[MPlayer-users] Questions about processes and process control

[Ed Greenberg]

I am using mplayer to download and save a stream. In a perl script, I 
fork and exec mplayer as follows:

mplayer -ao pcm:waveheader:file=filename.wav -cache 256 -quiet 
mms://urlcontinues.....

I get two processes :
edg       2333  2332  9 13:12 pts/3    00:00:05 mplayer -ao 
pcm:waveheader:file=xm1min.wav -cache 256 -quiet mms://urlcontinues...
edg       2334  2333  0 13:12 pts/3    00:00:00 mplayer -ao 
pcm:waveheader:file=xm1min.wav -cache 256 -quiet mms://urlcontinues...

My perl script gets 2333 as the child's PID.

Now I wait in a sleep until sufficient time has passed, and I then kill 
-1 the child pid. This works fine. The file is closed and I get a full 
recording of my stream.

Unfortunately, I am left with process 2334 still running.

On stderr I get:

MPlayer interrupted by signal 1 in module: decode_audio
- MPlayer crashed. This shouldn't happen.
  It can be a bug in the MPlayer code _or_ in your drivers _or_ in your
  gcc version. If you think it's MPlayer's fault, please read
  DOCS/HTML/en/bugreports.html and follow the instructions there. We 
can't and
  won't help unless you provide this information when reporting a 
possible bug.

I'm not reporting it as a bug, since, indeed it was interrupted by a 
signal 1.

So I reset my calling program to kill $process+1, which kills both of 
them (although, going forward, I know I can't depend on them being 
sequential) and now I get a second message on stderr:
MPlayer interrupted by signal 1 in module: enable_cache
followed by the paragraph about reporting bugs.

So I have several questions:

0. what's the purpose of the second process. Is one a caching process? 
Do I need it if my source is a nice fast cable connection, and my 
destination is -ao pcm:waveheader?

1. What's the best way to tell mplayer to run for a period of time and 
then stop?  Is the idea of forking it and then killing it the best choice?

2. If I'm going to kill it externally, what's the best signal to kill it 
on, so that it takes down both processes, if at all?

3, If I have to kill the two processes separately, which should I kill 
first?

Many thanks,
</edg>
Ed Greenberg