Re: [H] HDTV Math

[mark.dodge]

Hi speed DSL, phone and TV all in one.
http://www.att-services.net/att-u-verse.html?mv1=A1200131&gclid=CL3r24Dx8pkC
FR7yDAod3WHRSQ

-Original Message-
From: hardware-boun...@hardwaregroup.com
[mailto:hardware-boun...@hardwaregroup.com] On Behalf Of Sam Franc
Sent: Saturday, April 11, 2009 12:12
To: hardware@hardwaregroup.com
Subject: Re: [H] HDTV Math

What is Uverse400?
Sam

mark.dodge wrote:
> I do not know where to get any figures to give a size or fps figures but
all
> I know is that after switching from Direct TV to UVerse400 I have seen a
> significant improvement in the quality of the picture and very little
> pixelization in all HD channels. I had very frequent, daily problems with
> dropped signal, loss of audio, freezing and very bad pixelization on all
of
> the broadcast stations along with Discovery Showtime and HBO and skipping
> sound on ESPN2 just to name a few. I do not get it but once or twice a
week
> on UVerse. I am very happy with the switch and I had been with D-TV for
> close to 6 years.
>
> -Original Message-
> From: hardware-boun...@hardwaregroup.com
> [mailto:hardware-boun...@hardwaregroup.com] On Behalf Of Brian Weeden
> Sent: Wednesday, April 08, 2009 07:39
> To: hardware@hardwaregroup.com
> Subject: Re: [H] HDTV Math
>
> If you looked at satellite HD broadcasts I would suspect you would find
even
> worse bitrates among several of the HD stations.
>
> It all comes down to bandwidth - the cable satellite operators have
limited
> bandwidth and are trying to cram as many stations in as possible, and in
> many case this means highly compressing some stations.  Usually they try
to
> make sure that HD signals where it is most likely to be noticed (Discovery
> HD, PPV movies and live sports) get the best signal while other pseudo HD
> channels like History or HGTV will get re-compressed like crazy.
>
> ---
> Brian Weeden
> Technical Consultant
> Secure World Foundation <http://www.secureworldfoundation.org>
> +1 (514) 466-2756 Canada
> +1 (202) 683-8534 US
>
>
> On Wed, Apr 8, 2009 at 1:35 AM, James Maki 
wrote:
>
>   
>> I discovered something this week and am trying to understand its
>> ramifications. I noticed lots of pixelation and motion blur the last two
>> weeks of Heroes. NBC broadcasts at 1080i for HDTV. I checked the
>> 
> statistics
>   
>> for the show I recorded via HD Homerun tuners using Comcast cable, and
NBC
>> is averaging about 4.8 GB per hour for a 1080i show. I thought is a bit
>> 
> low
>   
>> but was even more surprised when I checked out shows on the other
>> 
> broadcast
>   
>> networks.
>>
>> ABC 720p/60fps  6.3 GB
>> NBC 1080i/29.97fps  4.8 GB
>> CBS 1080i/29.97fps  5.6 GB
>> PBS 720p/60fps  5.4 GB
>> CW  1080i/29.97fps  7.9 GB
>> FOX 720p/60fps  7.3 GB
>>
>> I find it strange that NBC has the lowest total file size but is
>> broadcasting at 1080i, so I assuming (and I know the drawback of that!)
it
>> is compressed more than the other channels and am again assuming that is
>> why
>> I am seeing the picture degradation. Calling Comcast is a joke, so I
>> 
> wanted
>   
>> to do the math to calculate the 'bits-per-second" for each case, but am
>> 
> not
>   
>> exactly sure if I am doing this correctly. It would seem that 4.8 GB/hr
>> would calculate as:
>>
>> 4.8 GB/hr * 1 hr/60 min * 1 min/60 sec * 1024 MB/GB * 8 Mb/MB = 10.9
Mbps.
>>
>> One online source indicated that for quality 1080i you should have at
>> 
> least
>   
>> 15 Mbps.
>>
>> For the FOX network, the calculation would give 16.6 Mbps, far better
than
>> the 12 Mbps my online source gave for quality 720p broadcasts.
>>
>> I can't understand why the 720p broadcast is actually providing better
>> throughput than the 1080i. It seems backwards (which is why I am
wondering
>> if my math is correct). I am not sure how to factor in the fps figures,
if
>> at all.
>>
>> If you can add some insight, it would be appreciated.
>>
>> Thanks,
>>
>> Jim Maki
>> jwm_maill...@comcast.net
>>
>>
>> 
>
>   
> 
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com 
> Version: 8.5.287 / Virus Database: 270.11.51/2052 - Release Date: 04/10/09
06:39:00
>
>   

