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L�hett�j�: Jan Peman[SMTP:[EMAIL PROTECTED]]
L�hetetty: 22. hein�kuuta 1998 23:02
Vastaanottaja: [EMAIL PROTECTED]
Aihe: Re: [MP3 ENCODER] 8Hz quality (was Re: just another format ...)
On 22 Jul 1998, Jeff Lightfoot wrote:
> Yann Guidon wrote:
> >> I'm very interested in what ways our encoder is lower quality.
> >> Cut off higher/lower freqs?
> >i don't think, it may reside in the psychoacoustic analysis
> >that has been "shortened" as to increas the encoding speed.
> >but it is clearly claimed in the 8Hz homepage that this
> >encoder is not as good as others.
>
> Seeing that I couldn't code my way out of a paper bag, anyone know if this
> would be able to be a command line switch to increase quality?
>
> Or does the more extreme analysis not exist in the ISO sources therefore we
> can't implement it?
I think the main quality-loss is because the 8hz/dist10 source lacks the
Joint_Stereo switch.. This means that the fraunhofer and other encoders
with better quality gets more bits to use for the audio than an encoder
that only supports stereo. I don't know how many bits you get extra when
using the joint_Stereo, but maybe someone else knows?
I think that this joint stereo basicly means that you can combine low hz elements
using a single channell (correct me if I'm wrong) ie. the ear can't hear very well
from what direction low frequency signal is coming from, same thing why subwoofers are
used for. Maybe this compresses data even more so that there is room for more bits for
high frequency components...
Another thing I have heard is that at least frauenhof encoder is meant to work best
with lower bitrates (where it is really good) meaning Internet radio and similar kind
of stuff (according the author of BladeEnc Tord Jansson home8.swipnet.se/~w-82625/ the
quality of his BladeEnc encoder passes l3enc in quality after 160 kbs and I think it
is a ISO based encoder too).
So for the best possible quality we are in the right course.
What keeps me thinking is that this in NOT a final release from MPEG group, maybe they
have added things to produce better quality in their final release which is available
when you buy ISO documents (maybe with NDA...)
- Lassi
application/ms-tnef
