[MPlayer-users] ssa reader for mplayer using vf_overlay

[Robert Henney]

On Wed, Sep 28, 2005 at 12:05:14PM -0400, Jason Tackaberry wrote:
> Hi Robert,
> 
> On Wed, 2005-09-28 at 07:09 -0400, Robert Henney wrote:
> > I've written a small demonstration of how the vf_overlay filter in
> > mplayer can be used to display SSA subtitles from an external reader.
> 
> Well, vf_overlay isn't in mplayer quite yet.  It's very nice to see
> others develop with vf_overlay though, since the more interest there is
> in this filter, the better chances we have of getting it merged.
>
> I haven't looked at your SSA code (I've no particular need for this
> feature), but I'm certainly interested in any feedback you might have
> with vf_overlay itself, such as any bugs you've run into or features you
> find you need as a developer using it.

I've run into two possible bugs so far, although it may be more likely
I'm just doing something wrong.  one is the locking.  after first
attaching to the shared memory and issuing a "visible=1", the lock byte
is 0x10.  I set it to 0x20 and make my writes and then issue an
"invalidate=...", but the lock byte never changes back from 0x20.  I've
ended up just ignoring the lock byte in my code because otherwise my
code doesn't seem to ever get access back to the shared memory. 

The other is that invalidate ranges don't seem to be working perfectly
right for me.  Currently to get around the problem I'm issuing an
"invalidate=.." with dimentions that cover the entire overlay memory.
If I use what I think are correct WIDTHxHEIGHT ranges, only small
rectangular portions of the areas I want to invalidate get drawn, and
stranger still some areas of what is drawn appear without all their
colors.

Oh, also.. not necessarily a problem or a bug, but I have noticed that
what I write to the overlay appears to get 'softened' with the colors
looking less than vibrant.


> Cheers,
> Jason.