Re: [Sndobj-devel] Triggered Wav File playback in Python
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Re: [Sndobj-devel] Triggered Wav File playback in Python
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From: Victor L. <Vic...@nu...> - 2007-02-08 08:49:33
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Generally speaking, you don't want or need to touch protected
members. If there is a need for accessing it, the way to do it
is to provide a Get/Set method in C++, which will be wrapped in
Swig. In Python, AFAIK, all members are public, so if you could
inherit the whole C++ class, you would be able to access it. Swig,
quite properly, does not let you do that.
In the specific case of m_vecpos, it might not be a good idea to
touch it, since it is an internal sample counter. If there is a funcionality
missing in a Class then a method should be added to provide it.
all the best
Victor
At 20:52 06/02/2007, Craig Lewiston wrote:
>you're right, there's no need to inherit and create a new class.
>
>the way i arrived at that solution was that i was trying to access the
>protected variable m_vecpos from the SndIO class (was trying to access
>this in an instance of SndWave). that's why i tried inheriting,
>because m_vecpos is protected. however, even when i inherited, i
>wasn't able to access m_vecpos, which i now believe is due to the SWIG
>interface between python and the cpp code.
>
>i had missed that SndWave is derived from SndFIO which is derived from
>SndIO (was only looking at the documentation for SndWave, and not at
>the library class tree near the beginning of the documentation).
>Since SetPos() is defined in SndFIO, i didn't know that it was a
>method available to SndWave.
>
>all that said, is there a method for accessing protected variables
>such as m_vecpos from Python? When i run dir() on a SndWave object,
>i see the following methods that might be able to accomplish this:
>
>__getattr__
>__getattribute__
>__setattr__
>
>can you suggest where i can find out how to use these?
>
>anyway, thanks for the continued help,
>Craig
>
>
>
>On 2/6/07, Victor Lazzarini <Vic...@nu...> wrote:
>>Looks good. But couldn't you just call sndobj.SndWave.SetPos(0) directly?
>>Inheriting is useful, though.
>>
>>all the best
>>
>>Victor
>>
>>At 08:03 06/02/2007, Craig Lewiston wrote:
>> >I was able to figure out how to reset the vector position for the
>> >SndWave() Class. Basically, you just inherit the class into a new
>> >class, and create a method to set the vector position:
>> >
>> >class N_SndWave(sndobj.SndWave):
>> > def resetpos(self):
>> > self.SetPos(0)
>> >
>> >of course, you could also create another method to set the vector
>> >position to whatever point you want:
>> >
>> >class N_SndWave(sndobj.SndWave):
>> > def resetpos(self):
>> > self.SetPos(0)
>> > def setpos(self, offset):
>> > self.SetPos(offset)
>> >
>> >
>> >so, in order play a wav file, then reset and play it again, you would
>> >do the following:
>> >------
>> >class N_SndWave(sndobj.SndWave):
>> > def resetpos(self):
>> > self.SetPos(0)
>> >
>> >wavfile = N_SndWave('C261.wav', 3)
>> >wavsoundL = sndobj.SndIn(wavfile,1)
>> >wavsoundR = sndobj.SndIn(wavfile,2)
>> >outp = sndobj.SndRTIO(2, sndobj.SND_OUTPUT)
>> >outp.SetOutput(2, wavsoundR)
>> >outp.SetOutput(1, wavsoundL)
>> >
>> >N1 = sndobj.SndThread()
>> >N1.AddObj(wavfile,sndobj.SNDIO_IN)
>> >N1.AddObj(wavsoundR)
>> >N1.AddObj(wavsoundL)
>> >N1.AddObj(outp, sndobj.SNDIO_OUT)
>> >
>> >N1.ProcOn()
>> >time.sleep(1)
>> >wavfile.resetpos()
>> >time.sleep(1)
>> >N1.ProcOff()
>> >-------
>> >by blocks, the above code:
>> >1) Defines new class inherited from SndWave, with method for resetting
>> >vector position
>> >2) Sets up standard SndIn->SndObj->SndIO chain, in this case using 2
>> >channels (L&R)
>> >3) Setup SndThread object and add components from 2)
>> >4) Turns SndThread on, plays for 1 second, resets vector to beginning,
>> >plays for 1 second, and then stops processing.
>> >
>> >This seems to do the trick, and the playback is very clean.
>> >
>> >-Craig
>> >
>> >
>> >
>> >On 2/5/07, Craig Lewiston <lew...@mi...> wrote:
>> > > I tried #1 & #3 extensively, as well as tinkering with SndRead()
>> > > quite a bit. I'm starting to think that in order to accomplish what i
>> > > want, I need to be able to reset SndWave() to start reading again from
>> > > the beginning of the file. From the documentation for Class SndIO, it
>> > > appears that the protected variable m_vecpos holds the value of the
>> > > current "place reader" in the wav file. Is there any way to access
>> > > this to reset it?
