GStreamer: introduce qiodevice:/ uri scheme

Using `QGstAppSource` to inject data into GStreamer has a few problems:

* it is a bit cumbersome to use, as it requires going through
signal/slot connections
* it is not possible to use the same stream in multiple locations (e.g.
player and discoverer)
* it is not thread-safe (gst_play sends on_need_data after the stream is
closed by another thread)
* the ownership of QGstAppSource is rather complicated, as it's owned by
both

So we replace the QGstAppSource by a qiodevice:/ uri scheme:
* multiple threads may access the same QIODevice in a thread-safe manner
* gstreamer handles the element construction under the hood

Task-number: QTBUG-129467
Pick-to: 6.5 6.7 6.8
Change-Id: I041d1e42368d19fb2ee64b6f3730c204458a6e85
Reviewed-by: Artem Dyomin <[email protected]>

src/plugins/multimedia/gstreamer/CMakeLists.txt

@@ -14,7 +14,6 @@ qt_internal_add_module(QGstreamerMediaPluginImplPrivate
  common/qgst_bus.cpp common/qgst_bus_p.h
  common/qgst_debug.cpp common/qgst_debug_p.h
  common/qgst_handle_types_p.h
- common/qgstappsource.cpp common/qgstappsource_p.h
  common/qgstreameraudioinput.cpp common/qgstreameraudioinput_p.h
  common/qgstreameraudiooutput.cpp common/qgstreameraudiooutput_p.h
  common/qgstreamerbufferprobe.cpp common/qgstreamerbufferprobe_p.h
@@ -36,6 +35,7 @@ qt_internal_add_module(QGstreamerMediaPluginImplPrivate
  mediacapture/qgstreamerimagecapture.cpp mediacapture/qgstreamerimagecapture_p.h
  mediacapture/qgstreamermediacapturesession.cpp mediacapture/qgstreamermediacapturesession_p.h
  mediacapture/qgstreamermediarecorder.cpp mediacapture/qgstreamermediarecorder_p.h
+ uri_handler/qgstreamer_qiodevice_handler.cpp uri_handler/qgstreamer_qiodevice_handler_p.h
  uri_handler/qgstreamer_qrc_handler.cpp uri_handler/qgstreamer_qrc_handler_p.h
 
  NO_UNITY_BUILD_SOURCES
@@ -44,6 +44,7 @@ qt_internal_add_module(QGstreamerMediaPluginImplPrivate
  common/qgstreamervideosink.cpp
 
  # preprocessor / internal linkage
+ uri_handler/qgstreamer_qiodevice_handler.cpp
  uri_handler/qgstreamer_qrc_handler.cpp
  NO_GENERATE_CPP_EXPORTS
  DEFINES

src/plugins/multimedia/gstreamer/audio/qgstreameraudiodecoder.cpp

@@ -5,9 +5,9 @@
 #include <audio/qgstreameraudiodecoder_p.h>
 
 #include <common/qgst_debug_p.h>
-#include <common/qgstappsource_p.h>
 #include <common/qgstreamermessage_p.h>
 #include <common/qgstutils_p.h>
+#include <uri_handler/qgstreamer_qiodevice_handler_p.h>
 
 #include <gst/gstvalue.h>
 #include <gst/base/gstbasesrc.h>
@@ -71,9 +71,6 @@ QGstreamerAudioDecoder::QGstreamerAudioDecoder(QAudioDecoder *parent)
 
  g_object_set(m_playbin.object(), "audio-sink", m_outputBin.element(), NULL);
 
- m_deepNotifySourceConnection = m_playbin.connect(
- "deep-notify::source", (GCallback)&configureAppSrcElement, (gpointer)this);
-
  // Set volume to 100%
  gdouble volume = 1.0;
  m_playbin.set("volume", volume);
@@ -86,18 +83,6 @@ QGstreamerAudioDecoder::~QGstreamerAudioDecoder()
  m_playbin.removeMessageFilter(this);
 }
 
-void QGstreamerAudioDecoder::configureAppSrcElement([[maybe_unused]] GObject *object, GObject *orig,
- [[maybe_unused]] GParamSpec *pspec,
- QGstreamerAudioDecoder *self)
-{
- QGstElementHandle appsrc;
- g_object_get(orig, "source", &appsrc, NULL);
-
- GstAppSrc *gstAppSrc = qGstSafeCast<GstAppSrc>(appsrc.release());
- if (gstAppSrc)
- QGstAppSource::attachQIODeviceToGstAppSrc(gstAppSrc, self->mDevice);
-}
-
 bool QGstreamerAudioDecoder::processBusMessage(const QGstreamerMessage &message)
 {
  qCDebug(qLcGstreamerAudioDecoder) << "received bus message:" << message;
@@ -310,7 +295,8 @@ void QGstreamerAudioDecoder::start()
  return;
  }
 
- m_playbin.set("uri", "appsrc://");
+ QUrl streamURL = qGstRegisterQIODevice(mDevice);
+ m_playbin.set("uri", streamURL.toEncoded().constData());
  } else {
  return;
  }

src/plugins/multimedia/gstreamer/audio/qgstreameraudiodecoder_p.h

@@ -72,9 +72,6 @@ private slots:
  static GstFlowReturn new_sample(GstAppSink *sink, gpointer user_data);
  GstFlowReturn newSample(GstAppSink *sink);
 
- static void configureAppSrcElement(GObject *, GObject *, GParamSpec *,
- QGstreamerAudioDecoder *_this);
-
  void setAudioFlags(bool wantNativeAudio);
  void addAppSink();
  void removeAppSink();