Hi Perry,
Thanks and sorry for all the trouble.
In the meanwhile i posted another mail to the mailinglist (answered by d.loberg.code@wmich.edu)
And he said that in SndBuf , in order to play backward,  you have to put de pos to -1 total lenght. Suppose your file has 1000 samples. Then you have to start from 1000 - 1 = 999.
This effectively works. In LiSa on the contrary you can start at 1000.

Cheers,

herman
 

Van: chuck-users-bounces@lists.cs.princeton.edu <chuck-users-bounces@lists.cs.princeton.edu> namens Perry Cook <prc@cs.princeton.edu>
Verzonden: woensdag 12 februari 2020 22:04
Aan: chuck-users@lists.cs.princeton.edu <chuck-users@lists.cs.princeton.edu>
Onderwerp: Re: [chuck-users] playing SndBuf backward
 
It is playing backward from 0, to 0, so it does nothing.  You have to set .pos
to .samples() (point to the end, so it can play backward).

In the example, you’d need to advance time to let it play forward:

mySndBuf.samples() :: samp => now; // you’d hear it play forward

then set rate to -1, then advance time again to hear it backward.

PRC

Looking at our book, I see that you didn’t copy all the lines.  You’ve
got to advance time to hear anything in ChucK. 

// 4.3 Playing sounds in reverse
// by ChucK Programmer 4102, yluJ #A

SndBuf mySound => dac;

me.dir()+"/audio/hihat_04.wav" => mySound.read; #1

mySound.samples() => int numSamples; #2

// play sound once forward
0 => mySound.pos;
numSamples :: samp => now; #3

// and once backward
numSamples => mySound.pos; #4
-1.0 => mySound.rate; #5
numSamples :: samp => now;


