[v3] audio/pwaudio.c: Add Pipewire audio backend for QEMU

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>
---
v3:
Wrap commit log
add checks for v->stream
use constants instead of literals
fix typo error

 audio/audio.c                 |   3 +
 audio/audio_template.h        |   4 +
 audio/meson.build             |   1 +
 audio/pwaudio.c               | 827 ++++++++++++++++++++++++++++++++++
 meson.build                   |   7 +
 meson_options.txt             |   4 +-
 qapi/audio.json               |  45 ++
 qemu-options.hx               |  17 +
 scripts/meson-buildoptions.sh |   8 +-
 9 files changed, 913 insertions(+), 3 deletions(-)
 create mode 100644 audio/pwaudio.c

On Friday, February 17, 2023 8:11:43 AM CET Dorinda Bassey wrote:
> 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>
> ---
> v3:
> Wrap commit log
> add checks for v->stream
> use constants instead of literals
> fix typo error
> 
>  audio/audio.c                 |   3 +
>  audio/audio_template.h        |   4 +
>  audio/meson.build             |   1 +
>  audio/pwaudio.c               | 827 ++++++++++++++++++++++++++++++++++
>  meson.build                   |   7 +
>  meson_options.txt             |   4 +-
>  qapi/audio.json               |  45 ++
>  qemu-options.hx               |  17 +
>  scripts/meson-buildoptions.sh |   8 +-
>  9 files changed, 913 insertions(+), 3 deletions(-)
>  create mode 100644 audio/pwaudio.c
> 
> diff --git a/audio/audio.c b/audio/audio.c
> index 4290309d18..aa55e41ad8 100644
> --- a/audio/audio.c
> +++ b/audio/audio.c
> @@ -2069,6 +2069,9 @@ void audio_create_pdos(Audiodev *dev)
>  #ifdef CONFIG_AUDIO_PA
>          CASE(PA, pa, Pa);
>  #endif
> +#ifdef CONFIG_AUDIO_PIPEWIRE
> +        CASE(PIPEWIRE, pipewire, Pipewire);
> +#endif
>  #ifdef CONFIG_AUDIO_SDL
>          CASE(SDL, sdl, Sdl);
>  #endif
> diff --git a/audio/audio_template.h b/audio/audio_template.h
> index 42b4712acb..0f02afb921 100644
> --- a/audio/audio_template.h
> +++ b/audio/audio_template.h
> @@ -355,6 +355,10 @@ AudiodevPerDirectionOptions *glue(audio_get_pdo_, TYPE)(Audiodev *dev)
>      case AUDIODEV_DRIVER_PA:
>          return qapi_AudiodevPaPerDirectionOptions_base(dev->u.pa.TYPE);
>  #endif
> +#ifdef CONFIG_AUDIO_PIPEWIRE
> +    case AUDIODEV_DRIVER_PIPEWIRE:
> +        return qapi_AudiodevPipewirePerDirectionOptions_base(dev->u.pipewire.TYPE);
> +#endif
>  #ifdef CONFIG_AUDIO_SDL
>      case AUDIODEV_DRIVER_SDL:
>          return qapi_AudiodevSdlPerDirectionOptions_base(dev->u.sdl.TYPE);
> diff --git a/audio/meson.build b/audio/meson.build
> index 0722224ba9..65a49c1a10 100644
> --- a/audio/meson.build
> +++ b/audio/meson.build
> @@ -19,6 +19,7 @@ foreach m : [
>    ['sdl', sdl, files('sdlaudio.c')],
>    ['jack', jack, files('jackaudio.c')],
>    ['sndio', sndio, files('sndioaudio.c')],
> +  ['pipewire', pipewire, files('pwaudio.c')],
>    ['spice', spice, files('spiceaudio.c')]
>  ]
>    if m[1].found()
> diff --git a/audio/pwaudio.c b/audio/pwaudio.c
> new file mode 100644
> index 0000000000..05a00b0859
> --- /dev/null
> +++ b/audio/pwaudio.c
> @@ -0,0 +1,827 @@
> +/*
> + * QEMU Pipewire audio driver
> + *
> + * Copyright (c) 2023 Red Hat Inc.
