| Re: Reading Wav files [message #31837 is a reply to message #23347] |
Thu, 22 August 2002 01:21   |
Mike Alport
Messages: 8
Registered: December 1998
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Junior Member |
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Thanks guys - both your suggestions have worked. When I was first playing
around with read_wav, I must have inavertently made it a variable. An
explicit ".compile read_wav" then seems overide that earlier definition. I
have now also learnt about STRICTARR.
Thanks again,
Mike
PS - now I just need to play .wav files from IDL - I see that Matt Feinstein
asked the same question a few days ago wrt IDL_Tools.
"JD Smith" <jdsmith@as.arizona.edu> wrote in message
news:pan.2002.08.21.20.24.41.192394.2937@as.arizona.edu...
> On Wed, 21 Aug 2002 09:08:35 -0700, Mike Alport wrote:
>
>> This seems a trivial problem: the IDL 5.5 documentation gives the
>> following syntax for reading sound .wav files: Result = READ_WAV (
>> Filename [, Rate] ) So, when I try it, I get: IDL> Result = READ_WAV(
>> "ramsay0150.wav" ) % Variable is undefined: READ_WAV.
>>
>> Have they switched the calling procedure name on us? Thanks, Mike Alport
>
> This is probably related to the ()/[] degeneracy in IDL array indexing.
> I can replicate your error:
>
> IDL> result = read_wav('/usr/share/licq/sounds/fun/Auth.wav')
> % Compiled module: READ_WAV.
> IDL> read_wav=2
> IDL> result = read_wav('/usr/share/licq/sounds/fun/Auth.wav')
> IDL> help,result
> RESULT BYTE = Array[5400]
>
> No problem thus far.. but what if I start IDL again with:
>
> IDL> read_wav=1
> IDL> r=temporary(read_wav)
> IDL> help
> % At $MAIN$
> I INT = 167
> R INT = 1
> READ_WAV UNDEFINED = <Undefined>
>
> Uh, oh, an "undefined variable" READ_WAV exists. You can imagine what
> will happen now:
>
> IDL> result = read_wav('/usr/share/licq/sounds/fun/Auth.wav')
> % Variable is undefined: READ_WAV.
> % Execution halted at: $MAIN$
>
> IDL thinks you're trying to index an undefined variable! The problem
> is, variables sometimes exists as "undefined" zombies, even after you
> think they're gone. In this state, that can still "shadow" or overlap
> with function calls. A few options for solving the problem:
>
> 1. Find out where the undefined variable READ_WAV is getting created,
> and eliminate that.
>
> 2. Use "compile_opt STRICTARR" at the beginning of your procedure, or
> at the main level:
>
> IDL> compile_opt STRICTARR
> IDL> result = read_wav('/usr/share/licq/sounds/fun/Auth.wav')
> % Compiled module: READ_WAV.
>
> 3. Use "forward_function READ_WAV" to declare it a function.
>
> 4. Clamor for RSI to make STRICTARR the default (though duck as Craig
> throws an eraser at your head.)
>
> You could also just put "compile_opt STRICTARR" in your startup file,
> and I think it then applies to all routines and interactive commands
> (anybody know for sure?).
>
> Good luck,
>
> JD
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