It is not possible to split the h.264 file directly in AS3.
It’s hard to offer anything with additional information. But I will try. What you can do, one way or another, tell the external process to share the file for you. For example: Java, C #, Python, something works outside the browser (or Adobe AIR.)
Splitting h.264 videos is non-trivial. Most likely, you will need to use third-party software. Two considerations come to life:
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