[FFmpeg-devel] [PATCH v2] libavfilter: add PipeWire-based grab

* [FFmpeg-devel] [PATCH v2] libavfilter: add PipeWire-based grab
@ 2024-05-10 21:12 François-Simon Fauteux-Chapleau
  2024-05-11 14:08 ` Andrew Sayers
  0 siblings, 1 reply; 13+ messages in thread
From: François-Simon Fauteux-Chapleau @ 2024-05-10 21:12 UTC (permalink / raw)
  To: ffmpeg-devel

This is a revised version of the "pipewiregrab" patch submitted by
Abhishek Ojha a few months ago:
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20231227162504.690730-1-abhishek.ojha@savoirfairelinux.com/
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20231227162504.690730-2-abhishek.ojha@savoirfairelinux.com/

The main change is that the patch is now implemented as a libavfilter
source filter instead of a libavdevice input device, as was requested in
a comment on the previous version. This version also adds support for
DMA buffer sharing and uses sd-bus instead of GDBus.

There are also several small changes meant to fix bugs or simplify the
code, but the overall structure remains the same as before: we use the
ScreenCast interface provided by XDG Desktop Portal to obtain a file
descriptor, which is then used to create a PipeWire stream. The data from
that stream can then be used to generate frames for FFmpeg.

Example usage:
ffmpeg -f lavfi -i pipewiregrab \
       -vf 'hwmap=derive_device=vaapi,scale_vaapi=format=nv12' \
       -c:v h264_vaapi -t 10 output.mp4

Signed-off-by: François-Simon Fauteux-Chapleau <francois-simon.fauteux-chapleau@savoirfairelinux.com>
---
 configure                       |   16 +
 libavfilter/Makefile            |    1 +
 libavfilter/allfilters.c        |    1 +
 libavfilter/vsrc_pipewiregrab.c | 1433 +++++++++++++++++++++++++++++++
 4 files changed, 1451 insertions(+)
 create mode 100644 libavfilter/vsrc_pipewiregrab.c

diff --git a/configure b/configure
index beb1fa6d3c..028020455e 100755
--- a/configure
+++ b/configure
@@ -304,6 +304,7 @@ External library support:
   --enable-libxcb-shm      enable X11 grabbing shm communication [autodetect]
   --enable-libxcb-xfixes   enable X11 grabbing mouse rendering [autodetect]
   --enable-libxcb-shape    enable X11 grabbing shape rendering [autodetect]
+  --enable-libpipewire     enable screen grabbing using PipeWire [autodetect]
   --enable-libxvid         enable Xvid encoding via xvidcore,
                            native MPEG-4/Xvid encoder exists [no]
   --enable-libxml2         enable XML parsing using the C library libxml2, needed
@@ -1845,6 +1846,8 @@ EXTERNAL_AUTODETECT_LIBRARY_LIST="
     libxcb_shm
     libxcb_shape
     libxcb_xfixes
+    libpipewire
+    libsystemd
     lzma
     mediafoundation
     metal
@@ -3895,6 +3898,7 @@ pad_opencl_filter_deps="opencl"
 pan_filter_deps="swresample"
 perspective_filter_deps="gpl"
 phase_filter_deps="gpl"
+pipewiregrab_filter_deps="libpipewire libsystemd pthreads"
 pp7_filter_deps="gpl"
 pp_filter_deps="gpl postproc"
 prewitt_opencl_filter_deps="opencl"
@@ -7230,6 +7234,18 @@ if enabled libxcb; then
     enabled libxcb_xfixes && check_pkg_config libxcb_xfixes xcb-xfixes xcb/xfixes.h xcb_xfixes_get_cursor_image
 fi
 
+# Starting with version 0.3.52, PipeWire's spa library uses the __LOCALE_C_ONLY macro to determine
+# whether the locale_t type (introduced in POSIX.1-2008) and some related functions are available (see
+# https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/2390 for more information).
+# Unfortunately, this macro is specific to uclibc, which can cause build issues on systems that use a
+# different implementation of libc if POSIX 2008 support isn't enabled (which is the case for FFmpeg currently).
+# As a workaround for this problem, we add a compilation flag to ensure that __LOCALE_C_ONLY is always defined.
+add_cppflags -D__LOCALE_C_ONLY
+enabled libpipewire && check_pkg_config libpipewire "libpipewire-0.3 >= 0.3.40" pipewire/pipewire.h pw_init
+if enabled libpipewire; then
+    enabled libsystemd  && check_pkg_config libsystemd "libsystemd >= 246" systemd/sd-bus.h sd_bus_call_method
+fi
+
 check_func_headers "windows.h" CreateDIBSection "$gdigrab_indev_extralibs"
 
 # check if building for desktop or uwp
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 5992fd161f..6352e91586 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -603,6 +603,7 @@ OBJS-$(CONFIG_NULLSRC_FILTER)                += vsrc_testsrc.o
 OBJS-$(CONFIG_OPENCLSRC_FILTER)              += vf_program_opencl.o opencl.o
 OBJS-$(CONFIG_PAL75BARS_FILTER)              += vsrc_testsrc.o
 OBJS-$(CONFIG_PAL100BARS_FILTER)             += vsrc_testsrc.o
+OBJS-$(CONFIG_PIPEWIREGRAB_FILTER)           += vsrc_pipewiregrab.o
 OBJS-$(CONFIG_QRENCODE_FILTER)               += qrencode.o textutils.o
 OBJS-$(CONFIG_QRENCODESRC_FILTER)            += qrencode.o textutils.o
 OBJS-$(CONFIG_RGBTESTSRC_FILTER)             += vsrc_testsrc.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index c532682fc2..3670a6d7e7 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -569,6 +569,7 @@ extern const AVFilter ff_vsrc_openclsrc;
 extern const AVFilter ff_vsrc_qrencodesrc;
 extern const AVFilter ff_vsrc_pal75bars;
 extern const AVFilter ff_vsrc_pal100bars;
+extern const AVFilter ff_vsrc_pipewiregrab;
 extern const AVFilter ff_vsrc_rgbtestsrc;
 extern const AVFilter ff_vsrc_sierpinski;
 extern const AVFilter ff_vsrc_smptebars;
diff --git a/libavfilter/vsrc_pipewiregrab.c b/libavfilter/vsrc_pipewiregrab.c
new file mode 100644
index 0000000000..51073c22b1
--- /dev/null
+++ b/libavfilter/vsrc_pipewiregrab.c
@@ -0,0 +1,1433 @@
+/*
+ * PipeWire input grabber (ScreenCast)
+ * Copyright (C) 2024 Savoir-faire Linux, Inc.
