[ardour-dev] Export

[R Parker]

Hi,

Ardour/GTK 0.460.0 running with libardour 0.734.3
jackd 0.95.3
cat /proc/sys/kernel/lowlatency = 1
Linux stepdaddy 2.4.24-1.ll.studio
>From "/usr/src/linux-2.4/include/linux/capability.h"
#define CAP_INIT_EFF_SET    to_cap_t(~0)
#define CAP_INIT_INH_SET    to_cap_t(~0)
.jackdrc, jackd -R -t500 -dalsa -dhw:0 -r44100 -p1024
-n2

I've started mastering with Ardour where I'm using a
bus as the return from JAMin. The final step is Export
the return bus. When run as a normal user and for each
song, I see:
cannot use real-time scheduling (FIFO/9) (1: Operation
not permitted)
/mnt/raid5/studio/clients/brunsberg/master/edergton-jam.wav

As superuser:
/mnt/raid5/studio/clients/brunsberg/master/edergton-jam.wav
/mnt/raid5/studio/clients/brunsberg/master/edergton-jam.wav
/mnt/raid5/studio/clients/brunsberg/master/stupid-jam.wav
/mnt/raid5/studio/clients/brunsberg/master/stupid-jam.wav
/mnt/raid5/studio/clients/brunsberg/master/away-jam.wav
/mnt/raid5/studio/clients/brunsberg/master/laureli-jam.wav

I haven't a clue why the first two superuser exports
produced a double entry.

The audible results between the two users are a little
different. With a normal user most of the songs will
have a digital zipper sound. With superuser most of
the songs have a skipping sound. It's almost as though
superuser has greater realtime priority and is
interupted less frequently. For both users and with
four different burns every song has the above problems
with the exception of one song. It's never the same
song. 

I'm fairly confidant that the peak output gain level
from JAMin for all songs varies between -0.5db to
-2db. I very carefully watch meters in Ardour, JAMin
and a hardware mixer. In fact, when routing the return
bus to an external CD-R via the hardware mixer,
there's no problem.

It seems there's a big difference between superuser
and root but lowlat is enabled and the kernel is
compiled with capability modifications. With a 1024
buffer and at the conclusion of each export; normal
user occasionaly produces an xrun, superuser did not
seem to xrun at that point.

A general observation with xruns is that once one
occurs, it's almost as though the light turns green
and they will continue to happen with greater
frequency.

Is Ardour entering freewheel mode when doing an
Export? I seem to recall seeing messages in the consol
to that affect with earlier versions of Ardour. I'm
not seeing any freewheel mode messages with this
version.

I'm more than happy to provide any requested
information.

ron

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