4 digit channel number and cable cards

[bigguy126]

Verizon has annouced that they are going to 4 digit channel numbers on their music channels. Can cable cards handle those?

[GiantsFan24]

Verizon has annouced that they are going to 4 digit channel numbers on their music channels. Can cable cards handle those?

Yes. My cableco (Oceanic Time Warner) has been using 4-digit channels for almost a year. No problem for the cablecards.

[AbMagFab]

Yes. My cableco (Oceanic Time Warner) has been using 4-digit channels for almost a year. No problem for the cablecards.

Anyone who isn't on an island that can bend space-and-time able to use 4-digit channels?

[OneGr8Mick]

In southwest MI Comcast I get signals for locals on 1300 and something I never use them but they show up in the guide and can be tuned.

[cableguy763]

Austin uses a lot of channels with four digit channel numbers just fine.

[Darthnice]

Anyone who isn't on an island that can bend space-and-time able to use 4-digit channels?

Is that a joke? I'm lost.

[fdeezle]

Is that a joke? I'm lost.

too funny

[wmcbrine]

I don't know where this notion arose that CableCards can only handle 0-999, but I've never seen anything like an authoritative source for it -- just people citing the apparent inability of their own particular models of TV. Even that may just be a sign of the sets adapting to three-digit entry when four-digit isn't required (because all the channels on the system fall within the three-digit range).

[hmm52]

It's not the cablecards. It's the devices they're in and it depends on which side of a decimal point you're talking about. I don't believe the Sony DVRs I have will tune to channels with 4 digits to the left. They will however tune channels clearQAM with 4-5 digits to the right (as long as there aren't other challenges). The S3 won't tune any clearQAMs with more than 2 digits to the right, meaning the TiVo gets a perfect zero in clearQAM from Phila. Verizon Home Office.

[astrohip]

My cableco (Oceanic Time Warner)

Anyone who isn't on an island that can bend space-and-time able to use 4-digit channels?

Is that a joke? I'm lost.

Oceanic. LOST.

[sfhub]

It's not the cablecards. It's the devices they're in and it depends on which side of a decimal point you're talking about. I don't believe the Sony DVRs I have will tune to channels with 4 digits to the left. They will however tune channels clearQAM with 4-5 digits to the right (as long as there aren't other challenges). The S3 won't tune any clearQAMs with more than 2 digits to the right, meaning the TiVo gets a perfect zero in clearQAM from Phila. Verizon Home Office.
For Terrestrial PSIP major.minor, major is limited to 1-99, minor is limited to 0-999 (major is a 10-bit field, minor is a 10-bit field) Channels must be two-part. If service_type is analog, minor must be set to 0. If service_type is ATSC digital television or ATSC audio only, minor is limited to 1-99. For other types of service, minor is limited to 1-999.

For Cable PSIP major.minor, major and minor are limited to under 1000 (major is a 10-bit field, minor is a 10-bit field). If it is just major (one-part channel #) then it can be 0-16383

CableCARDs do not use PSIP. The channel # for CableCARDs is a 12-bit field and is limited to the range from 0-4095.

This is what the specifications say. Your individual device could of course have bugs or have implemented the specs loosely so behavior could be different.

[jrm01]

Last year my local Comcast changed in-the-clear QAM to odd channel numbering. For instance, the local CBS channel (HD) showed as 73.2301 on my Mits, 73.230 on my Panasonic and 73.23 on Tivo HD. Fox was 73.2304 and showed up that way on Mits, but couldn't be found by Panny or TiVo.

Luckily, after many complaints and meetings with Franchise Authority we got them to change back to 2.1 format.

[sfhub]

Last year my local Comcast changed in-the-clear QAM to odd channel numbering. For instance, the local CBS channel (HD) showed as 73.2301 on my Mits, 73.230 on my Panasonic and 73.23 on Tivo HD. Fox was 73.2304 and showed up that way on Mits, but couldn't be found by Panny or TiVo.IMO 73.2301, 73.230, and 73.23 are not channel map #s at all. Rather they are implementation dependent counting methods squashed onto channel processing/display routines which use assumptions based on PSIP standards. So Comcast didn't change the channel number per se, rather they dropped PSIP channel mapping info and your devices defaulted to failsafe counting methods.

If the channel has PSIP, the #s are limited to what is in the specs, which wouldn't allow for a 4 digit subchannel. The subchannel field is limited to 10-bits in the PSIP specs and is limited to #s < 1000 (or 3-digit #s). Even if there was a liberal interpretation of the specs, 10-bits couldn't represent more than 1024 unique values and 2301 is unlikely to be represented by the 10-bits.

