I wish my local comcast headend was simulcasting some of the analog stations. The digital stations produce much clearer pictures and smaller file sizes. Instead I get about 6 TV Guide channels.
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| Comcast QAM tuning data & a question http://forum.linhes.org/viewtopic.php?f=15&t=13902 |
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| Author: | marc.aronson [ Sun Jan 28, 2007 11:18 am ] |
| Post subject: | Comcast QAM tuning data & a question |
I've completed the install of an AirStar-HD5000AV-PCI card for use as a QAM tuner. My service provider is Comcast in the San Francisco Bay Area. I went through the search process and found ~60 tunable channels and posted the results in the mythtv wiki at http://www.mythtv.org/wiki/index.php/Wo ... _-_Comcast in case anyone finds it useful. On to my question: My production box is still R5D1 (0.19). As others have observed, the scan was not able to provide any station identification for the various channels it found. Does this situation improve when scanning with 0.20, or is it truely the case the Comcast is stripping the necessary info? Thanks! Marc |
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| Author: | williammanda [ Sun Jan 28, 2007 1:33 pm ] |
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Review this, it may help. http://www.mythtv.org/wiki/index.php/Ad ... r_channels |
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| Author: | marc.aronson [ Sun Jan 28, 2007 6:32 pm ] |
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williammanda, thank you for the pointer. That is the guide I used to identify the 60 channels I found and properly configure my 0.19 / R5D1 system. My question was really around the improvements made in 0.20. I've done some more experimenting and I suspect the answer is "no" -- 0.20 will not somehow automatically identify the station each channel is associated with. I ran the scanner built into my Samsung HDTV, which has a built in HD tuner, and it was only able to automatically identify the same two channels that atscscan was able to automatically identify, so I suspect the problem is in the signal that Comcast is providing in my area. ie: They are not providing the necessary identification information. Marc |
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| Author: | opel70 [ Mon Jan 29, 2007 1:41 pm ] |
| Post subject: | Re: Comcast QAM tuning data & a question |
marc.aronson wrote: Does this situation improve when scanning with 0.20, or is it truely the case the Comcast is stripping the necessary info? Thanks!
Marc I have done the exact same thing, though using R5E50 (which uses myth .20) . No channel information came along during the scan. It seems that Comcast (contrary to FCC regs from what I have heard) does indeed strip all of the channel metadata from the digital stream. |
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| Author: | marc.aronson [ Sat Feb 03, 2007 6:32 pm ] |
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I'm finding that the quality of the digital version of the standard-defintion channels that Comcast "simulcasts" is significantly better than what I can get from tuning the analogue signal using the PVR-250. I've found most of the digital channels I'm interested in, but there are a few that I just can't seem to find not matter how I run the scan. I've tried "atscscan" with all of the "us cable" configuration files that were released with R5D1 in /usr/local/share/dvb/scan/atsc/. Has anyone using comcast in the San Francisco bay area found the digitial version of the following channels: 37 - TNT (Turner Network TV) 41 - Turner Broadcasting Sytems 42 - USA 43 - MTV 45 - Spike TV 46 - Lifetime 47 - A&E 48 - Bravo 64 - E! Entertainment Television 68 - Sci-Fi Channel Thanks! Marc |
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| Author: | cameraready [ Sat Feb 03, 2007 6:50 pm ] |
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My guess is that those channels are not simulcast in digital. Most of the digital channels on cables systems start in the 70+ range. My local Comcast switches from analog to QAM digital around channel 77. |
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| Author: | spalVl [ Sat Feb 03, 2007 7:00 pm ] |
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Quote: Does this situation improve when scanning with 0.20, or is it truely the case the Comcast is stripping the necessary info? Thanks!
