[mythtv-users] No closed captioning for any tuner in Mythtv SVN

Daniel Kristjansson danielk at cuymedia.net
Thu Nov 15 01:35:08 UTC 2007

On Wed, 2007-11-14 at 17:00 -0800, Sam Logen wrote:
> Thank you Daniel and Craig for getting back to me on
> this.  On my first email today, I included my hardware
> details at the bottom of my email.  As for my settings
> in the mythtv-setup program, the VBI is set to NTSC
> closed captions for my area (California).  Just to
> clarify, only my ATSC card used to be able to display
> VBI closed captioning for HD channels when I ran
> Mythtv 20.2.  After upgrading to SVN, neither card
> could display CC.  It seems that Mythtv took one step
> forward, and two steps back in its development.
> The drivers I am using for the cards are the very
> latest Conexant 2388x drivers, including the latest
> blackbird driver patches for the hardware mpeg card.

Hmm, did you upgrade the drivers when you upgraded to SVN?

If so this is a possible culprit. I've never gotten captions
with the Conexant 2388x drivers, so I can't tell you this will
work, but the fact that you had it working is promising.

What you probably want to do is first make sure that the drivers
are working. Do this by reverting to 0.20-fixes and seeing the
captions. If the drivers aren't working, the dvb-v4l mailing list
is the next stop. But assuming this is a MythTV issue, it's
probably something happening in libs/libmythtv/channel.cpp
This URL will give you a revision log of the file:

There have only been 5 changes to that file in that time.
My suggestion would be to test them in this order:
  12618 -- makes sure it was working a year ago, if it
           wasn't you'll need to start earlier like 9524
if 12618 works try 14444 next
  if 14444 works try 14592
     if 14592 works try 14762
        if 14762 doesn't work it's the probable culprit
     if 14592 doesn't work it's the probable culprit
  if 14444 doesn't work try 12739
     if 12739 works 14444 is the probable culprit
     if 12739 doesn't work try 12619
        if 12619 works 12739 is the probable culprit
        if 12619 doesn't work it's the probable culprit

This way of bisecting the change sets means you only need
to check 1 + ceil(log2 n) of the changes. In this case 4,
which is almost as bad as the 6 you would need to check
otherwise; but if 12618 doesn't work and you have to check
the 20 changes back to 9204, it means you only need to
check 6 revisions rather than 20.

Anyway to check out an old version of MythTV you just do
this: svn co -r REV http://svn.mythtv.org/svn/trunk/mythtv mythtv-REV
replacing REV with the revision you want.

PS Before doing this make sure you have your V4L format set to
"NTSC" and not "ATSC". MythTV used to be more forgiving of this
configuration mistake back in the day. But DTV support in the V4L
drivers has been completely dropped from the V4L drivers since
the V4L-DVB merger and we no longer have that code in SVN as of
about two months ago.

-- Daniel

More information about the mythtv-users mailing list