RME HDSPe MADI and ALSA
This page is probably out of date now, but I haven't had time to
update it. In the meantime it's hopefully some use as a guide to setting up
the HDSPe MADI card without hdspmixer.
The RME HDSPe MADI PCI Express card works with ALSA and Linux, but at the
time of writing hdspmixer doesn't recognize it. Many of the control
values can be set using amixer and alsamixer, but routing can not be
changed. This means that to get a low-latency monitor mix it either
has to be used with a small enough buffer size to allow software monitoring,
or the input signals need to be monitored with external hardware.
Controls can be displayed using amixer:
amixer -c0 controls | less
and current control values:
amixer -c0 contents | less
where -c0 refers to the first sound card in the system (use -c1 for second card,
-c2 for third, etc.).
To display a specific value, eg. Sample Clock Source:
amixer -c0 cget iface=MIXER,name="Sample Clock Source"
The default clock source is internal. To set the card to slave to an external
amixer -c0 cset iface=MIXER,name="Sample Clock Source" 0
which sets the sample clock source to AutoSync (item 0 in the enumerated list).
This presupposes that there is a valid clock source plugged in and the Error
LED is green (and in the case of Word Clock input, the green Lock LED is lit).
To change the input from the default coaxial to optical:
alsamixer -c0 cset iface=MIXER,name="Input Select" 0
Note that this isn't necessary to get a valid clock signal from the optical
MADI input, as AutoSync will detect it whether selected or not.
can be set using similar command syntax after looking at the information
displayed by `amixer -c0 controls'. Some of these are read-only and depend on
other writeable values being set; they are provided as indicators only.
Playback levels can be set using alsamixer.
The default playback
level is zero, so these need to be set to get any output.
Capture levels can not be altered
from unity gain, despite alsamixer showing movable faders when started with the
capture option (they don't do anything). To start alsamixer:
which starts it with playback level faders displayed.
Values range linearly from 0 to 100, with 100 being +6dB and 50 being unity