[LAD] Re: Direct Stream Digital / Pulse Density

Erik de Castro Lopo mle+la at mega-nerd.com
Fri Sep 28 04:06:41 UTC 2007

Maitland Vaughan-Turner wrote:

> This hits near something I was wondering:  Wouldn't it be pretty easy
> to do lossless compression on a DSD stream. Since it's only one bit,
> It seems like you could use simple run-length encoding to achieve
> pretty good results.

I pretty sure you are wrong here. Yes, RLE would probably work pretty
well on the DSD encoded version of a digitally generated sine wave.

However, on real analogue inputs there is sure to be a lot of very low
level noise which will result in very short run lengths.

Also be aware that all (neglecting ancient stuff like A-law, u-law and
IDPCM) recent audio codecs doe their encoding in the frequency domain
where it is easier to find redundancy than in the time domain.

Erik de Castro Lopo
"And MS thinks Linux is vulnerable to forking? 95, 95 OEM SR2, 98, 98SE,
ME, NT, 2000, Bob, .NET, CE, Datacenter, Server, Adv. Server, and now
Web Server, sheesh." -- BTS on LinuxToday.com

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