IMX Scaler / CSC m2m driver.

[Nicolas Dufresne]

Le lundi 08 février 2016 à 08:32 +0100, Florian Vaussard a écrit :
> Hello Nicolas,
> 
> On 02/06/2016 12:06 AM, Nicolas Dufresne wrote:
> > Le vendredi 05 février 2016 à 04:29 -0800, Florian Vaussard a écrit
> > :
> > > I am resurrecting this thread as I am also interested in using
> > > the
> > > mainline
> > > kernel to play video on iMX6. Has the status somehow evolved? So
> > > far
> > > I was
> > > able to use the hardware decoder with Linux 4.4 / gstreamer 1.6.1
> > > but
> > > with
> > > poor performances. By using Philipp's patches I am confident that
> > > I
> > > could
> > > use the mem2mem CSC as well. But has someone been able to play
> > > 1920x1080
> > > H264 smoothly on the HDMI or LVDS output?
> > > 
> > > The latest figure from Ian was 6.5FPS @ 1080p if I remember well.
> > > If
> > > this
> > > figure is still the best that one can get nowadays using mainline
> > > tools,
> > > where is the bottleneck compared to Freescale's BSP and is there
> > > any
> > > way one
> > > can help?
> > 
> > What sink are you using ? What settings to you apply to
> > v4l2videoNdec ?
> > 
> 
> The pipeline of Ian in the aforementioned thread was (if I am not
> mistaking):
> 
> gst-launch-1.0 filesrc location=
> Downloads/big_buck_bunny_1080p_h264.mov !
> qtdemux ! h264parse ! v4l2video3videodec capture-io-mode=dmabuf !
> v4l2video0convert output-io-mode=dmabuf-import !
> video/x-raw,width=1920,height=1080 ! ximagesink sync=false
> 
> Currently I am using only v4l2videoNdec + fbdevsink. I am porting
> Philipp's
> patches to linux 4.4 to get the IPU color converter but there is some
> work due
> to recent changes in media and I am lacking time. So first I am
> looking at the
> performances obtained by other people.
> 
> I saw some out-of-tree DRM/KMS sinks [1][2] but they don't appear to
> be merged
> in gstreamer and both appear to be 2 years old, thus it will probably
> take some
> time to get them up and running :-/ Do you know any other
> alternatives?

I believe this work will start being merges as soon as I have the time.
kmssink is the only way forward at the moment. Don't expect anything to
be fast with fbdevsink or ximagesink. They both require a copy and RGB
colorspace to be used. glimagesink gained support for DMABuf recently,
that works nicely on Intel GPU and ARM Mali (that my testing of it),
but unfortunatly DMABuf isn't part of the IMX.6 proprietary GL stack
(they got their own vendor API instead).

https://bugzilla.gnome.org/show_bug.cgi?id=761059

> 
> So before going into this, I just wanted to be sure that one can get
> good
> performances at the end of the day without being trapped in a dead-
> end.

It's not a dead-end, there is already people managing good performance
there. But clearly time constrained lead them to create not so nice
"vendor" branch of everything. The upstreaming process is going well
though, in all front. I see regular patches on the Linux Kernel, I also
receive patches and get bug report on GStreamer to tweak certain aspect
of the v4l2decoder support. Feel free to jump in and contribute
something.

cheers,
Nicolas
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