GST plugins 1.20.x break mopidy audio playback on intel machines

[troyxmccall]

i haven't pinpointed the root cause, but running a standard brew update broke mopidy audio playblack

changes/formula updates

gst-plugins-bad (1.18.5) -> 1.20.1
gst-plugins-base (1.18.5) -> 1.20.1
gst-plugins-good (1.18.5) -> 1.20.1
gst-plugins-ugly (1.18.5) -> 1.20.1
gst-python (1.18.5) > 1.20.1
gstreamer (1.18.5) > 1.20.1

Error:

ERROR    2022-04-03 23:39:01,816 [18108:Audio-2] pykka
  Unhandled exception in Audio (urn:uuid:b91a9751-5106-48bf-b6ba-7c2fde717ad6):
Traceback (most recent call last):
  File "/usr/local/Cellar/mopidy/3.2.0/libexec/lib/python3.9/site-packages/pykka/_actor.py", line 186, in _actor_loop
    self.on_start()
  File "/usr/local/Cellar/mopidy/3.2.0/libexec/lib/python3.9/site-packages/mopidy/audio/actor.py", line 460, in on_start
    self._setup_playbin()
  File "/usr/local/Cellar/mopidy/3.2.0/libexec/lib/python3.9/site-packages/mopidy/audio/actor.py", line 481, in _setup_playbin
    playbin.set_property("flags", _GST_PLAY_FLAGS_AUDIO)
AttributeError: 'NoneType' object has no attribute 'set_property'

restoring /usr/local/bin from a snapshot with GST plugins @1.18.5 fixed playback

in the interim, I suggest NOT upgrading homebrew

[crossjam]

Just stopped by to ask if there's any suggestions for those of us latecomers to Mopidy who don't have 1.18.5 available? Can't see an easy way to downgrade on Mac OS.

[spijet]

I got the same issue on an Apple Silicon machine, so it's not architecture-dependent.

The error log from Mopidy:

DEBUG    2022-06-01 10:46:38,820 [43130:MainThread] mopidy.commands
  Available Mopidy mixers: SoftwareMixer
INFO     2022-06-01 10:46:38,820 [43130:MainThread] mopidy.commands
  Starting Mopidy mixer: SoftwareMixer
DEBUG    2022-06-01 10:46:38,821 [43130:MainThread] mopidy.commands
  Mixer volume left unchanged
INFO     2022-06-01 10:46:38,821 [43130:MainThread] mopidy.commands
  Starting Mopidy audio
ERROR    2022-06-01 10:46:38,821 [43130:Audio-2] pykka
  Unhandled exception in Audio (urn:uuid:0ee60950-ce88-4b2d-ac46-29127b8254d9):
Traceback (most recent call last):
  File "/opt/homebrew/lib/python3.9/site-packages/pykka/_actor.py", line 179, in _actor_loop
    self.on_start()
  File "/opt/homebrew/lib/python3.9/site-packages/mopidy/audio/actor.py", line 460, in on_start
    self._setup_playbin()
  File "/opt/homebrew/lib/python3.9/site-packages/mopidy/audio/actor.py", line 481, in _setup_playbin
    playbin.set_property("flags", _GST_PLAY_FLAGS_AUDIO)
AttributeError: 'NoneType' object has no attribute 'set_property'
INFO     2022-06-01 10:46:38,821 [43130:MainThread] mopidy.commands
  Starting Mopidy backends: FileBackend, M3UBackend, StreamBackend, SubidyBackend

...

ERROR    2022-06-01 10:46:50,067 [43130:Core-7] mopidy.core.playback
  SubidyBackend backend caused an exception.
Traceback (most recent call last):
  File "/opt/homebrew/lib/python3.9/site-packages/mopidy/core/playback.py", line 350, in _change
    if not backend.playback.change_track(pending_tl_track.track).get():
  File "/opt/homebrew/lib/python3.9/site-packages/pykka/_threading.py", line 55, in get
    raise exc_value
  File "/opt/homebrew/lib/python3.9/site-packages/pykka/_actor.py", line 186, in _actor_loop
    response = self._handle_receive(envelope.message)
  File "/opt/homebrew/lib/python3.9/site-packages/pykka/_actor.py", line 286, in _handle_receive
    return callee(*message.args, **message.kwargs)
  File "/opt/homebrew/lib/python3.9/site-packages/mopidy/backend.py", line 318, in change_track
    self.audio.set_uri(
  File "/opt/homebrew/lib/python3.9/site-packages/pykka/_threading.py", line 55, in get
    raise exc_value
  File "/opt/homebrew/lib/python3.9/site-packages/pykka/_ref.py", line 106, in ask
    raise ActorDeadError(f"{self} not found")
pykka._exceptions.ActorDeadError: Audio (urn:uuid:0ee60950-ce88-4b2d-ac46-29127b8254d9) not found
WARNING  2022-06-01 10:46:50,069 [43130:Core-7] mopidy.core.tracklist
  Track is not playable: subidy:song:tr-45080

[troyxmccall]

hey @crossjam @spijet

I don't have an ETA on this fix, a lot of Open Source projects I contribute to are on life-support, and sadly, I don't have the time work on even 5% of the outstanding issues.

My suggestion would be to look into building/running your own Mopidy Docker image with pulseaudio running as a brew service in the interim

these might help you get started:

https://github.com/troyxmccall/pulseaudio-macos

https://github.com/jaedb/Iris/blob/master/Dockerfile

You're also more than welcome to fork this repo and build your own bottles/tap for GST 1.18

[crossjam]

No worries @troyxmccall ! Thanks for your previous Open Source contributions. Just saw a recent update of the gst libs on homebrew. Maybe that'll be the fix. 🤞

[2e0byo]

The problem seems to be that gstreamer somehow doesn't know where to look for plugins when called from within python, i.e. it's an env problem. See this SO question.

Setting the env var GST_PLUGIN_PATH fixes it (at least for me):

gst-inspect-1.0 playbin | grep Filename # to get the filename
GST_PLUGIN_PATH=/usr/local/lib/gstreamer-1.0/ mopidy

This is probably an upstream issue, but I don't know what the expectation is with load paths and python, and I barely know the gstreamer ecosystem.

For the time being a fix would be just to set the env var in the mopidy script installed by this repo.

[crossjam]

@2e0byo Thanks much! It's been a while since I got stuck into this but even a cursory attempt seems to improve things. I can actually do a mopidy local scan successfully.

[crossjam]

Can now also confirm that appropriately setting the GST_PLUGIN_PATH environment variable allows for proper audio playback. Here's what I did on my M1 MacBook Air (YMMV):

export GST_PLUGIN_PATH=/opt/homebrew/lib/gstreamer-1.0/