Why are an integers bytes stored backwards? Does this apply to headers only?

header wav pcm integer
Z3t picture Z3t · Sep 11, 2010 · Viewed 7.3k times · Source

I'm currently trying to decipher WAV files. From headers to the PCM data.

I've found a PDF (http://www.tdt.com/T2Support/technical_notes/tn0132.pdf) detailing the anatomy of a WAV file, and I've been able to extract and make sense of the appropriate header data using Ghex2. But my questions are:

Why are the integers bytes stored backwards? I.e. dec. 20 is stored as 0x14000000 instead of 0x00000014.

Are the integers of the PCM data also stored backwards?

Answer

FixerMark picture FixerMark · Sep 11, 2010

WAV files are little-endian (least significant bytes first) because the format originated for operating systems running on intel processor based machines which use the little endian format to store numbers.

If you think about it kind of makes sense because if you want to cast a long integer to a short one or even a character the starting address remains the same you just look at less bytes.

Consequently, for 16 bit encoding upwards, little-endian format will be used for the PCM as well. This is quite handy since you will be able to pull them in as integers. don't forget they will be stored as two's complement signed integers if they are 16 bit, but not if they are 8 bit. (see http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/WAVE.html for more detail)

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