# Roamio Pro recording capacity



## pkb (Sep 2, 2013)

On a Roamio Pro, with no expansion, how many hours of recording constitute 1% of used hard drive space? I record only HD cable programs.


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## CoxInPHX (Jan 14, 2011)

Roamio Pro 3TB is 476 Hrs HD approx,

It all really depends on the bitrate of the video you are recording, which can vary widely between channels and providers generally between ~8Mbps to 15Mbps for cable.

1 Hr of NBCHD (MPEG2) for me is approx 4.4 GB @ 10.3Mbps
1 Hr of FoxHD (MPEG2) for me is approx 6.2 GB @ 14.7Mbps
1 Hr of HBOHD (H.264) is approx 3.4 GB @ 7.4Mbps


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## lessd (Jan 23, 2005)

CoxInPHX said:


> Roamio Pro 3TB is 476 Hrs HD approx,
> 
> It all really depends on the bitrate of the video you are recording, which can vary widely between channels and providers generally between ~8Mbps to 15Mbps for cable.
> 
> ...


How do you know HBO is using H.264 ?


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## JoeKustra (Dec 7, 2012)

CoxInPHX said:


> Roamio Pro 3TB is 476 Hrs HD approx,
> 
> It all really depends on the bitrate of the video you are recording, which can vary widely between channels and providers generally between ~8Mbps to 15Mbps for cable.
> 
> ...


I find it interesting that your NBC bit rate is so low. The Fox is good and better than mine, with ABC being crap. How's your CBS? I have found my NBC and CBS share a channel with the Fox and PBS channels. So much for quality.

Perhaps it's because KPNX has two subchannels?


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## CoxInPHX (Jan 14, 2011)

lessd said:


> How do you know HBO is using H.264 ?


The DVR Diagnostics says so, and all the 32 Cox Contour HD channels are H.264

For HBO in Cox AZ
HBO (Pacific) is MPEG2
HBO2 (Pacific) is MPEG2
HBO Signature (Pacific) is H.264
HBO Family (Pacific) is H.264
HBO Zone (Pacific) is H.264
HBO (East) is H.264
HBO2 (East) is H.264


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## CoxInPHX (Jan 14, 2011)

JoeKustra said:


> I find it interesting that your NBC bit rate is so low. The Fox is good and better than mine, with ABC being crap. How's your CBS? I have found my NBC and CBS share a channel with the Fox and PBS channels. So much for quality.
> 
> Perhaps it's because KPNX has two subchannels?


CBSHD (KPHOHD) is 12.5Mbps
ABCHD (KNXVHD) is 14.0Mbps
PBS (KAETHD) is only 5.5Mbps for UK shows, and 7.5Mbps for US shows


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## lessd (Jan 23, 2005)

CoxInPHX said:


> The DVR Diagnostics says so, and all the 32 Cox Contour HD channels are H.264
> 
> For HBO in Cox AZ
> HBO (Pacific) is MPEG2
> ...


I did not know that, have to check that out using the DVR diag, Thanks


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## CoxInPHX (Jan 14, 2011)

lessd said:


> I did not know that, have to check that out using the DVR diag, Thanks


For Cox CT, HBO East and HBO2 East will be MPEG2 - so that those two are still compatible with legacy Motorola (non-Contour) receivers.

All the rest should be H.264


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## lessd (Jan 23, 2005)

CoxInPHX said:


> For Cox CT, HBO East and HBO2 East will be MPEG2 - so that those two are still compatible with legacy Motorola (non-Contour) receivers.
> 
> All the rest should be H.264


I have Comcast CT so I guess all my HBO will not be H.264


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## waynomo (Nov 9, 2002)

FWIW I consider each percent of space available to equal about 5 hours. (I forget how I did the calculation.) So I figure if I've used 90% used (10% available) I have about 50 hours left. However, it's really closer to 55 hours because there is still about 5 hours left when the counter changes from 99 to 100.


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## lessd (Jan 23, 2005)

waynomo said:


> FWIW I consider each percent of space available to equal about 5 hours. (I forget how I did the calculation.) So I figure if I've used 90% used (10% available) I have about 50 hours left. However, it's really closer to 55 hours because there is still about 5 hours left when the counter changes from 99 to 100.


Because there is a big difference in space needed for each hour of HD recording by channel that your recording, no *space left *can be very precise.


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## Dan203 (Apr 17, 2000)

I believe TiVo uses 15Mbps for it's estimate. In most cases that will be the top end of what you record, so you'll likely be able to hold more then the estimated 476 hours.


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## lessd (Jan 23, 2005)

Dan203 said:


> I believe TiVo uses 15Mbps for it's estimate. In most cases that will be the top end of what you record, so you'll likely be able to hold more then the estimated 476 hours.


To get to 476 hours on a 3Tb drive would mean TiVo uses about 6.3Mbps/hour, or is my math off.


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## CoxInPHX (Jan 14, 2011)

lessd said:


> To get to 476 hours on a 3Tb drive would mean TiVo uses about 6.3Mbps/hour, or is my math off.


3000GB / 476Hrs = 6.3GB/Hr which works out to about 15Mbps


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## krkaufman (Nov 25, 2003)

My maths say the TiVo 476 hour estimate for a 3TB hard drive translates to a 13.36Mbps average bitrate.

3TB = 3TB * 1000GB/1TB * 1000MB/1GB * 1000KB/1MB * 1000B/1KB * 8b/1B = 24,000,000,000,000 bits

476 hours = 476h * 60m/1h * 60s/1m = 1,713,600 seconds

24,000,000,000,000 bits / 1,713,600 secs = 14005602 bits/sec

and 14005602 bits/sec / 1024b/1Kb / 1024Kb/1Mb = *13.36 Mbps*

(You get around 14.69Mbps -- 15Mbps, rounded -- if you ignore the difference between hard drive manufacturer marketing and actual available disk space, thinking a 3TB drive has more bits than it really does -- which may be what TiVo has done.)


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