> + *
> + * Author: Dorinda Bassey       <dbassey@redhat.com>
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this software and associated documentation files (the "Software"), to deal
> + * in the Software without restriction, including without limitation the rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> + * THE SOFTWARE.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/module.h"
> +#include "audio.h"
> +#include <errno.h>
> +#include <spa/param/audio/format-utils.h>
> +#include <spa/utils/ringbuffer.h>
> +#include <spa/utils/result.h>
> +
> +#include <pipewire/pipewire.h>
> +
> +#define AUDIO_CAP "pipewire"
> +#define RINGBUFFER_SIZE    (1u << 22)
> +#define RINGBUFFER_MASK    (RINGBUFFER_SIZE - 1)
> +#define BUFFER_SAMPLES    512
> +
> +#include "audio_int.h"
> +
> +enum {
> +    MODE_SINK,
> +    MODE_SOURCE
> +};
> +
> +typedef struct pwaudio {
> +    Audiodev *dev;
> +    struct pw_thread_loop *thread_loop;
> +    struct pw_context *context;
> +
> +    struct pw_core *core;
> +    struct spa_hook core_listener;
> +    int seq;
> +} pwaudio;
> +
> +typedef struct PWVoice {
> +    pwaudio *g;
> +    bool enabled;
> +    struct pw_stream *stream;
> +    struct spa_hook stream_listener;
> +    struct spa_audio_info_raw info;
> +    uint32_t frame_size;
> +    struct spa_ringbuffer ring;
> +    uint8_t buffer[RINGBUFFER_SIZE];
> +
> +    uint32_t mode;
> +    struct pw_properties *props;
> +} PWVoice;
> +
> +typedef struct PWVoiceOut {
> +    HWVoiceOut hw;
> +    PWVoice v;
> +} PWVoiceOut;
> +
> +typedef struct PWVoiceIn {
> +    HWVoiceIn hw;
> +    PWVoice v;
> +} PWVoiceIn;
> +
> +static void
> +stream_destroy(void *data)
> +{
> +    PWVoice *v = (PWVoice *) data;
> +    spa_hook_remove(&v->stream_listener);
> +    v->stream = NULL;
> +}
> +
> +/* output data processing function to read stuffs from the buffer */
> +static void
> +playback_on_process(void *data)
> +{
> +    PWVoice *v = (PWVoice *) data;
> +    void *p;
> +    struct pw_buffer *b;
> +    struct spa_buffer *buf;
> +    uint32_t n_frames, req, index, n_bytes;
> +    int32_t avail;
> +
> +    if (!v->stream) {
> +        return;
> +    }
> +
> +    /* obtain a buffer to read from */
> +    b = pw_stream_dequeue_buffer(v->stream);
> +    if (b == NULL) {
> +        pw_log_warn("out of buffers: %m");
> +        return;
> +    }
> +
> +    buf = b->buffer;
> +    p = buf->datas[0].data;
> +    if (p == NULL) {
> +        return;
> +    }
> +    req = b->requested * v->frame_size;
> +    if (req == 0) {
> +        req = 4096 * v->frame_size;
> +    }
> +    n_frames = SPA_MIN(req, buf->datas[0].maxsize);
> +    n_bytes = n_frames * v->frame_size;
> +
> +    /* get no of available bytes to read data from buffer */
> +
> +    avail = spa_ringbuffer_get_read_index(&v->ring, &index);
> +
> +    if (!v->enabled) {
> +        avail = 0;
> +    }
> +
> +    if (avail == 0) {
> +        memset(p, 0, n_bytes);
> +    } else {
> +        if (avail < (int32_t) n_bytes) {
> +            n_bytes = avail;
> +        }
> +
> +        spa_ringbuffer_read_data(&v->ring,
> +                                    v->buffer, RINGBUFFER_SIZE,
> +                                    index & RINGBUFFER_MASK, p, n_bytes);
> +
> +        index += n_bytes;
> +        spa_ringbuffer_read_update(&v->ring, index);
> +    }
> +
> +    buf->datas[0].chunk->offset = 0;
> +    buf->datas[0].chunk->stride = v->frame_size;
> +    buf->datas[0].chunk->size = n_bytes;
> +
> +    /* queue the buffer for playback */
> +    pw_stream_queue_buffer(v->stream, b);
> +}
> +
> +/* output data processing function to generate stuffs in the buffer */
> +static void
> +capture_on_process(void *data)
> +{
> +    PWVoice *v = (PWVoice *) data;
> +    void *p;
> +    struct pw_buffer *b;
> +    struct spa_buffer *buf;
> +    int32_t filled;
> +    uint32_t index, offs, n_bytes;
> +
> +    if (!v->stream) {
> +        return;
> +    }
> +
> +    /* obtain a buffer */
> +    b = pw_stream_dequeue_buffer(v->stream);
> +    if (b == NULL) {
> +        pw_log_warn("out of buffers: %m");
> +        return;
> +    }
> +
> +    /* Write data into buffer */
> +    buf = b->buffer;
> +    p = buf->datas[0].data;
> +    if (p == NULL) {
> +        return;
> +    }
> +    offs = SPA_MIN(buf->datas[0].chunk->offset, buf->datas[0].maxsize);
> +    n_bytes = SPA_MIN(buf->datas[0].chunk->size, buf->datas[0].maxsize - offs);
> +
> +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> +
> +    if (!v->enabled) {
> +        n_bytes = 0;
> +    }
> +
> +    if (filled < 0) {
> +        pw_log_warn("%p: underrun write:%u filled:%d", p, index, filled);
> +    } else {
> +        if ((uint32_t) filled + n_bytes > RINGBUFFER_SIZE) {
> +            pw_log_warn("%p: overrun write:%u filled:%d + size:%u > max:%u",
