[FFmpeg-devel] [PATCH] Fix unaligned fill_rectangle in rv34.c
Fri Aug 28 18:44:54 CEST 2009
On Fri, Aug 28, 2009 at 03:33:57PM +0200, Michael Niedermayer wrote:
> On Fri, Aug 28, 2009 at 08:29:08AM +0300, Kostya wrote:
> > On Thu, Aug 27, 2009 at 09:57:56PM +0200, Reimar D?ffinger wrote:
> > > On Sat, Aug 22, 2009 at 04:11:19PM +0200, Michael Niedermayer wrote:
> > > > let me try again
> > > > if you write a rectangle of 8xC then there exists a semantic partitioning
> > > > of sizeof=8, and things could be aligned accordingly, if not you cannot
> > > > use fill_rectangle()
> > > > you would have to replace r->avail_cache + 5 by + 6 maybe and make other
> > > > related changes, its perfectly fine as well if you dont and remove all
> > > > calls to fill_rectangle() from your code but fill_rectangle() requires
> > > > aligned memory.
> > >
> > > So can we get over with this and use attached patch?
> > > The important cases needs something far simpler than fill_rectangle,
> > > so it is not that bad code-wise I think.
> > I'm not against it but Michael may complain since this function may be
> > useful for other pieces of code it should be put into some header.
> iam not sure if you try to be sarcastic but if so you are sucessfull
> Arrays should be aligned so that optimized accesses are possible.
> I dont want ffmpeg to become a trashcan of poorly writtem code that
> doesnt align things correctly, if you as maintainer of rv want this
> i wont stop you as i have noone else to maintain this code better
> but i do NOT want this to spread and be done elsewhere.
Let's see what are the cases when fill_rectangle() is used:
1) r->avail_cache - zeroes 8x2 bytes, stride is always 16 bytes,
alignment is 4
2) r->intra_types - zeroes 4x4 bytes, stride is multiple of 4,
alignment is 16
3) pic->motion_val - zeroes 8x2 bytes, stride is s->b8_stride*4,
alignment is 8
For the case 1 I will fix alignment to be 8, for the case 2 there's
nothing to do. In case 3 it fails because of stride since mpegvideo.c
s->b8_stride = s->mb_width*2 + 1
and allocates memory for pic->motion_val according to it.
So in this case I either need custom zeroing function or just strides
> Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
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