If you make sure to play N full cycles then you can simply copy and
paste without the need to fade in or out? Sounds like it might be
easier to use the CsoundAndroid player to do all of this rather than
LAS-9?

On 20 May 2014 15:47, Dave Seidel  wrote:
> I've been using an Android app called LAS-9 lately. It's a very useful tool
> that allows one to load a set of nine WAV files, and then to loops them in
> any combination using a very simple interface. I use it in live work to play
> back loops of field recording to accompany live electronic.
>
> I am now also using it to loop single-tone drones created in Csound, both
> for live playback and as tuning references (i.e., for tuning a set of
> hardware oscillators to a complex just intonation chord prior to
> performance). For these purposes, I generally use simple square or triangle
> waves using vco2.
>
> Creating the individual WAV files is trivial, but one thing I can't quite
> figure out: is there a technique for generating a file containing a simple
> oscillator tone that can be seamlessly looped? I have been using a very
> short linen envelope to avoid clicks, but of course it introduces a
> discontinuity when looped. I've been dealing with this by editing the loops
> in Audacity and trimming the files so so that they start and end at a point
> of zero crossing, but it would save a lot of time and trouble if I could
> just do this within Csound itself. Can it be done?
>
> - Dave

if i understand correctly what you want to do, you could redefine p3 in
your instrument to an integer multiple of periods. something like:


instr 1	

idur	=	p3
iamp	=	p4
ifreq	=	p5
it	=	1/ifreq	; period in seconds
inumt	=	round(idur*ifreq)	; number of periods, rounded
p3	=	it*inumt	; redefine p3

a1	vco2	iamp, ifreq
	out	a1

endin

does that help, or did i completely miss the point?

The problem is when (as will typically be the case) the required 
frequency does not exactly fit into N samples (most easily seen with 
high frequencies). Not all zero crossings are the same, and there will 
be some fraction of a period  at the end discontinuous with the 
(zero-sample) start. In effect it is the same problem as that of the 
truncated rectangular window used for an FFT. Looping on zero-crossings 
narrows the possible error down, but rarely eliminates it completely. 
The notion that looping on zero crossings ensures a glitch-free result 
is a bit of a myth, I fear.


Richard Dobson



On 20/05/2014 16:38, luis jure wrote:
>
>
> if i understand correctly what you want to do, you could redefine p3 in
> your instrument to an integer multiple of periods. something like:
>
>
> instr 1	
>
> idur	=	p3
> iamp	=	p4
> ifreq	=	p5
> it	=	1/ifreq	; period in seconds
> inumt	=	round(idur*ifreq)	; number of periods, rounded
> p3	=	it*inumt	; redefine p3
>
> a1	vco2	iamp, ifreq
> 	out	a1
>
> endin
>
> does that help, or did i completely miss the point?
>
>
> Send bugs reports to
>          https://github.com/csound/csound/issues
> Discussions of bugs and features can be posted here
> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe csound"
>
>
>
>

On Tue, 20 May 2014, Forrest Cahoon wrote:
> You need to make the length of the loop commensurate with both the period of
> the waveform and the sample rate.  I think I have the calculations right,
> using ruby (which has a nice gcd function) here:

Is it also necessary to have an integer number of control periods?

-- 
Matthew Skala
mskala@ansuz.sooke.bc.ca                 People before principles.
http://ansuz.sooke.bc.ca/

I wonder, would a crossfade be enough to do the job here, overlapping
the wave with a copy of itself?  I've got some code in the waveseq udo
here:

http://kunstmusik.com/2012/11/02/waveseq-wave-sequencing-user-defined-opcode-for-csound/

That might be handy for this.  Not as nice as having exact periods and
zero-crossings, but might be usable for long samples.

On Tue, May 20, 2014 at 12:02 PM, Richard Dobson
 wrote:
> The problem is when (as will typically be the case) the required frequency
> does not exactly fit into N samples (most easily seen with high
> frequencies). Not all zero crossings are the same, and there will be some
> fraction of a period  at the end discontinuous with the (zero-sample) start.
> In effect it is the same problem as that of the truncated rectangular window
> used for an FFT. Looping on zero-crossings narrows the possible error down,
> but rarely eliminates it completely. The notion that looping on zero
> crossings ensures a glitch-free result is a bit of a myth, I fear.
>
>
> Richard Dobson
>
>
>
>
> On 20/05/2014 16:38, luis jure wrote:
>>
>>
>>
>> if i understand correctly what you want to do, you could redefine p3 in
>> your instrument to an integer multiple of periods. something like:
>>
>>
>> instr 1
>>
>> idur    =       p3
>> iamp    =       p4
>> ifreq   =       p5
>> it      =       1/ifreq ; period in seconds
>> inumt   =       round(idur*ifreq)       ; number of periods, rounded
>> p3      =       it*inumt        ; redefine p3
>>
>> a1      vco2    iamp, ifreq
>>         out     a1
>>
>> endin
>>
>> does that help, or did i completely miss the point?
>>
>>
>> Send bugs reports to
>>          https://github.com/csound/csound/issues
>> Discussions of bugs and features can be posted here
>> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe
>> csound"
>>
>>
>>
>>
>
>
>
> Send bugs reports to
>        https://github.com/csound/csound/issues
> Discussions of bugs and features can be posted here
> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe
> csound"
>
>
>