Hi Al,
Thanks a lot for this information!
Out of curiosity, I did play for a couple of hours last sunday on istech problem...
For this purpose, I did rewrite a bit the crc32 stack you are talking about.
The main modification was to drop the hexValues field and replace it with an array, all set up in the script.
This permits to have the crc32 code in a script only stack (or to copy/paste in your own stack script)
Second one was about speed optimization: gain ~10%.
Finally, I made a test:
- parse 3 different animated png files
- for each apng chunk found, extract the data part and the corresponding crc
- process the data to calculate a new crc, and compare it with the original one.
So, processing around 500 Kbytes of binary datas,
did find 172 chunks and all the 172 checksums calculation were fine!
I consider this test quite encouraging, but it is certainly not a complete valid test.
All that said, if you remember some details about the crc32 calculation failures,
I would appreciate to know more before sharing this update.
Thanks again
Thierry