Make the script compatible with older version of ffmpeg.

removeads.py

@@ -255,7 +255,14 @@ def getFramesInStream(inputFile, begin, end, streamKind, subStreamId=0):
         if 'frames' in frames:
             frames = frames['frames']
             for frame in frames:
-                ts = timedelta(seconds=float(frame['pts_time'])) 
+                if 'pts_time' in frame:
+                    pts_time = frame['pts_time']
+                elif 'pkt_pts_time' in frame:
+                    pts_time = frame['pkt_pts_time']
+                else:
+                    logger.error('Impossible to find timestamp of frame %s' % frame)
+                    return None
+                ts = timedelta(seconds=pts_time)) 
                 if begin <= ts and ts <= end:
                     res.append(frame)
             return res