To do this with granular processing, you would normally need to use
two granular generators (e.g. two partikkel opcodes), one reading from
the "left" sound and one from the "right". You could do this by
copying the csound code for partikkel in your csd and just modifying
the pointer to the source waveform.
Then you would have to read your sound file into two different ftables
of course, one for left and one for right.
best
Oeyvind

2011/1/31 JLFerreira <jlfcomposer@gmail.com>:

> Hello List,
>
> objective: read a stereo sound file with ability to change the reading speed
> without changing pitch and keep it as faithful to the original as possible
> (prevent the usual sound distortion)
> I think the best way is to use a granulator, (is it?) - and
> SF_granular.csd written by joachim heintz (great job!!!!) does quite well
> the trick
> I'm also using the adaptation (made by |????) to use with Csound~ on MAX5
> the main problem is the use of a stereo file - do I need to use a double
> buffer to be read separately but in Sync by to partikkel opcodes? or is
> there a way to use both channels of a buffer? and how do I do this?
> the second problem is that partikkel opcode (in realtime) only accepts table
> (ftgen) #1 as a buffer.... and I would need two tables...
> I hope this isn't to much confusing.
>
> thanks in advance!
> --
> JLF
> http://www.youtube.com/user/JLFcompositor
>
>

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I think that the grain distribution might not be that important to
avoid artifacts when time stretching. In fact using a random
distribution might actually make more artifacts as it can lead to
artificial and abrupt changes in amplitude (when at some times several
grains overlap and you get a peak, at other times there might simply
be too few grains to fill gaps between individual grains). Using
slight randomness on the time pointer however, is quite effective and
will give minimal extra side effects as long as you don't overdo it.
Some randomness to grain rate might also help, but it's the time
pointer that is the most important to randomize in order to avoid the
ring modulation effect that granular techniques might give. A useful
starting point for grain rate may be around 40 Hz (normally in the
range 25Hz to 80Hz), with a grain duration of 2.5 to 3.0 (relative
grain duration, where a duration of 1.0 means that a grain lasts as
long as the time between grains).
I would also say that generally you might expect to adjust the
parameters differently for different kinds of source material, so
there's really no size fits all :-)

Do also check out Victor's opcodes for time modifications.

all best
Oeyvind


2011/2/1 JLFerreira <jlfcomposer@gmail.com>:

> Oeyvind: - thanks! I suspected that solution, and i've tried that and it
> works :)
> - noticed that the sound deteriorates a lot when i change (just a little)
> it's playback speed (nothing to do with the question above, of course) I
> must find a dependency between playback speed and grain distribuition
> (periodic to scattered)
>
> another question:
> Victor Lazzarini told about some vocoder opCodes, but it seems they are only
> available on v5.13 - I can't find it to work on my qutecsound 0.6.0....
> thanks again!
>
> On 31 January 2011 14:31, Oeyvind Brandtsegg <oyvind.brandtsegg@ntnu.no>
> wrote:
>>
>> To do this with granular processing, you would normally need to use
>> two granular generators (e.g. two partikkel opcodes), one reading from
>> the "left" sound and one from the "right". You could do this by
>> copying the csound code for partikkel in your csd and just modifying
>> the pointer to the source waveform.
>> Then you would have to read your sound file into two different ftables
>> of course, one for left and one for right.
>> best
>> Oeyvind
>>
>> 2011/1/31 JLFerreira <jlfcomposer@gmail.com>:
>> > Hello List,
>> >
>> > objective: read a stereo sound file with ability to change the reading
>> > speed
>> > without changing pitch and keep it as faithful to the original as
>> > possible
>> > (prevent the usual sound distortion)
>> > I think the best way is to use a granulator, (is it?) - and
>> > SF_granular.csd written by joachim heintz (great job!!!!) does quite
>> > well
>> > the trick
>> > I'm also using the adaptation (made by |????) to use with Csound~ on
>> > MAX5
>> > the main problem is the use of a stereo file - do I need to use a double
>> > buffer to be read separately but in Sync by to partikkel opcodes? or is
>> > there a way to use both channels of a buffer? and how do I do this?
>> > the second problem is that partikkel opcode (in realtime) only accepts
>> > table
>> > (ftgen) #1 as a buffer.... and I would need two tables...
>> > I hope this isn't to much confusing.
>> >
>> > thanks in advance!
>> > --
>> > JLF
>> > http://www.youtube.com/user/JLFcompositor
>> >
>> >
>>
>>
>> Send bugs reports to the Sourceforge bug tracker
>>            https://sourceforge.net/tracker/?group_id=81968&atid=564599
>> Discussions of bugs and features can be posted here
>> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe
>> csound"
>>
>
>
>
> --
> JLF
> http://www.youtube.com/user/JLFcompositor
>
>


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