hi, could you please clarify how did you run mpv?
In my case - 
>mpv --hwsub=auto <path_to_video>
doesn't print this error (tested on 19.1.0-rc1 and git master).
Also provide please link to video, if this may be important.

Since I only have an integrated graphics adapter I tried to make the build as slim as possible. Here are the configuration options I use to build mesa:

    -D b_lto=false \
    -D b_ndebug=true \
    -D platforms=x11,wayland,drm,surfaceless \
    -D dri-drivers=i965 \
    -D gallium-drivers=iris,swrast \
    -D vulkan-drivers=intel \
    -D swr-arches=avx,avx2 \
    -D dri3=true \
    -D egl=true \
    -D gallium-extra-hud=true \
    -D gallium-nine=true \
    -D gallium-omx=disabled \
    -D gallium-opencl=icd \
    -D gallium-va=false\
    -D gallium-vdpau=false \
    -D gallium-xa=false \
    -D gallium-xvmc=false \
    -D gbm=true \
    -D gles1=true \
    -D gles2=true \
    -D glvnd=true \
    -D glx=dri \
    -D libunwind=true \
    -D llvm=true \
    -D lmsensors=true \
    -D osmesa=gallium \
    -D shared-glapi=true \
    -D valgrind=false

Did I accidentally turn off any important options for hardware decoding?

The command line to run mpv is:

MESA_LOADER_DRIVER_OVERRIDE=iris mpv --no-config --hwdec=auto "https://www.youtube.com/watch?v=jKv4Pb0SEJE"

thanks for clarification. Could you also specify you HW information?

I reproduced this issue only on CFL with intel UHD630.
Issue wasn't reproduced on KBL's with UHD620 (manjaro) and HD620 (ubuntu and manjaro).

HW information:

$ lspci | grep -i vga
00:02.0 VGA compatible controller: Intel Corporation Iris Plus Graphics 640 (rev 06)

$ MESA_LOADER_DRIVER_OVERRIDE=iris glxinfo | grep -i opengl
OpenGL vendor string: Intel
OpenGL renderer string: Mesa Intel(R) Iris Plus Graphics 640 (Kaby Lake GT3e)
OpenGL core profile version string: 4.5 (Core Profile) Mesa 19.1.0-rc1
OpenGL core profile shading language version string: 4.50
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 3.1 Mesa 19.1.0-rc1
OpenGL shading language version string: 1.40
OpenGL context flags: (none)
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.2 Mesa 19.1.0-rc1
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20
OpenGL ES profile extensions:

Yes, Iris doesn't support nv12 EGL image import yet.

This won't be fixed on 19.1, but I hope to fix it on master at some point.

Hmm, actually this is working fine for me, with libva-intel-driver 2.3.0, mpv 0.29.1, and mesa master...

Hi Kenneth, yes, I can confirm the same. Looks like it was fixed/implemented with this commit (at least reversed bisect pointed on it):


Author: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>  2019-04-30 21:51:52
Committer: Kenneth Graunke <kenneth@whitecape.org>  2019-05-07 23:36:08
Parent: 748f603390bdfec129bc73d3d2608db20f1571ae (gallivm: fix broken 8-wide s3tc decoding)
Branches: master, remotes/origin/master
Follows: 19.1-branchpoint
Precedes: 

    iris: support dmabuf imports with offsets
    
    this adds support for imports where the image data begins at an offset
    from the start of the buffer, as used in h/x264
    
    fixes kwg/mesa#47

That makes sense.  Commit 4b5e8eb3c8d709bd7c6d1a33a114bf4b002548f8 from today should also help with NV12 support.

We're not backporting iris fixes to 19.1; feel free to use master.