> On Feb 12, 2020, at 1:30 PM, chuck-users-request@lists.cs.princeton.edu wrote:
>
> Send chuck-users mailing list submissions to
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> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of chuck-users digest..."
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>
> Today's Topics:
>
>   1. Re: playing SndBuf backward (Perry Cook)
>   2. Error in book "Programming for Musicians and digital artists
>      by Ge Wang" ? (herman verbaeten)
>   3. playing SndBuf backward (herman verbaeten)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 12 Feb 2020 12:58:36 -0800
> From: Perry Cook <prc@cs.princeton.edu>
> To: chuck-users@lists.cs.princeton.edu
> Subject: Re: [chuck-users] playing SndBuf backward
> Message-ID: <6DBAE4AC-7E7E-413D-8059-8CB929B9AC78@cs.princeton.edu>
> Content-Type: text/plain; charset=utf-8
>
> You can set the .pos to wherever you like, and set the .rate to a negative number.  The sample will happily play backward to zero and stick there (unless you have .loop set).
>
> PRC
>
> Sent from my iPad
>
>> On Feb 12, 2020, at 9:00 AM, chuck-users-request@lists.cs.princeton.edu wrote:
>>
>> ?Send chuck-users mailing list submissions to
>>   chuck-users@lists.cs.princeton.edu
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>>   https://lists.cs.princeton.edu/mailman/listinfo/chuck-users
>> or, via email, send a message with subject or body 'help' to
>>   chuck-users-request@lists.cs.princeton.edu
>>
>> You can reach the person managing the list at
>>   chuck-users-owner@lists.cs.princeton.edu
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of chuck-users digest..."
>>
>>
>> Today's Topics:
>>
>>  1. Re: => now (herman verbaeten)
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Tue, 11 Feb 2020 18:11:09 +0000
>> From: herman verbaeten <hverb54@hotmail.com>
>> To: ChucK Users Mailing List <chuck-users@lists.cs.princeton.edu>
>> Subject: Re: [chuck-users] => now
>> Message-ID:
>>   <AM0PR08MB389035F6190B1D2C897C097BA5180@AM0PR08MB3890.eurprd08.prod.outlook.com>
>>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Thanks again Mario,
>>
>> I have another question:
>> Can you recommend a procedure to address individual samples of a wave-file you read into the SndBuf.
>> I discovered a way to play a part of a wave file starting at a certain point using ".pos".
>> I also wonder if there's a way to play it backwards (reverse).
>>
>> Cheers,
>>
>> herman
>>
>>
>>
>> _______________________________
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 12 Feb 2020 21:15:51 +0000
> From: herman verbaeten <hverb54@hotmail.com>
> To: chuck mailing list <chuck-users@lists.cs.princeton.edu>
> Subject: [chuck-users] Error in book "Programming for Musicians and
>        digital artists by Ge Wang" ?
> Message-ID:
>        <AM0PR08MB38900B846EE7C57D44869411A51B0@AM0PR08MB3890.eurprd08.prod.outlook.com>
>       
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi,
>
> I was looking in your book and copied listing 4.3 " Playing a sound file backward"
> But it didn't work. Hopefully i did everything correctly. It did perform the first (forward) part but during the reverse part i heard nothing. Can you please help me....
>
> Kind regards,
>
> Herman
>
>
> // copy Listing 4.3 Playing a sound file backward
> // from Programming for Musicians and digital artists by Ge Wang
>
> me.sourceDir() + "sample.wav" => string filename;
> if( me.args() ) me.arg(0) => filename;
>
> // the patch
> SndBuf mySound => dac;
>
> // load the file in buf
> filename => mySound.read;
>
> mySound.samples() => int numSamples;
>
> 0 => mySound.pos;                  // this was ok
> numSamples::samp => now;
>
> numSamples => mySound.pos;     // This was not heard. Athough the program stayed in VM.
> -1.0 => mySound.rate;
> numSamples::samp => now;
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <http://lists.cs.princeton.edu/pipermail/chuck-users/attachments/20200212/622aecd2/attachment-0001.html>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 12 Feb 2020 21:29:59 +0000
> From: herman verbaeten <hverb54@hotmail.com>
> To: ChucK Users Mailing List <chuck-users@lists.cs.princeton.edu>
> Subject: [chuck-users] playing SndBuf backward
> Message-ID:
>        <AM0PR08MB3890357CDD692F4A42A2BC9DA51B0@AM0PR08MB3890.eurprd08.prod.outlook.com>
>       
> Content-Type: text/plain; charset="utf-8"
>
>
> Sorry PRC it doesn't work: When i set "buf.rate" to 1.0 and  "buf.pos"  to 0,  it does but not the other way around....
>
>
> me.sourceDir() + "aeiou.wav" => string filename;
> if( me.args() ) me.arg(0) => filename;
>
> SndBuf buf => dac;
>
> filename => buf.read;
>
> buf.length() => dur totalelengte;
> buf.samples() => int samples;
>
> samples => buf.pos;
> -1.0 => buf.rate;
>
> samples::ms => now;
>
> ________________________________
> Van: chuck-users-bounces@lists.cs.princeton.edu <chuck-users-bounces@lists.cs.princeton.edu> namens Perry Cook <prc@cs.princeton.edu>
> Verzonden: woensdag 12 februari 2020 20:58
> Aan: chuck-users@lists.cs.princeton.edu <chuck-users@lists.cs.princeton.edu>
> Onderwerp: Re: [chuck-users] playing SndBuf backward
>
> You can set the .pos to wherever you like, and set the .rate to a negative number.  The sample will happily play backward to zero and stick there (unless you have .loop set).
>
> PRC
>
> Sent from my iPad
>
>> On Feb 12, 2020, at 9:00 AM, chuck-users-request@lists.cs.princeton.edu wrote:
>>
>> ?Send chuck-users mailing list submissions to
>>   chuck-users@lists.cs.princeton.edu
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>>   https://lists.cs.princeton.edu/mailman/listinfo/chuck-users
>> or, via email, send a message with subject or body 'help' to
>>   chuck-users-request@lists.cs.princeton.edu
>>
>> You can reach the person managing the list at
>>   chuck-users-owner@lists.cs.princeton.edu
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of chuck-users digest..."
>>
>>
>> Today's Topics:
>>
>>  1. Re: => now (herman verbaeten)
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Tue, 11 Feb 2020 18:11:09 +0000
>> From: herman verbaeten <hverb54@hotmail.com>
>> To: ChucK Users Mailing List <chuck-users@lists.cs.princeton.edu>
>> Subject: Re: [chuck-users] => now
>> Message-ID:
>>   <AM0PR08MB389035F6190B1D2C897C097BA5180@AM0PR08MB3890.eurprd08.prod.outlook.com>
>>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Thanks again Mario,
>>
>> I have another question:
>> Can you recommend a procedure to address individual samples of a wave-file you read into the SndBuf.
>> I discovered a way to play a part of a wave file starting at a certain point using ".pos".
>> I also wonder if there's a way to play it backwards (reverse).
>>
>> Cheers,
>>
>> herman
>>
>>
>>
>> _______________________________
>
>
> _______________________________________________
> chuck-users mailing list
> chuck-users@lists.cs.princeton.edu
> https://lists.cs.princeton.edu/mailman/listinfo/chuck-users
> -------------- next part --------------
> An HTML attachment was scrubbed...
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>
> ------------------------------
>
> _______________________________________________
> chuck-users mailing list
> chuck-users@lists.cs.princeton.edu
> https://lists.cs.princeton.edu/mailman/listinfo/chuck-users
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>
> End of chuck-users Digest, Vol 174, Issue 14
> ********************************************

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