Results from os.system() different from execution at prompt

[Enno Middelberg]

Hi all,

I am using mpeg_encode under Linux to generate little movies. The 
parameter file is generated by a Python script, the last line of which is

os.system('mpeg_encode mpeg.par')

When I execute the same command at the bash prompt, the resulting movie 
is longer, i.e., it has more frames.

I have piped the outpout from both the Python-executed and 
prompt-executed mpeg_encode into files and found a difference, although 
the parameter files were the same file in both runs:

Prompt-executed:

MPEG ENCODER STATS (1.5b)
------------------------
TIME STARTED:  Mon Dec 29 16:33:08 2003
MACHINE:  PC227
FIRST FILE:  /homes/emiddelb/local/pics/eberg_movie/webcam/title.jpg
LAST FILE:  /homes/emiddelb/local/pics/eberg_movie/webcam/eff_1975
PATTERN:  ibbbpbbbpbbb
GOP_SIZE:  30
SLICES PER FRAME:  1
(...)

Python's os.system():

MPEG ENCODER STATS (1.5b)
------------------------
TIME STARTED:  Mon Dec 29 16:28:05 2003
MACHINE:  PC227
FIRST FILE:  /homes/emiddelb/local/pics/eberg_movie/webcam/title.jpg
LAST FILE:  /homes/emiddelb/local/pics/eberg_movie/webcam/eff_1
PATTERN:  ibbbpbbbpbbb                                 ^^^^^^^^^^^^
GOP_SIZE:  30
SLICES PER FRAME:  1
(...)


So, the Python-executed mpeg_encode reports fewer input files. Any clues 
why this could happen? Is there a limit on the command length or so? I 
see no reason why the results from the two ways of calling mpeg_encode 
should be different.


Kind regards,

Enno