Closed Captions for ComCast H264 channels?

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GregTippitt
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Closed Captions for ComCast H264 channels?

Post by GregTippitt » Mon Apr 23, 2018 2:51 am

Could someone running Myth29 and using ComCast tell me if the captions work for H264 encoded channels, like CNN, AMC, and SyFy?

I am using MythTV 28 with Ubuntu 16.04LTS on both my frontend HTPC and my separate backend media/storage server. I am using a SD HomeRun Prime with ComCast cable TV service, so I have the problem with closed captions not displaying on channels with H264 streams. With the stable release of Ubuntu 18.04LTS with MythTV.29 about to be dropped, I am trying to decide if I want to upgrade these two machines. (Unity is dead. Long live Gnome!) Other than this problem with closed caption not being available using MythFrontend, I'm happy with how everything is working and am thinking of just staying with my current versions. I've been using MythTV for a very long time and love it, but prior upgrades have always come with hassles, which I'm inclined to avoid unless version 29 has some major advantages that I've not seen so far in reading.

An old thread regarding this closed caption problem suggested that upgrading FFMpeg would fix this problem with MythFrontend, but loading FFMpeg 7:3.4.2-1 from a PPA didn't help me. When the captions don't work on programs with loud effects that make dialog difficult to understand, I can download the recorded show using MythWeb and then play it with VLC to see the captions. The backend is recording the captions fine, but MythFrontend doesn't recognize them.

The move to using H264 streams for many channels by ComCast has been great in that those shows take about half as much storage space to record, but the closed captions missing with MythFrontend is a hassle. Other than these missing captions, I could not be happier with how my setup is working, which is why I'm reluctant to bother upgrading unless this problem has been fixed in MythTV 29.

It took me some effort initially to explain to my local ComCast office what a CableCard or M-Card was for my HomeRun tuner. The technician to install the service brought one of their set top boxes, even though I had said I didn't want one. In a box I had of old PC parts, I found an old laptop PC-Card to show him what the card I needed looked like, to which he smiled big and said "Okay; you need a TIVO card", which I can bring by tomorrow. ComCast often gets a bad rap, but I've been really happy that I can record everything in my subscription, even HBO channels. I had stayed with my old OTA/ATSC setup for a few years because of the reports that many cable TV providers made it difficult to use open source TV systems to record many channels except for the broadcast networks.

Thanks,
Greg

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pgbennett
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Re: Closed Captions for ComCast H264 channels?

Post by pgbennett » Mon Apr 23, 2018 2:21 pm

Upgrading FFmpeg will not help because MythTV uses its own copy of FFmpeg built in. I can confirm that subtitles work for me with Comcast H264 in version 29. There were FFmpeg upgrades in each MythTV version so possibly that fixed it. I do not remember it being a problem with version 0.28, but at that stage Comcast was not using H264, so I cannot tell. Does the menu show the option to select subtitles? If the problem persists in V29 let us know.

Note - Comcast subtitles will not work with Raspberry Pi.

Another option is to run a job after each recording to extract the subtitles. I have a sample if you are interested. This will not work for "Live TV" but will work for recordings you watch later. This will also work with Raspberry Pi.

GregTippitt
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Re: Closed Captions for ComCast H264 channels?

Post by GregTippitt » Mon Apr 23, 2018 3:51 pm

Thank you for explaining the FFMpeg situation. I think that I will go ahead and update to Ubuntu MythTV 29 under 18.04LTS to get this closed captions problem fixed, but I'll maybe wait a month or so to allow time for any major problems to be discovered by others first.

I've also been thinking about changing my backend config to have MythTV with MySQL and other Myth dependencies running under a VM on my storage/media server. It will not only let me test the new 29 under 18.04LTS without risking my existing MythTV 28 setup on the server, but it will allow me in the future to be able to shutdown the VM and make a copy the Myth VM drive whenever I want. My server's got tons of RAM, CPU, and storage capacity to spare, so any overhead of running the MythBackend and MySQL in a VM should be insignificant. The server has lots of non-MythTV stuff that I've written and cobbled together for other functions, and I'd rather leave that muck running on 16.04LTS and not risk anything getting broken by upgrading it to 18.04.

Thanks,
Greg

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