> +            p, index, filled, n_bytes, RINGBUFFER_SIZE);
> +        }
> +    }
> +    spa_ringbuffer_write_data(&v->ring,
> +                                v->buffer, RINGBUFFER_SIZE,
> +                                index & RINGBUFFER_MASK,
> +                                SPA_PTROFF(p, offs, void), n_bytes);
> +    index += n_bytes;
> +    spa_ringbuffer_write_update(&v->ring, index);
> +
> +    /* queue the buffer for playback */
> +    pw_stream_queue_buffer(v->stream, b);
> +}
> +
> +static void
> +on_stream_state_changed(void *_data, enum pw_stream_state old,
> +                        enum pw_stream_state state, const char *error)
> +{
> +    PWVoice *v = (PWVoice *) _data;
> +
> +    printf("stream state: \"%s\"\n", pw_stream_state_as_string(state));
> +
> +    switch (state) {
> +    case PW_STREAM_STATE_ERROR:
> +    case PW_STREAM_STATE_UNCONNECTED:
> +        {
> +            break;
> +        }
> +    case PW_STREAM_STATE_PAUSED:
> +        printf("node id: %d\n", pw_stream_get_node_id(v->stream));
> +        break;
> +    case PW_STREAM_STATE_CONNECTING:
> +    case PW_STREAM_STATE_STREAMING:
> +        break;
> +    }
> +}
> +
> +static const struct pw_stream_events capture_stream_events = {
> +    PW_VERSION_STREAM_EVENTS,
> +    .destroy = stream_destroy,
> +    .state_changed = on_stream_state_changed,
> +    .process = capture_on_process
> +};
> +
> +static const struct pw_stream_events playback_stream_events = {
> +    PW_VERSION_STREAM_EVENTS,
> +    .destroy = stream_destroy,
> +    .state_changed = on_stream_state_changed,
> +    .process = playback_on_process
> +};
> +
> +static size_t
> +qpw_read(HWVoiceIn *hw, void *data, size_t len)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    const char *error = NULL;
> +    size_t l;
> +    int32_t avail;
> +    uint32_t index;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
> +        /* wait for stream to become ready */
> +        l = 0;
> +        goto done_unlock;
> +    }
> +    /* get no of available bytes to read data from buffer */
> +    avail = spa_ringbuffer_get_read_index(&v->ring, &index);
> +
> +    if (avail < (int32_t) len) {
> +        len = avail;
> +    }
> +
> +    spa_ringbuffer_read_data(&v->ring,
> +                             v->buffer, RINGBUFFER_SIZE,
> +                             index & RINGBUFFER_MASK, data, len);
> +    index += len;
> +    spa_ringbuffer_read_update(&v->ring, index);
> +    l = len;
> +
> +done_unlock:
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return l;
> +}
> +
> +static size_t
> +qpw_write(HWVoiceOut *hw, void *data, size_t len)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    const char *error = NULL;
> +    const int period = 3;

Better `periods`, plural?

> +    size_t l;
> +    int32_t filled, avail;
> +    uint32_t index;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
> +        /* wait for stream to become ready */
> +        l = 0;
> +        goto done_unlock;
> +    }
> +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> +
> +    avail = BUFFER_SAMPLES * v->frame_size * period - filled;
> +
> +    pw_log_debug("%u %u %u %zu", filled, avail, index, len);
> +
> +    if (len > avail) {
> +        len = avail;
> +    }
> +
> +    if (filled < 0) {
> +        pw_log_warn("%p: underrun write:%u filled:%d", pw, index, filled);
> +    } else {
> +        if ((uint32_t) filled + len > RINGBUFFER_SIZE) {
> +            pw_log_warn("%p: overrun write:%u filled:%d + size:%zu > max:%u",
> +            pw, index, filled, len, RINGBUFFER_SIZE);
> +        }
> +    }
> +
> +    spa_ringbuffer_write_data(&v->ring,
> +                                v->buffer, RINGBUFFER_SIZE,
> +                                index & RINGBUFFER_MASK, data, len);
> +    index += len;
> +    spa_ringbuffer_write_update(&v->ring, index);
> +    l = len;
> +
> +done_unlock:
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return l;
> +}
> +
> +static int
> +audfmt_to_pw(AudioFormat fmt, int endianness)
> +{
> +    int format;
> +
> +    switch (fmt) {
> +    case AUDIO_FORMAT_S8:
> +        format = SPA_AUDIO_FORMAT_S8;
> +        break;
> +    case AUDIO_FORMAT_U8:
> +        format = SPA_AUDIO_FORMAT_U8;
> +        break;
> +    case AUDIO_FORMAT_S16:
> +        format = endianness ? SPA_AUDIO_FORMAT_S16_BE : SPA_AUDIO_FORMAT_S16_LE;
> +        break;
> +    case AUDIO_FORMAT_U16:
> +        format = endianness ? SPA_AUDIO_FORMAT_U16_BE : SPA_AUDIO_FORMAT_U16_LE;
> +        break;
> +    case AUDIO_FORMAT_S32:
> +        format = endianness ? SPA_AUDIO_FORMAT_S32_BE : SPA_AUDIO_FORMAT_S32_LE;
> +        break;
> +    case AUDIO_FORMAT_U32:
> +        format = endianness ? SPA_AUDIO_FORMAT_U32_BE : SPA_AUDIO_FORMAT_U32_LE;
> +        break;