Re: [H] HDTV Math

[Sam Franc]

What is Uverse400?
Sam

mark.dodge wrote:

I do not know where to get any figures to give a size or fps figures but all
I know is that after switching from Direct TV to UVerse400 I have seen a
significant improvement in the quality of the picture and very little
pixelization in all HD channels. I had very frequent, daily problems with
dropped signal, loss of audio, freezing and very bad pixelization on all of
the broadcast stations along with Discovery Showtime and HBO and skipping
sound on ESPN2 just to name a few. I do not get it but once or twice a week
on UVerse. I am very happy with the switch and I had been with D-TV for
close to 6 years.

-Original Message-
From: hardware-boun...@hardwaregroup.com
[mailto:hardware-boun...@hardwaregroup.com] On Behalf Of Brian Weeden
Sent: Wednesday, April 08, 2009 07:39
To: hardware@hardwaregroup.com
Subject: Re: [H] HDTV Math

If you looked at satellite HD broadcasts I would suspect you would find even
worse bitrates among several of the HD stations.

It all comes down to bandwidth - the cable satellite operators have limited
bandwidth and are trying to cram as many stations in as possible, and in
many case this means highly compressing some stations.  Usually they try to
make sure that HD signals where it is most likely to be noticed (Discovery
HD, PPV movies and live sports) get the best signal while other pseudo HD
channels like History or HGTV will get re-compressed like crazy.

---
Brian Weeden
Technical Consultant
Secure World Foundation <http://www.secureworldfoundation.org>
+1 (514) 466-2756 Canada
+1 (202) 683-8534 US


On Wed, Apr 8, 2009 at 1:35 AM, James Maki  wrote:

  

I discovered something this week and am trying to understand its
ramifications. I noticed lots of pixelation and motion blur the last two
weeks of Heroes. NBC broadcasts at 1080i for HDTV. I checked the


statistics
  

for the show I recorded via HD Homerun tuners using Comcast cable, and NBC
is averaging about 4.8 GB per hour for a 1080i show. I thought is a bit


low
  

but was even more surprised when I checked out shows on the other


broadcast
  

networks.

ABC 720p/60fps  6.3 GB
NBC 1080i/29.97fps  4.8 GB
CBS 1080i/29.97fps  5.6 GB
PBS 720p/60fps  5.4 GB
CW  1080i/29.97fps  7.9 GB
FOX 720p/60fps  7.3 GB

I find it strange that NBC has the lowest total file size but is
broadcasting at 1080i, so I assuming (and I know the drawback of that!) it
is compressed more than the other channels and am again assuming that is
why
I am seeing the picture degradation. Calling Comcast is a joke, so I


wanted
  

to do the math to calculate the 'bits-per-second" for each case, but am


not
  

exactly sure if I am doing this correctly. It would seem that 4.8 GB/hr
would calculate as:

4.8 GB/hr * 1 hr/60 min * 1 min/60 sec * 1024 MB/GB * 8 Mb/MB = 10.9 Mbps.

One online source indicated that for quality 1080i you should have at


least
  

15 Mbps.

For the FOX network, the calculation would give 16.6 Mbps, far better than
the 12 Mbps my online source gave for quality 720p broadcasts.

I can't understand why the 720p broadcast is actually providing better
throughput than the 1080i. It seems backwards (which is why I am wondering
if my math is correct). I am not sure how to factor in the fps figures, if
at all.

If you can add some insight, it would be appreciated.

Thanks,

Jim Maki
jwm_maill...@comcast.net





  




No virus found in this incoming message.
Checked by AVG - www.avg.com 
Version: 8.5.287 / Virus Database: 270.11.51/2052 - Release Date: 04/10/09 06:39:00


  

Re: [H] HDTV Math

[Brian Weeden]

That's because U-verse has many times more bandwidth available to pipe
to your house.