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * PipeWireGrab video source
+ * @author Firas Ashkar <firas.ashkar at savoirfairelinux.com>
+ * @author Abhishek Ojha <abhishek.ojha at savoirfairelinux.com>
+ * @author François-Simon Fauteux-Chapleau <francois-simon.fauteux-chapleau at savoirfairelinux.com>
+ */
+
+#include <drm_fourcc.h>
+#include <fcntl.h>
+#include <pipewire/pipewire.h>
+#include <pipewire/thread-loop.h>
+#include <pthread.h>
+#include <spa/debug/types.h>
+#include <spa/param/video/format-utils.h>
+#include <spa/param/video/raw.h>
+#include <spa/param/video/type-info.h>
+#include <stdatomic.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <systemd/sd-bus.h>
+#include <systemd/sd-bus-protocol.h>
+#include <unistd.h>
+
+#include "avfilter.h"
+#include "formats.h"
+#include "video.h"
+
+#include "libavformat/avformat.h"
+#include "libavutil/avassert.h"
+#include "libavutil/avstring.h"
+#include "libavutil/hwcontext.h"
+#include "libavutil/hwcontext_drm.h"
+#include "libavutil/mem.h"
+#include "libavutil/opt.h"
+#include "libavutil/time.h"
+
+#ifndef __USE_XOPEN2K8
+#define F_DUPFD_CLOEXEC                                                        \
+    1030 /* Duplicate file descriptor with close-on-exit set.  */
+#endif
+
+#define DESTINATION "org.freedesktop.portal.Desktop"
+#define SENDER DESTINATION
+#define OBJECT_PATH "/org/freedesktop/portal/desktop"
+#define INTERFACE "org.freedesktop.portal.ScreenCast"
+#define REQUEST_PATH "/org/freedesktop/portal/desktop/request/%s/%s"
+
+#define BYTES_PER_PIXEL 4 /* currently all formats assume 4 bytes per pixel */
+#define MAX_SPA_PARAM 4 /* max number of params for spa pod */
+
+/**
+ * PipeWire capture types
+ */
+typedef enum {
+    DESKTOP_CAPTURE = 1,
+    WINDOW_CAPTURE = 2,
+} pw_capture_type;
+
+/**
+ * XDG Desktop Portal supported cursor modes
+ */
+enum PortalCursorMode {
+    PORTAL_CURSOR_MODE_HIDDEN = 1 << 0,
+    PORTAL_CURSOR_MODE_EMBEDDED = 1 << 1,
+};
+
+typedef struct PipewireGrabContext {
+    const AVClass *class;
+
+    sd_bus *connection;
+    atomic_int dbus_event_loop_running;
+    char *sender_name;
+    char *session_handle;
+
+    uint64_t pipewire_node;
+    int pipewire_fd;
+
+    pthread_cond_t pipewire_initialization_cond_var;
+    pthread_mutex_t pipewire_initialization_mutex;
+    atomic_int pipewire_initialization_over;
+    int pw_init_called;
+    struct pw_thread_loop *thread_loop;
+    struct pw_context *context;
+    struct pw_core *core;
+    struct spa_hook core_listener;
+    struct pw_stream *stream;
+    struct spa_hook stream_listener;
+    struct spa_video_info format;
+
+    uint32_t available_cursor_modes;
+    pw_capture_type capture_type;
+    int draw_mouse;
+
+    uint32_t width, height;
+    size_t frame_size;
+    uint8_t Bpp;
+    enum AVPixelFormat av_pxl_format;
+
+    int64_t time_frame;
+    int64_t frame_duration;
+    AVRational framerate;
+    pthread_mutex_t current_frame_mutex;
+    AVFrame *current_frame;
+    AVBufferRef *hw_device_ref;
+    AVBufferRef *hw_frames_ref;
+    int enable_dmabuf;
+    const char *device_path;
+
+    int portal_error;
+    int pipewire_error;
+} PipewireGrabContext;
+
+/**
+ * Data for DBus signals callbacks
+ */
+struct DbusSignalData {
+    AVFilterContext *ctx;
+    sd_bus_slot *slot;
+};
+
+#define OFFSET(x) offsetof(PipewireGrabContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+static const AVOption pipewiregrab_options[] = {
+    { "framerate", "set video frame rate", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, { .str = "ntsc" }, 0, INT_MAX, FLAGS },
+    { "draw_mouse", "draw the mouse pointer", OFFSET(draw_mouse), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
+    { "capture_type", "set the capture type (1 for screen, 2 for window)", OFFSET(capture_type), AV_OPT_TYPE_INT, { .i64 = 1 }, 1, 2, FLAGS },
+    { "fd", "set file descriptor to be used by PipeWire", OFFSET(pipewire_fd), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
+    { "node", "set PipeWire node (required when using the 'fd' option)", OFFSET(pipewire_node), AV_OPT_TYPE_UINT64, { .i64 = 0 }, 0, 0xffffffff, FLAGS },
+    { "enable_dmabuf", "enable DMA-BUF sharing", OFFSET(enable_dmabuf), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
+    { "device", "DRM device path", OFFSET(device_path), AV_OPT_TYPE_STRING, { .str = "/dev/dri/card0" }, 0, 0, FLAGS },
+    { NULL },
+};
+
+AVFILTER_DEFINE_CLASS(pipewiregrab);
+
+/**
+ * Helper function to allow portal_init_screencast to stop and return an error
+ * code if a DBus operation/callback fails.
+ *
+ * @param ctx
+ * @param error AVERROR code (negative)
+ * @param message error message
+ */
+static void portal_abort(AVFilterContext *ctx, int error, const char *message)
+{
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    pw_ctx->portal_error = error;
+    av_log(ctx, AV_LOG_ERROR, "Aborting: %s\n", message);
+
+    atomic_store(&pw_ctx->dbus_event_loop_running, 0);
+}
+
+/**
+ * Callback to handle PipeWire core info events
+ *
+ * @param user_data pointer to AVFilterContext
+ * @param info pw_core_info
+ */
+static void on_core_info_callback(void *user_data, const struct pw_core_info *info)
+{
+    AVFilterContext *ctx = user_data;
+    av_log(ctx, AV_LOG_DEBUG, "Server version: %s\n", info->version);
+    av_log(ctx, AV_LOG_INFO, "Library version: %s\n", pw_get_library_version());
+    av_log(ctx, AV_LOG_DEBUG, "Header version: %s\n", pw_get_headers_version());
+}
+
+/**
+ * Callback to handle PipeWire core done events
+ *
+ * @param user_data pointer to AVFilterContext
+ * @param id PipeWire object id of calling
+ * @param seq PipeWire object sequence
+ */
+static void on_core_done_callback(void *user_data, uint32_t id, int seq)
+{
+    AVFilterContext *ctx = user_data;
+    PipewireGrabContext *pw_ctx;
+
+    if (!ctx || !ctx->priv)
+        return;
+    pw_ctx = ctx->priv;
+
+    if (id == PW_ID_CORE)
+        pw_thread_loop_signal(pw_ctx->thread_loop, false);
+}
+
+/**
+ * Callback to handle Pipewire core error events
+ *
+ * @param user_data pointer to AVFilterContext
+ * @param id id of PipeWire proxy object where the error occured
+ * @param seq PipeWire sequence number which produced the error
+ * @param res error number
+ * @param message error message
+ */
+static void on_core_error_callback(void *user_data, uint32_t id, int seq,
+                                   int res, const char *message)
+{
+    AVFilterContext *ctx = user_data;
+    PipewireGrabContext *pw_ctx;
+
+    if (!ctx)
+        return;
+
+    av_log(ctx, AV_LOG_ERROR,
+           "PipeWire core error: %s (id=%u, seq=%d, res=%d: %s)\n",
+           message, id, seq, res, strerror(-res));
+
+    pw_ctx = ctx->priv;
+    if (!pw_ctx)
+        return;
+
+    pw_thread_loop_signal(pw_ctx->thread_loop, false);
+    pw_ctx->pipewire_error = res;
+    atomic_store(&pw_ctx->pipewire_initialization_over, 1);
