Unpack requires a buffer of 4 bytes

[amcchord]

Got the script to run but running into the following issue:
`mcwiggin@Kubuntu50:~/Downloads/finsta360-master$ sudo ./finsta360.py -s ../VID_20200513_174448_00_004.insv -r ../ref.insv -o ../out.insv
[sudo] password for mcwiggin:

########################################

1) extracting reference moov from

    ../ref.insv

########################################

2) regenerate sample tables from mdat in

    ../VID_20200513_174448_00_004.insv

Traceback (most recent call last):
File "./finsta360.py", line 1015, in
finsta360(
File "./finsta360.py", line 891, in finsta360
mov_table, aac_table = recover_sample_tables_from_mdat_fast(
File "./finsta360.py", line 463, in recover_sample_tables_from_mdat_fast
frame_length = struct.unpack('>I', buf)[0] + 4
struct.error: unpack requires a buffer of 4 bytes
`