> +    case AUDIO_FORMAT_F32:
> +        format = endianness ? SPA_AUDIO_FORMAT_F32_BE : SPA_AUDIO_FORMAT_F32_LE;
> +        break;
> +    default:
> +        dolog("Internal logic error: Bad audio format %d\n", fmt);
> +        format = SPA_AUDIO_FORMAT_U8;
> +        break;
> +    }
> +    return format;
> +}
> +
> +static AudioFormat
> +pw_to_audfmt(enum spa_audio_format fmt, int *endianness,
> +             uint32_t *frame_size)
> +{
> +    switch (fmt) {
> +    case SPA_AUDIO_FORMAT_S8:
> +        *frame_size = 1;
> +        return AUDIO_FORMAT_S8;
> +    case SPA_AUDIO_FORMAT_U8:
> +        *frame_size = 1;
> +        return AUDIO_FORMAT_U8;
> +    case SPA_AUDIO_FORMAT_S16_BE:
> +        *frame_size = 2;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_S16;
> +    case SPA_AUDIO_FORMAT_S16_LE:
> +        *frame_size = 2;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_S16;
> +    case SPA_AUDIO_FORMAT_U16_BE:
> +        *frame_size = 2;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_U16;
> +    case SPA_AUDIO_FORMAT_U16_LE:
> +        *frame_size = 2;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_U16;
> +    case SPA_AUDIO_FORMAT_S32_BE:
> +        *frame_size = 4;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_S32;
> +    case SPA_AUDIO_FORMAT_S32_LE:
> +        *frame_size = 4;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_S32;
> +    case SPA_AUDIO_FORMAT_U32_BE:
> +        *frame_size = 4;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_U32;
> +    case SPA_AUDIO_FORMAT_U32_LE:
> +        *frame_size = 4;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_U32;
> +    case SPA_AUDIO_FORMAT_F32_BE:
> +        *frame_size = 4;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_F32;
> +    case SPA_AUDIO_FORMAT_F32_LE:
> +        *frame_size = 4;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_F32;
> +    default:
> +        *frame_size = 1;
> +        dolog("Internal logic error: Bad spa_audio_format %d\n", fmt);
> +        return AUDIO_FORMAT_U8;
> +    }
> +}
> +
> +static int
> +create_stream(pwaudio *c, PWVoice *v, const char *name)
> +{
> +    int res;
> +    uint32_t n_params;
> +    const struct spa_pod *params[2];
> +    uint8_t buffer[1024];
> +    struct spa_pod_builder b;
> +
> +    v->stream = pw_stream_new(c->core, name, NULL);
> +
> +    if (v->stream == NULL) {
> +        res = -errno;
> +        goto error;
> +    }
> +
> +    if (v->mode == MODE_SOURCE) {
> +        pw_stream_add_listener(v->stream,
> +                            &v->stream_listener, &capture_stream_events, v);
> +    } else {
> +        pw_stream_add_listener(v->stream,
> +                            &v->stream_listener, &playback_stream_events, v);
> +    }
> +
> +    n_params = 0;
> +    spa_pod_builder_init(&b, buffer, sizeof(buffer));
> +    params[n_params++] = spa_format_audio_raw_build(&b,
> +                            SPA_PARAM_EnumFormat,
> +                            &v->info);
> +
> +    /* connect the stream to a sink or source */
> +    res = pw_stream_connect(v->stream,
> +                            v->mode ==
> +                            MODE_SOURCE ? PW_DIRECTION_INPUT :
> +                            PW_DIRECTION_OUTPUT, PW_ID_ANY,
> +                            PW_STREAM_FLAG_AUTOCONNECT |
> +                            PW_STREAM_FLAG_MAP_BUFFERS |
> +                            PW_STREAM_FLAG_RT_PROCESS, params, n_params);
> +    if (res < 0) {
> +        goto error;
> +    }
> +
> +    return 0;
> +error:
> +    return res;
> +}
> +
> +static void
> +pw_destroy(pwaudio *c)
> +{
> +    if (c->thread_loop) {
> +        pw_thread_loop_stop(c->thread_loop);
> +    }
> +    if (c->core) {
> +        pw_core_disconnect(c->core);
> +    }
> +
> +    g_free(c);
> +}
> +
> +static int
> +qpw_stream_new(pwaudio *c, PWVoice *v, const char *name)
> +{
> +    int r;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +
> +    switch (v->info.channels) {
> +    case 8:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> +        v->info.position[4] = SPA_AUDIO_CHANNEL_RL;
> +        v->info.position[5] = SPA_AUDIO_CHANNEL_RR;
> +        v->info.position[6] = SPA_AUDIO_CHANNEL_SL;
> +        v->info.position[7] = SPA_AUDIO_CHANNEL_SR;
> +        break;
> +    case 6:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> +        v->info.position[4] = SPA_AUDIO_CHANNEL_RL;
> +        v->info.position[5] = SPA_AUDIO_CHANNEL_RR;
> +        break;
> +    case 5:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> +        v->info.position[4] = SPA_AUDIO_CHANNEL_RC;
> +        break;
> +    case 4:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_RC;
> +        break;
> +    case 3:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_LFE;
> +        break;