+    pthread_cond_signal(&pw_ctx->pipewire_initialization_cond_var);
+}
+
+/**
+ * PipeWire core events callbacks
+ */
+static const struct pw_core_events core_events = {
+    PW_VERSION_CORE_EVENTS,
+    .info = on_core_info_callback,
+    .done = on_core_done_callback,
+    .error = on_core_error_callback,
+};
+
+/**
+ * Helper function: convert spa video format to AVPixelFormat
+ *
+ * @param video_format spa video format to convert
+ * @return the corresponding AVPixelFormat
+ */
+static enum AVPixelFormat
+spa_video_format_to_av_pixel_format(enum spa_video_format video_format)
+{
+    switch (video_format) {
+    case SPA_VIDEO_FORMAT_RGBA:
+    case SPA_VIDEO_FORMAT_RGBx:
+        return AV_PIX_FMT_RGBA;
+
+    case SPA_VIDEO_FORMAT_BGRA:
+    case SPA_VIDEO_FORMAT_BGRx:
+        return AV_PIX_FMT_BGRA;
+
+    default:
+        return AV_PIX_FMT_NONE;
+    }
+}
+
+static uint32_t spa_video_format_to_drm_format(enum spa_video_format video_format)
+{
+    switch (video_format) {
+    case SPA_VIDEO_FORMAT_RGBA:
+        return DRM_FORMAT_ABGR8888;
+    case SPA_VIDEO_FORMAT_RGBx:
+        return DRM_FORMAT_XBGR8888;
+    case SPA_VIDEO_FORMAT_BGRA:
+        return DRM_FORMAT_ARGB8888;
+    case SPA_VIDEO_FORMAT_BGRx:
+        return DRM_FORMAT_XRGB8888;
+    default:
+        return DRM_FORMAT_INVALID;
+    }
+}
+
+static const uint32_t pipewiregrab_formats[] = {
+    SPA_VIDEO_FORMAT_RGBA,
+    SPA_VIDEO_FORMAT_RGBx,
+    SPA_VIDEO_FORMAT_BGRx,
+    SPA_VIDEO_FORMAT_BGRA,
+};
+
+static const uint64_t pipewiregrab_default_modifiers[] = {
+    DRM_FORMAT_MOD_LINEAR,
+    DRM_FORMAT_MOD_INVALID,
+};
+
+/**
+ * PipeWire callback of parameters changed events
+ *
+ * @param user_data pointer to AVFilterContext
+ * @param id type of changed param
+ * @param param pointer to changed param structure
+ */
+static void on_stream_param_changed_callback(void *user_data, uint32_t id,
+                                             const struct spa_pod *param)
+{
+    struct spa_pod_builder pod_builder;
+    const struct spa_pod *params[MAX_SPA_PARAM];
+    uint32_t n_params = 0;
+    uint32_t buffer_types;
+    uint8_t params_buffer[4096];
+    int result;
+    int err;
+    PipewireGrabContext *pw_ctx;
+    AVFilterContext *ctx = user_data;
+    AVHWFramesContext *frames_ctx = NULL;
+
+    if (!ctx || !ctx->priv || !param)
+        return;
+
+    if (id != SPA_PARAM_Format) {
+        av_log(ctx, AV_LOG_WARNING,
+               "Ignoring non-Format param change\n");
+        return;
+    }
+
+    pw_ctx = ctx->priv;
+
+    result = spa_format_parse(param, &pw_ctx->format.media_type,
+                              &pw_ctx->format.media_subtype);
+    if (result < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Unable to parse media type\n");
+        pw_ctx->pipewire_error = AVERROR(EINVAL);
+        goto end;
+    }
+
+    if (pw_ctx->format.media_type != SPA_MEDIA_TYPE_video ||
+        pw_ctx->format.media_subtype != SPA_MEDIA_SUBTYPE_raw) {
+        av_log(ctx, AV_LOG_ERROR, "Unexpected media type\n");
+        pw_ctx->pipewire_error = AVERROR(EINVAL);
+        goto end;
+    }
+
+    spa_format_video_raw_parse(param, &pw_ctx->format.info.raw);
+
+    av_log(ctx, AV_LOG_INFO, "Negotiated format:\n");
+
+    av_log(ctx, AV_LOG_INFO, "Format: %d (%s)\n",
+           pw_ctx->format.info.raw.format,
+           spa_debug_type_find_name(spa_type_video_format,
+                                    pw_ctx->format.info.raw.format));
+    av_log(ctx, AV_LOG_INFO, "Size: %dx%d\n",
+           pw_ctx->format.info.raw.size.width,
+           pw_ctx->format.info.raw.size.height);
+    av_log(ctx, AV_LOG_INFO, "Framerate: %d/%d\n",
+           pw_ctx->format.info.raw.framerate.num,
+           pw_ctx->format.info.raw.framerate.denom);
+
+    pw_ctx->width = pw_ctx->format.info.raw.size.width;
+    pw_ctx->height = pw_ctx->format.info.raw.size.height;
+    pw_ctx->Bpp = BYTES_PER_PIXEL;
+    pw_ctx->frame_size = pw_ctx->width * pw_ctx->height * pw_ctx->Bpp;
+    if (pw_ctx->frame_size + AV_INPUT_BUFFER_PADDING_SIZE > INT_MAX) {
+        av_log(ctx, AV_LOG_ERROR, "Captured area is too large\n");
+        pw_ctx->pipewire_error = AVERROR(EINVAL);
+        goto end;
+    }
+
+    pw_ctx->av_pxl_format =
+        spa_video_format_to_av_pixel_format(pw_ctx->format.info.raw.format);
+    if (pw_ctx->av_pxl_format == AV_PIX_FMT_NONE) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Unsupported buffer format: %d\n", pw_ctx->format.info.raw.format);
+        pw_ctx->pipewire_error = AVERROR(EINVAL);
+        goto end;
+    }
+
+    /* Video crop */
+    pod_builder = SPA_POD_BUILDER_INIT(params_buffer, sizeof(params_buffer));
+    params[n_params++] = spa_pod_builder_add_object(
+        &pod_builder, SPA_TYPE_OBJECT_ParamMeta, SPA_PARAM_Meta,
+        SPA_PARAM_META_type, SPA_POD_Id(SPA_META_VideoCrop),
+        SPA_PARAM_META_size, SPA_POD_Int(sizeof(struct spa_meta_region)));
+
+    /* Buffer options */
+    buffer_types = (1 << SPA_DATA_MemPtr) | (1 << SPA_DATA_MemFd);
+    if (spa_pod_find_prop(param, NULL, SPA_FORMAT_VIDEO_modifier)) {
+        err = av_hwdevice_ctx_create(&pw_ctx->hw_device_ref, AV_HWDEVICE_TYPE_DRM,
+                                     pw_ctx->device_path, NULL, 0);
+        if (err < 0)
+            goto hw_fail;
+
+        pw_ctx->hw_frames_ref = av_hwframe_ctx_alloc(pw_ctx->hw_device_ref);
+        if (!pw_ctx->hw_frames_ref) {
+            err = AVERROR(ENOMEM);
+            goto hw_fail;
+        }
+        frames_ctx = (AVHWFramesContext*)pw_ctx->hw_frames_ref->data;
+        frames_ctx->format    = AV_PIX_FMT_DRM_PRIME;
+        frames_ctx->sw_format = pw_ctx->av_pxl_format;
+        frames_ctx->width     = pw_ctx->width;
+        frames_ctx->height    = pw_ctx->height;
+        err = av_hwframe_ctx_init(pw_ctx->hw_frames_ref);
+hw_fail:
+        if (!err) {
+            buffer_types |= 1 << SPA_DATA_DmaBuf;
+        } else {
+            av_log(ctx, AV_LOG_WARNING,
+                   "Failed to initialize hardware frames context: %s. "
+                   "Falling back to shared memory\n", av_err2str(err));
+        }
+    }
+
+    params[n_params++] = spa_pod_builder_add_object(
+        &pod_builder, SPA_TYPE_OBJECT_ParamBuffers, SPA_PARAM_Buffers,
+        SPA_PARAM_BUFFERS_dataType,
+        SPA_POD_Int(buffer_types));
+
+    /* Meta header */
+    params[n_params++] = spa_pod_builder_add_object(
+        &pod_builder, SPA_TYPE_OBJECT_ParamMeta, SPA_PARAM_Meta,
+        SPA_PARAM_META_type, SPA_POD_Id(SPA_META_Header),
+        SPA_PARAM_META_size,
+        SPA_POD_Int(sizeof(struct spa_meta_header)));
+
+    pw_stream_update_params(pw_ctx->stream, params, n_params);
+
+end:
+    // Signal pipewiregrab_init that PipeWire initialization is over (either
+    // because it was completed successfully or because there was an error, in
+    // which case pw_ctx->pipewire_error will have been set to a nonzero value).