Enjoy :)

On Saturday, April 11, 2009, mark.dodge  wrote:
> I do not know where to get any figures to give a size or fps figures but all
> I know is that after switching from Direct TV to UVerse400 I have seen a
> significant improvement in the quality of the picture and very little
> pixelization in all HD channels. I had very frequent, daily problems with
> dropped signal, loss of audio, freezing and very bad pixelization on all of
> the broadcast stations along with Discovery Showtime and HBO and skipping
> sound on ESPN2 just to name a few. I do not get it but once or twice a week
> on UVerse. I am very happy with the switch and I had been with D-TV for
> close to 6 years.
>
> -Original Message-
> From: hardware-boun...@hardwaregroup.com
> [mailto:hardware-boun...@hardwaregroup.com] On Behalf Of Brian Weeden
> Sent: Wednesday, April 08, 2009 07:39
> To: hardware@hardwaregroup.com
> Subject: Re: [H] HDTV Math
>
> If you looked at satellite HD broadcasts I would suspect you would find even
> worse bitrates among several of the HD stations.
>
> It all comes down to bandwidth - the cable satellite operators have limited
> bandwidth and are trying to cram as many stations in as possible, and in
> many case this means highly compressing some stations.  Usually they try to
> make sure that HD signals where it is most likely to be noticed (Discovery
> HD, PPV movies and live sports) get the best signal while other pseudo HD
> channels like History or HGTV will get re-compressed like crazy.
>
> ---
> Brian Weeden
> Technical Consultant
> Secure World Foundation <http://www.secureworldfoundation.org>
> +1 (514) 466-2756 Canada
> +1 (202) 683-8534 US
>
>
> On Wed, Apr 8, 2009 at 1:35 AM, James Maki  wrote:
>
>> I discovered something this week and am trying to understand its
>> ramifications. I noticed lots of pixelation and motion blur the last two
>> weeks of Heroes. NBC broadcasts at 1080i for HDTV. I checked the
> statistics
>> for the show I recorded via HD Homerun tuners using Comcast cable, and NBC
>> is averaging about 4.8 GB per hour for a 1080i show. I thought is a bit
> low
>> but was even more surprised when I checked out shows on the other
> broadcast
>> networks.
>>
>> ABC     720p/60fps              6.3 GB
>> NBC     1080i/29.97fps  4.8 GB
>> CBS     1080i/29.97fps  5.6 GB
>> PBS     720p/60fps              5.4 GB
>> CW      1080i/29.97fps  7.9 GB
>> FOX     720p/60fps              7.3 GB
>>
>> I find it strange that NBC has the lowest total file size but is
>> broadcasting at 1080i, so I assuming (and I know the drawback of that!) it
>> is compressed more than the other channels and am again assuming that is
>> why
>> I am seeing the picture degradation. Calling Comcast is a joke, so I
> wanted
>> to do the math to calculate the 'bits-per-second" for each case, but am
> not
>> exactly sure if I am doing this correctly. It would seem that 4.8 GB/hr
>> would calculate as:
>>
>> 4.8 GB/hr * 1 hr/60 min * 1 min/60 sec * 1024 MB/GB * 8 Mb/MB = 10.9 Mbps.
>>
>> One online source indicated that for quality 1080i you should have at
> least
>> 15 Mbps.
>>
>> For the FOX network, the calculation would give 16.6 Mbps, far better than
>> the 12 Mbps my online source gave for quality 720p broadcasts.
>>
>> I can't understand why the 720p broadcast is actually providing better
>> throughput than the 1080i. It seems backwards (which is why I am wondering
>> if my math is correct). I am not sure how to factor in the fps figures, if
>> at all.
>>
>> If you can add some insight, it would be appreciated.
>>
>> Thanks,
>>
>> Jim Maki
>> jwm_maill...@comcast.net
>>
>>
>
>

Re: [H] HDTV Math

[mark.dodge]

I do not know where to get any figures to give a size or fps figures but all
I know is that after switching from Direct TV to UVerse400 I have seen a
significant improvement in the quality of the picture and very little
pixelization in all HD channels. I had very frequent, daily problems with
dropped signal, loss of audio, freezing and very bad pixelization on all of
the broadcast stations along with Discovery Showtime and HBO and skipping
sound on ESPN2 just to name a few. I do not get it but once or twice a week
on UVerse. I am very happy with the switch and I had been with D-TV for
close to 6 years.

