22 Feb
2007
22 Feb
'07
5:55 p.m.
Hallo,
carmen hat gesagt: // carmen wrote:
i'm thinking of picking up the new korg pocket DSD recorder. and im wondering - does
anything support editing of 1-bit audio recordings in the OSS world? i know theress 3
dozen wave editors, but theyre all pretty mediocre and can usually not even connect to
jack and play a flac without crashing. i guess this is what happens when wave editor
developers have NIH syndrome?
Hey, that's actually the first time I read about 1-bit recording and
at first I thought you were joking or had a typo. But you weren't and
hadn't.
Nevertheless I found some interesting papers linked from the Wikipedia
SACD page. One is this:
Audio Engineering Society Convention Paper 5395: Why 1-Bit Sigma-Delta
Conversion is Unsuitable for High-Quality Applications
http://sjeng.org/ftp/SACD.pdf
and it states:
Single-stage, 1-bit sigma-delta converters are in principle
imperfectible. We prove this fact. The reason, simply stated, is that,
when properly dithered, they are in constant overload. Prevention of
overload allows only partial dithering to be performed. The
consequence is that distortion, limit cycles, instability, and noise
modulation can never be totally avoided. We demonstrate these effects,
and using coherent averaging techniques, are able to display the
consequent profusion of nonlinear artefacts which are usually hidden
in the noise floor. Recording, editing, storage, or conversion systems
using single-stage, 1-bit sigma-delta modulators, are thus inimical to
audio of the highest quality. In contrast, multi-bit sigma-delta
converters, which output linear PCM code, are in principle infinitely
perfectible. (Here, multi-bit refers to at least two bits in the
converter.) They can be properly dithered so as to guarantee the
absence of all distortion, limit cycles, and noise modulation. The
audio industry is misguided if it adopts 1-bit sigma-delta conversion
as the basis for any high-quality processing, archiving, or
distribution format to replace multi-bit, linear PCM.
The other is this by famous James A. Moorer et al.:
Audio Engineering Society Convention Paper 4719 on the 1st DSD
commercial editor
http://www.sonicstudio.com/pdf/papers/DSDStereoEdit.pdf
which abstracts to:
The editing in native form of 2.8224 Mhz 1-bit audio (Direct-Stream
Digital) is problematic since the required computation rate to
achieve level control, pan, and crossfade in real time is beyond the
capabilities of general-purpose digital signal processing chips. A
system has been developed which incorporates a special- purpose chip
designed specifically for computations on 1-bit audio. This is
embedded into the framework of a general-purpose audio editing and
premastering system. It behaves, looks and feels exactly like a
stereo, PCM editing system with full flexibility of sample-accurate
cross-fades, level control, metering, and non- linear random-access
editing, except that internally it is operating directly on the 1-
bit signal. This paper describes the data flow and architecture of
the system.
Now I'm wiser than before.
Ciao
--
Frank Barknecht _ ______footils.org_ __goto10.org__