chromium: enable WebRTC screen sharing via PipeWire

[Logarithmus]

[ci skip]

• libpipewire0.2
• patch chromium's template
• test for all supported archs:
  • x86_64 - works for Chromium 87: chromium: enable WebRTC screen sharing via PipeWire #26144 (comment) & 86: https://youtu.be/AgyxEC7SfGk
  • i686 - works for Chromium 86: https://youtu.be/j0MY9C1CwV4
  • x86_64-musl - works for Chromium 87: https://youtu.be/ZJorRl_7Sh4
    There are minor issues though:
  • you have to kill xdg-desktop-portal* processes sometimes, probably caused by some sort of race condition;
  • also you may need to start/restart screensharing for it to work.
    ✔️ https://www.webrtc-experiment.com/Pluginfree-Screen-Sharing
    ✔️ https://zoom.us (in-browser version)
    ✔️ https://discord.com (in-browser version)

Currently I'm investigating these stability issues with pipewire. It seems that pipewire is trying to use rtkit to make audio/video processing run in real time. Unfortunately, it fails to do so:

2020-11-16T03:49:59.73350 daemon.err: Nov 16 03:49:59 rtkit-daemon[3165]: Failed to make ourselves RT: Function not implemented
2020-11-16T03:49:59.73602 daemon.warn: Nov 16 03:49:59 rtkit-daemon[3165]: Warning: failed to read scheduler policy: Function not implemented
2020-11-16T03:49:59.73620 daemon.debug: Nov 16 03:49:59 rtkit-daemon[3165]: Supervising 0 threads of 0 processes of 1 users.
2020-11-16T03:49:59.73645 daemon.debug: Nov 16 03:49:59 rtkit-daemon[3165]: Supervising 0 threads of 0 processes of 1 users.
2020-11-16T03:49:59.74118 daemon.err: Nov 16 03:49:59 rtkit-daemon[3165]: Failed to make ourselves RT: Function not implemented

After a bit of searching, I've found these bugs:
https://bugzilla.redhat.com/show_bug.cgi?id=1229700
https://bugs.gentoo.org/show_bug.cgi?id=569546

I've built linux5.9 for x86_64 with CONFIG_RT_GROUP_SCHED disabled.
For some strange reason, nothing changed, the error persists. Luckily, screen sharing works without rtkit.
I guess that those rare issues with screen sharing, which were described above, may be caused by rtkit not working.

[Logarithmus]

@ericonr @q66 @Duncaen, finally, this PR is ready for review.
Related PR by @absrd (xdg-desktop-portal-wlr): #23296

[Logarithmus]

I hope this PR will ever be merged... I've spent so much time on it.
Enabling this compile option shouldn't be a problem, because there's a flag in chromium://flags to toggle PipeWire support.

[ifreund]

libpipewire0.2 needs to appear in common/shlibs. Also, I'm getting the following error building chromium:

