[mythtv] Firewire capture failing

[Brad Martin]

With recent SVN versions my firewire capture has stopped working.  The 
channel would change properly, but no video would ever be captured.  I 
did a binary search and tracked down the break to SVN 9168->9169.  That 
revision apparently added the ability to set the IEC61883 buffer size 
via the DB setting HDRingbufferSize.  On my setup that setting had a 
value of 18800, and I'm not sure where that value came from.  I have no 
idea where that setting can be found from the UI.  After some 
experimentation, I found that no video is received if I set 
HDRingbufferSize greater than about 16000, but 16000 and below works 
fine.  Is this supposed to be the case?  If so, then a value that is 
known to break should not have been allowed, whether it was a default 
value or the result of a UI setting.  If not, why am I experiencing this 
limit?  I'm running Gentoo with libiec61883 version 1.0.0-r1, libraw1394 
version 1.2.0, and kernel 2.6.15-gentoo-r1, all Gentoo packages.  I also 
tried using libiec61883 from their SVN tree revision 67.

    --Brad