[Bug 1708102] Re: Enable hardware video decoding by default in mpv

[Daniel van Vugt]

Thanks for that.

My focus for the past couple of months has been specifically on VAAPI
for Intel HD graphics. That is stable and performs very well too. Intel
HD graphics is important because that covers the vast majority of our
users.

As an example, with a UHD test video I get CPU usage of:
  hwdec=vaapi  5%
  hwdec=vaapi-copy  40%
  hwdec=no  300%

So yes, vaapi works remarkably well. I have not measured how that
translates to watts but the other benefit of using VAAPI is that videos
previously unplayably slow on many machines (UHD and particularly HEVC)
are now actually playable and smooth.

In order to avoid most of the issues you mention though, I think we
should constrain the default config at install time to just:

  if (only one GPU and it is handled by i915) then install:
hwdec=vaapi
  else
hwdec=no
  endif

I don't want to step on the toes of non-Intel users. However equally I
don't want to diminish the great experience we've achieved for users
with just Intel GPUs.

Anyone remaining who does install mpv and continues to experience problems can 
get around them with:
  echo "hwdec=no" > ~/.config/mpv/mpv.conf
I'm happy to monitor the bugs etc and advise people so.

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  Enable hardware video decoding by default in mpv

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[Bug 1708102] Re: Enable hardware video decoding by default in mpv

[Martin Herkt]

Re hwdec:
https://git.srsfckn.biz/mpv/commit/?id=dbef5b737e2f994f02923c8214cba368b663a655

Also, off the top of my head:
- vaapi-egl does not work on AMD hardware AFAIK, breaking hwdec on Wayland and 
resulting in low-quality or incorrect color conversion when vaapi-glx is used
- VDPAU does not support 10-bit video (and 8-bit HEVC is buggy with NVIDIA 
drivers), is generally broken with FOSS drivers
- CUDA decoding is just broken in general
- there’s this gem https://github.com/mpv-player/mpv/issues/4383
- video filtering does not work with non-copy hwdec

Also, at least in my testing, I’ve noticed no energy savings when using
hwdec, on both desktop (measuring at the wall) and my laptops (according
to PowerTOP). Nobody ever bothered to extend the comments in the default
config after all those issues that were encountered. Perhaps I should do
that.

If you *really* want to enable hwdec despite all that, at least restrict
it to the “safer” -copy modes by using auto-copy.

Re Wayland:
- video-sync=display-resample is unavailable with the Wayland backend, which 
also breaks interpolation (a very popular feature to reduce judder)
- Wayland support in mpv is not mature by any stretch, plus we have less than 
one person available to work on it regularly

** Bug watch added: github.com/mpv-player/mpv/issues #4383
   https://github.com/mpv-player/mpv/issues/4383

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[Bug 1708102] Re: Enable hardware video decoding by default in mpv

[Daniel van Vugt]

That is not true. The platform order fix was proposed to upstream 6 weeks 
before it was applied to Ubuntu:
  https://github.com/mpv-player/mpv/pull/4556
At the time the only reason given for upstream not liking it was that native 
wayland surfaces lack title bars. That's not good enough reason to deny users 
working video acceleration out of the box.

As for enabling acceleration by default, that's a goal of the desktop
team for 17.10. According to the default config in the source:

# Enable hardware decoding if available. Often, this does not work with all
# video outputs, but should work well with default settings on most systems.
# If performance or energy usage is an issue, forcing the vdpau or vaapi VOs
# may or may not help.
#hwdec=auto

So the decision to use it depends on the outputs and general
performance. For the outputs we have verified it works well on both X11
and Wayland. For the performance, we have verified that hwdec with VAAPI
provides an order of magnitude improvement. So it meets our goals. In
fact, mpv+hwdec is presently the only player that can compete with the
efficiency other platforms like macOS.

We would like to keep being able to recommend mpv as the optimal player.
However if Ubuntu was forced to disable acceleration out of the box we
would need to withdraw that recommendation because editing config files
is not sufficiently user friendly.

Of course, if users did complain about the state of mpv in Ubuntu then we would 
consider their input. For the moment though there are zero recent bug reports:
  https://bugs.launchpad.net/ubuntu/+source/mpv

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[Bug 1708102] Re: Enable hardware video decoding by default in mpv

[Martin Herkt]

Could you explain to me why you did not ask upstream about this? There
are reasons for these defaults, and this is likely going to flood our
issue tracker. Is this how Ubuntu maintains packages in general? Just
fuck upstream and change defaults because one user thinks he knows
better?

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Title:
  Enable hardware video decoding by default in mpv

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[Bug 1708102] Re: Enable hardware video decoding by default in mpv

[Launchpad Bug Tracker]

This bug was fixed in the package mpv - 0.26.0-3ubuntu1

---
mpv (0.26.0-3ubuntu1) artful; urgency=medium

  * Prefer Wayland over X11, so if both are present (e.g. Xwayland) then
VA-API gets a display type that works (LP: #1698287)
  * Enable hardware acceleration by default (LP: #1708102)

 -- Daniel van Vugt   Wed, 09 Aug 2017
16:38:55 +0800

** Changed in: mpv (Ubuntu)
   Status: Fix Committed => Fix Released

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  Enable hardware video decoding by default in mpv

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[Bug 1708102] Re: Enable hardware video decoding by default in mpv

[Sebastien Bacher]

** Changed in: mpv (Ubuntu)
   Status: In Progress => Fix Committed

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  Enable hardware video decoding by default in mpv

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[Bug 1708102] Re: Enable hardware video decoding by default in mpv

[Daniel van Vugt]

Here's the fix. Working hardware acceleration out-of-the-box, in Wayland
and Xorg.

** Patch added: "mpv_0.26.0-3ubuntu1.debdiff"
   
https://bugs.launchpad.net/ubuntu/+source/mpv/+bug/1708102/+attachment/4929265/+files/mpv_0.26.0-3ubuntu1.debdiff

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  Enable hardware video decoding by default in mpv

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[Bug 1708102] Re: Enable hardware video decoding by default in mpv

[Daniel van Vugt]

I will/should try to remember to patch mpv for bug 1698287 at the same
time as this.

** Summary changed:

- Enable hardware video decoding by default
+ Enable hardware video decoding by default in mpv

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