[FFmpeg-devel] [RFC] How to fix DR+lavfi+vflip crash

[Michael Niedermayer]

On Tue, Dec 28, 2010 at 11:32:27AM +0100, Stefano Sabatini wrote:
> On date Tuesday 2010-12-28 04:41:43 +0100, Michael Niedermayer encoded:
> > On Mon, Dec 27, 2010 at 11:39:53PM +0100, Stefano Sabatini wrote:
> > > On date Monday 2010-12-27 20:14:00 +0100, Michael Niedermayer encoded:
> > > > On Mon, Dec 27, 2010 at 07:07:53PM +0100, Stefano Sabatini wrote:
> > > > > On date Monday 2010-12-27 18:14:26 +0100, Stefano Sabatini encoded:
> > > > > > On date Monday 2010-12-27 16:13:14 +0100, Michael Niedermayer encoded:
> > > > > [...]
> > > > > > > applied (without typo)
> > > > > > 
> > > > > > Unfortunately can't work with pad, I was too quick to push the button.
> > > > > 
> > > > > Check attached, works for me, but since I've been confused tons of
> > > > > times by this problem I prefer to get another look by someone else.
> > > > 
> > > > pad crashes in put_pixels16_sse2() for me on its own and ironically not with
> > > > vflip but there are vissual artifacts on the left side
> 
> How can I reproduce the visual artifacts?

I dont remember, it looked like pad was drawing into reference frames though
if i stumble accros it again ill note the command but there are trivial bugs
in vf_pad they should be fixed first and then we should look if there are non
trivial bugs left


> 
> > > put_pixels16_sse2() is assuming some kind of 16-bit alignment for the
> > > value in pixels, it doesn't crash when the y pad value is a multiple
> > > of 16.
> > 
> > do you plan to put this in the documentation? ;)
> > 
> > 
> > > 
> > > > Ill look into this once you fixed pad working without vflip and if its then
> > > > still not working with vflip
> > > 
> > > Uh what's this a sort of bargain? The problems look completely
> > > unrelated.
> > 
> > It doesnt crash for me with vflip, just without :)
> > and you provide no gdb output so theres not much i can do about vflip+pad.
> > I do need a reproduceable testcase & gdb output first.
> > I can fix pad and alignment if you dont know how to do it ...
> 
> ffplay matrixbench_mpeg2.mpg -vf vflip,pad=1000:800:100:100
> 
> crashes with and without optimizations enabled.

also crashes with and without vflip.

And vf_pad is broken, even if you leave the alignment aside, just comment 
.get_video_buffer = get_video_buffer
out and think about what start_frame/draw_slice will then do
nothing gurantees you that the buffer you get in start_frame and draw_slice
has been allocated by your get_video_buffer() even if it is set.

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I do not agree with what you have to say, but I'll defend to the death your
right to say it. -- Voltaire
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