+    atomic_store(&pw_ctx->pipewire_initialization_over, 1);
+    pthread_cond_signal(&pw_ctx->pipewire_initialization_cond_var);
+}
+
+/**
+ * PipeWire callback of state changed events
+ *
+ * @param user_data pointer to AVFilterContext
+ * @param old old PipeWire stream state
+ * @param state current PipeWire stream state
+ * @param error received error information
+ */
+static void on_stream_state_changed_callback(void *user_data,
+                                             enum pw_stream_state old,
+                                             enum pw_stream_state state,
+                                             const char *error)
+{
+    AVFilterContext *ctx = user_data;
+    if (!ctx)
+        return;
+
+    av_log(ctx, AV_LOG_INFO, "stream state: \"%s\"\n",
+           pw_stream_state_as_string(state));
+}
+
+/**
+ * Find most recent buffer received in a PipeWire stream
+ *
+ * @param stream stream to get buffer from
+ * @return most recent buffer in the stream
+ */
+static struct pw_buffer *find_most_recent_buffer_and_recycle_olders(struct pw_stream *stream)
+{
+    struct pw_buffer *pw_buf = NULL;
+    while (1) {
+        struct pw_buffer *aux = pw_stream_dequeue_buffer(stream);
+        if (!aux)
+            break;
+        if (pw_buf)
+            pw_stream_queue_buffer(stream, pw_buf);
+        pw_buf = aux;
+    }
+    return pw_buf;
+}
+
+static void free_frame_desc(void *opaque, uint8_t *data)
+{
+    AVDRMFrameDescriptor *frame_desc = (AVDRMFrameDescriptor *)data;
+
+    for (int i = 0; i < frame_desc->nb_objects; i++)
+        close(frame_desc->objects[i].fd);
+    av_free(frame_desc);
+}
+
+static void process_dma_buffer(AVFilterContext *ctx, struct spa_buffer *spa_buf)
+{
+    AVFrame *frame = NULL;
+    AVDRMFrameDescriptor *frame_desc = NULL;
+    int ret;
+    int n_planes;
+    size_t size;
+    uint32_t offset, pitch;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    n_planes = spa_buf->n_datas;
+    av_assert0(n_planes <= AV_DRM_MAX_PLANES);
+
+    // Create frame descriptor
+    frame_desc = av_mallocz(sizeof(*frame_desc));
+    if (!frame_desc) {
+        av_log(ctx, AV_LOG_ERROR, "Failed to allocate frame descriptor\n");
+        goto fail;
+    }
+    *frame_desc = (AVDRMFrameDescriptor) {
+        .nb_objects = n_planes,
+        .nb_layers = 1,
+        .layers[0] = {
+            .format = spa_video_format_to_drm_format(pw_ctx->format.info.raw.format),
+            .nb_planes = n_planes,
+        },
+    };
+    for (int i = 0; i < n_planes; i++) {
+        offset = spa_buf->datas[i].chunk->offset;
+        pitch = spa_buf->datas[i].chunk->stride;
+        size = offset + pitch * pw_ctx->height;
+
+        frame_desc->objects[i] = (AVDRMObjectDescriptor) {
+            .fd              = spa_buf->datas[i].fd,
+            .size            = size,
+            .format_modifier = pw_ctx->format.info.raw.modifier,
+        };
+        frame_desc->layers[0].planes[i] = (AVDRMPlaneDescriptor) {
+            .object_index = i,
+            .offset       = offset,
+            .pitch        = pitch,
+        };
+    }
+
+    // Create frame
+    frame = av_frame_alloc();
+    if (!frame) {
+        av_log(ctx, AV_LOG_ERROR, "Failed to allocate frame\n");
+        goto fail;
+    }
+    frame->hw_frames_ctx = av_buffer_ref(pw_ctx->hw_frames_ref);
+    if (!frame->hw_frames_ctx) {
+        av_log(ctx, AV_LOG_ERROR, "Failed to create buffer reference\n");
+        goto fail;
+    }
+    frame->buf[0] = av_buffer_create((uint8_t *)frame_desc, sizeof(*frame_desc),
+                                     free_frame_desc, NULL, 0);
+    if (!frame->buf[0]) {
+        av_log(ctx, AV_LOG_ERROR, "Failed to create buffer\n");
+        goto fail;
+    }
+    frame->data[0] = (uint8_t *)frame_desc;
+    frame->format  = AV_PIX_FMT_DRM_PRIME;
+    frame->width = pw_ctx->width;
+    frame->height = pw_ctx->height;
+
+    // Update current_frame
+    pthread_mutex_lock(&pw_ctx->current_frame_mutex);
+    av_frame_unref(pw_ctx->current_frame);
+    ret = av_frame_ref(pw_ctx->current_frame, frame);
+    pthread_mutex_unlock(&pw_ctx->current_frame_mutex);
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Failed to create frame reference\n");
+        av_frame_free(&frame);
+    }
+    return;
+
+fail:
+    av_freep(&frame_desc);
+    av_frame_free(&frame);
+}
+
+static void process_shm_buffer(AVFilterContext *ctx, struct spa_buffer *spa_buf)
+{
+    uint8_t *map = NULL;
+    void *sdata = NULL;
+    struct spa_meta_region *region;
+    int crop_left, crop_right, crop_top, crop_bottom;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    // Get data
+    if (spa_buf->datas[0].type == SPA_DATA_MemFd ) {
+        map = mmap(NULL, spa_buf->datas[0].maxsize + spa_buf->datas[0].mapoffset,
+                   PROT_READ, MAP_PRIVATE, spa_buf->datas[0].fd, 0);
+        if (map == MAP_FAILED) {
+            av_log(ctx, AV_LOG_ERROR, "mmap failed: %s\n", strerror(errno));
+            return;
+        }
+        sdata = SPA_PTROFF(map, spa_buf->datas[0].mapoffset, uint8_t);
+    } else if (spa_buf->datas[0].type == SPA_DATA_MemPtr) {
+        if (spa_buf->datas[0].data == NULL) {
+            av_log(ctx, AV_LOG_ERROR, "No data in buffer\n");
+            return;
+        }
+        sdata = spa_buf->datas[0].data;
+    } else {
+        av_log(ctx, AV_LOG_ERROR, "Buffer is not valid\n");
+        return;
+    }
+
+    region = spa_buffer_find_meta_data(spa_buf, SPA_META_VideoCrop, sizeof(*region));
+    if (region && spa_meta_region_is_valid(region)) {
+        crop_left = region->region.position.x;
+        crop_top = region->region.position.y;
+        crop_right = pw_ctx->width - crop_left - region->region.size.width;
+        crop_bottom = pw_ctx->height - crop_top - region->region.size.height;
+    }
+
+    // Update current_frame with the new data
+    pthread_mutex_lock(&pw_ctx->current_frame_mutex);
+    memcpy(pw_ctx->current_frame->data[0], sdata, spa_buf->datas[0].chunk->size);
+    pw_ctx->current_frame->crop_top = crop_top;
+    pw_ctx->current_frame->crop_bottom = crop_bottom;
+    pw_ctx->current_frame->crop_left = crop_left;
+    pw_ctx->current_frame->crop_right = crop_right;
+    pthread_mutex_unlock(&pw_ctx->current_frame_mutex);
+
+    // Cleanup
+    if (spa_buf->datas[0].type == SPA_DATA_MemFd)
+        munmap(map, spa_buf->datas[0].maxsize + spa_buf->datas[0].mapoffset);
+}
+
+/**
+ * This function is called by PipeWire when a buffer
+ * is ready to be dequeued and processed.
