KH wrote:
On 6/12/2012 8:20 PM, Sebastian Kaliszewski wrote:
KH wrote:
On 6/9/2012 2:09 PM, Gary Eickmeier wrote:
[...]
Stereo has nothing to do with HRTF.
snip
Yes, that is the problem. The signal presented to the listener, in the
venue, has angular, temporal, and level clues that,
And phase as Audio Empire points out.
Well yes, but what is phase except a temporal shift?
You're conflating phase and wavefront. You can have 180deg off phase signals
coming at the same moment.
in conjunction with the HRTF of the listener, create a spacial image.
That information was not, however, encoded into the recording except
as temporal and level information.
And possibly phase as well.
Ditto
See above. Phase is a property different from timing.
No matter how that information is played back, the signal reaching the
listener cannot be the same as in the venue.
It will never be the same, but that's not the point. The point is
similar enough.
Well, no, the point is it still must be an illusion, because the
information is not in the recording.
PArt of the infomation is. You're making an error 180deg from Gary's error, but
stil an error.
Due to projection from higher to lower number of dimansions part of the
information is lost but part is still retained.
I agree, it only need be
"sufficient" to fool the listener. But it simply cannot be "the same".
But "the same" is not needed. Our ears have finite resolution and our brains are
sesnsitive obly to some parts of the signal.
Reflecting the sound cannot, except in the context of listener
preference, ameliorate this constraint.
It's not staright out prooven either way. But I'd say it's rather
improbable. But I'm open to be shown otherwise. That's why I wanted to
see a theory not a nice trick. Theory which would explain that the
needed clues are in the reproduced signal and distractions are either
masked or attenuated enough.
All subject to individual listener response however. Since the
reproduction *must* be different, and must present a different HRTF than
the original, it has to be listener dependent.
Only to a point. Listeners are humans not superbeings and all have their
limitations. If you have an device capable of running 30Mph you can outrun any
human going on his feet. IOW listener dependence has its bounds.
Can you create a model
that is statistically "better"? Certainly. But then, you must
understand, that statistically, *low* bit-rate MP3's are sonically fine.
And high bitrate Oggs, Musepacks or AC3s are sonically indistinguishable.
[...]
The "real thing" comes to us as a primarily reverberant field from a
multiplicity of incident angles.
No, it does not, except in a narrow subset of live events.
Oh, in fact it does. In majority of live events it does. You got it
wrong. In your typical concert hall critical distance is about 4m-5m. In
clubs and similar small venues it's even closer. That means that even
while one is sitting in a first row the sound of further away
instruments is dominated by reverberant sound.
I'm not thinking orchestra, I'm thinking small acoustic groups, in small
settings. Oftentimes 10 feet or less.
In small venues critical distance is also small.
Many times the direct component (lets think of outside live events for
example, shall we?)
Outside events are allmost allways reinforced. So there goes that
'natural' soundstage.
Realism is not confined to non-reinforced music.
But in case of reinforced music you don't have an natural audio scene to capture.
is the dominant component, and sometimes by wide margins.
Its very rare situation it's a dominant component and virtually never by
a wide margin.
In any amplified outdoor event, it certainly is.
Ditto. Besides those are most typically recorded by taping electical signals
before the go into PA reinforcement system. Any auditory scene is then created
in porstprocessing.
If the spacial is as important as you maintain, then reflecting the
direct portion of the signal is at least as egregious an error as
ignoring the reverberant part of the signal.
This is too simplistic.
I fail to see how, and your description below does not explain it
sufficiently, to my mind.
In fact real properly[*] recorded events are miked at a distance closer
than a typical listener is. Moreover mikes are typically high in the
air, so they get early reflections primarily just from the floor and not
from all the close surroundings of typical listener (as there aren't any
up there).
Yes, and how does reflecting these floor reflections - that arrive at
the listener from a specific incident angle - from a totally different
incident angle, during replay, provide an accurate representation?
First, one have to ascertain what acuracy of incident angles is really needed.
That's in fact a part of what I miss from what Gary presented.
Second, those floor reflections in real life listener position (i.e. not 10 feet
allmost above conductors head) get rereflected as well.
Stereo recordings recorderd from a typical listener position
do not sound too spectacularily. This is (partly) because that sound is
then replayed at listener venue where there are additional reflections
(nobody listens in anechoic chamber). So good recording already take
into account those additional reflections. Thus additional reflections
are often 'unnatural' -- they contain peaks due to room shape and
dimensions (the incorporate replay room info), in case of box speakers
they are much damped in the highs, etc...
I would basically agree. But, "taking into account those additional
reflections" means altering the recording to account for the playback
medium and venue. Such tailoring must make the information on the
recording inaccurate relative to the acoustic in the original venue, no?
Well, this information is accurate at the miking position(s). Only that position
is choosen
Almost analogous to an RIAA pre-emphasis and de-emphasis without a
reference standard.
Somewhat, I agree. But even without pre-emphasis standard no preemphasis at all
was worse.
Similarily, recordings miked from typical listener position tend to present
unimpressive audio scene rendidtion.
If someone came with good theory allowing us convicing audio scene recreation
without sacrificing other audio aspects some standard like -- place mikes always
12ft above flooor, pointed such as such, etc.
rgds
\SK
--
"Never underestimate the power of human stupidity" -- L. Lang
--
http://www.tajga.org -- (some photos from my travels)