[16699/43513] CXX obj/third_party/webrtc/modules/audio_processing/vad/vad/voice_activity_detector.o
[16700/43513] STAMP obj/third_party/webrtc/modules/desktop_capture/desktop_capture_generic.inputdeps.stamp
[16701/43513] CXX obj/third_party/webrtc/modules/congestion_controller/goog_cc/estimators/bitrate_estimator.o
[16702/43513] CXX obj/third_party/webrtc/modules/desktop_capture/primitives/shared_desktop_frame.o
[16703/43513] CXX obj/third_party/webrtc/modules/desktop_capture/pipewire_stubs/pipewire_stubs.o
FAILED: obj/third_party/webrtc/modules/desktop_capture/pipewire_stubs/pipewire_stubs.o 
clang++ -MMD -MF obj/third_party/webrtc/modules/desktop_capture/pipewire_stubs/pipewire_stubs.o.d -DUSE_UDEV -DUSE_AURA=1 -DUSE_GLIB=1 -DUSE_NSS_CERTS=1 -DUSE_OZONE=1 -DUSE_X11=1 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_GNU_SOURCE -DCR_CLANG_REVISION=\"llvmorg-12-init-5035-gd0abc757-3\" -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D_FORTIFY_SOURCE=2 -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DWEBRTC_ENABLE_PROTOBUF=1 -DRTC_ENABLE_VP9 -DHAVE_SCTP -DENABLE_EXTERNAL_AUTH -DWEBRTC_USE_H264 -DHAVE_WEBRTC_VIDEO -DLOGGING_INSIDE_WEBRTC -DGLIB_VERSION_MAX_ALLOWED=GLIB_VERSION_2_40 -DGLIB_VERSION_MIN_REQUIRED=GLIB_VERSION_2_40 -DWEBRTC_ENABLE_AVX2 -DWEBRTC_NON_STATIC_TRACE_EVENT_HANDLERS=0 -DWEBRTC_CHROMIUM_BUILD -DWEBRTC_POSIX -DWEBRTC_LINUX -DABSL_ALLOCATOR_NOTHROW=1 -DNO_MAIN_THREAD_WRAPPING -Igen/third_party/webrtc/modules/desktop_capture -I../.. -Igen -I../../third_party/perfetto/include -Igen/third_party/perfetto/build_config -Igen/third_party/perfetto -Igen/shim_headers/libevent_shim -I../../third_party/webrtc_overrides -I../../third_party/webrtc -Igen/third_party/webrtc -I../../third_party/abseil-cpp -I../../third_party/boringssl/src/include -I../../third_party/protobuf/src -Igen/protoc_out -fno-strict-aliasing --param=ssp-buffer-size=4 -fstack-protector -funwind-tables -fPIC -pthread -fcolor-diagnostics -fmerge-all-constants -fcrash-diagnostics-dir=../../tools/clang/crashreports -mllvm -instcombine-lower-dbg-declare=0 -mllvm -enable-dse-memoryssa=false -m64 -march=x86-64 -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -Xclang -fdebug-compilation-dir -Xclang . -no-canonical-prefixes -Wall -Wextra -Wimplicit-fallthrough -Wunreachable-code -Wthread-safety -Wextra-semi -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-unneeded-internal-declaration -Wno-undefined-var-template -Wno-psabi -Wno-ignored-pragma-optimize -Wno-implicit-int-float-conversion -Wno-final-dtor-non-final-class -Wno-builtin-assume-aligned-alignment -Wno-deprecated-copy -O2 -fno-ident -fdata-sections -ffunction-sections -fno-omit-frame-pointer -g0 -ftrivial-auto-var-init=pattern -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -std=c++14 -fno-trigraphs -Wno-trigraphs -fno-exceptions -fno-rtti -fvisibility-inlines-hidden     -c gen/third_party/webrtc/modules/desktop_capture/linux/pipewire_stubs.cc -o obj/third_party/webrtc/modules/desktop_capture/pipewire_stubs/pipewire_stubs.o
gen/third_party/webrtc/modules/desktop_capture/linux/pipewire_stubs.cc:18:10: fatal error: 'pipewire/pipewire.h' file not found
#include <pipewire/pipewire.h>
         ^~~~~~~~~~~~~~~~~~~~~
1 error generated.
[16704/43513] CXX obj/third_party/webrtc/modules/congestion_controller/congestion_controller/receive_side_congestion_controller.o
[16705/43513] CXX obj/third_party/webrtc/modules/congestion_controller/goog_cc/alr_detector/alr_detector.o
[16706/43513] CXX obj/third_party/webrtc/modules/congestion_controller/goog_cc/estimators/acknowledged_bitrate_estimator_interface.o
[16707/43513] CXX obj/third_party/webrtc/modules/desktop_capture/desktop_capture_generic/desktop_capture_options.o
[16708/43513] CXX obj/third_party/webrtc/modules/desktop_capture/desktop_capture_generic/desktop_capturer.o
[16709/43513] CXX obj/third_party/webrtc/modules/desktop_capture/desktop_capture_generic/desktop_and_cursor_composer.o
[16710/43513] CXX obj/third_party/webrtc/modules/congestion_controller/goog_cc/goog_cc/goog_cc_network_control.o
[16711/43513] CXX obj/third_party/webrtc/modules/congestion_controller/rtp/control_handler/control_handler.o
[16712/43513] CXX obj/third_party/webrtc/modules/congestion_controller/rtp/transport_feedback/transport_feedback_adapter.o
ninja: build stopped: subcommand failed.
=> ERROR: chromium-87.0.4280.66_1: do_build: 'ninja -C out/Release ${makejobs} chrome chromedriver mksnapshot' exited with 1
=> ERROR:   in do_build() at srcpkgs/chromium/template:269

