[MPlayer-dev-eng] About the future - libvo2...

[David Holm]

Ivan Kalvatchev wrote:

>//subtitles, query, comments
>I think that libvo2 drivers have nearly compleate set
>of function. I think that only one function should be
>added - for HW Subtitle support. It may be and through
>the control interface.
>I am sure that you know that gl,dxr3,dvb are not the
>only one that can do the trick, XV overlays with key
>color could be used to render subtitles (xv).
>I like the current format of subtitles one Gray and
>one Alpha image, but i think that it is good idea to
>support few formats as dvb,dxr3 may have it's own (ala
>DVD)
>Arpi mention about render once OSD, i understand it as
>making one bitmap for all subtitles. So i would like
>to discuss, should it be few bitmaps (x,y,w,h)( one
>for play sign, one for text line) or same kind of
>array (ala if(osd[y].w>0) drawsub(osd[y].x,y,...)
>
I think overlays should be implemented in several ways, which is the way 
I will present when I post spec-draft 1 of libvo2.
The device will be queried which method it prefers, for instance:
    1. Superimposed, mplayer superimposes the overlay (osd, subpics etc) 
onto the rendered image in buffer
    2. Written to a buffer in format IMGFMT_<spec> for harware support 
overlays, subpictures etc

>
> 
>I will discuss the negotiation, pp, covert in later
>mail, but these fuctionality must be added by libvo2
>core library.
>
>
>
>Just one remind, the query_format should return not
>only IMGFMT, but also and HW capabilities like scale,
>subtitles, direct surface, etc. I think that returning
>pointer to array of formats descriptions is ok, as
>this array may be inititlized on vo2_init_* time.
>imfmtInfo * query(...);
>
Yes, the query_format(..) call will be removed and implemented through 
the control(..) call, which works like normal ioctl's, so extending 
capabilites won't be a problem... A developer could for instance add 
VO2CTRL_QUERY_TEMPERATURE if the device supported it and it would be 
relevant (at least it would be a cool feature for the gui ;)

//David Holm

>
>
>btw. I would be happy if in the coments of libvo2 the
>word buffer have one meaning. Now it is used as memory
>buffer and as video surface. Once upon a time, the
>phrase double buffer mean one buffer in memory before
>making copy to video ram. Now in mplayer double buffer
>means to have 2 buffers in video ram and to flip them.
>
>oh, there is and mix of temp static frame buffer ;)
>Making thinks clear will help every body.
>
>   Best Regards
>Ivan Kalvachev
>
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