Deinterlacing problem

[Russel Winder]

On Fri, 2020-10-23 at 17:41 +0100, Tony Houghton wrote:
> VA-API probably has negligible benefit for SD MPEG 2 on a modern CPU, but
> you should try to use it for HDTV. Are you saying that the deinterlacing
> problems are caused by VA-API? What are the symptoms? Does gstreamer-vaapi
> let you control the deinterlacing mode? If all of its modes are
> problematic, perhaps it can be set to off and you can insert a separate
> deinterlacer element.

Without the VA-API available the GstDecodeBin uses a avdec_mpeg2video element.
Then there is a GstDeinterlace element further down the pipeline that does the
deinterlacing.

With the VA-API the GstDecodeBin uses a GstVaapiDecodeBin instead of a
avdec_mpeg2video element which then includes a GstVaapiPostproc that seems to
do deinterlacing except that it does it all wrong. The GstDeinterlacing
element is still in the pipeline but seems to have nothing to do since the
input is progressive.

I do some pipeline manipulation to deal with OpenGL as it is important to do
deinterlacing in the OpenGL memory. It seems as though I may have to do
something similar if using VA-API.

> Also, I noticed that although gstreamer-vaapi gives high ranks to its
> decoders to override software mode, it doesn't promote its sink, so if
> you're using something like playbin or autovideosink it will probably use
> something like xvimagesink. You might want to try making sure it's using
> vaapisink or opengl.

Both non-OpenGL/nonVA-API and VA-API pipelines use a GstPlaySinkVideoConvert
feeding into a GstGtkSink. I have attached PDF files of the two pipelines.

-- 
Russel.
===========================================
Dr Russel Winder      t: +44 20 7585 2200
41 Buckmaster Road    m: +44 7770 465 077
London SW11 1EN, UK   w: www.russel.org.uk

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