[Python-Dev] Change to ossaudiodev setparameters() method

[Guido van Rossum]

> Right, that's not a permissions problem.  It means that audiotest.c
> tried to set your hardware to unsigned 8-bit samples:
> 
>   fmt = AFMT_U8;   /* 8 */
>   ioctl(fd, SNDCTL_DSP_SETFMT, &fmt);
> 
> and the device driver refused, returning fmt == AFMT_S16_LE == 16
> (signed 16-bit little-endian), which seems to be the *other*
> lowest-common-denominator audio format.
> 
> > Maybe the audio hardward on the work box simply isn't capable of doing
> > anything besides 16-bit samples?  According to hwbrowser, it is
> 
> I suspect that is the case.
> 
> The good news is that I've modified audiotest.c so it now takes
> command-line options to set the sample format, eg.
> 
>   audiotest -b 16 -s
> 
> for signed, little-endian 16-bit samples.  (Currently little-endian is
> hardcoded.)

Trying this with the latest version gives:

  opening /dev/dsp ... done
  audiotest: error: /dev/dsp: unable to set number of channels to 1 (got 2)

> The bad news is that there's something wrong with my sine-wave
> generating code for 16-bit samples: I'm quite sure that both of the
> audio devices on my PC support both 8-bit and 16-bit audio, but the
> 16-bit sine waves produced by audiotest.c sound horribly wrong.
> 
> I suspect a second pair of eyeballs is needed here.  Can someone take a
> good hard look at nondist/sandbox/audiotest/audiotest.c, in particular
> the mkbuffer() and gen_sine() functions, and see if you can spot
> anything wrong?  It's probably a silly arithmetic error indicating a
> subtle misunderstanding on my part, but I'm stumped.

When this happened to me in a previous life, the byte order was wrong.

> > The home box (which works) is
> > 
> >   CRD-8400B
> >   Manufacturer: Unknown
> >   Driver: ignore
> >   Device: /dev/hdc
>             ^^^^^^^^
> 
> Wow, I wonder what hwbrowser is smoking.  I strongly advise you *not* to
> start writing audio data to /dev/hdc.  ;-)

What's /dev/hdc???

--Guido van Rossum (home page: http://www.python.org/~guido/)