[mythtv-users] Closed captioning?

Yeechang Lee ylee at pobox.com
Wed Jan 6 02:25:12 UTC 2010


Bart Whiteley <bart.lists at whiteley.org> says:
> I'm using mythbuntu 9.10 with a HDHomeRun for OTA ATSC programming.
> 
> I'm unable to get closed captioning to work.

There are two different standards for captions: ATSC (EIA-708) and VBI
(EIA-608). In theory, ATSC captions should be preferred over VBI
captions, and nowadays are supposed to exist in all recordings.

In practice, a) some recordings don't have ATSC (or VBI) captions, and
b) in any case MythTV's current support for ATSC captions is horribly,
horribly
broken(<URL:http://www.gossamer-threads.com/lists/mythtv/users/359532#359532>).
(Jim Stichnot meant to write "HDHR *VBI* captions work very well," not
" . . . ATSC . . .", and the HDHomeRun doesn't have anything to do
with captions, anyway; it, like other such tuners, simply captures
ATSC digital over-the-air television broadcast signals unaltered,
whether they have captions [ATSC, VBI, both, or neither] or not.) Also
note that MythFrontend's OSD menu will always list VBI captions as an
option even if the program doesn't have any, while ATSC captions are
only listed if they exist.

So, what to do?

* You definitely want "Prefer EIA-708 over EIA-608 captions" turned
  off. Then, use VBI captions even if ATSC captions are also listed on
  the OSD. If VBI captions exist, they will appear; if not, they
  won't.
* You are on what is more or less a wild-goose chase regarding VLC and
  examining mythfrontend debugging output. VLC is simply (correctly)
  displaying ATSC captions that MythFrontend currently cannot.
* Several patches by Clayton Smith will be or will likely to be
  included in 0.23--said to be coming in a few months--and fix most or
  all of MythFrontend's issues with ATSC captions.

Be aware that ATSC caption are--even with the patches--not necessarily
all that great, or preferable to VBI captions if the latter exist; see
<URL:http://www.gossamer-threads.com/lists/mythtv/users/414350#414350>.
In addition to my original post, I've also noticed that many programs
set their ATSC captions to use only a monospace font, which I find
less readable than proportional. (Yes, I could tell MythFrontend to
use a proportional font for monospace-marked captions too, but then
why bother having the option for multiple fonts in the first place?)

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