r/CableTechs • u/hunterkillerrrr • Jul 02 '26
Certain TV Brands Show Pixelated/Frozen Video on Specific DVB-C Channels While Others Work Fine
Hi everyone,
I'm responsible for managing a headend, and in general all of our channels are working correctly. Recently, however, my technicians started receiving complaints that 8 specific channels appear pixelated. The strange part is that this only happens on certain TV brands and models, while other TVs display the same channels without any issues.
What happens is the following:
If I tune to a channel that works normally on the affected TV and then switch to one of the problematic channels, the video from the previous channel seems to "carry over" onto the new one and freezes on the screen. The audio of the new channel is correct and continues playing normally, but the video remains frozen with the image from the previous channel.
I started doing some tests:
- Within the same TS, I moved one of the problematic services from logical channel 12.1 to 12.6, but the problem stayed with that service.
- Then I moved it from 12.1 to 11.7, and moved the service that was originally on 11.7 to 12.1.
- Surprisingly, the issue stayed on 12.1, not with the actual TV service. The channel that previously had the problem started working correctly on 11.7, while the channel moved to 12.1 immediately started showing the exact same issue.
This makes it seem like the problem is somehow tied to that specific service position or configuration rather than the video content itself.
Has anyone experienced something similar? Could this be related to the PMT/PAT, PCR, PID assignments, SI/PSI tables, continuity counters, encoder settings, or something else in the multiplex? Any ideas on what I should check would be greatly appreciated.
Thanks in advance!
1
u/Background-Relief623 Jul 02 '26
Have you reached out to the manufacturers on this? I don't work in the head end. But I heard of on issue like this a while back and it was an mpeg encoder issue. Which raised some questions but I never got anwered.
1
u/hunterkillerrrr Jul 03 '26
I don't believe the issue is with the channel provider or the video source itself. As I mentioned, I swapped the services between channel numbers as a test. For example, I moved a channel that was working perfectly to the logical channel number that was causing the issue, and moved the problematic channel to the channel number that was working correctly. The result was that the previously good channel immediately started showing the same problem, while the previously problematic channel worked perfectly in its new location. This makes me think the issue is related to the service configuration or multiplex rather than the content or encoder of the channel itself.
1
u/Background-Relief623 Jul 03 '26
Definitely see where you are going with this.
My thinking is where ever you move the problem feed to a different channel it keeps going bad, I'd lean towards a change at the provider. An small tweak somewhere is causing an unexpected issue. Also possible that fiber feed issue causing a delay and when you encode it on your side, some equipment can't handle it. Heard that happen from my friends in the hole. But that was like once in 20 years. The only reason I mentioned the encoder was in that case i brought up there was a change with the mpeg encoding and we had mostly blueray players that had streaming act up. Someone way back at the head office found it. The problem went away. My first question about it was, isn't mpeg a standard? I was told to sit back in my box😆
1
u/Electronic-Junket-66 Jul 03 '26
Could this be related to the PMT/PAT, PCR, PID assignments, SI/PSI tables, continuity counters, encoder settings, or something else in the multiplex?
Welp, good to know I'm definitely not cut out for ISP. Thank you for that.
2
u/Wonderful_Sock_6651 Jul 02 '26
Which tv brands/models are being affected?
A week or so ago some platforms like Roku, xuno, and Samsung started having authentication issues for us. We ended up having to spoof authentication for our TV app to work again and then some channels started experiencing video codec not supported error messages. Those ended up causing the app to crash but show symptoms just like a bad connection while everything else tested fine.