I also just added a digital tuners and went though the channel scan, editing data, figuring out what is what ordeal. I have Comcast I can say hasn't gotten any better in .20 or SVN either, but I don't expect it will. From what I have found Comcast doesn't have to provide the station IDs, they just can't encrypt certain channels. I even called up Comcast customer support to bitch but they are clueless. All the other DVR solutions are dealing with the same issues. I really hope SageTV and MythTV team up to create a zip code database so is easier for new users to get the right info. |
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| Author: | marc.aronson [ Sat Feb 03, 2007 8:06 pm ] |
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Cameraready, you state Quote: My guess is that those channels are not simulcast in digital. Most of the digital channels on cables systems start in the 70+ range
Are you saying that your experience is that none of the analogue channels below analgue channel 70 are simulcast? If so, the situation here is different as I have found 50+ analogue channels simulcast in SD digital including channels 2 through 23, inclusive. SpalVI -- The start of a zip-code-based database that maps frquences to channel numbers is in the mythtv wiki at http://www.mythtv.org/wiki/index.php/Wo ... ble_layout [Note: This post originally had an error in the link that I have now corrected] Marc |
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| Author: | cameraready [ Sun Feb 04, 2007 2:26 pm ] |
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I just set up my HD tuner, so I'm not 100% sure about this. I don't subscribe to digital cable. I just have internet and analog cable. I didn't find any simulcast channels on my local comcast feed, but maybe someone else might know if they simulcast all the analog channels. I was under the impression that none of the analog channels were duplicated in the digital sections. Were all of the simulcast channels using QAM256 or were they under some other format? |
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| Author: | opel70 [ Sun Feb 04, 2007 2:58 pm ] |
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Here in Wheaton (Chicago suburb) the only analog stations that Comcast simulcasts in digital unencrypted are the standard broadcast channels: CBS, NBC, ABC, etc. Pretty much any channel that can be had via antenna. I know that, as Marc has found, some Comcast head ends simulcast all, or most, of the basic cable tier. Though this appears to be a dwindling number. And those that do simulcast those channels sometime abruptly start encrypting them. I have flipped through some of the encrypted channels in my location and have found that for most of them only the audio is encrypted. So maybe there is a way to get the video from the digital encrypted channel and the audio from the analog one. The other fun item I found while scanning the channels is that they transmit everybody's OnDemand channels in the clear. So I can flip through that band of channels and watch what someone else is watching. I even saw someone fastforwarding through a portion of a movie. |
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| Author: | marc.aronson [ Sun Feb 04, 2007 6:36 pm ] |
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Opel70, thanks for the info. It's starting to sound like my "missing" simulcast channels are either not there or encrypted. Since I wasn't expecting to get anything but the clear hidef channels when I purchased my digital tuner, I'll accept the 50+ simulcast channels as a unexpected bonus. For anyone else that is watching this thread -- a quick explanation in case it isn't clear. In some of their networks Comcast will transmit the analogue channels in 2 formats -- standard analogue and digital. Comcast calls this "ADS", which stands for "Analogue Digitial Simulcast". This means that for FOX, which is channel 2, one can find 3 "copies" of it on the cable: 1. Analogue transmiison in NTSC / 720x480 format. 2. Standard defintiion digital transmission. Sometimes these transmissions are 720x480, sometimes that are 504x480. They are not hidef. 3. Hidef digital transmission, which for FOX would be 1280x720. The ADS transmission (# 2) is actually created by comcast and is quite good. Marc |
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| Author: | cameraready [ Mon Feb 05, 2007 9:36 am ] |
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I wish my local comcast headend was simulcasting some of the analog stations. The digital stations produce much clearer pictures and smaller file sizes. Instead I get about 6 TV Guide channels.
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| Author: | spalVl [ Mon Feb 05, 2007 10:26 am ] |
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Quote: I wish my local comcast headend was simulcasting some of the analog stations.
One of the developers over at SiliconDust has mentioned that the EFF is trying to get legislation that would force Cable providers to broadcast Digital channels that are available OTA. (In addition to the current HD requirements), I have not found the specific action item on EFF's site but I plan on writing my elected rep to encourage this. |
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