-Original Message-
From: hardware-boun...@hardwaregroup.com
[mailto:hardware-boun...@hardwaregroup.com] On Behalf Of Brian Weeden
Sent: Wednesday, April 08, 2009 07:39
To: hardware@hardwaregroup.com
Subject: Re: [H] HDTV Math

If you looked at satellite HD broadcasts I would suspect you would find even
worse bitrates among several of the HD stations.

It all comes down to bandwidth - the cable satellite operators have limited
bandwidth and are trying to cram as many stations in as possible, and in
many case this means highly compressing some stations.  Usually they try to
make sure that HD signals where it is most likely to be noticed (Discovery
HD, PPV movies and live sports) get the best signal while other pseudo HD
channels like History or HGTV will get re-compressed like crazy.

---
Brian Weeden
Technical Consultant
Secure World Foundation <http://www.secureworldfoundation.org>
+1 (514) 466-2756 Canada
+1 (202) 683-8534 US


On Wed, Apr 8, 2009 at 1:35 AM, James Maki  wrote:

> I discovered something this week and am trying to understand its
> ramifications. I noticed lots of pixelation and motion blur the last two
> weeks of Heroes. NBC broadcasts at 1080i for HDTV. I checked the
statistics
> for the show I recorded via HD Homerun tuners using Comcast cable, and NBC
> is averaging about 4.8 GB per hour for a 1080i show. I thought is a bit
low
> but was even more surprised when I checked out shows on the other
broadcast
> networks.
>
> ABC 720p/60fps  6.3 GB
> NBC 1080i/29.97fps  4.8 GB
> CBS 1080i/29.97fps  5.6 GB
> PBS 720p/60fps  5.4 GB
> CW  1080i/29.97fps  7.9 GB
> FOX 720p/60fps  7.3 GB
>
> I find it strange that NBC has the lowest total file size but is
> broadcasting at 1080i, so I assuming (and I know the drawback of that!) it
> is compressed more than the other channels and am again assuming that is
> why
> I am seeing the picture degradation. Calling Comcast is a joke, so I
wanted
> to do the math to calculate the 'bits-per-second" for each case, but am
not
> exactly sure if I am doing this correctly. It would seem that 4.8 GB/hr
> would calculate as:
>
> 4.8 GB/hr * 1 hr/60 min * 1 min/60 sec * 1024 MB/GB * 8 Mb/MB = 10.9 Mbps.
>
> One online source indicated that for quality 1080i you should have at
least
> 15 Mbps.
>
> For the FOX network, the calculation would give 16.6 Mbps, far better than
> the 12 Mbps my online source gave for quality 720p broadcasts.
>
> I can't understand why the 720p broadcast is actually providing better
> throughput than the 1080i. It seems backwards (which is why I am wondering
> if my math is correct). I am not sure how to factor in the fps figures, if
> at all.
>
> If you can add some insight, it would be appreciated.
>
> Thanks,
>
> Jim Maki
> jwm_maill...@comcast.net
>
>

Re: [H] HDTV Math

[Bino Gopal]

No, for the most part that covers the p vs i discussion. If you read
avsforums most people say that it's hardly noticeable, except in fast action
sequences where the p will look better since there's more frames so it
reduces "tearing", i.e. the feeling the image is choppy; it basically looks
a bit smoother, but some folks don't even notice it at all.

But the 3/2 pulldown (really 2/3) only matters when you have movies involved
at that's the telecine process; it's b/c movies are filmed at 24fps and tv
(NTSC) is displayed at 30fps, and to get the two to sync, they have to
add/duplicate extra frames to the movie to match up.

I read about this recently b/c the new Blu-Ray player that I got, the
Samsung BD-P2550 actually has a mode where it can output the movie in the
normal 24fps as long as your tv accepts that, which all the av nuts say is
the best way to do it (eliminating all the 2:3 issues).

HTH!

BINO


-Original Message-
From: hardware-boun...@hardwaregroup.com
[mailto:hardware-boun...@hardwaregroup.com] On Behalf Of Brian Weeden
Sent: Wednesday, April 08, 2009 9:27 AM
To: hardware@hardwaregroup.com
Subject: Re: [H] HDTV Math

Digital OTA broadcasts will be the best signal in terms of compression, no
doubts about it.  The only thing better is BluRay.

