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

[Ötvös Attila]

2007. szeptember 13. 14.41 dátummal Jason Tackaberry ezt írta:

Hi 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.

This patch uses the semaphores for buffer lock (stream_sharedmem.c).

> 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.

I made this shared memory stream for CCTV:
http://onebithq.com/root/mplayer/cctv

I needed to record more closed circuit TVs simultaneous with showing this on 
shared screen.

> > 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?

Now, the import filter can't use alpha blending.

Best regard.
Attila