[oss-devel] mixer API question about rec buttons (bug in SNDCTL_MIX_WRITE?)

[Hannu Savolainen]

Hi,

> Hi,
>
>   Most mixers contain "rec" buttons which let the user select recording 
> source. Some mixers let multiple recording sources be selected. 
>
> A. When setting the on/off value with SNDCTL_MIX_WRITE on a rec button, 
> val.value is always returned as 1. Shouldn't it be 0 or 1 according to 
> whether the source is selected?
>   
Right. This is a bug. It will be fixed in the next version.
> B. ossmix uses val.value = -1 to toggle the value of the button. But
> http://manuals.opensound.com/developer/MIXT_ONOFF.html says only 0 or 1 are 
> accepted values. I guess the doc is incomplete?
>   
0 and 1 are really the only acceptable values for MIXT_ONOFF. I think 
ossmix.c use -1 as a marker for invalud/uninitialized value.
> (Why am I asking this? There's a bug in ossxmix where if only one rec source 
> is enabled and the user unselects it, the button become unchecked, but the 
> source is still selected. I tried to check what value SNDCTL_MIX_WRITE 
> returned in set_value, and discovered A. above)
>   
Best regards,

Hannu