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ellentk
join:2011-01-18
New York, NY

ellentk

Member

[TV] DVR Compression? (Manhattan)

I've got a Scientific Atlanta 8300HDC. Ever since Time Warner switched to HD only programming it fills up very quickly. However, it also seems to occasionally compress the data. Twice the percentage full decreased from the high 80s to the mid 40s. I'm guessing the data is compressed. But is it compressed by the 8300 or on the TWC network? And is there any way that I can initiate the compression myself?
smcallah
join:2004-08-05
Home

smcallah

Member

The video streams they send are already highly compressed, once from the satellite transmission to TWC, and likely again by video encoders at TWC. There is no way that they are able to compress them by half again after that. I've never seen an SA DVR do that, it sounds like it has a problem.

The only time that a DVR would compress would be if it was recording an analog channel. An analog stream without compression would take up a ton of space. TWC is no longer using analog signals on DVRs as they've had digital simulcast for years. And even if you were recording an analog stream, it's done on the fly, so you wouldn't see the space available change from 80% to 40%.
ellentk
join:2011-01-18
New York, NY

ellentk

Member

Thanks for your reply.

From my point of view, the only problem is that compression doesn't happen with every recording.

Thinkdiff
MVM,
join:2001-08-07
Bronx, NY

Thinkdiff

MVM,

The DVR does not do compression. Whatever you're seeing with the full indicator is something else or a bug.
ellentk
join:2011-01-18
New York, NY

ellentk

Member

But data is compressed, however it is done, because I can record more shows once the indicator goes down. It's not just a faulty indicator.

Thinkdiff
MVM,
join:2001-08-07
Bronx, NY

Thinkdiff

MVM,

I don't know what to tell you other than the existing recordings are not being compressed. Lossless compression would not net as much savings as you're seeing (if the CPUs were even powerful enough to do it, which they aren't). And digital sources are saved to disk as-is.

You can see here: »www.cisco.com/c/dam/en/u ··· 6913.pdf

The only MPEG2 encoder in the box is for Analog SD channels.

Suit Up
join:2003-07-21
Los Angeles, CA
Ubiquiti EdgeRouter X
TP-Link Archer C7

Suit Up to ellentk

Member

to ellentk
There is no way to compress MPEG-2 and have a 50% reduction in size. You can re-encode it as MPEG-4 and save that much. But your DVR does not support MPEG-4 as far as I'm aware, thus that is not happening.

More likely what is happening is that the DVR deletes an old program to free up the space and you are not noticing that it did that.
ellentk
join:2011-01-18
New York, NY

ellentk

Member

To get the percentage down as much as it falls when this happens, it would have to delete many shows and I'd notice that.
sumotu
Premium Member
join:2014-07-25
Durham, NC

sumotu to ellentk

Premium Member

to ellentk
Same DVR, Durham, NC. Since they made the change, my DVR has been filling up rapidly. But if I reboot it, the percentage will drop at least 50%. It acts like the space freed up by deleting programs is not being completely freed up.
ellentk
join:2011-01-18
New York, NY

ellentk

Member

I havn't tried rebooting because it takes so long. But thank you for the tip. I will definitely give it a try.
ellentk

ellentk to sumotu

Member

to sumotu
Rebooting did the trick on my box too. Thanks.