Inconsistancy.  The number of frames per region is not constant.
 1         11         64

 1         11         64

 1       3166         11         25         39         53
 1       3165         12         26         40         54
 1       3041         13         27         41         55
 1       2917         14         28         42         56
 1       2792         15         29         43         57
 1       2667         16         30         44         58
 1       2542         17         31         45         59
 1       2417         18         32         46         60
 1       2418         19         33         47         61
 1       2543         20         34         48         62
 1       2668         21         35         49         63
 1       2793         22         36         50         64
 1       2918         23         37         51
 1       3042         24         38         52