[Jackit-devel] Re: [linux-audio-user] ices-jack pico-howto

Eric Dantan Rzewnicki rzewnickie at rfa.org
Wed Sep 22 14:58:44 EDT 2004

On Wed, Sep 22, 2004 at 12:50:52AM +0100, Karl Heyes wrote:
> On Tue, 2004-09-21 at 22:18, Joern Nettingsmeier wrote:
> > > Other than ices and icecast, do both the icecast box and the ices box 
> > > need all of the svn packages you list above?
> > the icecast box does not need the *-tools. (nor does ices strictly 
> > speaking, but they are nice to have). i described a "bleeding edge" 
> > best-of-xiph.org setup. if you don't want to play with video or 
> > very-low-bandwidth speech streaming, you can omit the speex and 
> > theora packages as well as flac. ices/icecast check for them at 
> > compile time - i wanted all bells and whistles, but if the libs are 
> > not present, those features will be left out with no problems.
> If you are taking from svn, then you need the autoconf etc tools, but if
> you are using tarballs then the configure script will be already built
> so it won't be needed in that case.
> > you may even get away with using your distro's libvorbis, although i 
> > think ices-kh does require ogg2 and won't compile with plain old ogg.
> no, ogg2 is not required, and AFAIK the vorbis codec may not be working
> with it just yet.

Thanks Karl.

> > when you do this, consider that under ideal circumstances, re-ogging 
> > a pcm stream that has been ogg-encoded before will not add new 
> > encoding artifacts, unless you reduce the bitrate.
> I don't think you can state that in general, as the second encoding will
> operate on different pcm input.  Given the same encoder settings it's
> unlikely to loose much.

My composition-thing will decode previously encoded portions of the
stream, apply manipulations (time-stretch/compress & possible reversing)
and then mix them together with others similarly manipulated. 
Additionally, the recording portion of the system will choose a vorbis 
quality at random from the range of worst-best for each recording. So, 
there will be some effect from the encode-decode cycles. But, even if 
that effect is minimal the system still messes with time scale 
stretch/compress, reversal of audio data and mixing streams together at
random. Something interesting, at least to me, will come of it. The ogg
vorbis part at least provides a larger pool of previous recordings to
feed back into the system by virtue of saving some disk space.

-Eric Rz.

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