[LAD] ALSA doumentation

Hannu Savolainen hannu at opensound.com
Fri Nov 14 13:47:17 UTC 2008

Paul Davis wrote:
> On Fri, 2008-11-14 at 01:08 +0100, Fons Adriaensen wrote:
>> Now if someone can point me to some existing docs that
>> explain how I can e.g. set the sample clock source on a
>> RME MADI card in less than ten lines of C code (knowing
>> the parameter names, ranges, etc - no need to find them
>> out dynamically, I can read them asound.state) then I'll
>> eat my hat. It shouldn't be difficult. On some competing
>> systems all it takes is one ioctl().     
> i don't want to defend the lamentable state of the ALSA docs, but this
> last shot was a bit cheap Fons. the idea behind the ALSA control API was
> that equivalent controls on different cards would be controlled in the
> same way. sure, OSS provides ioctl (fd,
> OSS_THIS_ONE_DOES_MADI_CLOCK_SOURCE, &int) but move that code to any
> other device and it breaks entirely. 
Old OSS/Free may have this kind of ioctl calls. However OSS 4.x has 
similar control API than ALSA.

MADI clock source is one of the "big red button" controls in OSS. They 
are supposed to be touched only when the whole studio wiring changes. 
This is to be done in the control panel by the system administrator. 
There is no point in letting any application to change such settings so 
it has intentionally been made pretty much impossible.

Best regards,


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