[MPlayer-dev-eng] [PATCH] bmovl2 updates

Jason Tackaberry tack at auc.ca
Wed Dec 10 16:18:27 CET 2003

On Sun, 2003-12-07 at 18:44, D Richard Felker III wrote:
> 1, it's incompatible with old bmovl so replacing the old one would
> break apps that depend on it.

Right.  The approach bmovl2 takes is quite different than the original

> 2, iirc it lacks some features bmovl has.

Actually, it's the other way around.  bmovl, more or less, just lets you
write to a single buffer which then gets blitted to each video frame.

bmovl2 has more intelligence, and can store multiple buffers and has a
notion of layers as well as atomic operations.  This gives you quite a
bit more flexibility and, unlike the original bmovl, allows for
transition effects like moving and fading without any performance hit.

I did look at modifying the existing bmovl before rewriting, but it was
quickly apparent that its design just didn't allow for efficient
transitions.  bmovl has one buffer that's the size of the mp_image,
whereas bmovl2 has buffers that's only the size of the bitmap it's

bmovl2, in terms of functionality (rather than interface), is a superset
of bmovl.

And (although it's not itself justification for writing a new filter)
with the extra flexibility bmovl2 provides, it's also much faster than
bmovl, even for systems without MMX.


Jason Tackaberry  ::  tack at auc.ca  :: 705-949-2301 x330 
Academic Computing Support Specialist
Information Technology Services
Algoma University College  ::  www.auc.ca

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