Re: Question Regarding Simple ALSA Stereo Output

[James Courtier-Dutton <James@superbug.demon.co.uk>]

Bill Kapralos wrote:
> Hi Clemens
> 
> Thanks for the prompt response!
> 
> Should have mentioned this in the original email however I am using an SGI
> "box" wit dual Pentium III processors running SuSe Linux with a
> (VT82C686 ACER AC97 Audio Controller).  The card does support stereo and I
> can successfully set the number of channels to two (using
> snd_pcm_hw_params_set_channels() ).  After adding the code you suggested,
> the following was output:
> 
>  stream       : PLAYBACK
>  access       : RW_INTERLEAVED
>  format       : S16_LE
>  subformat    : STD
>  channels     : 2
>  rate         : 44100
>  exact rate   : 44100 (44100/1)
>  msbits       : 16
>  buffer_size  : 20480
>  period_size  : 2048
>  period_time  : 46438
>  tick_time    : 10000
> 
> Once again, thanks for the response!
> 
> Regards,
> 
> ================================================
> 
> On Wed, 23 Jun 2004, Clemens Ladisch wrote:
> 
> 
>>Bill Kapralos wrote:
>>
>>>It appears as if it is simply outputting the data assuming one
>>>channel e.g. the same signal is heard in both the left and right
>>>ear even when I have deliberately made the signals different (e.g.
>>>introduced a considerable delay to one channel etc.). Furthermore,
>>>when I explicitly set all left channel samples to "0" and the
>>>right channel samples to "non-zero", no sound is heard at all - it
>>>seems as if only the left channel data is being output which is of
>>>course all zero.  In contrast, if i set all the right channel
>>>samples to zero and the left channel samples to non-zero, the
>>>sound is heard.
>>
>>Does the function snd_pcm_hw_params_set_channels() return an error?
>>
>>What is output when you add the following code after the call to
>>snd_pcm_hw_params():
>>
>>	snd_output_t *out;
>>	...
>>	snd_output_stdio_attach(&out, stdout, 0);
>>	snd_pcm_dump_hw_setup(pcm, out);
>>	snd_output_close(out);
>>
>>What hardware do you use?
>>
>>
>>Regards,
>>Clemens
>>
>>

Which device name are you opening?
Try using "plug:front" as the device name in snd_pcm_open()

James




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