# 1 Hour Buffer on Both Tuners



## eddieb187 (Jan 17, 2009)

I would like to be able to buffer both tuners up to one hour.
A half an hour is just not enough time.
With 20 minutes of commercials for an hour program we need more buffer time.
I just purchased a Tivo HD and I love it.
It's so much better than the Time Warner Cable DVR.
Thank you for an excellent Box with great software.


----------



## Phasers (May 29, 2008)

Ditto. This is my biggest complaint about TiVo is the buffer size. Although compared to my DirecTV I guess I should be glad to have 2 live buffers even if they are only 1/2 hour each.


----------



## burnside (Jan 12, 2009)

I switched to Tivo and kind of miss DirecTV dvr's 90 minute buffer... then again, they did not have dual buffers. I would love to see an increase in Tivo's buffer size though.


----------



## SpiritualPoet (Jan 14, 2007)

Actually, a "smart" buffer should hold programming from the beginning of the currently tuned event from its beginning regardless of when that event began. Since recordings are based on program guide data anyway, can't this be possible? If not, why?


----------



## WayneCarter (Mar 16, 2003)

SpiritualPoet said:


> Actually, a "smart" buffer should hold programming from the beginning of the currently tuned event from its beginning regardless of when that event began. Since recordings are based on program guide data anyway, can't this be possible? If not, why?


I think the "problem" is that the current "live-TV buffer(s)" are in system memory so as not to interfere with anything in the NPL. This requires a fixed allocation of storage. A dynamic allocation (as in your guide sensitive buffer) would potentially require a substantial amount of NPL storage to be deleted if the channel(s) currently tuned happen to have a long even scheduled, such as a long game, the olympics, a presidential innaguaration, etc -- even if noone is watching (and remember live-TV is always at max resolution).


----------



## lrhorer (Aug 31, 2003)

WayneCarter said:


> I think the "problem" is that the current "live-TV buffer(s)" are in system memory so as not to interfere with anything in the NPL.


No, they aren't. Since the TiVo has two buffers, the total buffer size is 1 hour, and 1 hour of recording can easily exceed 8 gigabytes of data. The system memory is only 128 Megs on a TiVo HD, and I think the same on an S3. It's possible there is some technical limitation of which I am unaware, but this certainly is not it.


----------



## lrhorer (Aug 31, 2003)

SpiritualPoet said:


> Actually, a "smart" buffer should hold programming from the beginning of the currently tuned event from its beginning regardless of when that event began. Since recordings are based on program guide data anyway, can't this be possible? If not, why?


No, that's a really bad idea. It wouldn't be difficult at all to overflow the total drive space on a THD with an unlimited buffer size, among other things.


----------



## WayneCarter (Mar 16, 2003)

lrhorer said:


> No, they aren't. Since the TiVo has two buffers, the total buffer size is 1 hour, and 1 hour of recording can easily exceed 8 gigabytes of data. The system memory is only 128 Megs on a TiVo HD, and I think the same on an S3. It's possible there is some technical limitation of which I am unaware, but this certainly is not it.


My bad! Clearly they're not in system memory (ie RAM), I believe they're in the system *partition* of the hard drive, which is what I meant by "memory". Keeping them in the system partition keeps them independent of the NPL recordings. Even if they're in the same partition as the NPL recordings, they'd have to be pre-allocated. Any dynamic allocation would have to interact with the NPL. Sorry for the confusion.


----------



## WayneCarter (Mar 16, 2003)

lrhorer said:


> No, that's a really bad idea. It wouldn't be difficult at all to overflow the total drive space on a THD with an unlimited buffer size, among other things.


I agree that this is a very bad idea but I feel the biggest reason is the amount of NPL recordings that would be overwritten if TiVo happened to tuned to a channel that carried an event that was several hours long (I gave some examples in a prior post).


----------



## lrhorer (Aug 31, 2003)

WayneCarter said:


> My bad! Clearly they're not in system memory (ie RAM), I believe they're in the system *partition* of the hard drive,


No, absolutely not. The systems partitions (two boot partitions, two root partitions) are read-only. Nothing ever gets written to them in normal operation. The only ordinary read-write Linux partition is /dev/hda9 which is mounted on /var, and var is quite small - only 248 MB on the TiVo HD. That's barely enough for 2 minutes of HD content. It would also be very inefficient, almost impractical, to copy over the buffer from one partition to the other whenever the user presses <Rec> during a live recording. No, the live buffers are ring buffers maintained in the ordinary MFS file areas which can easily be converted to regular MFS files whenever the user decides to record a live program.



