OTA channel black screen in WMC, works in HDHomeRun VIEW

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EricS
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Joined: Thu Jan 24, 2019 10:55 pm

OTA channel black screen in WMC, works in HDHomeRun VIEW

Postby EricS » Thu Jan 24, 2019 11:17 pm

I just set up a new Windows 7 build running Windows Media Center (WMC) connecting to an old dual-input HDHR-US tuner running software version 20180921. It's in a somewhat rural market (zip 92277) where I can only pick up three physical channels that are low-power translators of all the major networks and is run by the county and community college.

All of the channels are standard definition and the three physical channels and all the sub-channels work great in the HDHomeRun VIEW app and in VLC. In WMC two of the physical channels and those sub-channels work but the other physical channel and it's four sub-channels produce a black screen with no audio.

I can go into the "411", Ctrl-D" debug menus and see the content as playing with a position timer/counter going up in the transport state but it initially wasn't showing any codec info, but is now showing Dolby audio with "o" channels" and "not specified" and zero for video bitrate.

I ran across the following Microsoft knowledge base article about timing differences between certain broadcasters producing the black screen symptoms when the audio and video streams are too far out of sync.

https://support.microsoft.com/en-us/hel ... hanging-ch

I've already trying increasing the value to the suggested 3000 and also tried 5000 and 100000 with no difference. The signal strength in WMC shows as good and the in the hdhomerun_config_gui shows a clean signal at 75% strength and near perfect signal quality and perfect symbol quality.


Checking if anyone has any suggestions or if any SiliconDust staff run across this, can you tell anything from a captured log file if there's something wrong in the transport stream that might cause this?

Eric

signcarver
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Re: OTA channel black screen in WMC, works in HDHomeRun VIEW

Postby signcarver » Fri Jan 25, 2019 12:02 am

have you checked that it s actually tuning the same physical channel/subchannel.... wmc will tune by frequency and often it's scans are bad and occasionally may even add some that are not even there.

EricS
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Joined: Thu Jan 24, 2019 10:55 pm

Re: OTA channel black screen in WMC, works in HDHomeRun VIEW

Postby EricS » Fri Jan 25, 2019 12:18 am

That's one of the things I double-checked with no luck.

The local low powered translators aren't even listed in Microsoft's guide data and not scanning correctly in WMC setup. I had to manually add them to make sure they used the correct physical channel and then use the EPG123 utility to map them to their Los Angeles market channels. I also tried manually removing and re-adding the channels with no luck, reverting to the initial system restore point when WMC was installed and re-setting everything up, etc.

The other two channels continue to work fine but this one (K15FC-D) doesn't. WMC stays on the black screen and never goes to the blue, "no signal" error message.

jasonl
Silicondust
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Re: OTA channel black screen in WMC, works in HDHomeRun VIEW

Postby jasonl » Thu Jan 31, 2019 5:59 pm

Go into HDHomeRun Setup and change the BDA Compatibility Mode to Default. This will cause the BDA driver to ignore the filter set by WMC and always send the entire broadcast. There's a bug in the filtering code in WMC that causes it to not request the program clock reference (PCR) when it's sent on its own separate PID. 99.9% of stations send it on the same PID as the video, so it's just there automatically, but a handful don't for whatever reason. WMC will just show the black screen if the stream doesn't have a PCR. Oddly enough, it still knows how to find and use the PCR as long as it's present in the stream, it's just not smart enough to request it. Just another one of those bugs we didn't figure out until after Microsoft killed WMC development, so it never got fixed.

EricS
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Joined: Thu Jan 24, 2019 10:55 pm

Re: OTA channel black screen in WMC, works in HDHomeRun VIEW

Postby EricS » Sun Feb 03, 2019 7:52 am

Thanks for the suggestion. I just had a chance to try it and it doesn't fix the problem. After letting it sit on one of the digital sub-channels for a minute it did show a static single frame but no audio or video and the other sub-channels are all still showing as black.

jasonl
Silicondust
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Joined: Sun Oct 28, 2007 9:23 pm

Re: OTA channel black screen in WMC, works in HDHomeRun VIEW

Postby jasonl » Wed Feb 06, 2019 7:28 pm

Can you record an unfiltered clip of the affected station (see viewtopic.php?f=15&t=2491), upload it somewhere (Dropbox, Google Drive, iCloud, OneDrive, etc.) and reply back with a link to it? I can see if there's anything obviously wrong with it.

EricS
Posts: 4
Joined: Thu Jan 24, 2019 10:55 pm

Re: OTA channel black screen in WMC, works in HDHomeRun VIEW

Postby EricS » Thu Feb 07, 2019 8:39 pm

I just recorded the sample linked below. It play fine in VLC and via browser plug-in. After finishing running the capture I also streamed it live with VLC which has always worked.

https://drive.google.com/file/d/1b8CMdR ... sp=sharing

jasonl
Silicondust
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Re: OTA channel black screen in WMC, works in HDHomeRun VIEW

Postby jasonl » Mon Feb 11, 2019 4:14 pm

The PCR is on a different PID as I suspected, so switching the BDA mode ought to have fixed it. Can you enable the sending of diagnostic data and run a channel scan (see viewtopic.php?f=15&t=69066), reboot the PC, then open WMC and try to watch one of the problem channels for 5 minutes? Reply back with the device ID for your HDHomeRun and we'll check the logs.


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