Gst backend: allow rendering other video buffers than allocated

Moved checking the buffer type to the buffer pool
instead of comparing the buffer type in QVideoSurfaceGstSink.

Some gstreamer elements may push other buffer instance than
provided by sink but with the same data pointer.

Change-Id: Iab3bf4da2d5eeb5d2a9375aa609a89515b067ce3
Reviewed-by: Lev Zelenskiy <lev.zelenskiy@nokia.com>
Reviewed-by: Ling Hu <ling.hu@nokia.com>

src/gsttools/qgstxvimagebuffer.cpp

@@ -177,6 +177,9 @@ QAbstractVideoBuffer::HandleType QGstXvImageBufferPool::handleType() const
 
 QAbstractVideoBuffer *QGstXvImageBufferPool::prepareVideoBuffer(GstBuffer *buffer, int bytesPerLine)
 {
+    if (!G_TYPE_CHECK_INSTANCE_TYPE(buffer, bufferType()))
+        return 0;
+
     QGstXvImageBuffer *xvBuffer = reinterpret_cast<QGstXvImageBuffer *>(buffer);
     QVariant handle = QVariant::fromValue(xvBuffer->xvImage);
     return new QGstVideoBuffer(buffer, bytesPerLine, QAbstractVideoBuffer::XvShmImageHandle, handle);

src/gsttools/qvideosurfacegstsink.cpp

@@ -195,9 +195,10 @@ GstFlowReturn QVideoSurfaceGstDelegate::render(GstBuffer *buffer)
 
     QAbstractVideoBuffer *videoBuffer = 0;
 
-    if (m_pool && G_TYPE_CHECK_INSTANCE_TYPE(buffer, m_pool->bufferType()))
+    if (m_pool)
         videoBuffer = m_pool->prepareVideoBuffer(buffer, m_bytesPerLine);
-    else
+
+    if (!videoBuffer)
         videoBuffer = new QGstVideoBuffer(buffer, m_bytesPerLine);
 
     m_frame = QVideoFrame(

src/multimedia/gsttools_headers/qgstbufferpoolinterface_p.h

@@ -73,16 +73,14 @@ public:
     virtual ~QGstBufferPoolInterface() {}
 
     virtual bool isFormatSupported(const QVideoSurfaceFormat &format) const = 0;
-
-    virtual GType bufferType() const = 0;
     virtual GstBuffer *takeBuffer(const QVideoSurfaceFormat &format, GstCaps *caps) = 0;
     virtual void clear() = 0;
 
     virtual QAbstractVideoBuffer::HandleType handleType() const = 0;
 
     /*!
-      Build an QAbstractVideoBuffer instance from compatible (mathcing gst buffer type)
+      Build an QAbstractVideoBuffer instance from GstBuffer.
-      GstBuffer.
+      Returns NULL if GstBuffer is not compatible with this buffer pool.
 
       This method is called from gstreamer video sink thread.
      */
@@ -101,16 +99,14 @@ public:
     virtual ~QGstBufferPoolPlugin() {}
 
     virtual bool isFormatSupported(const QVideoSurfaceFormat &format) const = 0;
-
-    virtual GType bufferType() const = 0;
     virtual GstBuffer *takeBuffer(const QVideoSurfaceFormat &format, GstCaps *caps) = 0;
     virtual void clear() = 0;
 
     virtual QAbstractVideoBuffer::HandleType handleType() const = 0;
 
     /*!
-      Build an QAbstractVideoBuffer instance from compatible (mathcing gst buffer type)
+      Build an QAbstractVideoBuffer instance from compatible GstBuffer.
-      GstBuffer.
+      Returns NULL if GstBuffer is not compatible with this buffer pool.
 
       This method is called from gstreamer video sink thread.
      */