[MPlayer-users] Cannot play *.mp4 files?

[Lugo]

*.mp4 files sort of stutter.  Both sound and video go for half a
second then stop momently, go for half a second then stop momently.

I'm using Debian Lenny 5 backport completely up to date.  The browser
plugin does exactly the same.  Only relevant looking error message is:

==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec
family
Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.
264)
==========================================================================
==========================================================================
Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio
Coding)
FAAD: compressed input bitrate missing, assuming 128kbit/
s!
AUDIO: 44100 Hz, 2 ch, s16le, 128.0 kbit/9.07% (ratio: 16000-
>176400)
Selected audio codec: [faad] afm: faad (FAAD AAC (MPEG-2/MPEG-4 Audio)
decoder)
==========================================================================
AO: [alsa] 48000Hz 2ch s16le (2 bytes per
sample)
Starting
playback...
VDec: vo config request - 320 x 240 (preferred colorspace: Planar
YV12)
VDec: using Planar YV12 as output csp (no
0)
Movie-Aspect is undefined - no prescaling
applied.
VO: [xv] 320x240 => 320x240 Planar YV12
[vm]
XF86VM: Selected video mode 640x480 for image size 320x256.

Though it often plays perfectly well in other contexts with "assuming
128kbit/s! "

Thanks any help.