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<DIV><FONT face=Arial size=2>maybe this will be useful to someone</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>As far as I can tell the audio popping problem
I had was related to alsa 0.95 and 0.96. I had tried OSS without noatime
and had some glitches, but </FONT><FONT face=Arial size=2>going back to OSS and
using noatime fixed my problems. Now I'm recording mpeg4 @480x480
while watching playback on the frontend with no problems</FONT><FONT face=Arial
size=2>.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=bstoneaz@cox.net href="mailto:bstoneaz@cox.net">bstoneaz</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=mythtv-users@snowman.net
href="mailto:mythtv-users@snowman.net">mythtv-users@snowman.net</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, August 01, 2003 2:09
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [mythtv-users] the dreaded audio
pop</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>I'm getting random and sometimes
frequent/sometimes infrequent cases where myth is recording audio
pops. These occur with my recording with the backend and the
frontend idle. What has stumped me is that I have many recordings now
that are perfect, and some where there is much popping present, and this is
after I have been investigating and tweaking based on recommendations from the
archives. The last two recordings I tried had one almost perfect, and
the other with so many pops in a 30min period I would have called it a static;
I was using RTJPEG at 480x480 and the top shows <30% system load and I
don't see any load spikes. Based on this I don't think its an issue of my
cpu horsepower so I've been trying a lot of things to fix it. When I
listen to the line in from the tuner the audio sounds perfect. Also
these cases are with channels with a good incoming video quality.
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>So I'm stumped and need some advice.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Here's the setup and some options I've
tried:</FONT></DIV>
<DIV><FONT face=Arial size=2>1.8GHz pentium4, 1/2 gig ram, SoundBlaster Live!
(not 5.1), AverTV stereo with audio pass through to Live line in, Redhat 9,
ALSA .95 (also tried .94), mythtv 0.10, running both backend and frontend on
the same system.</FONT></DIV>
<DIV><FONT face=Arial size=2>yes DMA is on. and this is with a
single 120G drive with an 8MB buffer.</FONT></DIV>
<DIV><FONT face=Arial size=2>the vid card is a GF2MX running the nvidia driver
and it's working aok. the card output is at 800x600</FONT></DIV>
<DIV><FONT face=Arial size=2>I've reniced the frontend -10 and backend
-15</FONT></DIV>
<DIV><FONT face=Arial size=2>I've killed or removed all
non-essential services.</FONT></DIV>
<DIV><FONT face=Arial size=2>I've been using KDE, but I've tried TVWM and
Gnome with the same jitter, jerky, pop occurring randomly.</FONT></DIV>
<DIV><FONT face=Arial size=2>I've optimized the redhat kernel for the
p4</FONT></DIV>
<DIV><FONT face=Arial size=2>I added noatime to my /etc/fstab for the two hard
drive partions</FONT></DIV>
<DIV><FONT face=Arial size=2>I forced the SBLive IRQ to be on 7 and it's not a
shared IRQ</FONT></DIV>
<DIV><FONT face=Arial size=2>I've tried a few optimizations with myth so far,
including some where I've added extra statements in for the libs to include
-march=pentium4 (and tried w/ and w/out sse flags)</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>As far a settings, I'm using</FONT></DIV>
<DIV><FONT face=Arial size=2>mp3 recording, 44.1kHz. no change with
uncompressed</FONT></DIV>
<DIV><FONT face=Arial size=2>and 480x480 mpeg4 and rtjpeg.</FONT></DIV>
<DIV><FONT face=Arial size=2>on average with mpeg4 recording the load average
is about 0.8-1 and it's pushing the cpu. I see video jerks some times, but
most audio pops aren't associated with video jerkiness. </FONT></DIV>
<DIV><FONT face=Arial size=2>on average with rtjpeg is well under half load
and I don't see any load spikes (noted really good/bad cases above).
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>If I had to guess, this looks like a lack of
audio buffering in myth, but since I haven't seen anything in the archive, and
no myth errors I've been trying different options.</FONT></DIV>
<DIV><FONT face=Arial size=2>rgds</FONT></DIV>
<DIV><FONT face=Arial size=2>Brent</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
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