[XviD-devel] RE: possible vfw YV12 stride bug

Ivan Kalvachev ivan at cacad.com
Fri Jan 30 18:48:22 CET 2004


Christoph Lampert said:
> On Tue, 27 Jan 2004, Ivan Kalvachev wrote:
>> I resend this letter, as i didn't get it in the maillist
>> and i don't see it in the archives. I hope it will pass your spam
protection ...
>> I think it is the right time to remind you about
>> CSP_USER vs CSP_YV12 vs CSP_I420
>> these issues are still not fixed, but they should
>> be fixed before final 1.0 version.
>> Pleace do it now, or
>> you will have to patch interface later.
>
> Didn't I fix them a couple of weeks ago?
>
> XVID_CSP_I420 is YCrCb == internal colorspace for MPEG
>
> XVID_CSP_YV12 is YCbCr == U and V plane swapped
>
> XVID_CSP_USER is YCrCb, but with arbitrary pointers and different
strides
> for Y and UV (so it can emulate the other two)

ABSOLUTLY NO!!!

YV12 is YCbCr and accroding to mpeg standart the Chroma 4:2:0 blocks
are coded in that order
Y - 0,1,2,3
Cb- 4
Cr- 5

So, YV12 is the internal colorspace for MPEG. Currently
dshow and vfw modules map IYUV colorspace to YV12 that is wrong.
I420 is the same as IYUV. So it works becouse you double swap them.
I had pointed URL in my prevous mails... grep ml archives...
I had also send a patch...

Unix players use XVID_CSP_USER and are not affected by these changes.
And I obey you to change the XVID_CSP_USER to something more meaningfull,
like XVID_CSP_PLANAR or whatever.

Best Regards
   Ivan Kalvachev
  iive

>
> gruel
>
>



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