WayneCarter said:


> which is what I meant by "memory". Keeping them in the system partition keeps them independent of the NPL recordings.


No, the system merely writes to disk in empty space without setting up entries in the MFS file table, instead simply keeping pointers to the beginning and end of the ring buffer. The MFS file system considers the area unusable, and so does not write any scheduled recordinngs to the area until it has been released by the buffer pointers.



WayneCarter said:


> Even if they're in the same partition as the NPL recordings, they'd have to be pre-allocated. Any dynamic allocation would have to interact with the NPL. Sorry for the confusion.


No, the NPL is tied to actual file allocations, while the buffer area is dynamically allocated by a separate part of the MFS file system code. The MFS file system knows where the buffer areas are and avoids writing to them until the TiVo releases specific areas by sliding the start pointer further down the partition.


----------



## WayneCarter (Mar 16, 2003)

OK, Thanks.


----------



## jlb (Dec 13, 2001)

I have always thought that if one is worried about the buffer size, then you either don't have enough SPs or WLs. If you think in the future you might want to record something, then either create a season pass or an auto record wishlist.


----------



## Jonathan_S (Oct 23, 2001)

lrhorer said:


> No, that's a really bad idea. It wouldn't be difficult at all to overflow the total drive space on a THD with an unlimited buffer size, among other things.


Yeah, like WayneCarter said, you could lose a _lot _of recordings if you had the misfortune, in a couple years, to have your HD TiVo with both tuners randomly on channels on 8-hour long blocks of Olympic coverage. 16-hours of HD buffer is 80%  of the storage of a stock TiVo HD.

Yeah, unlimited dynamic buffers are a *BAD* idea.
Now, increasing the static size, especially on SD TiVos and TiVO HD-XLs makes sense, it's the unlimited dynamic resize that's dangerous.


----------



## Sanescience (Feb 12, 2009)

As a side note, while watching SD channels if you hit the record button on my series 3 it "recovers" much more than a half hour, as if much more than a half hour is actually being recorded.


----------



## nipster00 (Feb 9, 2009)

Sanescience said:


> As a side note, while watching SD channels if you hit the record button on my series 3 it "recovers" much more than a half hour, as if much more than a half hour is actually being recorded.


this is true, i have gotten up to 18 extra minutes beyond the 30 min buffer...


----------



## magnus (Nov 12, 2004)

I'm not even interested in this one at all. Unless it were to be something that I could control. I don't want to use up more of my drive with a bigger live buffer.


----------



## Resist (Dec 21, 2003)

magnus said:


> I don't want to use up more of my drive with a bigger live buffer.


Then why not increase the drive capacity to solve this? Amazon sells 1TB drives for $112, so you know Tivo could get them for much less. This shouldn't increase the cost of a Tivo by much and 1TB should be the minimum in all Tivo's, at least until higher capacity drives go down in price.


----------



## Adam1115 (Dec 15, 2003)

Keep in mind, with TiVo, say you are watching a 1 hour show and are 45 minutes into it. you lost the first 15 minutes right? Nope, hit record, TiVo will likely capture the entire show.


----------



## magnus (Nov 12, 2004)

Then I'd still want to use the extra space for actual shows and not the live buffer. In any case, I would want the ability to control it. And on the standard THD.... you would need the ability to keep it at 30 min each.



Resist said:


> Then why not increase the drive capacity to solve this? Amazon sells 1TB drives for $112, so you know Tivo could get them for much less. This shouldn't increase the cost of a Tivo by much and 1TB should be the minimum in all Tivo's, at least until higher capacity drives go down in price.


----------



## theviaumaster (Feb 24, 2009)

magnus said:


> I'm not even interested in this one at all. Unless it were to be something that I could control. I don't want to use up more of my drive with a bigger live buffer.


I agree that it would have to be something we can control. Basically a user-defined buffer size that you could raise or lower in increments. Couple that level of control with a sliding cap based on total drive capacity, and it'd be perfect. With the My DVR Expander, I frequently have over 100 items in Recently Deleted. Why not take some of that "wasted" space and use it to crank up the buffer? If, down the road, we start to receive more HD channels and need more space then we simply throttle it back down. Seems like a no-brainer to me...


----------

