Fixed audio out of sync when playing videos

Also in certain conditions, especially on slower hardware, when there is nothing to update on the screen and only videos are playing the framerate decreases significantly. Fixed by forcing screen update when at least one video is playing.

src/media.cpp

@@ -634,7 +634,9 @@ void FeVideoImp::video_thread()
 		//
 		if ( detached_frame )
 		{
-			wait_time = (sf::Int64)detached_frame->pts * time_base
+
+		wait_time = sf::seconds( detached_frame->pts
+					* av_q2d( m_parent->m_imp->m_format_ctx->streams[stream_id]->time_base ))
 					- m_parent->get_video_time();
 
 			if ( wait_time < max_sleep )
@@ -1159,8 +1161,8 @@ bool FeMedia::tick()
 		{
 			m_video->display_texture->update( m_video->display_frame );
 			m_video->display_frame = NULL;
-			return true;
 		}
+		return true;
 	}
 
 	return false;