Any ideas on how to directly modify bits in audio files? I've tried using a combination of soundfiler with -raw and the bit stuff in expr but no dice. basically i'm trying to get at the least significant bit for the purposes of a watermark/ steganography prototyper.
hi greg
your question inspired me and i made a little patch to illustrate, how this could be achieved. there is lots of fun stuff, that one could do with this kind of operation. as you mentioned, one could do stenography with it. but you could also use it as an very strange distortion effect, e.g. "add nth-bit signal of input to original signal". or you could alter the original signal by zero-ing a certain bit out... etc. etc...
yo, thank you for bringing this up... :-)
example-patch: http://romanhaefeli.net/software/pd/bitwise_reading_and_bit_replacement.pd
roman
On Thu, 2007-11-15 at 20:52 -0500, Greg wrote:
Any ideas on how to directly modify bits in audio files? I've tried using a combination of soundfiler with -raw and the bit stuff in expr but no dice. basically i'm trying to get at the least significant bit for the purposes of a watermark/ steganography prototyper.
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roman, that's awesome.
i'll try to use this to add markers to sound files in my sound editor.
i would like to test it out, but:
~ 0.5
... couldn't create
i have extended (Pd version 0.41.0-extended-20071114) - linux. i tried to [import zexy] but still not working. note that other external from zexy are working like [prime], [l2s].
and finally, not just the help of [coll] is not working with a right-click, all of them! is it the same situation for everyone using pd-extended: auto-build and "final" release from han's site?
pat
This is a file name problem which happens on some systems but not others which does not allow ">" or "<" to be used in filenames. Commonly reported problem.
Workaround is to replace with:
[expr~ $v1 > $v2]
best, d.
patrick wrote:
i would like to test it out, but:
~ 0.5
... couldn't create
i have extended (Pd version 0.41.0-extended-20071114) - linux. i tried to [import zexy] but still not working. note that other external from zexy are working like [prime], [l2s].
and finally, not just the help of [coll] is not working with a right-click, all of them! is it the same situation for everyone using pd-extended: auto-build and "final" release from han's site?
pat
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On Fri, 2007-11-16 at 10:41 -0500, patrick wrote:
i would like to test it out, but:
~ 0.5
... couldn't create
hm... didn't i just ask you yesterday, if you could fix this problem and you said: 'yeah, by changing pd-extended version' ?
if this bug is still there, report it to the bug tracker.
i have extended (Pd version 0.41.0-extended-20071114) - linux. i tried to [import zexy] but still not working. note that other external from zexy are working like [prime], [l2s].
and finally, not just the help of [coll] is not working with a right-click, all of them! is it the same situation for everyone using pd-extended: auto-build and "final" release from han's site?
i cannot confirm this. i installed the final release pd-extended-0.39.3 on my ubuntu dapper box and help-files seem to work generally (i tested only a few).
probably you have interfering .pdsettings file lying around somewhere?
roman
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On Fri, 2007-11-16 at 10:41 -0500, patrick wrote:
i would like to test it out, but:
~ 0.5
... couldn't create
actually, this object is not important at all. i just put it there to illustrate that the added signal should only contain 0 and 1. skip this object, if your signal is already 'binary'.
roman
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On Fri, 2007-11-16 at 20:40 +0900, hard off wrote:
roman, that's awesome.
i'll try to use this to add markers to sound files in my sound editor.
on cost of a bit? hm... i don't think that 16bit is that much a waste of bits, so that one of them should be 'abused' for something else than sound. also, as soon as you edit the file again with another editor the information might be lost. even if you just cut some parts and don't touch the volume, it probably adds a dither signal on the last bit (the one you would like to use as the marker information). all sound editors that i know use an extra file for this.
roman
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Derek Holzer -
Greg -
hard off -
patrick -
Roman Haefeli