Re: Audio Function Problem

[Thomas D. Dean]

On 10/13/17 12:16, Thomas D. Dean wrote:
> I have a problem with audio functions returning values that seem strange.
>
> getaudiodata () should return values between -1 and 1 but, does not. 
> Seems to be a problem in handling a 24 bit source.
>
> Tom Dean

<snip>

This is a bug in Octave.  I sent a patch to Savannah.

I used the sources from octave-4.2.1.tar.gz.

This problem in in the callback function, portaudio_record_callback. The 
same problem exists in the function octave_record_callback.

The variables used to convert from 24 bit to 32 bit are not zero'd 
inside the loop.  Therefore, bits in the high order byte remain, 
corrupting the data.  Fixing portaudio_record_callback fixes my problem, 
but octave_record_callback should be corrected at the same time.

> diff libinterp/dldfcn/audiodevinfo.cc.orig 
libinterp/dldfcn/audiodevinfo.cc
1347c1347,1349
<           for (int j = 0; j < 3; j++)
---
>                 // 20171013 tomdean
>                 sample_l32 = 0; sample_r32 = 0;
>                 for (int j = 0; j < 3; j++)
1423a1426,1427
>                 // 20171013 tomdean
>                 sample_l32 = 0; sample_r32 = 0;

Tom Dean