Waste of bandwidth?

[wmstar]

Just called cablevision to ask why a number of channels can be found at THREE different locations (e.g. - MSG (71, 716, 1071) ; ESPN (36, 736, 1036), etc.).

There are six channels with three different locations and another handful that appear twice. Seems to me that bandwidth could be used to solve their ongoing switch video problems or to add more content.

Of course, the customer service rep could offer no answers and only said she'd refer my question on to a supervisor. Anybody have any thoughts or insight on this? Thanks.

Bill

 

[meinename]

If you are talking about a digital-only channel, then it is simple- even trivial- to set multiple virtual channel numbers for one actual broadcast.

As an example, the Audio/Video usually is transmitted on one QAM channel. We will say it is on Ch. 80.2 for ESPN and 80.1 for MSG- if you used a Clear QAM tuner.

The Virtual Channel Table (VCT) would say to the cable box for channels 36, 736 and 1036 tune to 80.2
If 736 is English and 1036 is Spanish, the table will have the audio tracks adjusted and the cable box will change automatically.

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If you are talking about how they have it in analog on 36, in digital HD on 736 and um, digital SD on 1036, then yes it is quite the waste.

However, there is a lot of "legacy" equipment in installations holding back a switch to a more efficient systems.

Some places don't have good enough wiring for an all digital system. Analog degrades better to a point.
Old SD digital boxes don't have the capability to down-convert HD to SD, so they need their own digital SD feed.

New Motorola cable boxes tend to cost about $500 by the time they get to the end-user.

All of these things hold back an efficient all-digital system.

Comcast in my area switched to all digital this time last year.
I have no idea how much planning it took to switch close to a million people.
They took 6 months just with getting cable boxes out to the customers.

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Rereading your post, it seems you are on one of Cablevision's Switched Digital Video (SDV) systems. SDV is one of the most bandwidth-efficient systems
http://en.wikipedia.org/wiki/Switched_digital_video
SDV is also one of the most problematic since it requires two-way communication. SDV biggest problem is CLEAN transmissions to and from the cable box as well as expensive equipment to handle the on-demand transmission of different channels.

I would say my first block is your answer to what the "problem" is. As far as they are concerned it is a non-issue.
The extra channel numbers are legacy holdover and they will be removed when they are needed.

 

[wmstar]

Thanks for your response, meinename. I'm not quite sure I understood everything in your post so let me just use ESPN as an example...

a week or so ago Cablevision informed its customers that a number of channels would no longer have a seperate feed for SD and HD. Therefore ESPN - whether you tuned to it on Ch. 36 or 736 - would be the same HD signal. The same applied to the othe sports related channels I mentioned in my earlier post.

So I guess what I'm wondering is why Cablevision is using more than one channel to broadcast the same HD signal. In the case of ESPN why not eliminate the feed on Channel 736 and use that for something entirely different.

Thanks for your interest.

Bill

 

[Mr Tony]

Thanks for your response, meinename. I'm not quite sure I understood everything in your post so let me just use ESPN as an example...

a week or so ago Cablevision informed its customers that a number of channels would no longer have a seperate feed for SD and HD. Therefore ESPN - whether you tuned to it on Ch. 36 or 736 - would be the same HD signal. The same applied to the othe sports related channels I mentioned in my earlier post.

So I guess what I'm wondering is why Cablevision is using more than one channel to broadcast the same HD signal. In the case of ESPN why not eliminate the feed on Channel 736 and use that for something entirely different.

They're not wasting any bandwidth by mirroring it on multiple spots. All they are doing is plugging up a channel. IN the digital world they can use whatever SID (channel) they want.

Where my grandparents live (apt complex) there is a channel that shows the front entrance of the building (controlled entrance). It is on channel 6 if you do not have a cable box and 906 if you do. They dont upload it twice. Its just set on 2 channels

Here is a good example in the sat world. Some states have a state run PBS. Iowa is one of them. No matter where you live in Iowa you get the same PBS

Dish uplinks one channel of Iowa PBS. Depending on which market you are in, it shows on a different channel
If you look at the pic below, PBS shows on
8247
9116
9146
9161
Its not uplinked 4 times. Dish in their computer systems sends the output to SID (channel) 8247 if you live in Mason City, IA. It shows on 9146 if you live in Omaha/Council Bluffs etc

Its one of the advantages of digital. You can uplink it once and then send it out on 2 or 3 channels with no additional bandwidth.

From what you have mentioned above, it sounds like they SAVED bandwidth.
Old way...uplink 2 channels..ESPN SD & ESPN HD
New way...uplink just ESPN HD. When they send out the signal, send it out on 3 channels different ways
analog
digital cropped (the HD feed zoomed)
the legit HD feed