Re: hacksdmi?

[Knud Erik Hojgaard - CyberCity Support <kain () EGOTRIP DK>]

url for vqg de/encoders : www.vqf.com
sincerely

Knud Erik Hojgaard <knud () cybercity dk>
-----Original Message-----
From: VULN-DEV List [mailto:VULN-DEV () SECURITYFOCUS COM]On Behalf Of Vitaly
Osipov
Sent: 26. oktober 2000 13:02
To: VULN-DEV () SECURITYFOCUS COM
Subject: Re: hacksdmi?


about other lossy conversion format - only now I remembered about one very
 interesting thing - VQF format, they say it can do the same with 90kbps as
 mp3 with 128kbps or even better (and it really looks like this). Maybe it
 was worth a try just to encode/decode SDMI's .wav to see what happens.

 Vitaly.

 P.S. I do not remember url of the site where the standard is described,
but
 one of players supporting it is Kjofol (probably www.kjofol.com)


> ----- Original Message -----
> From: "Erhard Schwenk" <eschwenk () FTO DE>
> To: <VULN-DEV () SECURITYFOCUS COM>
> Sent: Friday, October 20, 2000 9:56 AM
> Subject: Re: hacksdmi?
>
>
> > On 16-Oct-00 Brooke, O'neil (EXP) wrote:
> > >       This maybe a silly question but, couldn't they put a watermark
> > > into the sound by using sounds that we cannot hear? Very high or very
> > > low
> > > frequencies could be used, so could sounds that will be overpowered
> > > by the
> > > watermarked content.
> >
> > This is NOT so easy as it looks like.
> >
> > First of all, a normal ear can detect frequencies between about 20 and
> > 20000 Hz, the same Bandwidth you have with an Audio CD or a 44.1 Khz
> > sampling rate in any other file (no, you won't hear, let's say, 2 Hz,
> > but most audio player have a High-Pass filter with about 16 Hz, so this
> > will get filtered out anyway). So in the principle, you cannot record a
> > frequency which you cannot hear since the recorder won't recognize it
> > (and if, it would be cut out at Mastering the final CD). So the only way
> > is to hide your information as a silent addition to a loud part of the
> > signal, so that noone realizes it.
> >
> > Then, modern lossy Compression algorithms base on things "we can't
> > hear" because they are overloaded by other things in the sound. So, the
> > risk to cut off the watermark by simply encoding it with a mp3 Encoder
> > or some future (and optimized) Version of lossy Compression algorithms
> > is evident. The better the Compressor is, the more "you can't hear" it
> > cuts out and the lesser space remains for watermarking. Since you need
> > many different watermarks (if you want to sue someone, you have to
> > identify him) I do not think this is very simple. And the watermark
> > needs to be very robust since you can simply record the signal once
> > over a standard analog out and in of a Soundcard. You will get marginal
> > quality losses then, but a normal consumer won't recognize them.
> >
> >
> > --
> > ===========================================================
> >      Erhard Schwenk - alias Bitrunner  =)B==o)
> > ===========================================================
> > No Spam replies please.