[FFmpeg-devel] Need suggestion for ROTATION
Tue Nov 27 10:47:01 CET 2007
Tilak Adhya a ?crit :
> On Thu, 22 Nov 2007 Michel Bardiaux wrote :
> >Tilak Adhya a ?crit :
> > >
> > > Hi Micheal,
> > >
> >Please dont top-post.
> > > Thanks for the reply.
> > > Yes, I meant yuv420P. But in the ffmpeg code-base
> > > it is really difficult to get the point, where to
> > > add the code. We thought to add the rotation specific
> > > code in the do_video_out() function of ffmpeg.c. Is it
> > > a right place to add code ?
> >The logical place would be where the re-scaler is called, maybe its
> >there. Other logical places would be as a vhook (but (1) that API is
> >being depercated (2) I dont know that it supports size change); and the
> >replacement for vhhok now in development. Read the archives about vhook.
> >Note that if your rotation *replaces* the rescaling, it must act as if a
> >-s was specified on the output side. So your best strategy would be to
> >remove the -s option on output, and see which variable that affects, and
> > remove that variable, etc... letting the compiler errors guide you.
> >If you have to keep both -s on output and a rotation...
> I am not using the rescaling. I am simply trying to rotate a frame by
Rotation of an image wxh will give an image hxw so you *do* a kind of
rescaling, so you will have to master what the rescaler code does in ffmpeg.
> And the good news is that, I have been able to rotate the
> frame by 90 degree in the Y plane, but not able to do the same in the U
> and V plane. Actually, it is the YUV420P and I've confused about the no
> of U and V. strlen(AVPicture->data)
strlen? Certainly not!
> represents the product of height
> and width but I don't get any relation for the U and V components.
For YUV420P there are wxh bytes in the Y plane, (w/2)x(h/2) in the U
plane, ditto V. Each byte in the U plane is the average of U for the 4
> Again in the rotated picture I am getting only the 80% of the picture,
> I mean some portion has been truncated. Not getting any idea to proceed.
Post precise descritions! '80% of the picture' is meaningless. Unless we
get a prize for guessing right? Hint: I suspect the output image is not
correctly initialized (wrong w or h or linesize or ...) or incorrectly
> Could you please help me out...
T +32  2 790 29 41
F +32  2 790 29 02
E mailto:mbardiaux at mediaxim.be
Vorstlaan 191 Boulevard du Souverain
Brussel 1160 Bruxelles
More information about the ffmpeg-devel