How to do CRC calculation for Base64 string

Hi all,
I am trying to calculate a CRC of a Base64 string.
I know the answer of the checksum, but I don't how to calculate it (It is for Adobe project).

I give you the correct checksum : 2942042514
And now the string :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dLsh3oZKkGVCck1AepvKhXOcyZNTY4+sVkrrUYN+z9NE4/N0aS6pTbNAn5TE
1aV67w3Q9MW/lL08UKSL+cuu8pc2yNoDGsRfkfYDqhPHOfRYtOtDGIVYwnxa
CXEujLaXyvamAMUop2PdFbzjv8g5pjHnC/HZWrI3pfkQH9MYMSckYQ8gI+DF
Uekpi6JpTfepzLh21dwyXVwH3h7JDwdZvJ46/vp9ZCiu5+8A6wHsM8D60Bs3
4p8qdrglsf0MqP2OicPE7bn4N1D1SBaUIU4loeQJ9ZKGHUPJE7IE7BPTP1hG
Pm1Y1iX9HReWY+jQyxEzEB/h31uKna3M00OMBAscki/hqDpUb5ojjpMQk4ck
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ZFVT6pufLeXytSP186xde88xRTbsoRiVHZ302NHLvgF0xuNDOfo/kpeMSS4c
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GcHx2+2psKQ8DrdUOxKhx9yTFDhn4ZfmxiwbY6JEM+CyI8gdtUqP5gPuKTY+
EQ/62QGt1+CccCMrI6TlyBL6bLUgGixDo+dxtZb+ewX69iQSQwzFG+WjeVFr
YbVVTf2w1Zp2mtKMzjCT7IT6F+20l81p6bn5Ykozn8Nf+RgP9OgV84UYnaT1
G9aS46o76xZiJZWNEuCcOuIntLp1bXlLCp/i7RbwdpWkPN+KGckneJtQlORx
nmdbdEzPp5PUHzPCjJVPL8gKddvHsc+LN6fQXzcU10eky+cst2irMeeKPDKM
jc/hxNU5PR/M89A9Gu+Nd7Ltos/xil0+tV6xdO0e4WdkO/eZLBeqh2I+0VQ+
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adx3viXOjBnmHd9OqN2+0Z4Jc1NcDKprjsHMiX/Oy/Qb3lM6EVMVcZ+io5He
ubTKLRLvs+htche02j26yRNPvxyoOyrZlp8Id0B3ZuFXO48w+pRxrDQ7s8Iy
dujuSr7ncMcr2ZxH1yXa3Mue1y/DzSwvuQ3kr3I3RjXHzl0vYF6dneGzuz8o
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YTAng3G3F95Ph1/6h6rXH52Tw9fK52Iea3DFJ3u/ZhLyKKTbybfZNJ10Wuwi
6qt5FIjPazWkOKX5oZGKMshn37pnbMvc7oOlLsu16l02Hcgw2oJvSGVdcOSq
CL4pFU/Q/U1ZqU8nKTcZU1sgBO/eYGnZq2+VFc/ID3k3Xuo21uUoK6pGzN0f
SANzCqdiRRHOy917GypZb6ew19n9LKyhng1jnL7ROkWjez+8rcWnrCp7+X6t
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LTvjjZburcsMwVPEeXewt1Rciv0PAP8HNpcDbw==


I tried CRC 16, 32 and with polynomial 0xEDB88320L, and with all these tries, I cannot find the correct checksum, it is my main problem.

I don't want C++ code source, but I am searching for the method or algorithm to find it.
If you can help me, it will be helpful! And it is possible to have a gift for...

To know, it is for my own pleasure, not for a work or something else.

If you want to know, this string in base64 contains an string compressed in zip, which contains an UTF16 XML. I want to modify information, and modify Adobe Projet (prproj)
I don't know for sure, but I would think that the CRC would be calculated on the decoded string?
This seems to be a popular question today, as someone has asked the very same question here as well:

http://www.dreamincode.net/forums/topic/326118-how-to-do-crc-calculation-for-base64-string/

Looks very much like hacking to me
Interesting, I will try it
I think it is not hacking, but just an automation to change subtitle in projects... or other information.
For example, when we want to change the language for a personnal movie :)
What algorithm are you using to calculate the checksum? If you don't know the correct algorithm to use, you're wasting your time, as you will never be able to calculate it.
I use CRC 16 and 32 algorithm, as I found it on Wikipedia...
Actually I am writing a method, which is calculating checksum with a incremtal (pol++) polynomial...
I hope to find it, and I will give all the source code for community.
It is possible to give all my source code to decode this string to find ascii xml if you want !
On Adobe forum, some people a talking about, but no admin give response. they just say : you have to calculate it by yourself... hmm

Thanks a lot by advance !

Again : sorry for my english ;)
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