[FFmpeg-devel] [PATCH 3/6] Add AV_PIX_FMT_NV12T.

Alexis Ballier aballier at gentoo.org
Fri Nov 21 10:12:06 CET 2014

On Fri, 21 Nov 2014 09:58:40 +0100
Jean-Baptiste Kempf <jb at videolan.org> wrote:

> On 21 Nov, Alexis Ballier wrote :
> > On Thu, 20 Nov 2014 18:40:18 +0100
> > Jean-Baptiste Kempf <jb at videolan.org> wrote:
> > 
> > > On 20 Nov, Alexis Ballier wrote :
> > > > This is the only format supported by MFC5 HW decoders (e.g.
> > > > Samsung exynos 4412).
> > > 
> > > Why not convert it to a normal format?
> > > 
> > 
> > That is exactly what the m2m filter is for: on 4412 you have MFC HW
> > codecs and fimc (camera & m2m module); the fimc m2m module acts
> > like a filter and accepts this format and outputs much saner ones.
> So you have a format outputted that is of no use, except if you use
> the filter.

On MFCv5 yes; I don't assume because I'm working on this that it is the
only one :)
MFCv6 and newer don't even understand nv12mt and can output standard

there are other v4l2 mem2mem drivers than mfc ones, and I expect more
to come in the future

> And you have a filter that is of no use, except if you
> use this v4l2 output.

again, filter is not bound to samsung socs; even fimc is useful
for other format conversions and even scaling:

(the filter supports fmt conversion and scaling but see also 'missing
features' in the filter patch i've submitted)

I've been using it to convert yuv output of an usb cam to nv12 fed to
the mfc hw enc so that I can stream H263 while leaving the cpu
free for other things.


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