Subject: -t option and realtime recording off by 6%???
From: Jim Sims (Jim_AT_eSims.org)
Date: Sat Sep 25 2004 - 01:44:06 EEST
First off... new to the list so let me take a sec and say how much I
love ecasound. I designed a headless recording appliance for use in
churches (we use it and love it) and seminars and ecasound is what I
on to the question...
I am limiting the length of recordings to either 80 or 90 minutes minus
track splits and such depending on the type of CD used. I started out
using the -t option to end the recording after the required number of
seconds... problem was that the recording ran too long.... 6% too long.
I tested a variety of conditions and it remains very consistent in
running 6% too long.
I am running on FreeBSD 5.1 (can't go current yet) and I am recording
with the following line: ecasound -t $cdlength -f:s16_le,2,44100
-i:/dev/dspW -o:stdout | some other progs.
I am just a sysadmin not a programmer so I may be missing something
basic. My first inclination was to look at the FreeBSD box itself. The
system is using a AC97 codec (I know...but it is mostly speaking that I
record) that shows up with a 48k rate... I set that down using sysctl to
ensure that I was actually recording 44100. The audio quality is
excellent with no skipping, hum, noise of any kind....
I am at a loss to explain the 6% difference and wouldn't have noticed it
on only a few minutes recording, but on a 90 minute recording it becomes
I can work around it since it's consistent, but I would like to at least
understand the cause...
This archive was generated by hypermail 2b28 : Sat Sep 25 2004 - 01:44:52 EEST