Questions on Comcast conversion from Anlg to Dig

[JoeMSG]

I have had Comcast Extended (? one step above Basic, not digital) service for a number of years. I have one HDTV tuner, one analog PVR, and an analog TV. Comcast has supposedly "upgraded" the San Francisco Peninsula to digital. I have received their digital conversion boxes, but have not hooked them up or activated them. My HDTV shows analog channels from 2 to 33. It also shows a large variety of digital channels with channel numbers that differ from their published ones. I also get Higher Definition for a number of local channels on strange channel numbers.

I don't want to run my PVR through Comcast's converter box. I can use its programming capability to record programs that come through on the analog channels. I do want to use Comcast's box on the analog TV to get the other channels. I don't know about using the box on the HDTV.

1) Is Comcast expected to "drop the other shoe" and cut off the remaining analog signals?

2) I have not activated the Comcast boxes. If I do activate a box and connect it to my analog TV, will Comcast do something to my feed that prevents my PVR from seeing the analog channels or prevents my HDTV from seeing all the channels that it currently sees? An other way of putting this is do all of the receivers need to go through the Comcast boxes once I activate?

3) My HDTV shows a noticably poorer image on 720 and 1080i HD than it does for Blu-ray DVDs. People often look like they are using gobs of pancake makeup (in Photoshop I would liken this to edge sharpening with surface blur). Is this a characteristic of the program source or is Comcast playing games to reduce the bandwidth of its "HD" channels?

I am a new member and to do not recognize many of the abbreviations that the cognoscenti use here. Please be gentle.

Thanks,

Joe

 

[meinename]

Sorry if I'm unclear but this is going to hurt.

I have had Comcast Extended (? one step above Basic, not digital) service for a number of years. I have one HDTV tuner, one analog PVR, and an analog TV.

From reading further, your HDTV seems to have a QAM tuner. This is good and you already seem to know how to use it.
Right or wrong, to make it easy I give the flawed analogy:
CATV=QAM and ATSC=Antenna
Comcast here in Portland changes the QAM lineup when it suits them, anywhere from 2-9 months. They don't support you watching through your QAM tuner and you should not expect any support that way.

Comcast has supposedly "upgraded" the San Francisco Peninsula to digital. I have received their digital conversion boxes, but have not hooked them up or activated them. My HDTV shows analog channels from 2 to 33.

These I assume are the Basic tier channels. Public Access, C-SPAN, Locals, Discovery, Shopping Channels

It also shows a large variety of digital channels with channel numbers that differ from their published ones. I also get Higher Definition for a number of local channels on strange channel numbers.

These would be the QAM channels

I don't want to run my PVR through Comcast's converter box. I can use its programming capability to record programs that come through on the analog channels. I do want to use Comcast's box on the analog TV to get the other channels. I don't know about using the box on the HDTV.

You seem to have it figured out except on the HDTV :up

1) Is Comcast expected to "drop the other shoe" and cut off the remaining analog signals?

No time frame has been given. When they shut off 33-71 here, we had 2 months warning. You should know ahead of time.

2) I have not activated the Comcast boxes. If I do activate a box and connect it to my analog TV, will Comcast do something to my feed that prevents my PVR from seeing the analog channels or prevents my HDTV from seeing all the channels that it currently sees? An other way of putting this is do all of the receivers need to go through the Comcast boxes once I activate?

2 parts to that question.
The first part on the analog PVR:
The Comcast boxes DO NOT PASS-THROUGH the signal when in standby or off.
If you want to keep using the PVR on 2-33, don't bother hooking the cable box in between the wall and the PVR.

Part 2 on the HDTV:
I would get an HD box if they don't cost extra. If that's not the case, the options are ugly. I used a Standard Definition Motorola DCT-something via the composite cables for a while with a high-grade splitter that I got from a Comcast technician. I ran one cable to the TV and the other to the Cable box.
That would let you watch the Clear-QAM SD and HD via the TV tuner and still watch other stuff as well via the Cable box.

3) My HDTV shows a noticably poorer image on 720 and 1080i HD than it does for Blu-ray DVDs. People often look like they are using gobs of pancake makeup (in Photoshop I would liken this to edge sharpening with surface blur). Is this a characteristic of the program source or is Comcast playing games to reduce the bandwidth of its "HD" channels?

If the channel is available via an antenna, then by FCC mandate, it is the source.
Cable companies are barred from re-compressing the Over-The-Air channels on their cable systems.
Now as for all the cable channels, both the source and the cable company are to blame.

