Bilibili AV/BV Code Conversion
Python 2, 170 + 150 = 320 bytes

AV to BV, 180 179 173 170 bytes:



lambda s:"BV1{2}{4}4{5}1{3}7{1}{0}".format(*["fZodR9XQDSUm21yCkr6zBqiveYah8bt4xsWpHnJE7jL5VG3guMTKNPAwcF"[((int(s[2:])^177451812)+8728348608)/58**i%58]for i in range(6)])


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BV to AV, 165 158 150 bytes:



s=input()
n=0
for i in 6,4,8,3,10,11:n=n*58+"fZodR9XQDSUm21yCkr6zBqiveYah8bt4xsWpHnJE7jL5VG3guMTKNPAwcF".find(s[i])
print"av"+`n-8728348608^177451812`


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