> +    case 2:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        break;
> +    case 1:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_MONO;
> +        break;
> +    default:
> +        for (size_t i = 0; i < v->info.channels; i++) {
> +            v->info.position[i] = SPA_AUDIO_CHANNEL_UNKNOWN;
> +        }
> +        break;
> +    }
> +
> +    /* create a new unconnected pwstream */
> +    r = create_stream(c, v, name);
> +    if (r < 0) {
> +        goto error;
> +    }
> +
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return r;
> +
> +error:
> +    AUD_log(AUDIO_CAP, "Failed to create stream.");
> +    pw_thread_loop_unlock(c->thread_loop);
> +    pw_destroy(c);
> +    return -1;
> +}
> +
> +static int
> +qpw_init_out(HWVoiceOut *hw, struct audsettings *as, void *drv_opaque)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +    struct audsettings obt_as = *as;
> +    pwaudio *c = v->g = drv_opaque;
> +    AudiodevPipewireOptions *popts = &c->dev->u.pipewire;
> +    AudiodevPipewirePerDirectionOptions *ppdo = popts->out;
> +    int r;
> +    v->enabled = false;
> +
> +    v->mode = MODE_SINK;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +
> +    v->info.format = audfmt_to_pw(as->fmt, as->endianness);
> +    v->info.channels = as->nchannels;
> +    v->info.rate = as->freq;
> +
> +    obt_as.fmt =
> +        pw_to_audfmt(v->info.format, &obt_as.endianness, &v->frame_size);
> +    v->frame_size *= as->nchannels;
> +
> +    /* call the function that creates a new stream for playback */
> +    r = qpw_stream_new(c, v, ppdo->stream_name ? : c->dev->id);
> +    if (r < 0) {
> +        pw_log_error("qpw_stream_new for playback failed\n ");
> +        goto fail;
> +    }
> +
> +    /* report the audio format we support */
> +    audio_pcm_init_info(&hw->info, &obt_as);
> +
> +    /* report the buffer size to qemu */
> +    hw->samples = BUFFER_SAMPLES;
> +
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return 0;
> +fail:
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return -1;
> +}
> +
> +static int
> +qpw_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +    struct audsettings obt_as = *as;
> +    pwaudio *c = v->g = drv_opaque;
> +    AudiodevPipewireOptions *popts = &c->dev->u.pipewire;
> +    AudiodevPipewirePerDirectionOptions *ppdo = popts->in;
> +    int r;
> +    v->enabled = false;
> +
> +    v->mode = MODE_SOURCE;
> +    pw_thread_loop_lock(c->thread_loop);
> +
> +    v->info.format = audfmt_to_pw(as->fmt, as->endianness);
> +    v->info.channels = as->nchannels;
> +    v->info.rate = as->freq;
> +
> +    obt_as.fmt =
> +        pw_to_audfmt(v->info.format, &obt_as.endianness, &v->frame_size);
> +    v->frame_size *= as->nchannels;
> +
> +    /* call the function that creates a new stream for recording */
> +    r = qpw_stream_new(c, v, ppdo->stream_name ? : c->dev->id);
> +    if (r < 0) {
> +        pw_log_error("qpw_stream_new for recording failed\n ");
> +        goto fail;
> +    }
> +
> +    /* report the audio format we support */
> +    audio_pcm_init_info(&hw->info, &obt_as);
> +
> +    /* report the buffer size to qemu */
> +    hw->samples = BUFFER_SAMPLES;
> +
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return 0;
> +fail:
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return -1;
> +}
> +
> +static void
> +qpw_fini_out(HWVoiceOut *hw)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +
> +    if (v->stream) {
> +        pwaudio *c = v->g;
> +        pw_thread_loop_lock(c->thread_loop);
> +        pw_stream_destroy(v->stream);
> +        v->stream = NULL;
> +        pw_thread_loop_unlock(c->thread_loop);
> +    }
> +}
> +
> +static void
> +qpw_fini_in(HWVoiceIn *hw)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +
> +    if (v->stream) {
> +        pwaudio *c = v->g;
> +        pw_thread_loop_lock(c->thread_loop);
> +        pw_stream_destroy(v->stream);
> +        v->stream = NULL;
> +        pw_thread_loop_unlock(c->thread_loop);
> +    }
> +}
> +
> +static void
> +qpw_enable_out(HWVoiceOut *hw, bool enable)
> +{
> +    PWVoiceOut *po = (PWVoiceOut *) hw;
> +    PWVoice *v = &po->v;
> +    v->enabled = enable;
> +}
> +
> +static void
> +qpw_enable_in(HWVoiceIn *hw, bool enable)
> +{
> +    PWVoiceIn *pi = (PWVoiceIn *) hw;
> +    PWVoice *v = &pi->v;
> +    v->enabled = enable;
> +}
> +
> +static void
> +on_core_error(void *data, uint32_t id, int seq, int res, const char *message)
> +{
> +    pwaudio *pw = data;
> +
> +    pw_log_warn("error id:%u seq:%d res:%d (%s): %s",
> +                id, seq, res, spa_strerror(res), message);
> +
> +    pw_thread_loop_signal(pw->thread_loop, FALSE);
> +}
> +
> +static void
> +on_core_done(void *data, uint32_t id, int seq)
> +{
> +    pwaudio *pw = data;
> +    if (id == PW_ID_CORE) {
