BGE: add audio/video synchronization capability to VideoTexture

Add optional parameter to VideoTexture.Texture refresh() method
to specify timestamp (in seconds from start of movie) of the frame
to be loaded. This value is passed down to image source and for
VideoFFmpeg source, it is used instead of current time to load
the frame from the video file.

When combined with an audio actuator, it can be used to synchronize
the sound and the image: specify the same video file in the sound
actuator and use the KX_SoundActuator time attribute as timestamp
to refresh: the frame corresponding to the sound will be loaded:

GameLogic.video.refresh(True, soundAct.time)

source/gameengine/VideoTexture/ImageBase.cpp

@@ -71,7 +71,7 @@ bool ImageBase::release (void)
 
 
 // get image
-unsigned int * ImageBase::getImage (unsigned int texId)
+unsigned int * ImageBase::getImage (unsigned int texId, double ts)
 {
 	// if image is not available
 	if (!m_avail)
@@ -82,12 +82,12 @@ unsigned int * ImageBase::getImage (unsigned int texId)
 			// get images from sources
 			for (ImageSourceList::iterator it = m_sources.begin(); it != m_sources.end(); ++it)
 				// get source image
-				(*it)->getImage();
+				(*it)->getImage(ts);
 			// init image
 			init(m_sources[0]->getSize()[0], m_sources[0]->getSize()[1]);
 		}
 		// calculate new image
-		calcImage(texId);
+		calcImage(texId, ts);
 	}
 	// if image is available, return it, otherwise NULL
 	return m_avail ? m_image : NULL;
@@ -305,12 +305,12 @@ void ImageSource::setSource (PyImage * source)
 
 
 // get image from source
-unsigned int * ImageSource::getImage (void)
+unsigned int * ImageSource::getImage (double ts)
 {
 	// if source is available
 	if (m_source != NULL)
 		// get image from source
-		m_image = m_source->m_image->getImage();
+		m_image = m_source->m_image->getImage(0, ts);
 	// otherwise reset buffer
 	else
 		m_image = NULL;