[FFmpeg-devel] [PATCH] libavcodec/qsvenc_hevc: correction for QSV HEVC default plugin selection on Windows

[Li, Zhong]

> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
> Of Maxym Dmytrychenko
> Sent: Sunday, October 14, 2018 3:36 AM
> To: ffmpeg-devel at ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH] libavcodec/qsvenc_hevc: correction for
> QSV HEVC default plugin selection on Windows
> 
> On Sat, Oct 13, 2018 at 6:43 PM Mark Thompson <sw at jkqxz.net> wrote:
> 
> > On 06/10/18 07:21, Landgraph wrote:
> > > 1. Old logic meaned: everywhere, except Windows, ffmpeg has to use
> > > HW
> > acceleration, but on Windows ffmpeg has to use (unavailable) software
> > encode by default
> > > 2. Software encode is available only if you provide corresponding
> > software MediaSDK library, which isn't provided with ffmpeg. More
> > information could be found in
> >
> https://github.com/Intel-Media-SDK/MediaSDK/blob/master/doc/samples/r
> e
> > adme-encode_linux.pdf
> > > 3. HW encode is available on Windows in the driver by default
> >
> > This has been proposed before - I can't find the original discussion
> > (maybe it was on IRC), but I did find <
> >
> https://lists.libav.org/pipermail/libav-devel/2016-November/080419.html>.
> > The reason for not doing it is that a subset of the Intel drivers
> > segfault immediately when the hardware plugin is loaded on some
> > platforms.  That's a pain for anyone wanting to support diverse
> > systems, so the decision was to continue to load the sw plugin by
> > default so it doesn't crash (even if the software plugin isn't
> > present), and leave the non-default case as the crashing one so the user
> has to do something to trigger it.
> >
> > If you can characterise either the set of platforms it crashes on or a
> > set of platforms it definitely works on then maybe we could
> > conditionally change the default behaviour?
> >
> > - Mark
> >
> >
> it was 2 years old discussion and with early drivers (we even had this
> development a bit ahead of general driver availability) now it should be
> working on most of the platforms - I would suggest to make a positive side.

Basically, HEVC HW encoding should be the default case if HW platform can support. 
If crashed with some specified drivers, thus should be a driver issue instead of hiding it in ffmpeg level. 
So, I agree with Maxym and the patch LGTM. 
(Of course, if we can verified on the platforms which was crashed as two years ago, 
that should be fine. However, IMHO this is not MUST. If it is still crash, reporting a bug to the driver developer should be the right way.)