[FFmpeg-devel] [PATCH] Implement recusive avfilter_get_video_buffer()

[Stefano Sabatini]

On date Saturday 2009-10-10 00:58:42 +0200, Michael Niedermayer encoded:
> On Fri, Oct 09, 2009 at 02:01:27AM +0200, Stefano Sabatini wrote:
[...]
> > I found this filterchain is somehow broken:
> > 
> > slicify=10,vflip,scale=20:20,scale=200:200
> 
> somehow?
> and i assume that this is a minimal chain ...

The last drawn slice, and only the last one (corresponding to the top
slice of the output image) results corrupted, or better it looks like
it isn't drawn at all (and so it may contain random data).

You can observe this behavior changing the slicify size, also the
first half part of the image looks always rendered correctly with
every slicify size.

Removing any of the filters in the chain (or increasing the slicify
value to X >= H) the problem doesn't show up, it looks like a glitch
in libswscale issued when dealing with negative linesizes, I still
didn't extensively investigated on it though so I may be wrong.

If that's not a problem I'll apply this patch anyway.

> > before and after the patch, 
> 
> 
> > as for the framereordering I'm not sure
> > what you mean.
> 
> well, a mpeg decoder will allocate frames in an order that differs from
> what is output if its a file with B frames.
> 
> And slices wont be in the order in which frames are if SLICE_FLAG_CODED_ORDER
> is set, i dont think libavfilter supports that ATM and its not really
> urgent to change that but it should not be forgotten

No, indeed lavfi doesn't support that ATM.

Regards.
-- 
FFmpeg = Fierce & Frightening Merciful Powerful Elitist Gorilla