In the *absence* of PSIP (or CableCARD channel maps), the device still needs some way of referring to the channel and program. I have seen 2 methods devices have chosen to deal with this situation when no channel map data is available.

the major # (left of decimal point) is the actual RF channel # (for both methods)
the minor # (right of decimal point) has 2 variations of counting methods as detailed below

For background, each stream has PMT/PID info. This includes the PID and a program_number (16-bit value)

1) Some implementations choose to use the "Program #" as the minor channel #. In the case of .2301 and .2304, that is what is being used.

2) Other implementations, like the one used by my Sharp TV, sort all the streams based on the PID then assign user friendly #s starting from 1. The advantage of this method is even if the program #s are very large, the user only sees the actual # of programs, usually < 99. It has the disadvantage that PMT/PID info in some cases changes more often than program_number.

This is all irrelevant when PSIP (or CableCARD) channel map info is present because that will override any implementation dependent counting methods.

This is a capture of PMT/PID and program_number information from my cable system (modified to illustrate your example). I describe the 2 different counting methods and how they come up with different #s.


Method #1 - use Program # as subchannel
PAT Version Number: 2
Transport Stream ID: 10242 (0x2802)

73.1 - PMT PID 54 (0x0036) - Program 1
73.2 - PMT PID 55 (0x0037) - Program 2
73.3 - PMT PID 48 (0x0030) - Program 3
73.2301 - PMT PID 53 (0x0035) - Program 2301
73.2304 - PMT PID 52 (0x0034) - Program 2304

Method #2 - sort by PID, assign user friendly subchannel # starting from 1
PAT Version Number: 2
Transport Stream ID: 10242 (0x2802)

73.1 - PMT PID 48 (0x0030) - Program 3
73.2 - PMT PID 52 (0x0034) - Program 2304
73.3 - PMT PID 53 (0x0035) - Program 2301
73.4 - PMT PID 54 (0x0036) - Program 1
73.5 - PMT PID 55 (0x0037) - Program 2


You are wondering then why do the Mits, Pana, and TiVo display different #s? They are all using the same counting method to assign the minor #, yet they each show different channel #s.

a) Mitsubishi channel processing/display routines are doing the right thing. The TV's implementation chose to use the program # as the minor #. The program #, being a 16-digit value, can go up to 5 digits. I don't know if the Mistubishi would do the right thing with 5 digit program #s, but it is doing the right thing with 4 digit #s and displaying the entire #.

b) Panasonic channel processing/display routines are doing the wrong thing, truncating the last digit. The likely cause of this is because the cable PSIP specs specify subchannel #s only up to 3 digits (< 1000) and the channel processing/display routines made the assumption the most they would ever need to handle is 3 digits, so when they encounter a 4 digit #, the last digit gets truncated. The assumption they made is incorrect, because, in the absence of PSIP data, they chose to use the program #, which can be up to 5 digits.

c) TiVo HD channel processing/display routines are doing the wrong thing, truncating the last 2 digits. The likely cause of this is because TiVo is using Terrestrial PSIP rules where the minor # is limited to 1-99 for ATSC video/audio programming. This is the wrong thing on multiple accounts. First, TiVo should be using Cable PSIP rules (instead of Terrestrial PSIP rules) where the minor # is limited to < 1000. So TiVo should at least have been able to handle 3 digits. The second reason they are not doing the right thing is because, just as with the Panasonic device, TiVo chose to use the Program # as the minor # and since this can be up to 5 digits, they should have had channel processing/display routines that could handle up to 5 digits.


Luckily, after many complaints and meetings with Franchise Authority we got them to change back to 2.1 format.
When you got them to change it back to 2.1, they didn't actually change the channel format. They added back the missing PSIP information, which then caused your devices to override their failsafe numbering method and use standard PSIP processing rules.

[jrm01]

sfhub,

Thanks for the great recap. The complaint that I filed and the argument that I made with Comcast was that they should provide proper PSIP and map the channel numbers to OTA-equivalent. I guess you're saying that the second request was redundant. I actually tried them to map to the cable channel numbers, but they refused.

In any case, I'm just glad they got it back to normal (or at least what I percive to be normal).

Now when TiVo provides clear-QAM support (just dreaming) I'll be ready.

