[mythtv] BluRay Subtitles...

[stev391 at email.com]

G'Day,

I have been working on adding BluRay sibtitles to MythTV.

The attached patch should perform nearly everything bar the actual displaying of the subtitle, 
this is were I need your help. MythTV appears to be processing the returned bitmap, dimensions, 
timing etc, and states that it has set a subtitle to visible, but it doesn't appear.

Also after looking at the code, it appears that MythTV scales the subtitle so it fits on a 720p 
screen, why is this? My BluRay's are all 1080p and scaling the image down then back up again 
will result in ugly looking images.

Attached to this email you can find my progress to date.  The patch performs the following:
* Modifies mpegts.c to identify the subtitle streams (so now you can select the subtitle when 
playing)
* Implements a basic parser for the subtitle packet
* Decodes the packet and produces a bitmap

Known limitations at the moment:
* Run Length Encoded subtitles over multiple packets is not supported (I know how to fix this)
* Cropping of the decoded bitmap (again I know how to fix this, but I haven seen a subtitle with 
this yet)
* Differianting forced subtitles from normal ones (so you can tell it to only show forced 
subtitle, any ideas on this [i know where the flag is in the data])

To enable debugging, uncomment the defines near the top of each file.  If you enable the option 
to save image for each subtitle, you can see that the code is correctly decoding the data and 
producing a bitmap.

Eventually the FFmpeg sections will be submitted upstream, however as I do not have a full 
working subtitle support to test with I will hold off for the moment.

Thanks for your assistance.

Stephen.


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