Which is faster in memory, ints or chars? And file-mapping or chunk reading?

Posted by Nick on Stack Overflow See other posts from Stack Overflow or by Nick
Published on 2010-04-07T05:09:55Z Indexed on 2010/04/07 5:13 UTC
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Okay, so I've written a (rather unoptimized) program before to encode images to JPEGs, however, now I am working with MPEG-2 transport streams and the H.264 encoded video within them. Before I dive into programming all of this, I am curious what the fastest way to deal with the actual file is.

Currently I am file-mapping the .mts file into memory to work on it, although I am not sure if it would be faster to (for example) read 100 MB of the file into memory in chunks and deal with it that way.

These files require a lot of bit-shifting and such to read flags, so I am wondering that when I reference some of the memory if it is faster to read 4 bytes at once as an integer or 1 byte as a character. I thought I read somewhere that x86 processors are optimized to a 4-byte granularity, but I'm not sure if this is true...

Thanks!

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