+ *
+ * @param user_data pointer to AVFilterContext
+ */
+static void on_stream_process_callback(void *user_data)
+{
+    struct spa_buffer *spa_buf;
+    struct pw_buffer *pw_buf = NULL;
+    struct spa_meta_header *header = NULL;
+
+    AVFilterContext *ctx = user_data;
+    PipewireGrabContext *pw_ctx;
+    if (!ctx || !ctx->priv)
+        return;
+    pw_ctx = ctx->priv;
+
+    // We need to wait for pw_ctx->current_frame to have been allocated before
+    // we can use it to get frames from the PipeWire thread to FFmpeg
+    pthread_mutex_lock(&pw_ctx->current_frame_mutex);
+    if (!pw_ctx->current_frame) {
+        pthread_mutex_unlock(&pw_ctx->current_frame_mutex);
+        return;
+    }
+    pthread_mutex_unlock(&pw_ctx->current_frame_mutex);
+
+    pw_buf = find_most_recent_buffer_and_recycle_olders(pw_ctx->stream);
+    if (!pw_buf) {
+        av_log(ctx, AV_LOG_ERROR, "Out of buffers\n");
+        return;
+    }
+
+    spa_buf = pw_buf->buffer;
+    header = spa_buffer_find_meta_data(spa_buf, SPA_META_Header, sizeof(*header));
+    if (header && (header->flags & SPA_META_HEADER_FLAG_CORRUPTED)) {
+        av_log(ctx, AV_LOG_ERROR, "Corrupted PipeWire buffer\n");
+        goto end;
+    }
+
+    if (spa_buf->datas[0].type == SPA_DATA_DmaBuf)
+        process_dma_buffer(ctx, spa_buf);
+    else
+        process_shm_buffer(ctx, spa_buf);
+
+end:
+    pw_stream_queue_buffer(pw_ctx->stream, pw_buf);
+}
+
+static const struct pw_stream_events stream_events = {
+    PW_VERSION_STREAM_EVENTS,
+    .state_changed = on_stream_state_changed_callback,
+    .param_changed = on_stream_param_changed_callback,
+    .process = on_stream_process_callback,
+};
+
+static int subscribe_to_signal(AVFilterContext *ctx,
+                               const char *sender_name,
+                               const char *request_token,
+                               sd_bus_message_handler_t callback)
+{
+    int ret;
+    char *request_path;
+    struct DbusSignalData *dbus_signal_data;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    dbus_signal_data = (struct DbusSignalData *)av_mallocz(sizeof(struct DbusSignalData));
+    if (!dbus_signal_data)
+        return AVERROR(ENOMEM);
+
+    dbus_signal_data->ctx = ctx;
+    request_path = av_asprintf(REQUEST_PATH, sender_name, request_token);
+
+    ret = sd_bus_match_signal(pw_ctx->connection,
+                              &dbus_signal_data->slot,
+                              SENDER,
+                              request_path,
+                              "org.freedesktop.portal.Request",
+                              "Response",
+                              callback,
+                              dbus_signal_data);
+    av_free(request_path);
+    return (ret < 0) ? ret : 0;
+}
+
+static struct spa_pod *build_format(PipewireGrabContext *pw_ctx,
+                                    struct spa_pod_builder *builder,
+                                    uint32_t format,
+                                    const uint64_t *modifiers,
+                                    int n_modifiers)
+{
+    struct spa_pod_frame format_frame;
+    struct spa_pod_frame modifier_frame;
+
+    spa_pod_builder_push_object(builder, &format_frame,
+                                SPA_TYPE_OBJECT_Format, SPA_PARAM_EnumFormat);
+    spa_pod_builder_add(builder, SPA_FORMAT_mediaType,
+                        SPA_POD_Id(SPA_MEDIA_TYPE_video), 0);
+    spa_pod_builder_add(builder, SPA_FORMAT_mediaSubtype,
+                        SPA_POD_Id(SPA_MEDIA_SUBTYPE_raw), 0);
+    spa_pod_builder_add(builder, SPA_FORMAT_VIDEO_format,
+                        SPA_POD_Id(format), 0);
+    spa_pod_builder_add(builder, SPA_FORMAT_VIDEO_size,
+                        SPA_POD_CHOICE_RANGE_Rectangle(
+                            &SPA_RECTANGLE(320, 240),
+                            &SPA_RECTANGLE(1, 1),
+                            &SPA_RECTANGLE(4096, 4096)
+                        ), 0);
+    spa_pod_builder_add(builder, SPA_FORMAT_VIDEO_framerate,
+                        SPA_POD_CHOICE_RANGE_Fraction(
+                            &SPA_FRACTION(pw_ctx->framerate.num, pw_ctx->framerate.den),
+                            &SPA_FRACTION(0, 1),
+                            &SPA_FRACTION(144, 1)
+                        ), 0);
+    if (n_modifiers > 0) {
+        spa_pod_builder_prop(builder, SPA_FORMAT_VIDEO_modifier,
+                             SPA_POD_PROP_FLAG_MANDATORY | SPA_POD_PROP_FLAG_DONT_FIXATE);
+        spa_pod_builder_push_choice(builder, &modifier_frame, SPA_CHOICE_Enum, 0);
+
+        // A choice POD consists of a "default" value followed by the list of
+        // all possible values (https://docs.pipewire.org/page_spa_pod.html)
+        // This is why we need to add one of the modifiers twice.
