Re: [PATCH v10] audio/pwaudio.c: Add Pipewire audio backend for QEMU

[Volker Rümelin]

Hi Dorinda,

> This commit adds a new audiodev backend to allow QEMU to use Pipewire as
> both an audio sink and source. This backend is available on most systems
>
> Add Pipewire entry points for QEMU Pipewire audio backend
> Add wrappers for QEMU Pipewire audio backend in qpw_pcm_ops()
> qpw_write function returns the current state of the stream to pwaudio
> and Writes some data to the server for playback streams using pipewire
> spa_ringbuffer implementation.
> qpw_read function returns the current state of the stream to pwaudio and
> reads some data from the server for capture streams using pipewire
> spa_ringbuffer implementation. These functions qpw_write and qpw_read
> are called during playback and capture.
> Added some functions that convert pw audio formats to QEMU audio format
> and vice versa which would be needed in the pipewire audio sink and
> source functions qpw_init_in() & qpw_init_out().
> These methods that implement playback and recording will create streams
> for playback and capture that will start processing and will result in
> the on_process callbacks to be called.
> Built a connection to the Pipewire sound system server in the
> qpw_audio_init() method.
>
> Signed-off-by: Dorinda Bassey <dbassey@redhat.com>
> ---
> v10:
> improve error handling
> fix volume functions
> add locks in enable_in out functions
> cleanup in reverse order of intialization
> add triggers for the sync method on the core object
> add waiting function for pw_thread_loop_signal
> improve trace
>
>   audio/audio.c                 |   3 +
>   audio/audio_template.h        |   4 +
>   audio/meson.build             |   1 +
>   audio/pwaudio.c               | 906 ++++++++++++++++++++++++++++++++++
>   audio/trace-events            |   8 +
>   meson.build                   |   8 +
>   meson_options.txt             |   4 +-
>   qapi/audio.json               |  44 ++
>   qemu-options.hx               |  21 +
>   scripts/meson-buildoptions.sh |   8 +-
>   10 files changed, 1004 insertions(+), 3 deletions(-)
>   create mode 100644 audio/pwaudio.c

> diff --git a/audio/trace-events b/audio/trace-events
> index e1ab643add..d6c36139e5 100644
> --- a/audio/trace-events
> +++ b/audio/trace-events
> @@ -18,6 +18,14 @@ dbus_audio_register(const char *s, const char *dir) "sender = %s, 
> dir = %s"
>   dbus_audio_put_buffer_out(size_t len) "len = %zu"
>   dbus_audio_read(size_t len) "len = %zu"
>   
> +# pwaudio.c
> +pw_state_changed(int nodeid, const char *s) "node id: %d stream state: %s"
> +pw_read(int32_t avail, uint32_t index, size_t len) "avail=%d index=%u len=%zu"
> +pw_write(int32_t filled, int32_t avail, uint32_t index, size_t len) "filled=%d 
> avail=%d index=%u len=%zu"
> +pw_vol(const char *ret) "set volume: %s"
> +pw_timer(uint64_t buf_samples) "buffer samples = %lu"

The compilation fails on Windows. It's "%" PRIu64 instead of "%lu". Btw. 
I think it would be better to trace the 'quantum' instead of 'buffer 
samples'.

FAILED: libqemuutil.a.p/meson-generated_.._trace_trace-audio.c.obj
"cc" "-m64" "-mcx16" "-Ilibqemuutil.a.p" "-I." "-I../qemu" "-Iqapi" 
"-Itrace" "-Iui" "-Iui/shader" 
"-IC:/usr/msys64/mingw64/include/glib-2.0" 
"-IC:/usr/msys64/mingw64/lib/glib-2.0/include" 
"-IC:/usr/msys64/mingw64/include/pixman-1" "-fdiagnostics-color=auto" 
"-Wall" "-Winvalid-pch" "-Werror" "-std=gnu11" "-O2" "-g" "-iquote" "." 
"-iquote" "C:/usr/msys64/home/ruemelin/git/qemu" "-iquote" 
"C:/usr/msys64/home/ruemelin/git/qemu/include" "-iquote" 
"C:/usr/msys64/home/ruemelin/git/qemu/tcg/i386" "-U_FORTIFY_SOURCE" 
"-D_FORTIFY_SOURCE=2" "-fno-pie" "-no-pie" "-D_GNU_SOURCE" 
"-D_FILE_OFFSET_BITS=64" "-D_LARGEFILE_SOURCE" "-fno-strict-aliasing" 
"-fno-common" "-fwrapv" "-Wundef" "-Wwrite-strings" 
"-Wmissing-prototypes" "-Wstrict-prototypes" "-Wredundant-decls" 
"-Wold-style-declaration" "-Wold-style-definition" "-Wtype-limits" 
"-Wformat-security" "-Wformat-y2k" "-Winit-self" "-Wignored-qualifiers" 
"-Wempty-body" "-Wnested-externs" "-Wendif-labels" 
"-Wexpansion-to-defined" "-Wimplicit-fallthrough=2" 
"-Wmissing-format-attribute" "-Wno-missing-include-dirs" 
"-Wno-shift-negative-value" "-Wno-psabi" "-fstack-protector-strong" 
"-pthread" -MD -MQ 
libqemuutil.a.p/meson-generated_.._trace_trace-audio.c.obj -MF 
"libqemuutil.a.p/meson-generated_.._trace_trace-audio.c.obj.d" -o 
libqemuutil.a.p/meson-generated_.._trace_trace-audio.c.obj "-c" 
trace/trace-audio.c
In file included from trace/trace-audio.c:5:
C:/usr/msys64/home/ruemelin/git/qemu/audio/trace-events: In function 
'_nocheck__trace_pw_timer':
C:/usr/msys64/home/ruemelin/git/qemu/audio/trace-events:26:22: error: 
format '%lu' expects argument of type 'long unsigned int', but argument 
5 has type 'uint64_t' {aka 'long long unsigned int'} [-Werror=format=]
   26 | pw_timer(uint64_t buf_samples) "buffer samples = %lu"
      |                      ^~~~~~~~~~~~~~~~~~~~~~~~
......
   29 | # audio.c
      |
      |                        |
      |                        uint64_t {aka long long unsigned int}
C:/usr/msys64/home/ruemelin/git/qemu/audio/trace-events:26:22: error: 
format '%lu' expects argument of type 'long unsigned int', but argument 
2 has type 'uint64_t' {aka 'long long unsigned int'} [-Werror=format=]
   26 | pw_timer(uint64_t buf_samples) "buffer samples = %lu"
      |                      ^~~~~~~~~~~
|                                                               |
| uint64_t {aka long long unsigned int}
cc1.exe: all warnings being treated as errors

With best regards,
Volker

> +pw_audio_init(void) "Initialize Pipewire context"
> +
>   # audio.c
>   audio_timer_start(int interval) "interval %d ms"
>   audio_timer_stop(void) ""