is a hybrid system. The drive could be used as a backup to RAM.

GTFan

join:2004-12-03
At one update a day (pretty much all any DVR or STB needs for guide data download), flash would last forever.

C'mon, these are all just excuses for cheaped-out boxes. Let's get real.


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15
Well, I don't think there is only one update a day, as programming changes happen fairly frequently, but maybe the box can back up the current guide data periodically, maybe once every few hours.

And yes, while flash memory does "wear out" over time, current chips can last quite a while:

From: »en.wikipedia.org/wiki/Flash_memory
[Flash] Memory wear:
Another limitation is that flash memory has a finite number of program-erase (P/E) cycles. Most commercially available flash products are guaranteed to withstand around 100,000 P/E cycles, before the wear begins to deteriorate the integrity of the storage. Micron Technology and Sun Microsystems announced an SLC NAND flash memory chip rated for 1,000,000 P/E cycles on December 17, 2008.

However, while adding even the small cost of a flash chip to a box might seem a minor thing, over millions of boxes the total cost adds up. With the competitive nature of the STB business, that could concern a manufacturer.

But, having that backup memory would allow one to unplug an STB while it's not being used, saving the not-so-insignificant amount of power that many boxes use when "off." See: »[STB] PACE RNG110 HD Only Box (with no clock)


cypherstream
Premium,MVM
join:2004-12-02
Reading, PA
kudos:3
reply to lmacmil
You have a few choices here.

1. Stay with Comcast but install a small APC UPS in line with the cable box. During quick power blips it won't reset and you won't loose any data.

2. Go to DirecTV. The regular HD box has 128MB Flash for OS and 1GB NVRAM for all other data. A power outage or reboot does not take guide data with it, unless you reboot it twice within a 30 min interval (thats a built in feature to purge corrupt guide data). The DVR I have has a 500GB drive and stores recordings in MPEG4 so that's even more efficient. Plus you would get Pandora, Youtube and a HD interface complete with poster art and rich graphic branding on each VOD channel screen.

3. Get Tivo. Tivo works with Comcast, just get an appropriate cable card.

4. Build a Windows 7 HTPC with Ceton or SiliconDust cable card tuner. Media Center is pretty slick. If you have a good PC or the nack to tinker and build one of these, its a pretty rewarding system once up and running. You can use an xbox 360 to connect to it and play the content in other rooms as well.

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
reply to GTFan
The Guide data is constantly being altered/deleted/etc... It's not like it just downloads once a day and slowly deletes. In reality, it's always deleting 'expired' programs, and adding new stuff at the end. Plus, constantly checking and setting up series recordings, etc...

GTFan

join:2004-12-03
The point is that the guide data only needs to be downloaded and written to once a day. This is exactly what Tivo, MythTV, and other DVR software does. That's all that matters for flash, not how many times its read for recordings etc. The guide data itself is not written to more than that, all the other stuff you mention has to do with DVR functions which are entirely separate and saved to the drive.

There's no reason I can see why this shouldn't have been done long ago other than they just cheaped out. Which, again, I understand, but it's a hassle to the consumer if you have multiple boxes and power issues.

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
But remember that the Motorola's do not use a high-speed download channel. It can take 8-12+ hours for the full 2-weeks of data to download. Plus, if the OOB gets overloaded, it may even skip some entries, so you still have to wait for the next pass. This is not an 'demand' download, but just a continuous stream sent that the box has to sit, listen, and pick out the data it needs.


celeritypc
For Lucky Best Wash, Use Mr. Sparkle
Premium
join:2004-05-15
Caldwell, NJ
reply to lmacmil
I think what most people forget is that the Motorola platform is 20+ years old. Even though you may have only had digital cable for around 10 or so years, the platform was rolled out in the mid 90s. The patents and development are older than that. My system added digital in 1997. At the time of development, flash memory was not that cheap.

At this point you would have to ask yourself is it worth updating and re-engineering a platform (set-top boxes) that many think only has a few more years left anyway.


markofmayhem
Why not now?
Premium
join:2004-04-08
Pittsburgh, PA
kudos:5
reply to andyross
said by andyross:

But remember that the Motorola's do not use a high-speed download channel. It can take 8-12+ hours for the full 2-weeks of data to download. Plus, if the OOB gets overloaded, it may even skip some entries, so you still have to wait for the next pass. This is not an 'demand' download, but just a continuous stream sent that the box has to sit, listen, and pick out the data it needs.

Actually, it is worse than that. These are not mini-computers, the guide data in the OOB stream is direct memory address mapped (similar to ROM's behavior on smart phones). There is no application layer to determine what is "needed", the addresses are destroyed/written on every pass. Near zero computational power needed, which is why this system worked on Broadcom "tuners-in-a-box" in 1993. OCAP (Tru2Way) is the "next gen tech" that moved away from direct address mapping to a more extensible system that many in this thread believe is possible on today's IGuide, which it is not. The "data" in the guide is not a database, nor is it extensible, it is 0's and 1's stored in a hexadecimal address mapped to channel # and time offset (current hour, +.5 hour, +1 hour) for use by the guide. It is THAT hardcoded... OCAP moved away from that, allowing layers and applications to sit-on-top to do the very things wanted in this thread. Iguide doesn't "process", it just "displays".
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Show off that hardware: join Team Discovery and Team Helix


Days

@comcast.net
reply to lmacmil
I wish there was a feature, maybe in On Demand, where we could manually make the full guide download.


gar187er
I do this for a living

join:2006-06-24
Dover, DE
kudos:4
you get it periodically as its released....so i dont see a need to ask for a push...
--
I'm better than you!


mikedz4

join:2003-04-14
Weirton, WV
when it takes 2 days to fill in after a power interruption it is a royal pain in the a**.