Gabriel, there was a presentation on this at the ICMC that you can find in
your Proceedings:

Roger Dannenberg, "Interpolation Error in Waveform Table Lookup", page 240.

You could email Dannenberg to see if he has suggestions on the best way to
do this in Csound.

By the way, I had a chat with Jim Wright from IBM about using TCP/IP or UDP
as a protocol for MIDI. He was against it because delivery latency cannot be
guaranteed with straight IP. He suggested that FireWire be used, and said he
was looking into it.

Coincidentally, I ran into the following Web page when doing my semi-regular
Web search for Csound related stuff:

http://www.pavo.com/index.htm.

This is a very interesting site because this outfit appears to be working
with Analog Devices on an Extended Csound related project, and with Yamaha
on a FireWire protocol for both multi-channel real-time digital audio, and
MIDI information.

I think we should talk to the Pavo people and see what the specification of
their FireWire protocol is, and whether any manufacturers (Yamaha?) are
going to make controllers for it. If so, it might be a good choice to put
into Csound.


-----Original Message-----
From: Gabriel Maldonado 
To: Josep M Comajuncosas 
Cc: csound@maths.ex.ac.uk 
Date: Thursday, October 22, 1998 8:17 AM
Subject: Re: Interpolation schemes and SB Live!


Josep M Comajuncosas wrote:
>
> Hi all,
> I recently saw the promotional prospectus of a low-cost PC sound card
> (called MaxiSound or so) and I was *really* disapointed with its specs.
> compared to Csound. Specifically, it is said to use a 3rd order
> polynomial scheme for wavetable interpolation, when Csound only accepts
> linear (1st order) interpolation.
> As you may agree this cannot be accepted ;-), I´d suggest at least 3 new
>
> opcodes, called maybe
> oscilp
> tablep
> deltapp
> with an additional parameter to choose the polynomial degree used for
> interpolated readout.
> I´m not very sure about the improvement in the s/n ratio and in the
> frequency response in relation to the degree of the Lagrange
> interpolator. Maybe some of you have any clues. But it would be nice to
> implement such feature.

The problem is: does it improve the sound quality? How much does it cost in
processing
speed?
My new SoundBlaster Live has an internal wavetable synthesizer who does 8
point
interpolation in realtime. Actually the sound quality is excellent. I don't
know if it
depends of the interpolation algorithm or of the hardware analog converter.

Where is it possble to get the algorithm to implement 8 point interpolation?
If I could
see an example of it I will implement it in Csound.



> Another question related to waveguide opcodes. Does deltapi (and delayw
> btw) accept fractional sample delay lengths (well, fractional 1/kr
> units) ?

Yes it does.


> If not, is it expected to implement it soon? Otherwise it could
> be difficult to tune a delay line at a precise high frequency, esp. at
> low k-rates.
> This is specially noticeable when developing waveguide models.

The problem is that the first order filters that are implemented in the
waveguide opcodes
don't use fractional delay, so the pitch of high notes is not precise.


--
Gabriel Maldonado

http://www.agora.stm.it/G.Maldonado/home2.htm

Michael Gogins wrote:
> This is a very interesting site because this outfit appears to be working
> with Analog Devices on an Extended Csound related project, and with Yamah=
> a
> on a FireWire protocol for both multi-channel real-time digital audio, an=
> d
> MIDI information.
> 
> I think we should talk to the Pavo people and see what the specification =
> of
> their FireWire protocol is, and whether any manufacturers (Yamaha?) are
> going to make controllers for it.

Sounds like this is Yamaha's mLan proposal -- specs and such at:
http://www.yamaha.co.jp/tech/1394mLAN/

This is very promising stuff.  1394 is fast enough to push a lot of
data, and mLan does it isochronously for good timing.

My understanding of the process here is that mLan was developed
within the 1394 group; industry MIDI and audio groups are now getting
on board, harmonizing with their notions, maybe negotiating tweaks.
Might still be a bit before gear hits the streets.

--