> +        pw->seq = seq;
> +        pw_thread_loop_signal(pw->thread_loop, FALSE);
> +    }
> +}
> +
> +static const struct pw_core_events core_events = {
> +    PW_VERSION_CORE_EVENTS,
> +    .done = on_core_done,
> +    .error = on_core_error,
> +};
> +
> +static void *
> +qpw_audio_init(Audiodev *dev)
> +{
> +    pwaudio *pw;
> +    pw = g_new0(pwaudio, 1);
> +    pw_init(NULL, NULL);
> +
> +    AudiodevPipewireOptions *popts;
> +    AUD_log(AUDIO_CAP, "Initialize PW context\n");
> +    assert(dev->driver == AUDIODEV_DRIVER_PIPEWIRE);
> +    popts = &dev->u.pipewire;
> +
> +    if (!popts->has_latency) {
> +        popts->has_latency = true;
> +        popts->latency = 15000;
> +    }
> +
> +    pw->dev = dev;
> +    pw->thread_loop = pw_thread_loop_new("Pipewire thread loop", NULL);
> +    if (pw->thread_loop == NULL) {
> +        goto fail;
> +    }
> +    pw->context =
> +        pw_context_new(pw_thread_loop_get_loop(pw->thread_loop), NULL, 0);
> +
> +    if (pw_thread_loop_start(pw->thread_loop) < 0) {
> +        goto fail;
> +    }
> +
> +    pw_thread_loop_lock(pw->thread_loop);
> +
> +    pw->core = pw_context_connect(pw->context, NULL, 0);
> +    if (pw->core == NULL) {
> +        goto fail;
> +    }
> +
> +    pw_core_add_listener(pw->core, &pw->core_listener, &core_events, pw);
> +
> +    pw_thread_loop_unlock(pw->thread_loop);
> +
> +    return pw;
> +
> +fail:
> +    AUD_log(AUDIO_CAP, "Failed to initialize PW context");
> +    pw_thread_loop_unlock(pw->thread_loop);
> +    pw_context_destroy(pw->context);
> +    pw_thread_loop_destroy(pw->thread_loop);
> +    g_free(pw);
> +    return NULL;
> +}
> +
> +static void
> +qpw_audio_fini(void *opaque)
> +{
> +    pwaudio *pw = opaque;
> +
> +    pw_thread_loop_stop(pw->thread_loop);
> +
> +    if (pw->core) {
> +        spa_hook_remove(&pw->core_listener);
> +        spa_zero(pw->core_listener);
> +        pw_core_disconnect(pw->core);
> +    }
> +
> +    if (pw->context) {
> +        pw_context_destroy(pw->context);
> +    }
> +    pw_thread_loop_destroy(pw->thread_loop);
> +
> +    g_free(pw);
> +}
> +
> +static struct audio_pcm_ops qpw_pcm_ops = {
> +    .init_out = qpw_init_out,
> +    .fini_out = qpw_fini_out,
> +    .write = qpw_write,
> +    .buffer_get_free = audio_generic_buffer_get_free,
> +    .run_buffer_out = audio_generic_run_buffer_out,
> +    .enable_out = qpw_enable_out,
> +
> +    .init_in = qpw_init_in,
> +    .fini_in = qpw_fini_in,
> +    .read = qpw_read,
> +    .run_buffer_in = audio_generic_run_buffer_in,
> +    .enable_in = qpw_enable_in
> +};
> +
> +static struct audio_driver pw_audio_driver = {
> +    .name = "pipewire",
> +    .descr = "http://www.pipewire.org/",
> +    .init = qpw_audio_init,
> +    .fini = qpw_audio_fini,
> +    .pcm_ops = &qpw_pcm_ops,
> +    .can_be_default = 1,
> +    .max_voices_out = INT_MAX,
> +    .max_voices_in = INT_MAX,
> +    .voice_size_out = sizeof(PWVoiceOut),
> +    .voice_size_in = sizeof(PWVoiceIn),
> +};
> +
> +static void
> +register_audio_pw(void)
> +{
> +    audio_driver_register(&pw_audio_driver);
> +}
> +
> +type_init(register_audio_pw);
> diff --git a/meson.build b/meson.build
> index a76c855312..686fdd5b81 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -734,6 +734,11 @@ if not get_option('jack').auto() or have_system
>    jack = dependency('jack', required: get_option('jack'),
>                      method: 'pkg-config', kwargs: static_kwargs)
>  endif
> +pipewire = not_found
> +if not get_option('pipewire').auto() or (targetos == 'linux' and have_system)
> +  pipewire = dependency('libpipewire-0.3', required: get_option('pipewire'),
> +                    method: 'pkg-config', kwargs: static_kwargs)
> +endif

Doesn't compile for me with libpipewire-0.3.19:

../audio/pwaudio.c: In function ‘playback_on_process’:
../audio/pwaudio.c:118:12: error: ‘struct pw_buffer’ has no member named ‘requested’
  118 |     req = b->requested * v->frame_size;
      |            ^~

^- Requires libpipewire-0.3.50

../audio/pwaudio.c: In function ‘capture_on_process’:
../audio/pwaudio.c:204:33: error: implicit declaration of function ‘SPA_PTROFF’; did you mean ‘SPA_PTRDIFF’? [-Werror=implicit-function-declaration]
  204 |                                 SPA_PTROFF(p, offs, void), n_bytes);
      |                                 ^~~~~~~~~~
      |                                 SPA_PTRDIFF
../audio/pwaudio.c:204:33: error: nested extern declaration of ‘SPA_PTROFF’ [-Werror=nested-externs]
../audio/pwaudio.c:204:53: error: expected expression before ‘void’
  204 |                                 SPA_PTROFF(p, offs, void), n_bytes);
      |

^- Requires libpipewire-0.3.28

So you probably want to raise the version dependency in meson.build, or adjust
the demanding code.

