Re: gstreamer: v4l2videodec plugin

[Nicolas Dufresne <nicolas.dufresne@collabora.com>]

Le lundi 11 avril 2016 à 15:11 +0300, Stanimir Varbanov a écrit :
> adding gstreamer-devel
> 
> On 04/11/2016 03:03 PM, Stanimir Varbanov wrote:
> > 
> > Hi,
> > 
> > I'm working on QCOM v4l2 video decoder/encoder driver and in order
> > to
> > test its functionalities I'm using gstreamer v4l2videodec plugin. I
> > am
> > able to use the v4l2videodec plugin with MMAP, now I want to try
> > the
> > dmabuf export from v4l2 and import dmabuf buffers to glimagesink. I
> > upgraded gst to 1.7.91 so that I have the dmabuf support in
> > glimagesink.
> > Mesa version is 11.1.2.

I'm very happy to see this report. So far, we only had report that this
element works on Freescale IMX.6 (CODA) and Exynos 4/5.

> > 
> > I'm using the following pipeline:
> > 
> > GST_GL_PLATFORM=egl GST_GL_API=gles2 gst-launch-1.0 $GSTDEBUG
> > $GSTFILESRC ! qtdemux name=m m.video_0 ! h264parse ! v4l2video32dec
> > capture-io-mode=dmabuf ! glimagesink
> > 
> > I stalled on this error:
> > 
> > eglimagememory
> > gsteglimagememory.c:473:gst_egl_image_memory_from_dmabuf:<eglimagea
> > llocator0>
> > eglCreateImage failed: EGL_BAD_MATCH
> > 
> > which in Mesa is:
> > 
> > libEGL debug: EGL user error 0x3009 (EGL_BAD_MATCH) in
> > dri2_create_image_khr_texture
> > 
> > Do someone know how the dmabuf import is tested when the support
> > has
> > been added to glimagesink? Or some pointers how to continue with
> > debugging?

So far the DMABuf support in glimagesink has been tested on Intel/Mesa
and libMALI. There is work in progress in Gallium/Mesa, but until
recently there was no support for offset in imported buffer, which
would result in BAD_MATCH error. I cannot guaranty this is the exact
reason here, BAD_MATCH is used for a very wide variety of reason in
those extensions. The right place to dig into this issue would be
through the Mesa list and/or Mesa code. Find out what is missing for
you driver in Mesa and then I may help you further.

For the reference, the importation strategy we use in GStreamer has
been inspired of Kodi (xmbc). It consist of importing each YUV plane
seperatly using R8 and RG88 textures and doing the color conversion
using shaders. Though, if the frame is allocated as a single DMABuf,
this requires using offset to access the frame data, and that support
had only been recently added in Gallium base code and in Radeon driver
recently. I don't know if Freedreno, VC4 have that, and I know nouveau
don't.

cheers,
Nicolas