Part of this goes back to past discussions we've had on here about whether
1080i is better than 720p.  The biggest reason for the difference you are
seeing is in the framerate.  720p is progressive scanned, which means that
they are scanning every line of video from top to bottom.  1080i is
interlaced, meaning they only scan every other line and alternate between
frames.  This way you get appearance of a full image for only half the
bandwidth, and that shows up in your measurements.  So 1080i does have more
lines of resolution, but 720p is sending more frames.

And for you videophiles, yes I know I greatly oversimplified the
progressive/interlaced, 3/2 pulldown and fps definitions for the sake of
argument.

---
Brian Weeden
Technical Consultant
Secure World Foundation <http://www.secureworldfoundation.org>
+1 (514) 466-2756 Canada
+1 (202) 683-8534 US


On Wed, Apr 8, 2009 at 12:16 PM, James Maki wrote:

> Brian,
>
> I pay for HD and would like to think I get HD, but if comcast is only
> giving
> 2/3 of the bandwidth that is considered HD, I may look elsewhere. I have
> read that digital over the air broadcasts better than analog. I am about
> 30-40 miles from Seattle and Tacoma, where all the networks have broadcast
> towers, so am thinking of investigating an antenna. It is a shame that we
> have investing in a switch-over to HD only to not really be getting HD.
>
> I would rather have 100 quality stations than 600 crappy stations. But
that
> is just me. I am sure there are people who get cable just for the soap
> network or game network, but not me.
>
> Anyway, I was just looking for confirmation or correction on my math.
>
> Thanks,
>
> Jim
>
> > -Original Message-
> > From: Brian Weeden
>
> > If you looked at satellite HD broadcasts I would suspect you
> > would find even
> > worse bitrates among several of the HD stations.
> >
>
> > Brian Weeden
> > Technical Consultant
>
> > On Wed, Apr 8, 2009 at 1:35 AM, James Maki
>
> > > I discovered something this week and am trying to understand its
> > > ramifications. I noticed lots of pixelation and motion blur
> > > the last two weeks of Heroes.
>
> > > NBC is averaging about 4.8 GB per hour for a 1080i show. I
> > > thought is a bit low
>
> > > I am wondering
> > > if my math is correct). I am not sure how to factor in the
> > > fps figures, if at all.
> > >
> > > If you can add some insight, it would be appreciated.
> > >
> > > Thanks,
> > >
> > > Jim Maki
>
>
>

Re: [H] HDTV Math

[Brian Weeden]

Digital OTA broadcasts will be the best signal in terms of compression, no
doubts about it.  The only thing better is BluRay.

Part of this goes back to past discussions we've had on here about whether
1080i is better than 720p.  The biggest reason for the difference you are
seeing is in the framerate.  720p is progressive scanned, which means that
they are scanning every line of video from top to bottom.  1080i is
interlaced, meaning they only scan every other line and alternate between
frames.  This way you get appearance of a full image for only half the
bandwidth, and that shows up in your measurements.  So 1080i does have more
lines of resolution, but 720p is sending more frames.

And for you videophiles, yes I know I greatly oversimplified the
progressive/interlaced, 3/2 pulldown and fps definitions for the sake of
argument.

---
Brian Weeden
Technical Consultant
Secure World Foundation 
+1 (514) 466-2756 Canada
+1 (202) 683-8534 US


On Wed, Apr 8, 2009 at 12:16 PM, James Maki wrote:

> Brian,
>
> I pay for HD and would like to think I get HD, but if comcast is only
> giving
> 2/3 of the bandwidth that is considered HD, I may look elsewhere. I have
> read that digital over the air broadcasts better than analog. I am about
> 30-40 miles from Seattle and Tacoma, where all the networks have broadcast
> towers, so am thinking of investigating an antenna. It is a shame that we
> have investing in a switch-over to HD only to not really be getting HD.
>
> I would rather have 100 quality stations than 600 crappy stations. But that
> is just me. I am sure there are people who get cable just for the soap
> network or game network, but not me.
>
> Anyway, I was just looking for confirmation or correction on my math.
>
> Thanks,
>
> Jim
>
> > -Original Message-
> > From: Brian Weeden
>
> > If you looked at satellite HD broadcasts I would suspect you
> > would find even
> > worse bitrates among several of the HD stations.
> >
>
> > Brian Weeden
> > Technical Consultant
>
> > On Wed, Apr 8, 2009 at 1:35 AM, James Maki
>
> > > I discovered something this week and am trying to understand its
> > > ramifications. I noticed lots of pixelation and motion blur
> > > the last two weeks of Heroes.
>
> > > NBC is averaging about 4.8 GB per hour for a 1080i show. I
> > > thought is a bit low
>
> > > I am wondering
> > > if my math is correct). I am not sure how to factor in the
> > > fps figures, if at all.
> > >
> > > If you can add some insight, it would be appreciated.
> > >
> > > Thanks,
> > >
> > > Jim Maki
>
>
>

