[TV] North American Closed Captions (4 Viewers)

[misterd]

Perhaps your hardware encoder just encodes the CC to the video stream? But this behavior is not guaranteed for all analog cards and especially encoders. So you should say that with the patch it can work but it is not guaranteed and if it is not working than mostly you have to adjust the graph building algorithm for your system. I would not even say that you have to do this for the card.

MisterD

 

[greybox]

Somehow Microsoft managed to enable EIA-608 analog CC in their mediacenter for all ATI and Hauppauge capture cards I ever used.

Migue: could you post your graph?

Deda and the team: will you be able to adjust the skin to enable/disable CC with the remote control, same way you did for the DVD playback?

 

[Migue]

According to Wikipedia all tuners in the US are required to encode CC by law.

In the US, since the passage of the Television Decoder Circuitry Act, manufacturers of most television receivers sold have been required to include closed captioning display capability. High-definition TV sets, receivers, and tuner cards are also covered, though the technical specifications are different. (High-definition display screens, as opposed to high-definition TVs, may lack captioning.) Canada has no similar law, but receives the same sets as the US in most cases.

http://en.wikipedia.org/wiki/Closed_captioning#Television_and_video

The graphs are the same one you posted earlier.

I'm a member of the team and the thread I linked to (visible only to team members) discusses precisely what you're asking greybox, where I've added CC as another "subtitle" so you can use remote or context menu window to switch to CC mode.

 

[greybox]

Well, it looks like MP without NA CC would be illegal in the US if it was commercial product!

Migue: somehow EIA-608 analog CC never worked for me in MP. I am very curious what was wrong.

 

[Migue]

The Line21 decoder wasn't being added to graph. And I think that even if added through post processing, the status for the decoder was set to off.

greybox, do you know how to compile MP source, I could post patch here so you can test.

 

[misterd]

Just to clarify some things. AFAIK all analog tuners can handle the CC subtitles. They all have a VBI output pin on their capture devices (or atleast they should have). Here a normal application can grab the VBI data and extract with Line21 decoder the CC subtitles. Also those capture devices normally provide an output pin which has the analog unencoded video signal. This video signal has normally no CC information included.
I assume that WMC is using this VBI pin in a specific combination with their own stream buffer engine, which the current TvServer doesn't use. For more information I refer to the MSDN: Viewing Closed Captions (Windows)

So what does the TvServer do?
The TvServer now uses this analog video signal and tries to encode it to a MPEG-2 Video stream or uses a direct output pin on the capture device. Unfortunately not all encoders support the possibility to combine the analog video signal with the CC information from the VBI output pin. Additionally you can't even detect it properly. That's why the TvServer currently doesn't do this.

The patch Migue is referring to just analyses the MPEG-2 video stream and enables the Line 21 decoder from the video stream within the MPEG-2 video. So if the encoder doesn't have added the CC information they are not there and you are lost. So with the patch you can have luck and CC works for you or not.

MisterD

 

[greybox]

Migue: I installed your patched files and after enabling CC in subtitle menu, I got ATSC CC, but not analog. I used MPC codecs. When I switched to Microsoft codec on my Windows 7 boot (this codec is not available in Windows XP), I got CC in analog as well! And even the recorded file shows CC! Thank you, mister Miracle Worker!!


I am going to try some other codecs. Are we stuck with W7 and Microsoft codec only?

However the video is somewhat choppy. And when I tried to disable CC in subtitles menu, I still have CC.

 

[Migue]

In my testing if using Core CC Parser then CC would always show in analog, but in ATSC it can be toggled on/off. If not using Core CC Parser then analog CC can be toggled but then there's no CC in ATSC. I could try to fix this by removing Core CC Parser from graph when turning CC off but there's no much point to it.

Like misterd said and you confirmed, with my patch it is mostly about luck and having a specific configuration, so we should try to look for a correct way to do it.

 

[greybox]

I think we need to be able to control both CCs. And as I understand, they still mix analog CC into ATSC so there are two CC streams in ATSC, is that right?

You have the source code of CoreCC Parser. Is it possible to modify it and recompile for our needs?

 

[greybox]

Migue: I tried a few different MPEG2 decoders today with your patch and this is what I found:

Microsoft decoder: Analog CC - OK, video - choppy (maybe this has nothing to do with CC, maybe this is just my system does not coopetate with Microsoft decoder);
MPC Video decoder - Analog CC - NO, video - OK;
Cyberlink video decoder (PDVD10): CC - OK, video - OK
FFDShow video decoder: CC - OK, video - OK

I think you are on the right track. My tests were on W7, I didn't have time to test on XP, but with FFDShow or Cyberlink everything should work on XP same way.