[hmm52]

IMO 73.2301, 73.230, and 73.23 are not channel map #s at all. Rather they are implementation dependent counting algorithms squashed onto channel processing/display routines that made assumptions based on PSIP standards. So Comcast didn't change the channel number per se, rather they dropped PSIP channel mapping info and your devices defaulted to failsafe counting algorithms.

....

c) TiVo HD channel processing/display routines are doing the wrong thing, truncating the last 2 digits. The likely cause of this is because TiVo is using Terrestrial PSIP rules where the minor # is limited to 1-99 for ATSC video/audio programming. This is the wrong thing on multiple accounts. First, TiVo should be using Cable PSIP rules (instead of Terrestrial PSIP rules) where the minor # is limited to < 1000. So TiVo should at least have been able to handle 3 digits. The second reason they are not doing the right thing is because, just as with the Panasonic device, TiVo chose to use the Program # as the minor # and since this can be up to 5 digits, they should have had channel processing/display routines that could handle up to 5 digits.

I'm still a good distance from understanding all this, but thanks much for the tutorial. I was incorrect in my last post as the clearQAM channels seen from Phila. VHO range from 63.2 to 128.12845. Most of the SDs are 2 digit major, 2 digit minor; music channels 2 & 3 mostly. The Lg receiver tunes all and displays channels the same as the 3 Sony devices do. For whatever reason (I still haven't finished with the Broadband Reports thread) the Sonys will not pick up the local HDs in a channel scan, nor accept direct input for same; They are in the range 71.140, 71.141, 73.145, 73.146, 73.147 and so on. I don't recall where they were before November. (cablecards used except while testing). No problems for the Sonys with anything else.

The S3 picks up nothing clearQAM from Phila. VHO, only converted analogs, nor responds successfully to direct input for any channels. My questions are why would TiVo use Terrestrial PSIP rules and why did they provide such feeble support for clearQAM? The 3 Sonys were built late in '05; the LG receiver in '03 or '04, I think. The S3 was introduced late in '06. As I've mentioned before, there's something peculiar still going on at VHO8 - local HDs - but that's a separate issue.

[sfhub]

My questions are why would TiVo use Terrestrial PSIP rules and why did they provide such feeble support for clearQAM?
Most likely because they shared the channel processing code either not realizing the rules are slightly different for cable PSIP (and when using the program_number as the subchannel #) or knowing they were slightly different but it didn't matter to them because they expected most users to use CableCARD.

Just to be clear, 73.2301 and 73.2304 are *not* PSIP channel maps. There is likely some code in TiVo that parses and processes PSIP to get a channel # major.minor. This code is not being used to retrieve .2301 and .2304 and is instead is being replaced by code that generates the channel # from the RF channel # and program_number as the subchannel.

There is some other code that displays the channel #, allows channel # input, etc. This is the section of code I'm guessing is being shared and is the section of code that makes assumptions as to the # of digits a subchannel can be.

In OPs case, I think it could be more a display problem than an internal representation problem because the original poster was able to tune the channels. Classic symptoms of a display problem with proper internal representation is ability to ch+/- to see the channel, but not being able to directly input the major.minor channel #.

[Darthnice]

Oceanic. LOST.

The others might understand that explanation.

fdeezle may be able to explain it as well since he really seems to get it.

[AbMagFab]

Okay, easier question -

Anyone with a Tivo S3/Tivo HD that can tune to 4-digit cable-card channels? It seems yes, but we got sidetracked by a theoretical/specification discussion.

Thanks!

[moyekj]

Okay, easier question -

Anyone with a Tivo S3/Tivo HD that can tune to 4-digit cable-card channels? It seems yes, but we got sidetracked by a theoretical/specification discussion.

Thanks! Yes, there used to be VOD channels numbered 1001 to 1080 in my digital lineup that I could direct tune by punching in the 4 digit channel number. (with a fairly recent channel map update those VOD channels dissapeared)

[cableguy763]

Okay, easier question -

Anyone with a Tivo S3/Tivo HD that can tune to 4-digit cable-card channels? It seems yes, but we got sidetracked by a theoretical/specification discussion.

Thanks!
Yes. All of Austin's local HD's are in the 1500's. Tuneable with cablecards and without cablecards through clear QAM (with guide data as well :)).

[AbMagFab]

Yes. All of Austin's local HD's are in the 1500's. Tuneable with cablecards and without cablecards through clear QAM (with guide data as well :)).

Through your TivoHD/S3? Thanks!