Help with gstreamer-vaapi + rockchip vpu vaapi driver

[Nicolas Dufresne]

Le lundi 15 octobre 2018 à 17:04 -0300, Ezequiel Garcia a écrit :
> On Mon, 15 Oct 2018 at 10:07, Víctor Jáquez <vjaquez at igalia.com>
> wrote:
> > 
> > Hi,
> > 
> > On Fri, 12 Oct 2018 at 16:58, Ezequiel Garcia wrote:
> > > Victor,
> > > 
> > > Found some time to pick up my investigation on vaapi on v4l,
> > > using
> > > bootlin's vaapi backend.
> > > I am using gst-build to get latest sources, and set the env
> > > variables
> > > as you suggested.
> > > The vaapi backend is properly detected:
> > > 
> > > # gst-inspect-1.0 vaapi
> > > Plugin Details:
> > >   Name                     vaapi
> > >   Description              VA-API based elements
> > >   Filename
> > > /root/gst-build/build/subprojects/gstreamer-
> > > vaapi/gst/vaapi/libgstvaapi.so
> > >   Version                  1.15.0.1
> > >   License                  LGPL
> > >   Source module            gstreamer-vaapi
> > >   Binary package           gstreamer-vaapi
> > >   Origin URL
> > > http://bugzilla.gnome.org/enter_bug.cgi?product=GStreamer
> > > 
> > >   vaapimpeg2dec: VA-API MPEG2 decoder
> > >   vaapipostproc: VA-API video postprocessing
> > >   vaapidecodebin: VA-API Decode Bin
> > >   vaapisink: VA-API sink
> > > 
> > >   4 features:
> > >   +-- 4 elements
> > > 
> > > The pipeline I  am trying now is (see full log below):
> > > 
> > > GST_DEBUG=vaapi*:4 gst-launch-1.0 filesrc
> > > location=~/big_buck_bunny_480p_MPEG2_MP2_25fps_1800K.MPG !
> > > mpegpsdemux
> > > ! vaapimpeg2dec ! video/x-raw,width=854,height=480 ! kmssink
> > > 
> > > Now, my question is: is it possible to connect a vaapi decoder to
> > > a
> > > non-vaapi sink? Judging from this traces:
> > > 
> > > 0:00:01.230428590 32630   0x555350 INFO             vaapidecode
> > > gstvaapipluginbase.c:959:gst_vaapi_plugin_base_decide_allocation:
> > > <vaapidecode_mpeg2-0>
> > > ignoring non-VAAPI pool: <kmsbufferpool1>
> > > 0:00:01.270321791 32630   0x555350 ERROR                  vaapi
> > > gstvaapibufferproxy.c:228:gst_vaapi_buffer_proxy_new_from_object:
> > > failed to acquire the underlying VA buffer handle
> > > 0:00:01.270796060 32630   0x555350 ERROR                default
> > > gstvaapisurface_drm.c:54:gst_vaapi_surface_get_drm_buf_handle:
> > > failed
> > > to allocate export buffer proxy
> > > 
> > > I think not. So, I need to add proper support for a vaapisink DRM
> > > display, right?
> > 
> > Nope, you should be capable to use (almost) any sink.
> > 
> 
> OK, cool. So I have dig it further and managed to get some
> results. Still not working fully.
> 
> > For example, I have a blog post, using an atom board, playing a
> > video with vaapi
> > and kmssink
> > 
> > 
https://blogs.igalia.com/vjaquez/2016/07/01/va-api-and-drmkms-in-minnowboard/
> > 
> > If I understand correctly the logs, vaapi decides to use the dmabuf
> > allocator
> > for the src allocator but when the decode wants to use those
> > surfaces, the
> > cannot be allocated.
> > 
> > I would recommend, as a test, to change the code to use the surface
> > allocator
> > and use the vaapi mapping when copying the frames to kmssink.
> > 
> > 
https://cgit.freedesktop.org/gstreamer/gstreamer-vaapi/tree/gst/vaapi/gstvaapipluginbase.c#n532
> > 
> > Is dmabuf supported bye the v4l2 vaapi driver??
> > 
> 
> Yes, it does.
> 
> However, I found a few things that seemed off:
> 
> 1. On this particular platform, the library requires
> PRIME_2 buffer type for AcquireBufferHandle.
> It's done only if the pixel format is tiled,
> but I have relaxed the requirement, since it
> doesn't seem needed to acquire the buffer.
> 
> See: 
> https://github.com/bootlin/libva-v4l2-request/blob/master/src/buffer.c#L212
> 
> 2. Also, since there is no GetImage implementation
> I have enabled GST_VAAPI_ENABLE_DIRECT_RENDERING=1,
> so DeriveImage is used.
> 
> Although there are some artifacts, see image attached,
> and also there's a SIGSEGV somewhere in v4l library.
> 
> However, I think this will prevent proper zero-copy to work,
> since DeriveImage is effectively memcpying
> the surface into an image.
> 
> Does gst-vaapi support zero-copy VAAPI to DRM ?

Not at the moment. There is no VAAPI DRM backend, and the dmabuf
exportation need to be ported to PRIME_2 in order to expose the
modifiers. Whenever there is no modifiers, normal DMABuf will be used
and then kmssink could work.

> 
> Do you know what hooks should I implement in the vaapi backend?
> GetImage is not implemented, but I suspect it would
> be another memcpy, or am I wrong?
> 
> Thanks a lot!
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