>> > >
>> > > Better yet, is there a way to copy the wav sample into memory and have
>> > > it triggered?
>> > >
>> > > -Craig
>> > >
>> > >
>> > >
>> > > On 2/5/07, Victor Lazzarini <vic...@nu...> wrote:
>> > > > Off the top of my head:
>> > > >
>> > > > 1. Using Enable() and Disable() on the SndIn object to
>> > > > switch it on an off. You might get clicks.
>> > > >
>> > > > 2. Using an envelope (eg. Interp + Ring) and
>> > > > trigger the envelope (SetCurve()) on/off.
>> > > > Use Ring to multiply the envelope signal by the
>> > > > SndIn signal.
>> > > >
>> > > > 3. If you delete the Wave reader object from
>> > > > the thread it will also stop reading the file
>> > > > (but SndIn will also need to be disabled)
>> > > >
>> > > > 4. Have a look at the SndRead class. Another
>> > > > alternative is to load the file on a table and
>> > > > read it with an oscillator or with Lookup/i
>> > > >
>> > > > You're right in that ProcOn() and ProcOff() should
>> > > > perhaps just be used at the start/end of synthesis.
>> > > >
>> > > > Victor
>> > > >
>> > > >
>> > > > >
>> > > > > Anyone have advice on the best route to creating triggered
>> > > > > file playback? I'd like to have my program be able to
>> > > > > start the playback of a wav file when a flag is set, and
>> > > > > then cease playback of that file once the flag is reset.
>> > > > > i want this to happen in a thread, though, because there
>> > > > > will be other processing (and sounds) taking place (such
>> > > > > as a metronome) while the file is playing back. also, the
>> > > > > length of playback will vary depending on when the flag is
>> > > > > reset (which is controlled by user input)
>> > > > >
>> > > > > i'm using SndWave, and patching both channels into SndIn
>> > > > > objects. everything is then added to a SndThread:
>> > > > > ----------------------
>> > > > > wavfile = sndobj.SndWave('C261.wav', 3, 2,16)
>> > > > > wavsoundR = sndobj.SndIn(wavfile,1)
>> > > > > wavsoundL = sndobj.SndIn(wavfile,2)
>> > > > > outp = sndobj.SndRTIO(2, sndobj.SND_OUTPUT)
>> > > > > outp.SetOutput(2, wavsoundR)
>> > > > > outp.SetOutput(1, wavsoundL)
>> > > > >
>> > > > > IT = sndobj.SndThread()
>> > > > > IT.AddObj(wavfile,sndobj.SNDIO_IN)
>> > > > > IT.AddObj(wavsoundR)
>> > > > > IT.AddObj(wavsoundL)
>> > > > > IT.AddObj(outp, sndobj.SNDIO_OUT)
>> > > > >
>> > > > > IT.ProcOn()
>> > > > > time.sleep(5)
>> > > > > IT.ProcOff()
>> > > > > -----------------------------------
>> > > > >
>> > > > > I thought about just turning the thread on and off, but
>> > > > > when the thread is turned on again after being turned off,
>> > > > > it just resumes processing where it left off. is there a
>> > > > > way i can get it to resume from the beginnig of the wav
>> > > > > file?
>> > > > >
>> > > > >
>> > > > > thanks,
>> > > > > craig
>> > > > >
>> > > > > ----------------------------------------------------------
>> > > > > --------------- Using Tomcat but need to do more? Need to
>> > > > > support web services, security? Get stuff done quickly
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>> > > > > Download IBM WebSphere Application Server v.1.0.1 based on
>> > > > > Apache Geronimo
>> > > > >
>> > > >
>> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
>> > > > > _______________________________________________
>> > > > > Sndobj-devel mailing list
>> > > > > Snd...@li...
>> > > > > https://lists.sourceforge.net/lists/listinfo/sndobj-devel
>> > > >
>> > >
>> >
>> >-------------------------------------------------------------------------
>> >Using Tomcat but need to do more? Need to support web services, security?
>> >Get stuff done quickly with pre-integrated technology to make your job
>> easier.
>> >Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
>> >http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
>> >_______________________________________________
>> >Sndobj-devel mailing list
>> >Snd...@li...
>> >https://lists.sourceforge.net/lists/listinfo/sndobj-devel
>>
>>Victor Lazzarini
>>Music Technology Laboratory
>>Music Department
>>National University of Ireland, Maynooth
>>
>
>Victor Lazzarini
>Music Technology Laboratory
>Music Department
>National University of Ireland, Maynooth
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