ao_pipewire: mpv hangs on quit after a second "loadfile replace" when the video output fails to initialize (ao thread spins in epoll_wait on a closed fd)

mpv Information

mpv v0.41.0 Copyright © 2000-2025 mpv/MPlayer/mplayer2 projects
libplacebo version: v6.338.2
FFmpeg version: 6.1.1-3ubuntu5
FFmpeg library versions:
   libavcodec      60.31.102
   libavdevice     60.3.100
   libavfilter     9.12.100
   libavformat     60.16.100
   libavutil       58.29.100
   libswresample   4.12.100
   libswscale       7.5.100

Other Information

- Linux version: Ubuntu 24.04.5 LTS (Noble), kernel 6.8.0-139-generic #139-Ubuntu SMP PREEMPT_DYNAMIC
- Source of mpv: PPA ppa:ubuntuhandbook1/mpv, package mpv 0.41.0-0ubuntu5~ubuntu2404
- PipeWire: pipewire 1.0.5, libpipewire-0.3-0t64 1.0.5-1ubuntu3.3 (32/64-bit)
- Session: SSH only. XDG_SESSION_TYPE=tty, no DISPLAY / WAYLAND_DISPLAY.
  The local seat0 session owns DRM master, so the default vo=gpu cannot initialize:
      [vo/gpu/drm] Failed to acquire DRM master: Permission denied
      [vo/gpu] Failed initializing any suitable GPU context!
      [cplayer] Video: no video
- Reproduces with --no-config, so user config/scripts are not involved.

Reproduction Steps

Any two video files (with an audio track) work; I tested two 1080p MKVs.
Audio-only files do not reproduce (see the condition table below).

1. Run from a session where the default video output cannot be initialized
   (here: SSH without a display / DRM master; mpv ends up with Video: no video).

2. Use the attached script mpv_repro_pipewire_quit_hang.sh:

   ./mpv_repro_pipewire_quit_hang.sh <media1> <media2>
   

   It starts mpv with
   --idle=yes --keep-open=yes --no-config --no-terminal --input-ipc-server=... --log-file=...
   and then sends, over IPC:

   loadfile <media1> replace     # wait 2 s
   loadfile <media2> replace     # wait 2 s
   quit
   

3. quit replies success, but the mpv process never exits.

Reproduction rate on this machine: 5/5 runs of the script, 7/8 runs of a
parameterized loop (random 0.2–2 s delays between commands). It is a race.

mpv_repro_pipewire_quit_hang.sh

Expected Behavior

quit should terminate the mpv process.

Actual Behavior

The IPC quit command returns success and mpv logs a normal shutdown up to
the end of the player core teardown, but the process stays alive:

• mpv/ao/pipewire is the only thread in state R (spinning);
• the main thread is blocked in pw_thread_loop_stop() → pthread_join;
• SIGTERM still terminates the process.

/proc/<pid>/task/*/stat at hang time:

mpv                    state=S wchan=futex_wait_queue
log                    state=S wchan=futex_wait_queue
worker                 state=S wchan=futex_wait_queue
mpv/ao/pipewire        state=R wchan=0
module-rt              state=S wchan=ep_poll
pw-data-loop           state=S wchan=ep_poll

gdb backtrace of the hung process:

Thread 1 (Thread ... "mpv"):
#0  __futex_abstimed_wait_common64 (...)
#2  __GI___futex_abstimed_wait_cancelable64 (...)
#3  __pthread_clockjoin_ex (...) at ./nptl/pthread_join_common.c:102
#4  pw_thread_loop_stop () from /lib/x86_64-linux-gnu/libpipewire-0.3.so.0
#5  ... (mpv, no symbols) ...
#6  ... (mpv, no symbols) ...
#9  main ()

Thread 36 (Thread ... "mpv/ao/pipewire"):
#0  epoll_wait (epfd=0, events=..., maxevents=32, timeout=-1) at epoll_wait.c:30
        sc_ret = -9            # -EBADF
#1  ... libspa-support.so
#2  ... libspa-support.so
#3  ... libpipewire-0.3.so.0
#4  start_thread ...

At hang time fd 0 is closed in the process (it was /dev/null at start), so
the PipeWire thread loop keeps calling epoll_wait() on an invalid fd, gets
EBADF, and busy-loops; pw_thread_loop_stop() can therefore never join it.
(/proc/<pid>/fd list attached; there is no fd/0 entry.)

Log File

Attached (--log-file output of a run that hung). The log ends mid-teardown,
after the player core is gone and while the audio output is being destroyed:

[cplayer] finished playback, success (reason 3)
[cplayer] Running hook: ytdl_hook/on_after_end_file
[cplayer] Exiting... (Quit)
...
[osc] Destroying client handle...

[mpv-pipewire-quit-hang.zip](https://github.com/user-attachments/files/32434729/mpv-pipewire-quit-hang.zip)

### Sample Files

Cannot share the original files, but any video file works. Tested with:

A.mkv : hevc 1920x800 10-bit, dts 48000 Hz 5.1
B.mkv : h264 1920x800, eac3 48000 Hz 5.1

### I carefully read all instruction and confirm that I did the following:

- [x] I tested and confirmed that the issue exists with the [latest release version](https://github.com/mpv-player/mpv/releases/latest) or newer.
- [x] I provided all required information including system and mpv version.
- [x] I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of `--log-file=output.txt`.
- [x] I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
- [x] I attached the full, untruncated log file.
- [x] I attached the backtrace in the case of a crash.

Start with the ao_pipewire teardown and PipeWire thread-loop shutdown paths, using the attached reproduction script under the documented SSH/no-video-output conditions. Confirm the race around the closed file descriptor and verify that the two-loadfile sequence followed by quit exits cleanly without leaving the audio thread spinning.