Here is where it gets technical, so I'll try to keep it simple.
What you need to take away from all the numbers is that they are sending a squeezed picture and having the cable box re-stretch it to 4x3 or 16x9 Aspect Ratio
Simply they are sending the following:

Almost EVERY digital SD channel on the Comcast system here is 512x480i
Analog TV, DVD and my OTA SD channels are 704x480i
720p OTA is 1280x720p
1080i OTA is 1920x1080i
Comcast HD is 3 formats I've seen. All are flagged widescreen.
1440x1080i
1920x1080i
1280x720p

Now the SD boxes will only put out 704x480i
512x480i => 704x480i
1280x720p => 1280x720p
1440x1080i => 1920x1080i
1920x1080i => 1920x1080i

Now I haven't even covered bitrates, and that's where it gets really bad.
This is how much information (I think of color) is allowed per picture.

Comcast SD here is 1.5 Megabits-per-second to 3 Megabits-per-second
Analog TV is generally recorded to a Hard Disk at 4Mbps
DVD has maximum video bitrate of 8 Mbps
Blu-ray supports a maximum video bitrate of 40 Mbps but nothing so far has gone above 25 Mbps last I checked
OTA HD can vary from 9 Mbps to 15 Mbps (ATSC supports a Max of 18 Mbps)
Cable HD channels I've seen vary from 7.5 to 15Mbps

What amount is minimum is an eye-of-the-beholder, Personally:
1080i still-shots with little-to-no-movement are fine with 11Mbps
1080i with movement need more than 15Mbps
720p needs everything it can get. 12Mbps
480i needs a minimum of 3Mbps for everything to look about new VHS quality

Mind you I like to be able to READ what is on screen even if it is only there for a second. That is where my standard is set.
I can't read what is on Comcast SD unless the letter/sign/note is on screen for more than 2 seconds in the center.

I am a new member and to do not recognize many of the abbreviations that the cognoscenti use here. Please be gentle.

Thanks,

Joe

Now some details I've glossed on but I hope this helps.

Please ask if there is anything more!

 

[bicker]

I think meinename answered all of your questions; I thought I'd just try to clarify some items...

1) Is Comcast expected to "drop the other shoe" and cut off the remaining analog signals?

Not before 2012. There was a general feeling that they and other legacy service providers would continue providing some analog after that, but that sentiment has been waning as it becomes obvious that newer service providers have no intention of doing so (some already having dropped analog completely).

I keep on forgetting how they're figuring the exact date in 2012; I think the date is either 2/17/12, 6/12/12, or 12/31/12, but don't quote me on that. Also, that's just the date in 2012 when they might start getting rid of the local over-the-air broadcast channels via analog... they might not do it on the applicable date, but rather sometime after the applicable date.

2) I have not activated the Comcast boxes. If I do activate a box and connect it to my analog TV, will Comcast do something to my feed that prevents my PVR from seeing the analog channels or prevents my HDTV from seeing all the channels that it currently sees?

Not as a direct consequence. If they are to do anything along those lines, they're going to do it regardless of what you do.

An other way of putting this is do all of the receivers need to go through the Comcast boxes once I activate?

No.

3) My HDTV shows a noticably poorer image on 720 and 1080i HD than it does for Blu-ray DVDs. People often look like they are using gobs of pancake makeup (in Photoshop I would liken this to edge sharpening with surface blur). Is this a characteristic of the program source or is Comcast playing games to reduce the bandwidth of its "HD" channels?

Generally, you only see this on cable channels. There is only a limited amount of bandwidth but a practically unlimited amount of consumer desire for more HD channels. How do you fit what is effectively 1200 MHz of data in a 750 MHz pipe? There is no way to do that other than to use compression. For folks who would rather have fewer channels but each one full bitrate, that sucks, but the problem is that there are so many more of "them" (people who reward service providers for providing more and more and more channels, without much regard for how compression affects picture quality).

 

[JoeMSG]

Thanks, meinename. I appreciate your help.

You seem to have it figured out except on the HDTV :up

No time frame has been given. When they shut off 33-71 here, we had 2 months warning. You should know ahead of time.

Actually, I think I have the best handle on the HDTV QAM tuner. They have already cut off 34 and up on analog. My other shoe reference was asking about dropping the analog on 2-33. If Bicker is right, that seems to be coming in 2012 or so.

If you want to keep using the PVR on 2-33, don't bother hooking the cable box in between the wall and the PVR.

