[ardour-users] My stupid clock goof

Paul Winkler pw_lists at slinkp.com
Sun Jul 24 13:51:29 PDT 2005

Well, this is an interesting problem...
I have a session where the soundcard clock was wrong during
most of the recording. 

I was led to discover this because,
while everything sounded fine during recording and playback, the
position displays were very wrong both for bars/beats and
minutes/seconds... the clocks were moving very very slow.
I thought maybe it was an ardour bug I hadn't noticed before, but 
when I fired up Hydrogen for the first time in a long while,
it was playing all samples and patterns in slow motion.
So I figured there was not an ardour problem but a jack or hardware
problem.  Thanks to some kind guy in #lad whose screen name I've forgotten
for reminding me to check the clock settings on envy24control,
where I discovered the Delta 66 was set to set to use S/PDIF input as 
the clock, and there was an unterminated cable plugged into that jack.  

This apparently confused the heck out of ardour and jackd.

Now that the hardware settings are corrected, hydrogen is happy, 
but the ardour session I was working on sounds like the chipmunks!

As far as I can tell, while I was recording, ardour and jack thought 
it was a 44.1 kHz session, since that's how I started jackd, but 
the hardware was apparently actually running 
at a much slower rate, apparently somewhat less than 11025 Hz.
And yet the sounds/*.wav files all report as 44100 sampling rate
according to sndfile-info. But if I play them back, it's way fast.

After much playing with sox, I can get the recorded files to sound
approximately correct via e.g.
sox -t raw -r 10500 -l -f lead\ vox-1.wav  -r 44100 ~/tmp/fixed.wav 

This would also explain why I couldn't seem to get adequate treble out
of the percussion and vocal tracks :-\   
The first few tracks were bass and drum machine and they sounded OK 
since they didn't have much high-freq content in the first place.

I'd like to salvage what I can. So, I've made a backup tarball of the 
session and am hoping I can hack it into shape by twiddling the 
session file somehow.  Any suggestions what I should fiddle with? 
I don't see anywhere to set the sample rate for the session. Is it
implicitly set by the jackd parameters?

I'm assuming I'll also have to convert (but not resample) the audio
files.  Sox okay for this?

Paul Winkler

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