dw wrote:
It claimed to use state of the art applications of binaural rendering.
Because I cited one white paper does not mean I have only read one in
my life, or base my opinions on those of the BBC. ´
and ...
Previous work <http://www.bbc.co.uk/rd/publications/whitepaper250> has
shown...
Ok, I allow myself to cite two short passages from Mr. Theile's mail:
The test method applied in the BBC study was based on “not known
target quality” (Chapter 5.1). However, the target is known, it should
be the real room which was measured and aimed as original surround
listening experience. Assessing a surround room synthesis technology
in comparison to the ITU stereo down-mix is synonymous with assessing
a real surround monitoring in comparison to ITU 2-channel down-mix
headphone monitoring. · The BBC comparison test does not clarify basic
preferences of the subjects regarding “5-ch surround vs. 2-ch stereo”
and “2-ch loudspeaker vs. 2-ch headphone listening”. Results plotted
in Fig. 6 indicate that listening group 2 prefers 2-ch headphone
listening and one cannot exclude that this would be found basically in
comparison to loudspeaker listening. In contrast, listening group 1
should prefer basically surround sound and out-of-head localization.
...
It seems clear to me that further causes have effected this result. I
suggest that the “individualised head-tracked BRIR system” was not
calibrated correctly or ...
I wrote to several people before receiving this feedback:
http://downloads.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP250.pdf
Experimental evidence has suggested that for plausible virtual sound
sources located outside of the head with good directional accuracy,
HRIR measurements specific to the individual are required [4, 5].
However when impulse responses containing the room response, known as
binaural room impulse responses (BRIRs), are used in combination with
head-tracking, to compensate for head motion, plausible synthesis of
virtual sound sources can be achieved with high localisation accuracy
[6, 7]. The relative importance of these system components has been
addressed in terms of localisation [8] however the effects on overall
sound quality are not clear.
(pag 5)
and then:
In the context of broadcast distribution, the state-of-the-art virtual
surround systems were shown not to give a great improvement over an
ITU down-mix for playback of 5.1 audio over headphones, when used in a
black box approach. Many systems performed significantly worse than
the downmix, including the dynamic individualised BRIR system. The
best performing systems were graded similarly to the down-mix.
(in 7, Conclusions and Discussion. If so, we should pack our luggage...)
Well, and this is why I don't trust every study....
You could conclude
a) that binaural representation of surround sound is just not being
worth it to be studied
OR
b) that they didn't do things in the right way.
Actually I believe the conclusion is more like b), because "my"
reference system
http://smyth-research.com/technology.html
just happens to reproduce 5.1/7.1 via headphones very well, according
to everybody who has listened to this.
It is a fact that the Smyth Research system has been rated highly by <
any > person I know which listened to, and there are plenty of listening
reviews available in the Internet. ("HiFi" reviews etc. ...)
It is also obvious that this system can reproduce sound from the front,
as it is used for 5.1/7.1/2.0 studio mixing, and as HiFi system.
Some reviews:
http://www.soundonsound.com/sos/jul13/articles/smyth-realiser-a8.htm
A big concern many people have about headphone monitoring is the lack
of physical bass sensation, but I was genuinely surprised at how
little difference the use of the Tactile output actually made to my
mixing decisions in the long term. Just hearing the low-frequency mix
components within such a believably speaker-like context seems to
clarify most low-frequency level and quality questions on its own
somehow, and in no less reliable a manner than 95 percent of nearfield
monitoring systems I've heard, given the strong influence of room
resonances on real-world bass reproduction. Furthermore, the
Realiser's nifty Direct Bass feature (see the 'Better Than The Real
Thing?' box) can remove the effects of LF room modes from its
emulation entirely, delivering low-end fidelity that's well beyond the
capabilities of the speaker system you originally sampled!
(LF properties of headphones...)
My biggest gripe about the Realiser has nothing to do with the sound,
though: it's the clunkiness of the user interface.
I also missed the psychological 'averaging' effect that you get with
real speakers when you stroll round your room. Although you can move
around quite a bit without losing the head-tracking, your virtual
monitoring position remains riveted in the stereo sweet spot, which
might not be the position that provides the most useful frequency
balance in your sampled room
(Position tracking vs. "orientational" head-tracking...)
But what blows my tiny mind even more is the tantalising prospect that
SVS technology might trickle down beyond this first-generation proof
of concept.
http://www.positive-feedback.com/Issue63/smyth_realiser.htm
After all the time and effort invested, how did the Realiser perform?
In a word, brilliantly.
You wrote:
Previous work <http://www.bbc.co.uk/rd/publications/whitepaper250> has
shown that even with the state-of-the-art virtual surround systems we
don't currently get a big improvement in quality over a conventional
stereo down-mix.
I have presented arguments and observation confirming that < headphones
can adequately represent surround sound >. (rendered to binaural
representation, of course...)
The BBC itself says that 5.1/Ambisonics < is > an improvement over
stereo. In we should have doubted. O:-)
(http://downloads.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP221.pdf)
There are plenty of organisations which have done more and methodically
well thought studies. (Mpeg etc.), including perceptual evalutation.
(For codecs, Mpeg Surround etc. etc.)
I would really not overrate a single BBC study which doesn't seem to fit
to a lot of other results and observations. (There are plenty of studies
available which fail somewhere.)
Cheers,
Stefan
I did not say you '_represent_ "binaural science"'.
I do not pretend to understand it. Others do. I think they are wrong
due to the lack of observational support for the implied predictions
of said theories.
On 22/11/2014 02:34, Stefan Schreiber wrote:
dw wrote:
On 19/11/2014 22:12, Stefan Schreiber wrote:
Your posting seems to be meaningless if not arrogant, BTW.
Let me put it in a more positive way then.. Your thinking is
representative of the state of the art in binaural science.:-)
"Previous work <http://www.bbc.co.uk/rd/publications/whitepaper250>
has shown that even with the state-of-the-art virtual surround
systems we don't currently get a big improvement in quality over a
conventional stereo down-mix. The perceived quality was found to
vary significantly according to the source material used."
http://www.bbc.co.uk/rd/blog/2014/10/tommies-in-3d
I actually have discussed this study with some people. (for example,
Günther Theile)
Experience with Realiser A8 from Smyth Research and IRT's BRS system
seems to indicate that binaural systems with head-tracking and
personalized HRTF filters < can't be distinguished from real (5.1)
speakers >.
(They used BRIRs of the listening room and the reference 5.1 speaker
system, of course.)
I don't believe that the BBC study is really flawless, BTW. (Günther
Theile thought the same.)
(I am too lazy to discuss this now, have some other stuff to do.)
Your thinking is representative of the state of the art in binaural
science.:-)
Maybe you should read more than (just) one "paper", before claiming
that nobody beside you has some clue? :-D
I also didn't claim to represent "binaural science", if I remember well.
Best,
Stefan
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