Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-27 Thread Fons Adriaensen
On Sat, Feb 27, 2016 at 01:19:40PM +, Politis Archontis wrote: > > The point is that, since the direct method is equivalent to > > a decoding for the set of directions used to compute the SHT > > (which will be the set for which you have HRIR), there is > > nothing 'ideal' or special to it. It

Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-27 Thread Politis Archontis
> The point is that, since the direct method is equivalent to > a decoding for the set of directions used to compute the SHT > (which will be the set for which you have HRIR), there is > nothing 'ideal' or special to it. It is just one specific case > of the decoder + virtual speakers method in

Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-27 Thread Fons Adriaensen
On Sat, Feb 27, 2016 at 12:52:20PM +, Politis Archontis wrote: > One case I can think of when it is really necessary is when one needs > to auralize binaurally the effect of a certain decoder, e.g. due to > non-uniform arrangement of virtual loudspeakers, compared to an ideal case.. The

Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-27 Thread Politis Archontis
>> So what is the benefit then of adding a decoding stage in the middle? > The advantage of having an explicit decoder stage is that you > can tweak the decoder for optimum results. For example it can > be dual-band [1], or have some front preference, etc. I see. I find that more a matter of

Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-27 Thread Politis Archontis
> No, this is not true. The decoder and convolution matrix can be combined > into a (N+1)^2 * 2 convolution matrix. Ah true! by summing the terms.. > The only remaining difference is the set of directions. And it is known > that using too many speakers for a given order is suboptimal. So what

Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-27 Thread Fons Adriaensen
On Sat, Feb 27, 2016 at 11:54:39AM +, Politis Archontis wrote: > And I forgot to mention in the previous message that, while I don't > see any benefit in the virtual loudspeaker approach, I see benefits > in the direct approach. Doing the virtual loudspeaker decoding, you'll > need some

Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-27 Thread Politis Archontis
...@linuxaudio.org] Sent: 27 February 2016 12:14 To: sursound@music.vt.edu Subject: Re: [Sursound] expressing HRTFs in spherical harmonics On Thu, Feb 25, 2016 at 09:25:48PM +, Politis Archontis wrote: > - Measure the HRIRs at Q directions around the listener > - Take the FFT of all measurements > -

Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-27 Thread Politis Archontis
ase. Regards, Archontis From: Sursound [sursound-boun...@music.vt.edu] on behalf of Fons Adriaensen [f...@linuxaudio.org] Sent: 27 February 2016 12:14 To: sursound@music.vt.edu Subject: Re: [Sursound] expressing HRTFs in spherical harmonics On Thu, Feb

Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-27 Thread Fons Adriaensen
On Thu, Feb 25, 2016 at 09:25:48PM +, Politis Archontis wrote: > - Measure the HRIRs at Q directions around the listener > - Take the FFT of all measurements > - For each frequency bin perform the SHT to the complex HRTFs, > up to maximum order that Q directions permit (and their

Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-25 Thread Politis Archontis
Hi Jorn, Yes, you’re right. To summarize the process: - Measure the HRIRs at Q directions around the listener - Take the FFT of all measurements - For each frequency bin perform the SHT to the complex HRTFs, up to maximum order that Q directions permit (and their arrangement: for equiangular

Re: [Sursound] expressing HRTFs in spherical harmonics

2016-02-25 Thread Politis Archontis
:48 To: sursound@music.vt.edu Subject: [Sursound] expressing HRTFs in spherical harmonics On 01/27/2016 01:56 PM, Jörn Nettingsmeier wrote: > On 01/26/2016 11:05 PM, Politis Archontis wrote: >> Hi Jorn, >> >> yes that is correct. I think however that the virtual loudspeaker

[Sursound] expressing HRTFs in spherical harmonics

2016-02-25 Thread Jörn Nettingsmeier
On 01/27/2016 01:56 PM, Jörn Nettingsmeier wrote: On 01/26/2016 11:05 PM, Politis Archontis wrote: Hi Jorn, yes that is correct. I think however that the virtual loudspeaker stage is unnecessary. It is equivalent if you expand the left and right HRTFs into spherical harmonics and multiply