Re: [H] HDTV Math

[James Maki]

Brian,

I pay for HD and would like to think I get HD, but if comcast is only giving
2/3 of the bandwidth that is considered HD, I may look elsewhere. I have
read that digital over the air broadcasts better than analog. I am about
30-40 miles from Seattle and Tacoma, where all the networks have broadcast
towers, so am thinking of investigating an antenna. It is a shame that we
have investing in a switch-over to HD only to not really be getting HD. 

I would rather have 100 quality stations than 600 crappy stations. But that
is just me. I am sure there are people who get cable just for the soap
network or game network, but not me.

Anyway, I was just looking for confirmation or correction on my math.

Thanks,

Jim

> -Original Message-
> From: Brian Weeden
 
> If you looked at satellite HD broadcasts I would suspect you 
> would find even
> worse bitrates among several of the HD stations.
> 

> Brian Weeden
> Technical Consultant
 
> On Wed, Apr 8, 2009 at 1:35 AM, James Maki 

> > I discovered something this week and am trying to understand its
> > ramifications. I noticed lots of pixelation and motion blur 
> > the last two weeks of Heroes. 

> > NBC is averaging about 4.8 GB per hour for a 1080i show. I 
> > thought is a bit low

> > I am wondering
> > if my math is correct). I am not sure how to factor in the 
> > fps figures, if at all.
> >
> > If you can add some insight, it would be appreciated.
> >
> > Thanks,
> >
> > Jim Maki

Re: [H] HDTV Math

[James Maki]

Yes, I have read about how comcast compresses their already compressed (by
the network) signals trying to cram more HD stations into less space. I am
just trying to figure out why our local NBC affiliate seems to be getting
compressed to a greater extent with worse results? FOX and CW give a better
picture (one at 720p and the other at 1080i). 

I am just looking for confirmation if my calculation is correct or I am
approaching the problem incorrectly.

Thanks,

Jim

> -Original Message-
> From: Eli Allen
 
> You know Comcast recompresses, right?
> 
> -Original Message-
> From: James Maki
 
> I discovered something this week and am trying to understand its
> ramifications. I noticed lots of pixelation and motion blur 
> the last two
> weeks of Heroes. NBC broadcasts at 1080i for HDTV. I checked 
> the statistics
> for the show I recorded via HD Homerun tuners using Comcast 
> cable, and NBC
> is averaging about 4.8 GB per hour for a 1080i show. I 
> thought is a bit low
> but was even more surprised when I checked out shows on the 
> other broadcast
> networks. 
> 
> 

Re: [H] HDTV Math

[Brian Weeden]

If you looked at satellite HD broadcasts I would suspect you would find even
worse bitrates among several of the HD stations.

It all comes down to bandwidth - the cable satellite operators have limited
bandwidth and are trying to cram as many stations in as possible, and in
many case this means highly compressing some stations.  Usually they try to
make sure that HD signals where it is most likely to be noticed (Discovery
HD, PPV movies and live sports) get the best signal while other pseudo HD
channels like History or HGTV will get re-compressed like crazy.

