mplayer Keeps Surprising Me.

[Martin McCormick]

	I have been using mplayer to listen to Internet radio and
generally been quite pleased.  I did accidentally discover something
today that really startled me.  I was listening to the BBC World
Service and decided to try something clever.  I looked up the process
number being used at the time for mplayer and set an at job to kill
that process and then restart mplayer to play a different radio
station.

	Well, I accidentally put in the wrong process number so the
kill command, fortunately, sent the kill signal to a process that
didn't exist.

	To my shock, the new process to listen to the other radio
station ran and, to my utter amazement, I began listening to both
audio feeds at the same time.  Other than making an utter mess of the
sound, both were perfectly proper.  It just sounded like the sort of
mistake you hear on radio or television when two sound sources are
playing at the same time due to a switching error.

	I suspect that if one or the other signal had a different
sampling rate, there would have been some sort of problem such as
maybe one of the streams trying to play at the wrong speed or
producing static, but I figured that the existing playback would
either block the new job or cause it to end immediately with an error.

	The only bad thing I have encountered with mplayer is that the
English documentation appears to be missing although all the
directories are there, and certain Windows Media Audio files with
graphics absolutely blow the player sky high, causing jobs to end
prematurely or hang forever.  Some of the public radio stations on
line have a short message that plays as soon as one starts to listen.
It tells you how to pledge money or who is sponsoring the feed and
displays a logo and graphics on the screen.  That seems to kill things
and cause various problems.  One such snag makes the player just hang
forever until you finally kill it and put it out of its misery.
Another similar link to a different NPR station plays a little of the
announcement making one think it is going to work and then it ends,
returning one to the shell prompt before playing the second link which
is the live stream.  On one of the two feeds, I edited the play list
to remove the opening message and it then works perfectly on the live
feed.

	I own a 600 MHZ Dell desktop at home and it is almost the twin
brother of a similar computer at work and both choke on the same WMA
files.  I am not sure if I could set some parameters dealing with
video drivers differently and clear up the problem, but since it is
the same on both systems, I imagine it is related to video handling
and possibly to the fact that I am using a serial terminal on both so
that the video may not have anywhere to go.

	One last observation.  While listening to the BBC World
Service, I tried festival as in

festival --tts testfile

It spoke right over the audio.  Again, kind of messy, but it didn't
break anything.

Martin McCormick WB5AGZ  Stillwater, OK 
OSU Information Technology Division Network Operations Group