FIFO/Pipe changes between debian 5 and 6

We're currently building a chain of linux tools to do some realtime encoding for video broadcast purposes. In order to archieve this, we created a program in C++ that spawns some ffmpeg decoder processes (for both audio and video), p开发者_运维知识库ipe this output to the encoders (ffmpeg & mpeg2enc) through fifo's, and then pipe the encoded output to our muxer which caches a few MB of data and then outputs the muxed file through an ASI output card.

In debian 5, this setup works flawlessly, and generally doesn't even create a high CPU load. On debian 6 and Ubuntu 10.04 however, the internal buffer of the muxer gradually decreases until it hits zero, after which frequent output hickups start to occur.

Using nice and ionice doesn't seem to fix this issue. I've also tried various custom kernel compile options (increased frequency, preemptation, etc) but this also doesn't seem to work.

Altough it might be possible that there has been serious regression in either ffmpeg or mpeg2enc, I'm guessing that the problem has to do with the way the new kernel/distro handles FIFO's.

Does anybody know what could be causing this problem? Or what have been recent changes in both Debian or it's kernel configuration (between version 5 and 6) and Ubuntu that could possibly caused this undesired behaviour?