---
Brian Weeden
Technical Consultant
Secure World Foundation 
+1 (514) 466-2756 Canada
+1 (202) 683-8534 US


On Wed, Apr 8, 2009 at 1:35 AM, James Maki  wrote:

> I discovered something this week and am trying to understand its
> ramifications. I noticed lots of pixelation and motion blur the last two
> weeks of Heroes. NBC broadcasts at 1080i for HDTV. I checked the statistics
> for the show I recorded via HD Homerun tuners using Comcast cable, and NBC
> is averaging about 4.8 GB per hour for a 1080i show. I thought is a bit low
> but was even more surprised when I checked out shows on the other broadcast
> networks.
>
> ABC 720p/60fps  6.3 GB
> NBC 1080i/29.97fps  4.8 GB
> CBS 1080i/29.97fps  5.6 GB
> PBS 720p/60fps  5.4 GB
> CW  1080i/29.97fps  7.9 GB
> FOX 720p/60fps  7.3 GB
>
> I find it strange that NBC has the lowest total file size but is
> broadcasting at 1080i, so I assuming (and I know the drawback of that!) it
> is compressed more than the other channels and am again assuming that is
> why
> I am seeing the picture degradation. Calling Comcast is a joke, so I wanted
> to do the math to calculate the 'bits-per-second" for each case, but am not
> exactly sure if I am doing this correctly. It would seem that 4.8 GB/hr
> would calculate as:
>
> 4.8 GB/hr * 1 hr/60 min * 1 min/60 sec * 1024 MB/GB * 8 Mb/MB = 10.9 Mbps.
>
> One online source indicated that for quality 1080i you should have at least
> 15 Mbps.
>
> For the FOX network, the calculation would give 16.6 Mbps, far better than
> the 12 Mbps my online source gave for quality 720p broadcasts.
>
> I can't understand why the 720p broadcast is actually providing better
> throughput than the 1080i. It seems backwards (which is why I am wondering
> if my math is correct). I am not sure how to factor in the fps figures, if
> at all.
>
> If you can add some insight, it would be appreciated.
>
> Thanks,
>
> Jim Maki
> jwm_maill...@comcast.net
>
>

Re: [H] HDTV Math

[Eli Allen]

You know Comcast recompresses, right?

-Original Message-
From: hardware-boun...@hardwaregroup.com
[mailto:hardware-boun...@hardwaregroup.com] On Behalf Of James Maki
Sent: Wednesday, April 08, 2009 1:36 AM
To: hardware@hardwaregroup.com
Subject: [H] HDTV Math

I discovered something this week and am trying to understand its
ramifications. I noticed lots of pixelation and motion blur the last two
weeks of Heroes. NBC broadcasts at 1080i for HDTV. I checked the statistics
for the show I recorded via HD Homerun tuners using Comcast cable, and NBC
is averaging about 4.8 GB per hour for a 1080i show. I thought is a bit low
but was even more surprised when I checked out shows on the other broadcast
networks. 

[H] HDTV Math

[James Maki]

I discovered something this week and am trying to understand its
ramifications. I noticed lots of pixelation and motion blur the last two
weeks of Heroes. NBC broadcasts at 1080i for HDTV. I checked the statistics
for the show I recorded via HD Homerun tuners using Comcast cable, and NBC
is averaging about 4.8 GB per hour for a 1080i show. I thought is a bit low
but was even more surprised when I checked out shows on the other broadcast
networks. 

ABC 720p/60fps  6.3 GB
NBC 1080i/29.97fps  4.8 GB
CBS 1080i/29.97fps  5.6 GB
PBS 720p/60fps  5.4 GB
CW  1080i/29.97fps  7.9 GB
FOX 720p/60fps  7.3 GB

I find it strange that NBC has the lowest total file size but is
broadcasting at 1080i, so I assuming (and I know the drawback of that!) it
is compressed more than the other channels and am again assuming that is why
I am seeing the picture degradation. Calling Comcast is a joke, so I wanted
to do the math to calculate the 'bits-per-second" for each case, but am not
exactly sure if I am doing this correctly. It would seem that 4.8 GB/hr
would calculate as:

4.8 GB/hr * 1 hr/60 min * 1 min/60 sec * 1024 MB/GB * 8 Mb/MB = 10.9 Mbps. 

One online source indicated that for quality 1080i you should have at least
15 Mbps.

For the FOX network, the calculation would give 16.6 Mbps, far better than
the 12 Mbps my online source gave for quality 720p broadcasts.

I can't understand why the 720p broadcast is actually providing better
throughput than the 1080i. It seems backwards (which is why I am wondering
if my math is correct). I am not sure how to factor in the fps figures, if
at all.

If you can add some insight, it would be appreciated.

Thanks,

Jim Maki
jwm_maill...@comcast.net