[FFmpeg-soc] [soc]: r5665 - libavfilter/vf_rotate.c

[Bobby Bingham]

On Mon, 15 Mar 2010 12:44:32 +0100
Stefano Sabatini <stefano.sabatini-lala at poste.it> wrote:

> On date Sunday 2010-03-14 20:24:34 -0500, Bobby Bingham encoded:
> > On Sat, 13 Mar 2010 14:55:11 +0100 (CET)
> > stefano <subversion at mplayerhq.hu> wrote:
> > 
> > > Author: stefano
> > > Date: Sat Mar 13 14:55:11 2010
> > > New Revision: 5665
> > > 
> > > Log:
> > > Prevent rotate from calling avfilter_default_draw_slice(), which
> > > was causing randomic behaviour.
> > > 
> > > Only one slice has to be passed to the next filter, in the
> > > end_frame() callback.
> > 
> > Perhaps a better solution is actually to change
> > av_filter_draw_slice() to not call avfilter_default_draw_slice().
> > I see three cases:
> > 
> > 1. filters like vf_rotate, vf_transpose, etc which only send one
> > slice at the very end.  These should not call
> > avfilter_default_draw_slice().
> > 
> > 2. filters which do some filtering in their own draw_slice.  These
> > always override avfilter_default_draw_slice().
> > 
> > 3. filters which do not touch the video data: vf_null, vf_setpts,
> > etc. These can use avfilter_default_draw_slice(), but I think they
> > are the minority of filters.  They can simply specify
> > avfilter_default_draw_slice as their draw_slice callback.
> 
> I think the semantics for the default callbacks is this:
> "call the default callback if the callback is not explicitely defined
> in the filter".
> 
> and should be respected for all the types of default_* callbacks.

That is the way it's has been, but I originally did that with the goal
of making things easier for filter writers, rather than for
consistency.  The default callbacks should be what filters are most
likely to use, and it looks like for draw_slice, a default
implementation which does nothing is more useful than
avfilter_default_draw_slice().

Another idea would be do provide an avfilter_null_draw_slice() so that
each filter doesn't have to provide its own.

> 
> BTW, it's great to see you back in action on lavfi!! :-)
> 

:-)

> Regards.
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-- 
Bobby Bingham
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