+        spa_pod_builder_long(builder, modifiers[0]);
+        for (int i = 0; i < n_modifiers; i++)
+            spa_pod_builder_long(builder, modifiers[i]);
+
+        spa_pod_builder_pop(builder, &modifier_frame);
+    }
+    return spa_pod_builder_pop(builder, &format_frame);
+}
+
+static int play_pipewire_stream(AVFilterContext *ctx)
+{
+    int ret;
+    uint8_t buffer[4096];
+    struct spa_pod_builder pod_builder;
+    const struct spa_pod **params;
+    uint32_t n_params;
+
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    pw_init(NULL, NULL);
+    pw_ctx->pw_init_called = 1;
+
+    pw_ctx->thread_loop =
+        pw_thread_loop_new("thread loop", NULL);
+    if (!pw_ctx->thread_loop) {
+        av_log(ctx, AV_LOG_ERROR, "pw_thread_loop_new failed\n");
+        return AVERROR(ENOMEM);
+    }
+
+    pw_ctx->context =
+        pw_context_new(pw_thread_loop_get_loop(pw_ctx->thread_loop), NULL, 0);
+    if (!pw_ctx->context) {
+        av_log(ctx, AV_LOG_ERROR, "pw_context_new failed\n");
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    if (pw_thread_loop_start(pw_ctx->thread_loop) < 0) {
+        av_log(ctx, AV_LOG_ERROR, "pw_thread_loop_start failed\n");
+        ret = AVERROR(EFAULT);
+        goto fail;
+    }
+
+    pw_thread_loop_lock(pw_ctx->thread_loop);
+
+    // Core
+    pw_ctx->core =
+        pw_context_connect_fd(pw_ctx->context,
+                              fcntl(pw_ctx->pipewire_fd, F_DUPFD_CLOEXEC, 3),
+                              NULL, 0);
+    if (!pw_ctx->core) {
+        ret = AVERROR(errno);
+        av_log(ctx, AV_LOG_ERROR, "pw_context_connect_fd failed\n");
+        pw_thread_loop_unlock(pw_ctx->thread_loop);
+        goto fail;
+    }
+
+    pw_core_add_listener(pw_ctx->core, &pw_ctx->core_listener, &core_events,
+                         ctx /* user_data */);
+
+    // Stream
+    pw_ctx->stream = pw_stream_new(
+        pw_ctx->core, "wayland grab",
+        pw_properties_new(PW_KEY_MEDIA_TYPE, "Video", PW_KEY_MEDIA_CATEGORY,
+                          "Capture", PW_KEY_MEDIA_ROLE, "Screen", NULL));
+
+    if (!pw_ctx->stream) {
+        av_log(ctx, AV_LOG_ERROR, "pw_stream_new failed\n");
+        ret = AVERROR(ENOMEM);
+        pw_thread_loop_unlock(pw_ctx->thread_loop);
+        goto fail;
+    }
+
+    pw_stream_add_listener(pw_ctx->stream, &pw_ctx->stream_listener,
+                           &stream_events, ctx /* user_data */);
+
+    // Stream parameters
+    pod_builder = SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));
+    params = av_mallocz(2 * FF_ARRAY_ELEMS(pipewiregrab_formats) * sizeof(*params));
+    n_params = 0;
+
+    for (int i = 0; i < FF_ARRAY_ELEMS(pipewiregrab_formats); i++) {
+        if (pw_ctx->enable_dmabuf)
+            params[n_params++] = build_format(pw_ctx, &pod_builder, pipewiregrab_formats[i],
+                                              pipewiregrab_default_modifiers,
+                                              FF_ARRAY_ELEMS(pipewiregrab_default_modifiers));
+        params[n_params++] = build_format(pw_ctx, &pod_builder, pipewiregrab_formats[i],
+                                          NULL, 0);
+    }
+
+    ret = pw_stream_connect(
+        pw_ctx->stream, PW_DIRECTION_INPUT, (uint32_t)pw_ctx->pipewire_node,
+        PW_STREAM_FLAG_AUTOCONNECT | PW_STREAM_FLAG_MAP_BUFFERS, params, n_params);
+    if (ret != 0) {
+        av_log(ctx, AV_LOG_ERROR, "pw_stream_connect failed\n");
+        pw_thread_loop_unlock(pw_ctx->thread_loop);
+        goto fail;
+    }
+
+    av_log(ctx, AV_LOG_INFO, "Starting screen capture ...\n");
+    pw_thread_loop_unlock(pw_ctx->thread_loop);
+    return 0;
+
+fail:
+    if (pw_ctx->core) {
+        pw_core_disconnect(pw_ctx->core);
+        pw_ctx->core = NULL;
+    }
+    if (pw_ctx->context) {
+        pw_context_destroy(pw_ctx->context);
+        pw_ctx->context = NULL;
+    }
+    if (pw_ctx->thread_loop) {
+        pw_thread_loop_destroy(pw_ctx->thread_loop);
+        pw_ctx->thread_loop = NULL;
+    }
+
+    return ret;
+}
+
+static void portal_open_pipewire_remote(AVFilterContext *ctx)
+{
+    int ret;
+    int fd;
+    sd_bus_message *reply = NULL;
+    sd_bus_error err = SD_BUS_ERROR_NULL;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    const char *method_name = "OpenPipeWireRemote";
+    ret = sd_bus_call_method(pw_ctx->connection,
+                             DESTINATION,
+                             OBJECT_PATH,
+                             INTERFACE,
+                             method_name,
+                             &err,
+                             &reply,
+                             "oa{sv}",
+                             pw_ctx->session_handle,
+                             0);
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Call to DBus method '%s' failed: %s\n",
+               method_name, err.message);
+        sd_bus_error_free(&err);
+        portal_abort(ctx, ret, "Failed to open PipeWire remote");
+        return;
+    }
+
+    ret = sd_bus_message_read(reply, "h", &fd);
+    if (ret < 0) {
+        portal_abort(ctx, ret, "Failed to read file descriptor");
+        return;
+    } else
+        av_log(ctx, AV_LOG_DEBUG, "PipeWire fd: %d\n", fd);
+
+    pw_ctx->pipewire_fd = fd;
+    atomic_store(&pw_ctx->dbus_event_loop_running, 0);
+}
+
+static void dbus_signal_data_free(struct DbusSignalData *dbus_signal_data)
+{
+    sd_bus_slot_unref(dbus_signal_data->slot);
+    av_free(dbus_signal_data);
+}
+
+static int on_start_response_received_callback(
+    sd_bus_message *message, void *user_data, sd_bus_error *err)
+{
+    int ret;
+    uint32_t response;
+    uint32_t node;
+    struct DbusSignalData *dbus_signal_data = user_data;
+    AVFilterContext *ctx = dbus_signal_data->ctx;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    dbus_signal_data_free(dbus_signal_data);
+
+    ret = sd_bus_message_read(message, "u", &response);
+    if (ret < 0) {
+        portal_abort(ctx, ret, "Failed to read DBus response");
+        return -1;
+    }
+    if (response != 0) {
+        portal_abort(ctx, AVERROR(EACCES),
+                     "Failed to start screen cast, denied or cancelled by user");
+        return -1;
+    }
+
+    sd_bus_message_enter_container(message, SD_BUS_TYPE_ARRAY, "{sv}");
+    sd_bus_message_enter_container(message, SD_BUS_TYPE_DICT_ENTRY, "sv");
+    sd_bus_message_skip(message, "s");
+    sd_bus_message_enter_container(message, SD_BUS_TYPE_VARIANT, "a(ua{sv})");
+    sd_bus_message_enter_container(message, SD_BUS_TYPE_ARRAY, "(ua{sv})");
+    sd_bus_message_enter_container(message, SD_BUS_TYPE_STRUCT, "ua{sv}");
+
+    ret = sd_bus_message_read(message, "u", &node);
+    if (ret < 0) {
+        portal_abort(ctx, ret, "Failed to read PipeWire node: %s");
+        return -1;
+    }
+    pw_ctx->pipewire_node = node;
+
+    av_log(ctx, AV_LOG_DEBUG, "PipeWire node: %"PRIu64"\n", pw_ctx->pipewire_node);
+    av_log(ctx, AV_LOG_INFO, "Monitor selected, setting up screen cast\n\n");
+
+    portal_open_pipewire_remote(ctx);
+    return 0;
+}
+
+static void portal_start(AVFilterContext *ctx)
+{
+    int ret;
+    sd_bus_error err = SD_BUS_ERROR_NULL;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    const char *method_name = "Start";
+    const char *request_token = "pipewiregrabStart";
+
+    ret = subscribe_to_signal(ctx, pw_ctx->sender_name, request_token,
+                              on_start_response_received_callback);
+    if (ret < 0) {
+        portal_abort(ctx, ret, "Failed to subscribe to DBus signal");
+        return;
+    }
+
+    av_log(ctx, AV_LOG_INFO, "Asking for monitor…\n");
+    ret = sd_bus_call_method(pw_ctx->connection,
+                             DESTINATION,
+                             OBJECT_PATH,
+                             INTERFACE,
+                             method_name,
+                             &err,
+                             NULL,
+                             "osa{sv}",
+                             pw_ctx->session_handle,
+                             "",
+                             1,
+                             "handle_token", "s", request_token);
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Call to DBus method '%s' failed: %s\n",
