15 Nov
2008
15 Nov
'08
6:24 p.m.
Fons Adriaensen wrote:
On Fri, Nov 14, 2008 at 03:47:17PM +0200, Hannu
Savolainen wrote:
You missed the point. With OSS you can change the sync source any time
you want by launching the control panel (ossxmix) and by changing the
control exposed by the driver. If you do the change incorrectly it's all
your fault.
However it has been made almost impossible to make this kind of changes
from your audio application (say media player). With OSS you may have up
to 32 different applications playing audio at the same time with MADI.
If some of them changes the sync source on fly it will break everything.
Such uncontrolled changes might (for example) drop whole radio station
off-air.
Application programmers seem to be very innovative when inventing wrong
solutions to problems they encounter. I would not be surprised in some
application has a comment like:
/*
* There seems to be a bug in OSS. It doesn't permit changing the
sampling rate if the sync source is set to
* external sync. As a workaround we can try to switch the device to
internal sync before setting the rate.
*/
By making this kind of changes pretty much impossible we can prevent
programmers from doing stupid mistakes. Before ading this kind of stupid
workarounds they will probably ask somebody to help them. In this way
there is a chance that somebody with better knowledge can stop them.
Best regards,
Hannu
There is no point in letting any application to
change such settings so
it has intentionally been made pretty much impossible.
If you think this applies to my situation you are
wrong on all accounts.
1. It not "made pretty much impossible" in ALSA, all
it takes (on the command line) is an 'amixer sset'.
2. I am the system administrator. I may want to use
an application to do part of my work.
3. The studio wiring can change at any time. There are
four PCs, four ADI648s and MADI connections between them
are made via an RME MADI switch. This is controlled by
software as well. MADI wiring is in function of the
current project or session.
4. If ALSA would allow me to set "Sample Clock Source"
to "AutoSync", "Preferred Sync Reference" to "MADI"
and "System Clock Mode" to "Slave" AND ENSURE THEY
STAY SET LIKE THAT then I wouldn't have to touch them.
But it will switch to "Internal 44.1 kHz" and "Master"
whenever there is no MADI signal on the input and it
will *not* go back to the original settings when a
signal is present again. Since the MADI links are
switched, this can happen and it should not leave
the system in an inconsistent state. Hence I do have
to monitor these settings permanently and take action
when they are wrong.