I understand and did not plan to put a box in that path. My main concern was that an activation of the box would change the feed from Comcast in some way that made it impossible to use a receiver without a cable box. It appears that the activation will not change anything for PVRs and tuners that do not have a cable box in their input path. My understanding is that I will be able to use a QAM tuner directly hooked to the cable feed to get everything after the box activation with some caveats: 1) Weird and possibly slowly varying channel numbers; 2) no "on demand"; and 3) no scrambled stuff like the premium channels.

If the channel is available via an antenna, then by FCC mandate, it is the source.
Cable companies are barred from re-compressing the Over-The-Air channels on their cable systems.
Now as for all the cable channels, both the source and the cable company are to blame.

This is a little off topic, but does that mean the the feed for over-the-air channels will have the same quality for both cable and satellite (future decision)?

Here is where it gets technical, so I'll try to keep it simple.

I expressed myself poorly. Technical is OK. The abbreviations are strange.

What you need to take away from all the numbers is that they are sending a squeezed picture and having the cable box re-stretch it to 4x3 or 16x9 Aspect Ratio. ...

This is news. Are you saying they are sending a squeezed picture (my read is something like 1280 horizontal for an 1920 image) or are they sending a picture compressed with a lossy compresion technique. The 1440x1080i signal was not something I was aware of.

There is not much I can do about it. My underlying concern is if I should expect differentces in this area between Comcast and satellite competitors.

Now I haven't even covered bitrates, and that's where it gets really bad.

This is news. My guess was that they handled the bitrate constraint with lossy compression. I was thinking more in terms of static images or images changing at a constant rate. I did not think about manipulating the frame change rates. Do they vary compression so that highly/quickly changing frames are more lossy?

Joe

 

[JoeMSG]

Thanks Bicker. Between you and meinename I have learned a lot.

...Not before 2012.

...Not as a direct consequence. If they are to do anything along those lines, they're going to do it regardless of what you do.

I was concerned that the rest of the analog will not disappear as a second step in the 2009 conversion. It makes sense that it will go away some time.

Generally, you only see this on cable channels. There is only a limited amount of bandwidth but a practically unlimited amount of consumer desire for more HD channels.

My underlying concern is whether this is different between Comcast and competitive satellite services.

 

[bicker]

If Bicker is right, that seems to be coming in 2012 or so.

Just adding some details to this: Legacy providers (like Comcast) have committed (voluntarily) to keep local over-the-air broadcast channels available via analog until sometime in 2012, at least. Some other suppliers, such as RCN, have already taken them away.

Regardless: If any are provided as analog, they all must be.

My main concern was that an activation of the box would change the feed from Comcast in some way that made it impossible to use a receiver without a cable box. It appears that the activation will not change anything for PVRs and tuners that do not have a cable box in their input path.

It is important to understand this from the other direction: Everything a video service distributor does, these days, is aimed away from having to make physical changes to customize the service delivered to each individual subscriber. The objective is to get all service variations between subscribers to be handled via software. That's not the case everywhere yet, but that is the direction.

My understanding is that I will be able to use a QAM tuner directly hooked to the cable feed to get everything after the box activation with some caveats: 1) Weird and possibly slowly varying channel numbers; 2) no "on demand"; and 3) no scrambled stuff like the premium channels.

Encryption can, and probably eventually will, be applied to any programming, except for the local over-the-air broadcast channels. (Cablevision has even petitioned the FCC for permission to encrypt those channels, though I hope that'll get rejected.)

This is a little off topic, but does that mean the the feed for over-the-air channels will have the same quality for both cable and satellite (future decision)?

I'm not sure I know exactly what you mean, but I think the answer is yes.

There is not much I can do about it. My underlying concern is if I should expect differentces in this area between Comcast and satellite competitors.

There are always going to be differences between suppliers. The absence of differences would prompt me to suspect illegal collusion. However, there is nothing about the technology that necessarily means one will be better and less expensive than the other. Except this: Cable can support two-way services natively, while satellite requires (usually cable) Internet to provide the return loop on two-way services. That has ramifications. Also, older cable systems tend to have less bandwidth available in total (but that's just a matter of upgrading the facilities).

 

[meinename]

Thanks, meinename. I appreciate your help.

Actually, I think I have the best handle on the HDTV QAM tuner. They have already cut off 34 and up on analog. My other shoe reference was asking about dropping the analog on 2-33. If Bicker is right, that seems to be coming in 2012 or so.

2010 and 2012 are the major expiration years but I can't keep straight which rules expired when right now.

I understand and did not plan to put a box in that path. My main concern was that an activation of the box would change the feed from Comcast in some way that made it impossible to use a receiver without a cable box. It appears that the activation will not change anything for PVRs and tuners that do not have a cable box in their input path. My understanding is that I will be able to use a QAM tuner directly hooked to the cable feed to get everything after the box activation with some caveats: 1) Weird and possibly slowly varying channel numbers; 2) no "on demand"; and 3) no scrambled stuff like the premium channels.