+               method_name, err.message);
+        sd_bus_error_free(&err);
+        portal_abort(ctx, ret, "Failed to start screen cast session");
+    }
+}
+
+static int on_select_sources_response_received_callback(
+    sd_bus_message *message, void *user_data, sd_bus_error *err)
+{
+    int ret;
+    uint32_t response;
+    struct DbusSignalData *dbus_signal_data = user_data;
+    AVFilterContext *ctx = dbus_signal_data->ctx;
+
+    dbus_signal_data_free(dbus_signal_data);
+
+    ret = sd_bus_message_read(message, "u", &response);
+    if (ret < 0) {
+        portal_abort(ctx, ret, "Failed to read DBus response");
+        return -1;
+    }
+    if (response != 0) {
+        portal_abort(ctx, AVERROR(EACCES),
+                     "Failed to select screen cast sources");
+        return -1;
+    }
+
+    portal_start(ctx);
+    return 0;
+}
+
+static void portal_select_sources(AVFilterContext *ctx)
+{
+    int ret;
+    uint32_t cursor_mode;
+    sd_bus_error err = SD_BUS_ERROR_NULL;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    const char *method_name = "SelectSources";
+    const char *request_token = "pipewiregrabSelectSources";
+
+    ret = subscribe_to_signal(ctx, pw_ctx->sender_name, request_token,
+                              on_select_sources_response_received_callback);
+    if (ret < 0) {
+        portal_abort(ctx, ret, "Failed to subscribe to DBus signal");
+        return;
+    }
+
+    if ((pw_ctx->available_cursor_modes & PORTAL_CURSOR_MODE_EMBEDDED)
+             && pw_ctx->draw_mouse)
+        cursor_mode = PORTAL_CURSOR_MODE_EMBEDDED;
+    else
+        cursor_mode = PORTAL_CURSOR_MODE_HIDDEN;
+
+    ret = sd_bus_call_method(pw_ctx->connection,
+                             DESTINATION,
+                             OBJECT_PATH,
+                             INTERFACE,
+                             method_name,
+                             &err,
+                             NULL,
+                             "oa{sv}",
+                             pw_ctx->session_handle,
+                             4,
+                             "types", "u", pw_ctx->capture_type,
+                             "multiple", "b", 0,
+                             "handle_token", "s", request_token,
+                             "cursor_mode", "u", cursor_mode);
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Call to DBus method '%s' failed: %s\n",
+               method_name, err.message);
+        sd_bus_error_free(&err);
+        portal_abort(ctx, ret, "Failed to select sources for screen cast session");
+    }
+}
+
+static int on_create_session_response_received_callback(
+    sd_bus_message *message, void *user_data, sd_bus_error *err)
+{
+    int ret;
+    uint32_t response;
+    const char *session_handle;
+    const char *type;
+    struct DbusSignalData *dbus_signal_data = user_data;
+    AVFilterContext *ctx = dbus_signal_data->ctx;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    dbus_signal_data_free(dbus_signal_data);
+
+    ret = sd_bus_message_read(message, "u", &response);
+    if (ret < 0) {
+        portal_abort(ctx, ret, "Failed to read DBus response");
+        return -1;
+    }
+    if (response != 0) {
+        portal_abort(ctx, AVERROR(EACCES),
+                     "Failed to create screen cast session");
+        return -1;
+    }
+
+    sd_bus_message_enter_container(message, SD_BUS_TYPE_ARRAY, "{sv}");
+    sd_bus_message_enter_container(message, SD_BUS_TYPE_DICT_ENTRY, "sv");
+    sd_bus_message_skip(message, "s");
+    // The XDG Desktop Portal documentation says that the type of `session_handle`
+    // is "o" (object path), but at least on some systems it's actually "s" (string),
+    // so we need to check to make sure we're using the right one.
+    sd_bus_message_peek_type(message, NULL, &type);
+    ret = sd_bus_message_read(message, "v", type, &session_handle);
+    if (ret < 0) {
+        portal_abort(ctx, ret, "Failed to read session handle");
+        return -1;
+    }
+    pw_ctx->session_handle = av_strdup(session_handle);
+
+    portal_select_sources(ctx);
+    return 0;
+}
+
+/**
+ * Function to create a screen cast session
+ *
+ * @param ctx
+ */
+static void portal_create_session(AVFilterContext *ctx)
+{
+    int ret;
+    sd_bus_error err = SD_BUS_ERROR_NULL;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    const char *method_name = "CreateSession";
+    const char *request_token = "pipewiregrabCreateSession";
+
+    ret = subscribe_to_signal(ctx, pw_ctx->sender_name, request_token,
+                              on_create_session_response_received_callback);
+    if (ret < 0) {
+        portal_abort(ctx, ret, "Failed to subscribe to DBus signal");
+        return;
+    }
+
+    ret = sd_bus_call_method(pw_ctx->connection,
+                             DESTINATION,
+                             OBJECT_PATH,
+                             INTERFACE,
+                             method_name,
+                             &err,
+                             NULL,
+                             "a{sv}",
+                             2,
+                             "handle_token", "s", request_token,
+                             "session_handle_token", "s", "pipewiregrab");
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Call to DBus method '%s' failed: %s\n",
+               method_name, err.message);
+        sd_bus_error_free(&err);
+        portal_abort(ctx, ret, "Failed to create screen cast session");
+    }
+}
+
+/**
+ * Helper function: get available cursor modes and update the
+ *                  PipewireGrabContext accordingly
+ *
+ * @param ctx
+ */
+static int portal_update_available_cursor_modes(AVFilterContext *ctx)
+{
+    int ret;
+    sd_bus_error err = SD_BUS_ERROR_NULL;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    ret = sd_bus_get_property_trivial(pw_ctx->connection,
+                                      DESTINATION,
+                                      OBJECT_PATH,
+                                      INTERFACE,
+                                      "AvailableCursorModes",
+                                      &err,
+                                      'u',
+                                      &pw_ctx->available_cursor_modes);
+    if (ret < 0)
+        av_log(ctx, AV_LOG_ERROR,
+               "Couldn't retrieve available cursor modes: %s\n", err.message);
+
+    sd_bus_error_free(&err);
+    return ret;
+}
+
+static int create_dbus_connection(AVFilterContext *ctx)
+{
+    const char *aux;
+    int ret;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    ret = sd_bus_open_user(&pw_ctx->connection);
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Failed to create DBus connection: %s\n", strerror(-ret));
+        return ret;
+    }
+
+    ret = sd_bus_get_unique_name(pw_ctx->connection, &aux);
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Failed to get bus name: %s\n", strerror(-ret));
+        return ret;
+    }
+    // From https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.Request.html:
+    // "SENDER is the caller's unique name, with the initial ':' removed and all '.' replaced by '_'"
+    pw_ctx->sender_name = av_strireplace(aux + 1, ".", "_");
+    av_log(ctx, AV_LOG_DEBUG,
+           "DBus connection created (sender name: %s)\n", pw_ctx->sender_name);
+    return 0;
+}
+
+
+/**
+ * Use XDG Desktop Portal's ScreenCast interface to open a file descriptor that
+ * can be used by PipeWire to access the screen cast streams.
+ * (https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.ScreenCast.html)
+ *
+ * @param ctx
+ */
+static int portal_init_screencast(AVFilterContext *ctx)
+{
+    int ret;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+
+    ret = create_dbus_connection(ctx);
+    if (ret < 0)
+        return ret;
+
+    ret = portal_update_available_cursor_modes(ctx);
+    if (ret < 0)
+        return ret;
+
+    portal_create_session(ctx);
+    if (pw_ctx->portal_error)
+        return pw_ctx->portal_error;
+
+    // The event loop will run until it's stopped by portal_open_pipewire_remote (if
+    // all DBus method calls completed successfully) or portal_abort (in case of error).
+    // In the latter case, pw_ctx->portal_error gets set to a negative value.
