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/*
* Copyright (C) 2022 Igalia S.L
* Copyright (C) 2022 Metrological Group B.V.
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "config.h"
#include "AppSinkWorkaround.h"
#if USE(GSTREAMER)
#include <gst/gst.h>
#include <gst/pbutils/gstpluginsbaseversion.h>
#include <mutex>
#include <wtf/PrintStream.h>
#include <wtf/glib/GRefPtr.h>
#include <wtf/glib/WTFGType.h>
GST_DEBUG_CATEGORY(webkit_app_sink_workaround_debug);
#define GST_CAT_DEFAULT webkit_app_sink_workaround_debug
namespace WebCore {
static bool checkNeedsAppsinkWorkaround()
{
GRefPtr<GstElementFactory> factory = adoptGRef(gst_element_factory_find("appsink"));
if (!factory) {
WTFLogAlways("GStreamer element appsink not found. Please install it");
return false;
}
GST_DEBUG("gst-plugins-base version is %s", gst_plugins_base_version_string());
guint major, minor, micro;
gst_plugins_base_version(&major, &minor, µ, nullptr);
if (major < 1)
return true;
if (major > 1)
return false;
if (minor < 20)
return true;
if (minor >= 22)
return false;
if (minor == 21)
return micro < 1; // Fix landed in 1.21.1 https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2413
ASSERT(minor == 20);
return micro < 3; // Fix was backported to 1.20.3 https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2442
}
static std::once_flag appSinkWorkaroundOnceFlag;
void registerAppsinkWorkaroundIfNeeded()
{
std::call_once(appSinkWorkaroundOnceFlag, [] {
GST_DEBUG_CATEGORY_INIT(webkit_app_sink_workaround_debug, "webkitappsink", 0, "WebKit AppSink Workarounds");
bool needsWorkaround = checkNeedsAppsinkWorkaround();
GST_DEBUG("appsink workaround will%s be registered.", needsWorkaround ? "" : " NOT");
if (!needsWorkaround)
return;
gst_element_register(nullptr, "appsink", GST_RANK_PRIMARY + 100, WEBKIT_TYPE_APP_SINK_WITH_WORKAROUND);
});
}
} // namespace WebCore
struct WebKitAppSinkWithWorkaroundPrivate {
// Must only be read and written with the pad lock.
bool needsResendCaps { false };
};
#define webkit_app_sink_with_workaround_parent_class parent_class
WEBKIT_DEFINE_TYPE(WebKitAppSinkWithWorkaround, webkit_app_sink_with_workaround, GST_TYPE_APP_SINK);
static GstPadProbeReturn appsinkWorkaroundProbe(GstPad* pad, GstPadProbeInfo* info, void* userData)
{
auto priv = static_cast<WebKitAppSinkWithWorkaroundPrivate*>(userData);
// Changes to the flushing flag of a pad only occur while the pad lock is held.
// By holding it, we can reliably prevent the flushing flag from changing during the execution of our code.
// The pad lock also ensures there are no data races over `priv->needsResendCaps`.
GST_OBJECT_LOCK(pad);
bool willResendCaps = false;
if ((info->type & GST_PAD_PROBE_TYPE_EVENT_FLUSH) && GST_EVENT_TYPE(info->data) == GST_EVENT_FLUSH_STOP) {
GST_TRACE_OBJECT(pad, "Flush event received, setting needsResendCaps = true");
priv->needsResendCaps = true;
} else if (!GST_PAD_IS_FLUSHING(pad) && (info->type & GST_PAD_PROBE_TYPE_EVENT_DOWNSTREAM) && GST_EVENT_TYPE(info->data) == GST_EVENT_CAPS) {
GST_TRACE_OBJECT(pad, "Caps event received, setting needsResendCaps = false");
priv->needsResendCaps = false;
} else if (!GST_PAD_IS_FLUSHING(pad) && (info->type & GST_PAD_PROBE_TYPE_BUFFER) && priv->needsResendCaps) {
GST_DEBUG_OBJECT(pad, "Buffer received, but first need to resend pad caps to workaround bug. Will resend caps.");
willResendCaps = true;
}
GST_OBJECT_UNLOCK(pad);
if (willResendCaps) {
GRefPtr<GstCaps> caps = adoptGRef(gst_pad_get_current_caps(pad));
GST_DEBUG_OBJECT(pad, "Sending stored pad caps to appsink: %" GST_PTR_FORMAT, caps.get());
// This will cause a recursive call to appsinkWorkaroundProbe() which will also set `needsResendCaps` to false.
bool capsSent = gst_pad_send_event(pad, gst_event_new_caps(caps.get()));
GST_DEBUG_OBJECT(pad, "capsSent = %s. Returning from the probe so that the buffer is sent: %" GST_PTR_FORMAT, boolForPrinting(capsSent), info->data);
}
return GST_PAD_PROBE_OK;
}
static void webkitAppSinkWithWorkAroundConstructed(GObject* object)
{
G_OBJECT_CLASS(webkit_app_sink_with_workaround_parent_class)->constructed(object);
WebKitAppSinkWithWorkaroundPrivate* priv = WEBKIT_APP_SINK_WITH_WORKAROUND(object)->priv;
GstElement* element = GST_ELEMENT(object);
GRefPtr<GstPad> pad = adoptGRef(gst_element_get_static_pad(element, "sink"));
gst_pad_add_probe(pad.get(), static_cast<GstPadProbeType>(GST_PAD_PROBE_TYPE_BUFFER
| GST_PAD_PROBE_TYPE_EVENT_FLUSH | GST_PAD_PROBE_TYPE_EVENT_DOWNSTREAM),
appsinkWorkaroundProbe, priv, nullptr);
GST_DEBUG_OBJECT(object, "appsink with workaround probe instantiated.");
}
static void webkit_app_sink_with_workaround_class_init(WebKitAppSinkWithWorkaroundClass* klass)
{
auto* gobjectClass = G_OBJECT_CLASS(klass);
gobjectClass->constructed = webkitAppSinkWithWorkAroundConstructed;
}
#endif // USE(GSTREAMER)
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