>  sndio = not_found
>  if not get_option('sndio').auto() or have_system
>    sndio = dependency('sndio', required: get_option('sndio'),
> @@ -1671,6 +1676,7 @@ if have_system
>      'jack': jack.found(),
>      'oss': oss.found(),
>      'pa': pulse.found(),
> +    'pipewire': pipewire.found(),
>      'sdl': sdl.found(),
>      'sndio': sndio.found(),
>    }
> @@ -3949,6 +3955,7 @@ endif
>  if targetos == 'linux'
>    summary_info += {'ALSA support':    alsa}
>    summary_info += {'PulseAudio support': pulse}
> +  summary_info += {'Pipewire support':   pipewire}
>  endif
>  summary_info += {'JACK support':      jack}
>  summary_info += {'brlapi support':    brlapi}
> diff --git a/meson_options.txt b/meson_options.txt
> index 7e5801db90..1b7847250d 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -21,7 +21,7 @@ option('tls_priority', type : 'string', value : 'NORMAL',
>  option('default_devices', type : 'boolean', value : true,
>         description: 'Include a default selection of devices in emulators')
>  option('audio_drv_list', type: 'array', value: ['default'],
> -       choices: ['alsa', 'coreaudio', 'default', 'dsound', 'jack', 'oss', 'pa', 'sdl', 'sndio'],
> +       choices: ['alsa', 'coreaudio', 'default', 'dsound', 'jack', 'oss', 'pa', 'pipewire', 'sdl', 'sndio'],
>         description: 'Set audio driver list')
>  option('block_drv_rw_whitelist', type : 'string', value : '',
>         description: 'set block driver read-write whitelist (by default affects only QEMU, not tools like qemu-img)')
> @@ -255,6 +255,8 @@ option('oss', type: 'feature', value: 'auto',
>         description: 'OSS sound support')
>  option('pa', type: 'feature', value: 'auto',
>         description: 'PulseAudio sound support')
> +option('pipewire', type: 'feature', value: 'auto',
> +       description: 'Pipewire sound support')
>  option('sndio', type: 'feature', value: 'auto',
>         description: 'sndio sound support')
>  
> diff --git a/qapi/audio.json b/qapi/audio.json
> index 4e54c00f51..b872e9f10d 100644
> --- a/qapi/audio.json
> +++ b/qapi/audio.json
> @@ -324,6 +324,48 @@
>      '*out':    'AudiodevPaPerDirectionOptions',
>      '*server': 'str' } }
>  
> +##
> +# @AudiodevPipewirePerDirectionOptions:
> +#
> +# Options of the Pipewire backend that are used for both playback and
> +# recording.
> +#
> +# @name: name of the sink/source to use
> +#
> +# @stream-name: name of the Pipewire stream created by qemu.  Can be
> +#               used to identify the stream in Pipewire when you
> +#               create multiple Pipewire devices or run multiple qemu
> +#               instances (default: audiodev's id, since 7.1)
> +#
> +#
> +# Since: 7.2
> +##
> +{ 'struct': 'AudiodevPipewirePerDirectionOptions',
> +  'base': 'AudiodevPerDirectionOptions',
> +  'data': {
> +    '*name': 'str',
> +    '*stream-name': 'str' } }
> +
> +##
> +# @AudiodevPipewireOptions:
> +#
> +# Options of the Pipewire audio backend.
