[alsa-devel] [Alsa-devel]JACK will block audio application and audio application will also blcok JACK

[cong fu]

Hi experts:
I installed JACK and the GUI of it looks good.
 But it seems it will block the "audio application" and "audio
application" will also blcok it.
That is to say:
1) If I started the JACK by:
sudo /usr/bin/jackd -r -m -dalsa -dhw:0 -r44100 -p1024 -n2 -P
Then I open my web brower and try to play a streaming song(play by
flash), the song can't play!

2) If I stoped the JACK
Then  I open my web brower and try to play a streaming song, the song
played good!

3)if I play a song by mplayer or web brower at first
Then I try to start the JACK, there is an error:

Acquire audio card Audio0
creating alsa driver ... hw:0|-|1024|2|44100|0|0|nomon|swmeter|-|32bit
Using ALSA driver HDA-Intel running on card 0 - HDA NVidia at 0xfe024000 irq 23
the playback device "hw:0" is already in use. Please stop the
application using it and run JACK again
Cannot initialize driver
JackServer::Open() failed with -1
Failed to start server

My system is Debian Lenny.

So how can I play sound with JACK started?