Conversion of 24bit binary to int

Idar ip at itk.ntnu.no
Wed Nov 12 10:53:17 CET 2003



On Tue, 11 Nov 2003 10:11:05 -0500, Peter Hansen <peter at engcorp.com> wrote:

> Idar wrote:
>>
>> Is there an effecient/fast way in python to convert binary data from 
>> file
>> (24bit hex(int) big endian) to 32bit int (little endian)? Have seen
>> struct.unpack, but I am unsure how and what Python has to offer. Idar
>
> I think the question is unclear.  You say you've seen struct.unpack.
> So what then?  Don't you think struct.unpack will work?  What do you
> mean you are unsure how and what Python has to offer?  The documentation
> which is on the web site clearly explains how and what struct.unpack
> has to offer...

It is due to slack reading........

The doc says "Standard size and alignment are as follows: no alignment is 
required for any type (so you have to use pad bytes)................"

It was unclear (at the time of reading) in the sence that I didn't see the 
above text + there was no example on how to handle odd-byte/padding 
conversion and the test program crashed!

But if you know how to convert this format (the file is about 6MB) 
effeciently, pls do give me a hint. The data is stored binary with the 
format:
Ch1: 1536B (512*3B)
..
Ch6  1536B (512*3B)
Then it is repeated again until end:
Ch1  1536B (512*3B)
..
Ch6  1536B (512*3B)


>
> Please clarify.
>
> -Peter
>



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