+    atomic_store(&pw_ctx->dbus_event_loop_running, 1);
+    while(atomic_load(&pw_ctx->dbus_event_loop_running)) {
+        ret = sd_bus_process(pw_ctx->connection, NULL);
+        if (ret < 0) {
+            av_log(ctx, AV_LOG_ERROR,
+                   "Failed to process DBus event: %s\n", strerror(-ret));
+            return ret;
+        }
+
+        ret = sd_bus_wait(pw_ctx->connection, 2000);
+        if (ret < 0) {
+            av_log(ctx, AV_LOG_ERROR,
+                   "Error while waiting on bus: %s\n", strerror(-ret));
+            return ret;
+        }
+    }
+    return pw_ctx->portal_error;
+}
+
+static av_cold int pipewiregrab_init(AVFilterContext *ctx)
+{
+    int ret;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+    if (!pw_ctx) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Invalid private context data\n");
+        return AVERROR(EINVAL);
+    }
+
+    atomic_init(&pw_ctx->dbus_event_loop_running, 0);
+    atomic_init(&pw_ctx->pipewire_initialization_over, 0);
+    pthread_cond_init(&pw_ctx->pipewire_initialization_cond_var, NULL);
+    pthread_mutex_init(&pw_ctx->pipewire_initialization_mutex, NULL);
+    pthread_mutex_init(&pw_ctx->current_frame_mutex, NULL);
+
+    if (pw_ctx->pipewire_fd == 0) {
+        ret = portal_init_screencast(ctx);
+        if (ret != 0) {
+            av_log(ctx, AV_LOG_ERROR, "Couldn't init screen cast\n");
+            return ret;
+        }
+    }
+
+    ret = play_pipewire_stream(ctx);
+    if (ret != 0)
+        return ret;
+
+    // Wait until PipeWire initialization is over
+    pthread_mutex_lock(&pw_ctx->pipewire_initialization_mutex);
+    while (!atomic_load(&pw_ctx->pipewire_initialization_over)) {
+        pthread_cond_wait(&pw_ctx->pipewire_initialization_cond_var,
+                          &pw_ctx->pipewire_initialization_mutex);
+    }
+    pthread_mutex_unlock(&pw_ctx->pipewire_initialization_mutex);
+
+    return pw_ctx->pipewire_error;
+}
+
+static void pipewiregrab_uninit(AVFilterContext *ctx)
+{
+    int ret;
+    PipewireGrabContext *pw_ctx = ctx->priv;
+    if (!pw_ctx)
+        return;
+
+    // PipeWire cleanup
+    if (pw_ctx->thread_loop) {
+        pw_thread_loop_signal(pw_ctx->thread_loop, false);
+        pw_thread_loop_unlock(pw_ctx->thread_loop);
+        pw_thread_loop_stop(pw_ctx->thread_loop);
+    }
+    if (pw_ctx->stream) {
+        pw_stream_disconnect(pw_ctx->stream);
+        pw_stream_destroy(pw_ctx->stream);
+        pw_ctx->stream = NULL;
+    }
+    if (pw_ctx->core){
+        pw_core_disconnect(pw_ctx->core);
+        pw_ctx->core = NULL;
+    }
+    if (pw_ctx->context) {
+        pw_context_destroy(pw_ctx->context);
+        pw_ctx->context = NULL;
+    }
+    if (pw_ctx->thread_loop) {
+        pw_thread_loop_destroy(pw_ctx->thread_loop);
+        pw_ctx->thread_loop = NULL;
+    }
+    if (pw_ctx->pw_init_called) {
+        pw_deinit();
+        pw_ctx->pw_init_called = 0;
+    }
+    if (pw_ctx->pipewire_fd > 0) {
+        close(pw_ctx->pipewire_fd);
+        pw_ctx->pipewire_fd = 0;
+    }
+    av_frame_free(&pw_ctx->current_frame);
+    av_buffer_unref(&pw_ctx->hw_frames_ref);
+    av_buffer_unref(&pw_ctx->hw_device_ref);
+
+    // DBus cleanup
+    if (pw_ctx->session_handle) {
+        ret = sd_bus_call_method(pw_ctx->connection,
+                                 DESTINATION,
+                                 pw_ctx->session_handle,
+                                 "org.freedesktop.portal.Session",
+                                 "Close",
+                                 NULL, NULL, NULL);
+        if (ret < 0)
+            av_log(ctx, AV_LOG_DEBUG,
+                   "Failed to close portal session: %s\n", strerror(-ret));
+
+        av_freep(&pw_ctx->session_handle);
+    }
+    sd_bus_flush_close_unref(pw_ctx->connection);
+    av_freep(&pw_ctx->sender_name);
+}
+
+static int pipewiregrab_config_props(AVFilterLink *outlink)
+{
+    AVFrame *frame;
+    PipewireGrabContext *pw_ctx = outlink->src->priv;
+
+    AVRational time_base = av_inv_q(pw_ctx->framerate);
+    pw_ctx->frame_duration = av_rescale_q(1, time_base, AV_TIME_BASE_Q);
+    pw_ctx->time_frame = av_gettime_relative();
+
+    outlink->w = pw_ctx->width;
+    outlink->h = pw_ctx->height;
+    outlink->time_base = AV_TIME_BASE_Q;
+    outlink->frame_rate = pw_ctx->framerate;
+
+    frame = ff_get_video_buffer(outlink, pw_ctx->width, pw_ctx->height);
+    if (!frame)
+        return AVERROR(ENOMEM);
+    pthread_mutex_lock(&pw_ctx->current_frame_mutex);
+    pw_ctx->current_frame = frame;
+    pthread_mutex_unlock(&pw_ctx->current_frame_mutex);
+
+    return 0;
+}
+
+static int pipewiregrab_request_frame(AVFilterLink *outlink)
+{
+    int ret;
+    int64_t curtime, delay;
+    PipewireGrabContext *pw_ctx = outlink->src->priv;
+    AVFrame *frame = av_frame_alloc();
+    if (!frame)
+        return AVERROR(ENOMEM);
+
+    pw_ctx->time_frame += pw_ctx->frame_duration;
+    while (1) {
+        curtime = av_gettime_relative();
+        delay   = pw_ctx->time_frame - curtime;
+        if (delay <= 0)
+            break;
+        av_usleep(delay);
+    }
+
+    pthread_mutex_lock(&pw_ctx->current_frame_mutex);
+    ret = av_frame_ref(frame, pw_ctx->current_frame);
+    pthread_mutex_unlock(&pw_ctx->current_frame_mutex);
+    if (ret < 0) {
+        av_frame_free(&frame);
+        return ret;
+    }
+
+    frame->pts = av_gettime();
+    frame->duration = pw_ctx->frame_duration;
+    frame->sample_aspect_ratio = (AVRational) {1, 1};
+
+    return ff_filter_frame(outlink, frame);
+}
+
+static int pipewiregrab_query_formats(AVFilterContext *ctx)
+{
+    PipewireGrabContext *pw_ctx = ctx->priv;
+    enum AVPixelFormat pix_fmts[] = {pw_ctx->av_pxl_format, AV_PIX_FMT_NONE};
+
+    return ff_set_common_formats_from_list(ctx, pix_fmts);
+}
+
+static const AVFilterPad pipewiregrab_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .request_frame = pipewiregrab_request_frame,
+        .config_props  = pipewiregrab_config_props,
+    },
+};
+
+const AVFilter ff_vsrc_pipewiregrab= {
+    .name = "pipewiregrab",
+    .description = NULL_IF_CONFIG_SMALL("Capture screen or window using PipeWire."),
+    .priv_size = sizeof(struct PipewireGrabContext),
+    .priv_class = &pipewiregrab_class,
+    .init = pipewiregrab_init,
+    .uninit = pipewiregrab_uninit,
+    .inputs = NULL,
+    FILTER_OUTPUTS(pipewiregrab_outputs),
+    FILTER_QUERY_FUNC(pipewiregrab_query_formats),
+};
-- 
2.34.1

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