This is a little off topic, but does that mean the the feed for over-the-air channels will have the same quality for both cable and satellite (future decision)?

The only promise/rule I read applied to cable companies. Something to the effect that the OTA stations and the satellite companies already agree on bitrate during carriage negotiations.
Yet cable companies were sending an unaltered analog broadcast of the OTA stations, So the OTA stations wanted an FCC rule stating that the cable compaines CAN NOT alter the broadcast audio and video sent to the cable company.
The fear was that the cable companies were going to compress everything down, giving cable viewers the impression that the OTA channels looking just as bad to dissuade "basic-only" customers from ditching cable and going antenna-only

Now the cable co needs to alter some "tags" in the datastream so that your QAM tuner doesn't get confused by ATSC info on a QAM channel (this is a good thing) and is allowed.
Unfortunately here, that means guide data is lost in the process.

I expressed myself poorly. Technical is OK. The abbreviations are strange.

This is news. Are you saying they are sending a squeezed picture (my read is something like 1280 horizontal for an 1920 image) or are they sending a picture compressed with a lossy compresion technique. The 1440x1080i signal was not something I was aware of.

Sorry to muddle this, but I want to be a bit more clear. Some stuff like PalladiaHD is shot at 1440x1080i.
However everything in the shot is already 16x9 Aspect Ratio
A trick from DVD's is the Widescreen vs. fullscreen.
Both editions are 720x480.
In the widescreen edition everything is skinny until the DVD player stretches it out, and letterboxes it or crops it off at your preference. The video is square pixels streachedby the DVD player to rectangular pixels.
In the fullscreen edition, the extra edges are lost to the purchaser. The video stored is rectangular pixels.

How does this apply to Dish/Cable?
The HD picture size of 1440x1080i can be those square pixels ready to be expanded to rectangular pixels.
The Dish/Cable companies are taking that already expanded picture and squishing it again, while applying tirck on the set-top boxes to make it not so obvious.
Usually softening.

There is not much I can do about it. My underlying concern is if I should expect differences in this area between Comcast and satellite competitors.

The satellite providers are well known for their compression and squeezed picture.
Dish and Direct will sell you their HD at 1280x1080i at 10Mbps. Hence the nickname HD-lite. Well back then it was 1440x1080i at 12Mbps...
I say I get better HD out of the Comcast cable I have here in Portland vs. Dish Network or DirecTV.
Remember, cable providers under the same company name vary from area to area in "how bad things are" on each channel

This is news. My guess was that they handled the bitrate constraint with lossy compression. I was thinking more in terms of static images or images changing at a constant rate. I did not think about manipulating the frame change rates. Do they vary compression so that highly/quickly changing frames are more lossy?

Not so much "lossy compression" as "transcoding"
They take the source channel and make a new A/V stream at their requirements.
Mostly chucking Picture data out via softening and "losing" color data (there is a name for removing colors, but I can't remember it).
Numbers again:
Source =transcoded=> To your cable box
SD 704x480i @ 4Mbps-6Mbps => 512x480i @ 2.5Mbps-3Mbps
HD 1440x1080 @ 12Mbps-15Mbps => 1280x1080i @ 8Mbps-10Mbps
HD 1920x1080i @ 15Mbps-18Mbps => 1440x1080i @ 9Mbps-12Mbps

The gripe with the HD-Pixel-Quality fans is the fact that the companies are reducing the shot and not the studios, who take all the extra time and effort to make it all come out pretty and nice within the given boundaries.
The cable companies run it through a real-time transcoder which focuses on meeting bitrate quotas, no real attention to how it all comes out.

 

[jayn_j]

The satellite providers are well known for their compression and squeezed picture.
Dish and Direct will sell you their HD at 1280x1080i at 10Mbps. Hence the nickname HD-lite. Well back then it was 1440x1080i at 12Mbps...
I say I get better HD out of the Comcast cable I have here in Portland vs. Dish Network or DirecTV.
Remember, cable providers under the same company name vary from area to area in "how bad things are" on each channel.

A good post. Just wanted to bring up the following. My local Comcast has noticably lowered bitrate on the locals. They also lowered the HD channel's bitrates when they went from 2 HD/channel to 3 last year.

Meinename would imply that Comcast is better than satellite in this aspect, but given my local Comcast, I would have to give the edge to DISH right now. As he mentioned, Comcasts vary greatly, and you really need to do some comparison shopping.