> +#
> +# @in: options of the capture stream
> +#
> +# @out: options of the playback stream
> +#
> +# @latency: add latency to playback in microseconds
> +#           (default 44100)
> +#
> +# Since: 7.2
> +##
> +{ 'struct': 'AudiodevPipewireOptions',
> +  'data': {
> +    '*in':     'AudiodevPipewirePerDirectionOptions',
> +    '*out':    'AudiodevPipewirePerDirectionOptions',
> +    '*latency': 'uint32' } }
> +
>  ##
>  # @AudiodevSdlPerDirectionOptions:
>  #
> @@ -416,6 +458,7 @@
>              { 'name': 'jack', 'if': 'CONFIG_AUDIO_JACK' },
>              { 'name': 'oss', 'if': 'CONFIG_AUDIO_OSS' },
>              { 'name': 'pa', 'if': 'CONFIG_AUDIO_PA' },
> +            { 'name': 'pipewire', 'if': 'CONFIG_AUDIO_PIPEWIRE' },
>              { 'name': 'sdl', 'if': 'CONFIG_AUDIO_SDL' },
>              { 'name': 'sndio', 'if': 'CONFIG_AUDIO_SNDIO' },
>              { 'name': 'spice', 'if': 'CONFIG_SPICE' },
> @@ -456,6 +499,8 @@
>                     'if': 'CONFIG_AUDIO_OSS' },
>      'pa':        { 'type': 'AudiodevPaOptions',
>                     'if': 'CONFIG_AUDIO_PA' },
> +    'pipewire':  { 'type': 'AudiodevPipewireOptions',
> +                   'if': 'CONFIG_AUDIO_PIPEWIRE' },
>      'sdl':       { 'type': 'AudiodevSdlOptions',
>                     'if': 'CONFIG_AUDIO_SDL' },
>      'sndio':     { 'type': 'AudiodevSndioOptions',
> diff --git a/qemu-options.hx b/qemu-options.hx
> index cafd8be8ed..95ed5e5c2d 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -779,6 +779,11 @@ DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
>      "                in|out.name= source/sink device name\n"
>      "                in|out.latency= desired latency in microseconds\n"
>  #endif
> +#ifdef CONFIG_AUDIO_PIPEWIRE
> +    "-audiodev pipewire,id=id[,prop[=value][,...]]\n"
> +    "                in|out.name= source/sink device name\n"
> +    "                latency= desired latency in microseconds\n"
> +#endif
>  #ifdef CONFIG_AUDIO_SDL
>      "-audiodev sdl,id=id[,prop[=value][,...]]\n"
>      "                in|out.buffer-count= number of buffers\n"
> @@ -942,6 +947,18 @@ SRST
>          Desired latency in microseconds. The PulseAudio server will try
>          to honor this value but actual latencies may be lower or higher.
>  
> +``-audiodev pipewire,id=id[,prop[=value][,...]]``
> +    Creates a backend using Pipewire. This backend is available on
> +    most systems.
> +
> +    Pipewire specific options are:
> +
> +    ``latency=latency``
> +        Add extra latency to playback in microseconds
> +
> +    ``in|out.name=sink``
> +        Use the specified source/sink for recording/playback.
> +
>  ``-audiodev sdl,id=id[,prop[=value][,...]]``
>      Creates a backend using SDL. This backend is available on most
>      systems, but you should use your platform's native backend if
> diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
> index 939cc114dd..05c0090118 100644
> --- a/scripts/meson-buildoptions.sh
> +++ b/scripts/meson-buildoptions.sh
> @@ -1,7 +1,8 @@
>  # This file is generated by meson-buildoptions.py, do not edit!
>  meson_options_help() {
> -  printf "%s\n" '  --audio-drv-list=CHOICES Set audio driver list [default] (choices: alsa/co'
> -  printf "%s\n" '                           reaudio/default/dsound/jack/oss/pa/sdl/sndio)'
> +  printf "%s\n" '  --audio-drv-list=CHOICES Set audio driver list [default] (choices: al'
> +  printf "%s\n" '                           sa/coreaudio/default/dsound/jack/oss/pa/'
> +  printf "%s\n" '                           pipewire/sdl/sndio)'
>    printf "%s\n" '  --block-drv-ro-whitelist=VALUE'
>    printf "%s\n" '                           set block driver read-only whitelist (by default'
>    printf "%s\n" '                           affects only QEMU, not tools like qemu-img)'
> @@ -135,6 +136,7 @@ meson_options_help() {
>    printf "%s\n" '  oss             OSS sound support'
>    printf "%s\n" '  pa              PulseAudio sound support'
>    printf "%s\n" '  parallels       parallels image format support'
> +  printf "%s\n" '  pipewire        Pipewire sound support'
>    printf "%s\n" '  png             PNG support with libpng'
>    printf "%s\n" '  pvrdma          Enable PVRDMA support'
>    printf "%s\n" '  qcow1           qcow1 image format support'
> @@ -370,6 +372,8 @@ _meson_option_parse() {
>      --disable-pa) printf "%s" -Dpa=disabled ;;
>      --enable-parallels) printf "%s" -Dparallels=enabled ;;
>      --disable-parallels) printf "%s" -Dparallels=disabled ;;
> +    --enable-pipewire) printf "%s" -Dpipewire=enabled ;;
> +    --disable-pipewire) printf "%s" -Dpipewire=disabled ;;
>      --with-pkgversion=*) quote_sh "-Dpkgversion=$2" ;;
>      --enable-png) printf "%s" -Dpng=enabled ;;
>      --disable-png) printf "%s" -Dpng=disabled ;;
>