file demux 0.1 <dennis@conus.info>

The demux command-line utility can be used to demultiplex a file to set of files.

usage: demux input_file <pattern> <output_file1> <output_file2> ...

Examples:

Put all odd bytes into file1 and even bytes to file2:
demux file 12 file1 file2

Put all odd bytes into file1 and ignore even bytes:
demux file 1. file1

Collect all 1st and 2nd bytes and ignore 3rd bytes in byte triplet:
demux file_in 11. file_out

Demux 5.1 raw audio file into 6 files (one per channel)
demux file.raw 112233445566 FL.raw FR.raw C.raw S.raw RL.raw RR.raw

Get front left/right channels and put into stereo raw file
demux file.raw 1111........ stereo.raw

Let's imagine we have a headerless DBF-file with record length 30 bytes.
First field is 5 byte, second is 10 byte and third is 15 bytes.
Split it into 3 files:
demux file.dbf 111112222222222333333333333333 file1.dat file2.dat file3.dat

* DVD example:

Extract 5.1 WAV file from VOB:
ffmpeg -i file.vob -vn 1.wav -acodec wav

Convert it to RAW (cut header):
sox 1.wav 1.raw

Convert 5.1 RAW audio file to stereo (from front channels) RAW file + center channel:
demux 1.raw 111122...... stereo.raw center.raw

Convert stereo RAW file back to WAV:
sox -r 48000 -b 16 -s -c 2 stereo.raw stereo.wav

Convert center mono RAW file back to WAV:
sox -r 48000 -b 16 -s -c 1 center.raw center.wav

-- http://conus.info/utils/demux/