How Come Dish won't carry PBS- HD?

[whatchel1]

Multipath

And you believe with a roof antenna only 4 miles from the esb I can't even get wnet reliable. One day it can be in the 70s and the next day it is borderline or weak and just breaks up bad. Go to the avs forums under ota NYC reception threat where I do much complaining over this.

Even the other local PBS stations ota are unreliable. I just wish dish would wake up and carry at least wnet in hd as there ota signal reliablity is horrible.

Sounds like you have multipath problems to me.

 

[kstuart]

I just emailed them to ask. I see no reason for them to do that if they are using 2nd gen encoders for their transmitter. With the new encoders they can do 1080i at 12mb on the HD and 480i at 3 mb on the 3 SD channels and still have room for a data feed. The 2nd gen encoders have VBR so that it can shift the bits from the 4 diff feeds to give a good picture.

Uh 12 + 3x3 = 21 , not 18.

I hope you are not one of these people who thinks that the resolution is the same as the picture quality. Sure, if you have 40M like on a blu-ray disc, then 1080 is always going to look better than 720.

But when your bitrate is less than optimal, 720 is going to make better use of the limited number of bits.

A frame of 1920x1080 = 2073600

A frame of 1280x720 = 921600, which is 44% of 2073600

So, in general, you get the same PQ (in terms of artifacts, blurring and blocking) with 44% of the bitrate if you use 720 instead of 1080.

Now that is an oversimplification (and I have not got into interlacing - " i " ), but in a nation where the majority of HD sets are still native 720p (even when they "accept" 1080), then broadcasting 720p is preferable if you are going to have subchannels that use up some of the bandwidth.

 

[whatchel1]

VBR

Uh 12 + 3x3 = 21 , not 18.

I hope you are not one of these people who thinks that the resolution is the same as the picture quality. Sure, if you have 40M like on a blu-ray disc, then 1080 is always going to look better than 720.

But when your bitrate is less than optimal, 720 is going to make better use of the limited number of bits.

A frame of 1920x1080 = 2073600

A frame of 1280x720 = 921600, which is 44% of 2073600

So, in general, you get the same PQ (in terms of artifacts, blurring and blocking) with 44% of the bitrate if you use 720 instead of 1080.

Now that is an oversimplification (and I have not got into interlacing - " i " ), but in a nation where the majority of HD sets are still native 720p (even when they "accept" 1080), then broadcasting 720p is preferable if you are going to have subchannels that use up some of the bandwidth.

You are not using VBR in your formula. What happens w/ Variable Bit Rate you assign it as if there are more bits available than there really are. Then it shifts bits between the 4 with adaptive delta prediction. So it is 12 3 x3. Then it constantly shifts it to give the best for all PQ. As far as 720p I do prefer 1080i over 720p. When using VBR you give it the max that it can use then let the system move the bits to which ever needs it at the time. Now you are correct with the 1st gen encoder you would have to divide the 19 (not 18) that is used in a different way. Now If it were Fox or ABC it's a different story. I don't like the down converting of the PBS feeds down to 720p. I just don't like down conversion.I also hope to see the OTA's allowed in the next few years to be able to shift to the use of MPEG4 since the 2nd gen encoders we installed are capable of transmitting in that standard.

 

[bobvick]

What I wonder about is why Dish is offering HD in some smaller markets and not in the larger ones. For example, I am in the Birmingham DMA (40) and Dish does not have WBIQ in HD, but they have WMAE in HD which is the PBS station for Columbus-Tupelo, MS DMA (133) which is just to the west of me.

 

[kstuart]

What I wonder about is why Dish is offering HD in some smaller markets and not in the larger ones.

Two reasons:

1 - In general, the larger markets have multiple PBS HD channels (SF Bay Area has 4, IIRC), which requires more bandwidth and spot beam space.

2 - For years, Dish has uplinked smaller markets while larger markets were still missing. This is usually because of negotiations where the larger market channels think they are in a position to ask for more money than anyone else.