[mythtv] [mythtv-users] Subtitles and Comcast x264

David Engel david at istwok.net
Wed Nov 9 21:03:00 UTC 2016

On Wed, Nov 09, 2016 at 03:35:55PM -0500, Peter Bennett wrote:
> On 11/09/2016 02:20 PM, John P Poet wrote:
> > On Wed, Nov 9, 2016 at 12:07 PM Gary Buhrmaster
> > <gary.buhrmaster at gmail.com <mailto:gary.buhrmaster at gmail.com>> wrote:
> >
> >     On Wed, Nov 9, 2016 at 6:41 PM, Peter Bennett
> >     <pgbennett at comcast.net <mailto:pgbennett at comcast.net>> wrote:
> >
> >     > MythTV does not detect the subtitles.
> >
> >     What version of MythTV?  There was a discussion about
> >     4 months ago where (I think) a dev thought the FFMpeg
> >     in 0.28 should have the needed support (but it was
> >     unverified, and AFAIR no one confirmed/denied).
> >
> >
> > Maybe start here:
> >
> > https://code.mythtv.org/trac/ticket/12893
> >
> > I have a patch which I can contribute from a work colleague, which
> > adds it for a 2 or 3 year old version of ffmpeg, but I am pretty sure
> > it does not apply against the current ffmpeg.
> >  
> > John
> >
> Thanks John
> Is it acceptable to add a fix to our local ffmpeg, knowing that it will
> be lost when we pull in the next version? If so I can give this a test
> and see what happens.

It won't get lost.  Whenever we resync to a newer version of ffmpeg,
we re-work and re-apply any patches that are still needed.  Jean-Yves
has done the last several resyncs.  He'd be the person to check with
on how best to do it without causing future problems.

> One problem - it may work with ffmpeg but fail with vdpau and other
> hardware assisted decoders.

This isn't my area of expertise, but I don't see how it would cause
any issues with current decoders.  As I undertand it, we use ffmpeg to
parse the streams and then pass the video packets on for further
decoding by hardware.  The audio and all other packets, including
those with the subtitles, get decoded by us and handled appropriately.
Now, I believe ffmpeg has its own API for agnostically handling
hardware acceleration.  When/if we swtich to it, the above could

David Engel
david at istwok.net

More information about the mythtv-dev mailing list