[bug] extraction break

[ain-soph]

Not quite sure if the extraction is finished. The extract.py breaks, but the raw-to-wav.py still works and transform 7757 files in total. I just doubt whether there would be more wav files in LuoTianyi_V4_Meng.ddb.

......
Writing sample: 7756
Found beginning of sample!
Found end of sample
Writing sample: 7757
Found beginning of sample!
Traceback (most recent call last):
  File "E:\vocaloid\LuoTianyi_V4_Meng_Mac\BK8H76TAEHXWSKDB\extract.py", line 34, in <module>
    if array[i] == 83 and array[i+1] == 78 and array[i+2] == 68 and sp == -1:
IndexError: index out of range

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Another unrelated question: Could we name the files according to ddi or vvd files (or generate a dict json)? I guess there should be some tables in those files which could provide a human-understanding indexing.