phoenix: more accurate timestamps, duration and dropped frame count

Timestamp and duration now set using Phoenix timer, recorded at frame start and end (FVAL high then low).

Only more than one dropped frame can be reliably detected.

sys/phoenix/gstphoenixsrc.h

@@ -67,9 +67,13 @@ struct _GstPhoenixSrc
   gchar *config_filepath;
   guint num_capture_buffers;
 
+  GstClockTime first_phoenix_ts;
+  guint64 *frame_start_times;
+  guint64 *frame_end_times;
   guint32 buffer_size;
   gboolean buffer_ready;
   guint buffer_ready_count;
+  guint frame_start_count;
   guint frame_end_count;
   guint buffer_processed_count;
   gboolean timeout_occurred;