Didn't have time to look into what's causing it yet. I'm on x86_64 glibc for what it's worth.

[Logarithmus]

@ifreund that's because for some strange reason chromium package doesn't depend on libpipewire0.2-devel, even though I've added it into the template's makedepends section. I had to build and install it manually. Possibly It's mandatory to add libpipewire0.2 into common/shlibs. Anyway, I've just added it and 'll re-package with this change and see where it goes.

[ericonr]

Possibly It's mandatory to add libpipewire0.2 into common/shlibs

You may need to do this if you want the package to detect the libpipewire dependency, but it shouldn't make any difference for the header to be found.

[Logarithmus]

@ifreund OK, I've fixed libpipewire0.2's template, now headers should be visible. It was correct on my VPS and laptop, but not on GitHub.
@ericonr I've added libpipewire0.2 into common/shlibs. Unfortunately, chromium still doesn't depend on libpipewire0.2. That's because chromium's binary dlopens libpipewire, and thus libpipewire is missing in ldd /lib/chromium/chromium.
IMHO that's a bug in xbps. If this is intended behavior, then we should probably add notice about it to https://docs.voidlinux.org

[ericonr]

That's because chromium's binary dlopens libpipewire, and libpipewire is missing in ldd /lib/chromium/chromium.
IMHO that's a bug in xbps.

That's all working as intended. Applications use dlopen exactly to allow for optional dependencies, and scanning a binary for what it does open will 1) be fragile and 2) remove the usefulness of dlopening in the first place.

[Logarithmus]

That's because chromium's binary dlopens libpipewire, and libpipewire is missing in ldd /lib/chromium/chromium.
IMHO that's a bug in xbps.

That's all working as intended. Applications use dlopen exactly to allow for optional dependencies, and scanning a binary for what it does open will 1) be fragile and 2) remove the usefulness of dlopening in the first place.

OK, if I'll explicitly include libpipewire0.2 into depends section, in addition to makedepends, will it finally work?
IMHO the right solution to such problems is to implement the support for optional dependencies in xbps, like pacman does.
There's an issue about that void-linux/xbps#1, but unfortunately xbps isn't actively developed anymore (I guess that's related to Juan RP's departure).
UPD: Just seen your fairly recent PRs in xbps repo, OK, I was wrong about non-active development.
UPD 2: Seems that including libpipewire0.2 into depends section finally solve the issue! Pushed it

[ifreund]

I still get the same error with the latest commit. I also don't see the include dir for pipewire in the clang++ command line flags, so it seems like pipewire's pkgconfig is not getting used for whatever reason.

[Logarithmus]

@ifreund can I ask you to check if /usr/include/pipewire directory presents in libpipewire0.2-devel package? If it's called pipewire-0.2 instead, then please rebuild the package.

[ifreund]

Looks like it's there, still get the same error building chromium though.

