On Mon, 24 Mar 2014 22:25:35 +0100
Luca Barbato <[email protected]> wrote:

> On 24/03/14 22:09, Rémi Denis-Courmont wrote:
> > Le lundi 24 mars 2014, 21:53:35 Luca Barbato a écrit :
> >> First friendly warning: please tone down two notches.
> > 
> > I suggest you check your facts before you flame me then taunt me.
> 
> Nobody is flaming you, just this kind of tone is not welcome.
> 
> >>> If you keep a single pixel format regardless, the only way for the
> >>> application to know the correct parameters is look at the last pixel
> >>> format (i.e. software) in the list and second-guess libavcodec that this
> >>> indicates the correct chroma type and pixel depth. This would be
> >>> vomitively ugly, and it would forever lock libavcodec into offering only
> >>> a single software output pixel format ever. Is that really what you want?
> >>
> >> It is actually what normally happens, as explained by Hendrik, Anton and
> >> wm4.
> > 
> > This is patently false. Look at get_pixel_format() from h264.c for yourself!
> 
> The code in avconv_vdpau and mpv does the surface mapping based on the
> global context (set by the very same application).
> 
> VDA does the same.

I think the problem at hand is that there's no way for the hwaccel API
to signal to the application which surface format should be used.

And he's right: if new surface types other than 420 were ever
supported, it would probably break dxva/vdpau/vaapi.

So the basic problem is that even if the decoder reports a higher
level profile as supported, the application (written against the
current API) would allocate the wrong surface type.

> > libavcodec does not currently call get_format() for anything other than 420 
> > content(*)- Therefore, it does not offer AV_PIX_FMT_(VDPAU|VAAPI) for 422. 
> > Instead, it just hard codes the software decoding pixel format in that case.
> 
> That can be easily fixed, I guess.
> 
> >> I'm sorry about this misconception, sadly hwaccel hadn't been documented
> >> so everybody had an understanding on how it works and all the time a
> >> detail or another might fit by pure chance.
> > 
> > You are distorting reality here. This stuff (non-420 hwaccel) is not 
> > implemented yet. Of the two potential ways to implement it, you defend the 
> > backward-incompatible and ugliest one.
> 
> I'm not distorting anything, please tone down.
> 
> You assume one way is the correct one, the other people involved assume
> the other.
> 
> As I told you, the original hwaccel does not assume anything beside
> black boxes and opaque pointers.
> 
> What Hendrik, Anton, wm4 consider correct as approach had been
> implemented on their side, you assumed otherwise and implemented that
> way in VLC.
> 
> It can be *calmly* discussed w/out considering a war.
> 
> Worst case I'll fix that part in VLC if you do not want to.
> 
> lu
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