sound problem with 5.2.1 + aviplay

[Peter Much]

Hi all,

I have very distorted sound with aviplay on 5.2.1.

The problem can be reproduced when aviplay is started without video
output - then the sound is not as much distorted, but still very
distorted, while I see about 8% CPU usage.

When running Release 4.4 on the same system, the problem does
not appear. Also there is no problem on 5.2.1 when playing mp3 files.

On /dev/sndstat I see figures like these:

FreeBSD Audio Driver (newpcm)
Installed devices:
pcm0: <ESS 1869 DSP> at io 0x220 irq 5 drq 1:0 bufsz 4096 (1p/1r/0v channels duplex default)
        [pcm0:record:0]: spd 0, fmt 0x00000000/0x00000008, flags 0x00000000, 0x00000000
        interrupts 0, overruns 0, hfree 4096, sfree 0
        {hardware} -> feeder_root(0x00000000) -> {userland}
        [pcm0:play:0]: spd 48000, fmt 0x10000010, flags 0x00007030, 0x00000000, pid 768
        interrupts 3322, underruns 3190, ready 4036
        {userland} -> feeder_root(0x10000010) -> {hardware}

Obviousely these underruns are the problem. And -interesting- as long
as I move the mouse over the aviplay control window, the sound is ok
and the underrun counter does not increase (but this helps only when
video is switched off).
It seems like aviplay (I tried avifile-0.7.38_4,2 and 0.7.41,2) is having
some problem with the scheduling of its threads... 
But how to fix?

PMc