some channels missing - Billi23

Reception, channel detection, network issues, CableCARD setup, etc.
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Billi23
Posts: 111
Joined: Mon Mar 20, 2017 8:08 pm
Device ID: 1323AADB

some channels missing - Billi23

Post by Billi23 »

Don't know if it's related, but thought I'd mention that Comcast is in the process of changing local channels from mpeg2 to AVC/H.264.
The last capture of http://x.x.x.x/lineup.xml?show=all&tuning I did before rescanning today showed 1003 as unsubscribed and 703 (same as channel 1003) subscribed and mpeg2.
The scan I did today shows 1003 unsubscribed still, but 703 is showing as H.264.

BEFORE

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<Program><GuideNumber>703</GuideNumber><GuideName>KCRADT</GuideName><Modulation>auto</Modulation><Frequency>117000000</Frequency><ProgramNumber>1</ProgramNumber><VideoCodec>MPEG2</VideoCodec><AudioCodec>AC3</AudioCodec><HD>1</HD><URL>http://192.168.1.7:5004/auto/v703</URL></Program>
AFTER

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<Program><GuideNumber>703</GuideNumber><GuideName>KCRADT</GuideName><Modulation>auto</Modulation><Frequency>117000000</Frequency><ProgramNumber>1</ProgramNumber><VideoCodec>H264</VideoCodec><AudioCodec>AC3</AudioCodec><HD>1</HD><URL>http://192.168.1.7:5004/auto/v703</URL></Program>
NOTE THAT 703 is the same channel as 1003

Code: Select all

<Program><GuideNumber>1003</GuideNumber><GuideName>KCRADT</GuideName><Modulation>auto</Modulation><Frequency>117000000</Frequency><ProgramNumber>1</ProgramNumber><Subscribed>0</Subscribed></Program>

gtb
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Re: some channels missing

Post by gtb »

Billi23 wrote:
Tue Apr 07, 2020 6:10 pm
Don't know if it's related, but thought I'd mention that Comcast is in the process of changing local channels from mpeg2 to AVC/H.264.
Comcast has been doing this conversion market by market, channel group by channel group (first the national channels because they are all done in a few places (primary and backup) so they could be done with one group of transcoders, and then moving to the locals), for, at this point, years, leaving the major network OTAs (ABC, CBS....) as the last in some markets. During the last steps of the transition the CableCARD maps are updated, but not all channels are necessarily transitioned at exactly the same moment. Despite a previous RFE request, there is no logging in the tuner logs when the CableCARD maps change (unlike a competitors offering), so only by doing some manual sleuthing might one notice. You have noticed. Some people perceive a difference in quality (as the H.264 format is 720p, rather than MPEG2 1920i for some channels, and tends to be more compressed than the MPEG2 variant, although, as with all else, your experience may vary). One important advantage of H.264, in addition to the lower bitrate (which may also make wifi more viable in some cases) is that many mobile and dongle/TV devices have hardware decoding of H.264 (and not always for MPEG2) so they may result in a better experience (there is no need for software de-interlacing, that is done in the hardware transcoders which can do HQ de-interlacting, and lower power usage since the hardware can do the decode in almost all platforms).

I, for one, welcome our AV1 overlords (and H.264 is an interim step because it is deployable today).

Billi23
Posts: 111
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Re: some channels missing

Post by Billi23 »

I know what you're saying about picture quality, but that's a topic for another discussion. :(

I was just trying to point out that immediately before I made my post, enabled diagnostics, rebooted the Prime and scanned channels that the Prime thought this channel was mpeg2 and after that it says it's H.264. May be a coincidence, but I doubt Comcast/Xfinity switched the channel from mpeg2 to H.264 at the exact moment I did the reboot of the Prime. And IIRC it background scans about every 3 days.

In this case I don't really have an issue with this particular channel (1003) being marked as unsubscribed (other than it's not) because as a workaround I always record/watch the lower numbered channel (703).

My point is the Prime should not be telling me I'm not subscribed to a channel that I'm subscribed to. And it does this behind my back (during a background scan).

This is constantly happening with other channels and SD did fix the firmware so if you enable/disable channels that setting sticks, but the continuing problem is the Prime does not reliably scan cable channels.

Billi23
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Re: some channels missing

Post by Billi23 »

For scans and background scans, (not sure how the Prime firmware works, don't have source code) couldn't you have it consult the CabelCard when it scans channels to see if the subscriber is subscribed to the channel and not mark it as unsubscribed, or offer the subscriber a "Slow Scan" option that takes twice as long (timeout x2, or whatever) to detect the channels it currently misses (for whatever reason it does miss them)?

As a user and subscriber, it's very annoying to have your tuner device (HDHR Prime) unsubscribe you from channels you pay for and are subscribed to.

gtb
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Re: some channels missing

Post by gtb »

Billi23 wrote:
Tue Apr 07, 2020 9:24 pm
For scans and background scans, (not sure how the Prime firmware works, don't have source code) couldn't you have it consult the CabelCard when it scans channels to see if the subscriber is subscribed to the channel and not mark it as unsubscribed
As I recall, you have to try to tune/decode the channel to determine if you are subscribed, as that information is opaque to the device itself (and I am too lazy to go back and re-read the CableLabs specs to find if my memory is correct, but you are free to read the specs, it's in there!).

Billi23
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Re: some channels missing

Post by Billi23 »

gtb wrote:
Tue Apr 07, 2020 10:05 pm
As I recall, you have to try to tune/decode the channel to determine if you are subscribed
Is that not what a manual/background channel scan does?

As far as I know the HDHR tuner tunes the channel (I know, freq/PID, etc.) and the cablecard says go/no-go.
Does this not happen during a manual/background channel scan?

If it can't lock and get whatever signals/status it needs in the time allotted by the firmware settings, then extend the timeout with a "slow scan" option or consult the cablecard to see if it's a subscribed channel.

After all, I'm pretty sure the CableCard tells it whether the channel is subscribed or not when it's tuned? Otherwise how would a channel scan know if it's subscribed/unsubscribed.

Seems simple to us end users, SD never really explained how it works or why it doesn't work "as we expect it to" giving us our subscribed channels.

Don't know how else to explain the fact it's broken.

rpcameron
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Re: some channels missing

Post by rpcameron »

IIRC, the CableCARD has the mapping of channels, but not your subscription information. The only way for the tuner to know if a channel is subscribed or not is if you manually tell it (like T-Vo does, IIRC), or to try and tune the channel and see if it succeeds (which is what the Prime currently does). I don't believe there's any provision for the tuner to ask the CableCARD if a channel is in the subscription or not; just try to tune it and see if the card will allow decryption.

NedS
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Re: some channels missing

Post by NedS »

(thread split because it's turning into a discussion about how CableCARD works over-all)

Billi23
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Re: some channels missing - Billi23

Post by Billi23 »

Since my thread appears to have been split-off from rykr's here viewtopic.php?f=113&t=72665&start=30#p358512
Just wanted to add that my manual channel scan on April 7th missed channel 1003 and my manual scan today April 16th picked up channel 1003.

rykr
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Re: some channels missing - Billi23

Post by rykr »

Lucky. I just did a manual scan and still missing 1002

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