[FFmpeg-devel] [PATCH] avutil/motion_vector: export subpel motion information

[Michael Niedermayer]

On Mon, Nov 23, 2015 at 11:01:02AM +0100, Clément Bœsch wrote:
> On Sun, Nov 22, 2015 at 04:27:02PM +0100, Michael Niedermayer wrote:
> [...]
> > > > IIUC src_x/y are only an approximation, as the exact motion vector
> > > > isnt an integer in fullpel units so it would be mostly cosmetic
> > > > if x + 4 >> 8, or /8 is used
> > > 
> > > yes
> > > 
> > > mpeg used x >> n, i replaced with x / (1<<n), but i could switch back to
> > > the original shift, or even do x+(1<<(n-1))>>n if you want some rounding.
> > > 
> > > same for snow... what would you prefer? i have no real opinion, this code
> > > doesn't interfere with normal decoding anyway (so performance is less
> > > relevant)
> > 
> > i really dont know, i think something mostly symmetrical should be
> > preferred so that for visualization the vectors arent biased in
> > some direction
> > thus a plain >> 3 might be bad
> > 
> 
> So I kept the division, but hardcoded the 8 in snow.
> 
> Applied, thanks
> 
> BTW: can't we get more information on the "direction" (that is, the source
> ref) for h264? Currently in the mpegvideo code, we have two ref possible
> (forward and backward), but h264 (and maybe other similar codecs sharing
> that code) can pick from more refs, right?

yes

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have often repented speaking, but never of holding my tongue.
-- Xenocrates
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