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Mythtv + Comcast Digital Cable, SD problems...

Posted: Wed May 13, 2009 3:09 am
by mrdek11
Hi there! My name is Derek and I'm located in 84037, Utah, USA.

I'm running MythTV on Ubuntu Jaunty using a Hauppauge WinTV HVR-1600 tuner card. This card has an ATSC analog side and a digital (QAM-256) side.
Comcast Digital Cable isn't fully digital. Channels 1-99 are actually broadcast analog, and generally converted by the cable box to digital. Therefore, I've been forced to use both sides of the tuner card, one for my local HD (as well as a few others, such as History) through Comcast, and one for channels 1-99.
The ATSC (analog) side of the card works fantastically with SD (I used the Comcast standard (non digital) lineup). I was able to get all of the channels broadcast on this side fetched using SD, and the guide data has been flawless since.
However, the Digital side of the card is not working quite as well.
I tried setting up SD through MythTV on this side of the card the same way I did with the ATSC side, but using the Comcast Digital lineup in my area. Everything seemed to work fine, until I clicked the "Fetch Channels from listings Source" button. It did nothing. (When I had done it on the ATSC side, it hung for a few moments).
To double check, I checked the channel list, and, sure enough, there were no channels listed on this side of the card.

As an alternative, I scanned this side of the card manually (Cable IRC High, QAM-256) using MythTV. It found a number of channels, but only 5 had Call names, and none had XMLTV ids. I went through a number of the channels, and fixed the Call names, XMLTV ids, Channel names, and changed the Channel numbers to what they are when the cable is plugged directly into my TV. (KSL 5, KSLDT 5.1, etc)

After running mythfilldatabase, I find that the guide data on these channels (everything on the digital, QAM-256 side of the card) is still empty.

I have the Digital (QAM-256) side of the card configured as follows:

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Card Type: DVB DTV capture card (v3.x)
DVB Device Number: 0
Frontend ID: Samsung S5H1409 QAM/ Subtype: ATSC
Signal Timeout: 3000
Tuning Timeout: 5500
The Digital "Video source" is configured as follows:

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Video Source name: Digital
Listings Grabber: North America ( (Internal)
User ID: mrdek11
Password: **********
Data Direct Lineup: UT43414:X [This shows a full name, including Comcast Digital Cable, when I configure, but reverts to this upon reloading the page.]
Perform EIT Scan: [ ] [unchecked]
Channel Frequency Table: us-cable-irc
My Input Connection on this side of the card shows up as:

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[ DVB : 0 ] (DVBInput) -> Digital
and is configured as follows:

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Capture Device: [ DVB : 0 ]
Input: DVBInput
Display Name: Digital
Video Source: Digital
Use quick tuning: Live TV only
Unencrypted Channels only: [x] [checked]
Allow Audio only Channels: [x] [checked]   Use DishNet Longer-term EIT Data: [ ] [unchecked]

[update] While posting this, I read that I should try

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mythfilldatabase --refresh-all
This seems to have done the trick for the channels I was able to identify. There are still about 20 channels listed simply as "UNKNOWN83#9", "UNKNOWN83#10", "UNKNOWN83#11", etc.[/update]

If anybody has any ideas, I'd really appreciate any help I can get.

Thanks so much for this great service,

[edit] I went through and was able to get most of those UNKNOWN channels working, now, but some seemed to be duplicates of other channels, and overall it was very hard to configure. I plan on getting another of the same card to maximize recording, but I don't want to do this all again. How can I do it automatically?


Re: Mythtv + Comcast Digital Cable, SD problems...

Posted: Wed May 13, 2009 4:07 pm
by rmeden
You're a little confused First let's start with some terminology.

ATSC is not analog. It is a digital format used for "over the air" broadcast transmissions. NTSC is the name of the analog format.

QAM is the name of the digital format used by cable companies. QAM output is usually encrypted. if it is encrypted, it has to be decoded by a "cable box" or "cablecard" in a PC. There are also usually some unencrypted stations called "Clear QAM".

Your cable box does not convert anything to digital (unless it has a digital output, but let's not go there). You cable box decodes analog NTSC and digital QAM and sends it to your TV (usually analog). It uses "friendly" channel numbers. Often the cable box substitutes a QAM signal for a channel in the 1-99 range, even if it is also available analog. You have no way to know what it's really doing.

Your HVR-1600 has an analog NTSC tuner and a digital ATSC/QAM tuner.

What's working correctly is not ATSC, but the analog NTSC tuner.

You're having trouble mapping the QAM tuning information to MythTV. Unfortunately, the cable companies will not allow Tribune to provide QAM tuning information, so our data feed can't include it right now. If you manually configure it, you'll only be able to receive open-QAM signals, which are usually a subset of the analog lineup.

I suggest you hook the *analog* port of the HVR-1600 to the cable box and set up a IR Blaster to allow your MythTV box to change channels. This will be able to receive all the stations you're paying for.

You can also manually configure the digital side for the clear-QAM stations you can find. You can get a list of the XMLIDs via a "lineup report" on the "My account" page on the SD web site. You can guess QAM tuning info (which sometimes changes) via the Hauppage web page, or trial and error. There probably won't be a lot of them.


Re: Mythtv + Comcast Digital Cable, SD problems...

Posted: Sun Jun 07, 2009 11:41 am
by slim
You can also Connect & change channels by Firewire if you use the Motorola 6200 cable box. This won't do Scrabbled channels but you will able to do HD & SD channels (including local) if they are not Premium (scrabbled) channels.

See the Myth sites for help on this.