[MPlayer-dev-eng] [PATCH] shmem - filter, doc

[Jason Tackaberry]

Hi Attila,

On Wed, 2007-09-12 at 00:47 +0200, Ötvös Attila wrote:
> Export filter can modify format of video frame, scale and osd render (similar 
> expand filter).

Just curious, what are the use cases for this?

I've done something similar, which we use for Freevo, where the primary
use case is to be able to manipulate the video from mplayer onto a
canvas controlled by another application.

But your patch doesn't appear to implement any locking with the buffer.
Consequently an application reading the frame from shared memory may end
up reading at a point where the frame is currently being overwritten,
resulting in a corrupt frame.

So I suppose the patch might be useful for, say, a GUI wrapper for
mencoder that wants to output visual progress of the encode.  I'm
curious if there are other use cases you had in mind.

> Import filter implement insert video frames from shared memory stream similar 
> bmovl filter. Import filter can modify size and set insert positions.

Does shmemin do any alpha blending like bmovl?

Cheers,
Jason.