$ xls libpipewire0.2-devel

/usr/include/pipewire/array.h
/usr/include/pipewire/client.h
/usr/include/pipewire/command.h
/usr/include/pipewire/control.h
/usr/include/pipewire/core.h
/usr/include/pipewire/data-loop.h
/usr/include/pipewire/extensions/client-node.h
/usr/include/pipewire/extensions/protocol-native.h
/usr/include/pipewire/factory.h
/usr/include/pipewire/global.h
/usr/include/pipewire/interfaces.h
/usr/include/pipewire/introspect.h
/usr/include/pipewire/link.h
/usr/include/pipewire/log.h
/usr/include/pipewire/loop.h
/usr/include/pipewire/main-loop.h
/usr/include/pipewire/map.h
/usr/include/pipewire/mem.h
/usr/include/pipewire/module.h
/usr/include/pipewire/node.h
/usr/include/pipewire/pipewire.h
/usr/include/pipewire/port.h
/usr/include/pipewire/properties.h
/usr/include/pipewire/protocol.h
/usr/include/pipewire/proxy.h
/usr/include/pipewire/remote.h
/usr/include/pipewire/resource.h
/usr/include/pipewire/stream.h
/usr/include/pipewire/thread-loop.h
/usr/include/pipewire/type.h
/usr/include/pipewire/utils.h
/usr/include/pipewire/version.h
/usr/include/pipewire/work-queue.h
/usr/include/spa/buffer/buffer.h
/usr/include/spa/buffer/meta.h
/usr/include/spa/clock/clock.h
/usr/include/spa/graph/graph.h
/usr/include/spa/monitor/monitor.h
/usr/include/spa/node/command.h
/usr/include/spa/node/event.h
/usr/include/spa/node/io.h
/usr/include/spa/node/node.h
/usr/include/spa/param/audio/format-utils.h
/usr/include/spa/param/audio/format.h
/usr/include/spa/param/audio/raw-utils.h
/usr/include/spa/param/audio/raw.h
/usr/include/spa/param/buffers.h
/usr/include/spa/param/format-utils.h
/usr/include/spa/param/format.h
/usr/include/spa/param/io.h
/usr/include/spa/param/meta.h
/usr/include/spa/param/param.h
/usr/include/spa/param/props.h
/usr/include/spa/param/video/chroma.h
/usr/include/spa/param/video/color.h
/usr/include/spa/param/video/encoded.h
/usr/include/spa/param/video/format-utils.h
/usr/include/spa/param/video/format.h
/usr/include/spa/param/video/multiview.h
/usr/include/spa/param/video/raw-utils.h
/usr/include/spa/param/video/raw.h
/usr/include/spa/pod/builder.h
/usr/include/spa/pod/command.h
/usr/include/spa/pod/event.h
/usr/include/spa/pod/iter.h
/usr/include/spa/pod/parser.h
/usr/include/spa/pod/pod.h
/usr/include/spa/support/log-impl.h
/usr/include/spa/support/log.h
/usr/include/spa/support/loop.h
/usr/include/spa/support/plugin.h
/usr/include/spa/support/type-map-impl.h
/usr/include/spa/support/type-map.h
/usr/include/spa/utils/defs.h
/usr/include/spa/utils/dict.h
/usr/include/spa/utils/hook.h
/usr/include/spa/utils/list.h
/usr/include/spa/utils/ringbuffer.h
/usr/include/spa/utils/type.h
/usr/lib/pkgconfig/libpipewire-0.2.pc
/usr/lib/pkgconfig/libspa-0.1.pc
/usr/lib/libpipewire-0.2.so -> /usr/lib/libpipewire-0.2.so.1

[Logarithmus]

Looks like it's there, still get the same error building chromium though.

$ xls libpipewire0.2-devel

I guess you have to rerun configure & build stages for chromium in order for it to see the headers.

[ifreund]

I guess you have to rerun configure & build stages for chromium in order for it to see the headers.

Looks like you were right, after a git clean and several hours it finished building. I should have time to get xdpw/pipewire setup and give this a test later tonight or tomorrow.

[ifreund]

Confirmed that this works with #23296 to screenshare on sway x86_64 glibc using the webrtc test page here: https://mozilla.github.io/webrtc-landing/gum_test.html

[Logarithmus]

Finally, my changes have been merged (#27060)! Thanks to everyone who were involved.