Being a low budget man, this has been of considerable interest to me. Does 
ambisonic systems have to be of the same quality as a stereo system? I doubt 
very much. For one thing, a stereo system has to excite the room in which it 
sits. That means power and extended frequency response. The cheapest system I 
tried was two “5.1” speaker  sets, each costing about 10USD. I did not persist 
with it, but was very satisfactory for the money. Two subwoofers too. (even if 
they woofed at about 100 Hz). I have KEF 5 speakers and 50 watt per channel 
eight watt amplifier, and it is rarely stressed.



I think there will be similar tradeoffs in compression, phase errors etc which 
we have really explored



umashankar



Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10



________________________________
From: Sursound <sursound-boun...@music.vt.edu> on behalf of Marc Lavallée 
<m...@hacklava.net>
Sent: Wednesday, October 25, 2017 6:15:28 PM
To: Surround Sound discussion group
Subject: Re: [Sursound] Simple Software to Play a 6-channel WAV File (Windows)?


Just a question: despite possible degradation of the decoded
ambisonics stream (due to phase errors), could it be that our perception
mechanisms (from the ears to the brain) can "fix" some distortions?
Also, what are the frequency ranges affected by phase errors (for
example in a AAC or Opus multi-channel stream) that could induce
perceptual problems? What's the limit: 16, 12, 8 or 4Khz?

To what extent do we have to care about Hi-Fi and High Resolution
when dealing with Ambisonics? This is an important issue for the
acceptance of Ambisonics... Do we need a fusion reactor to enjoy
Ambisonics? ;-)

--
Marc

Le Wed, 25 Oct 2017 14:08:49 +0200
David Pickett <d...@fugato.com> a écrit:

> But I have been thinking about it -- fatal!
>
> If you start off from WXY, which is what I use, and make these into
> 4.0, you have merely done a linear transform (a sophisticated LR-->SD
> relationship). As this is totally lossless, any added phase anomalies
> either before or after the transform, while they may not give the
> same effect, could be significant. All I can say is that I have not
> heard any significant degradation of my recordings when coding them
> into high rate MP4 and playing them over the internet before
> subsequent decoding.
>
> I am not trying to be awkward, just trying to make sense of this!
>
> David
>
> At 13:12 25-10-17, Dave Malham wrote:
>  >I should have said "storing pre-decoded signals in a compressed
>  >format has less potential to be problematic" since phase errors
>  >likely to upset pre-decoded material would probably also cause
>  >problems with stereo which hopefully would have been picked up and
>  >dealt with during testing. I should say here that that's just what
>  >I feel likely to be the case, I can't say that I've actually tested
>  >it.
>  >
>  >  Dave
>  >
>  >On 25 October 2017 at 11:30, David Pickett <d...@fugato.com> wrote:
>  >
>  >> At 09:55 25-10-17, Dave Malham wrote:
>  >>
>  >> >   Just a word of warning, take care using compressed formats
>  >> > like mp4 for
>  >> >storing B format. If the compression used is lossy, this can
>  >> >screw up the decoding since phase errors can result in the sum
>  >> >and difference equations involved producing wrong results. Of
>  >> >course, storing pre-decoded signals
>  >> in
>  >> >a compressed format doesn't suffer from this.
>  >>
>  >> Dave,
>  >>
>  >> I always add add shelf filtering and then decode from B format to
>  >> 4.0 before encoding to MP4. I dont see why there should not also
>  >> be phase problems with encoding 4.0 signals in MP4 (why do you
>  >> say not?); but I have never noticed any.
>  >>
>  >> David
>  >>
>  >> _______________________________________________
>  >> Sursound mailing list
>  >> Sursound@music.vt.edu
>  >> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe
>  >> here, edit account or options, view archives and so on.
>  >>
>  >
>  >
>  >
>  >--
>  >
>  >As of 1st October 2012, I have retired from the University.
>  >
>  >These are my own views and may or may not be shared by the
>  >University
>  >
>  >Dave Malham
>  >Honorary Fellow, Department of Music
>  >The University of York
>  >York YO10 5DD
>  >UK
>  >
>  >'Ambisonics - Component Imaging for Audio'
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