$ mplayer -identify -frames 0 /mnt/usb/mp_root/100anv01/mav00001.mp4 
MPlayer dev-SVN-rUNKNOWN-4.1.2 (C) 2000-2007 MPlayer Team
CPU: AMD Athlon(tm) 64 Processor 3500+ (Family: 15, Model: 31, Stepping: 0)
3DNow supported but disabled
3DNowExt supported but disabled
CPUflags:  MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 SSE SSE2

Playing /mnt/usb/mp_root/100anv01/mav00001.mp4.
ISO: Unknown File Type Major Brand: MSNV
Quicktime/MOV file format detected.
ID_VIDEO_ID=0
ID_AUDIO_ID=1
VIDEO:  [avc1]  320x240  24bpp  29.970 fps    0.0 kbps ( 0.0 kbyte/s)
ID_FILENAME=/mnt/usb/mp_root/100anv01/mav00001.mp4
ID_DEMUXER=mov
ID_VIDEO_FORMAT=avc1
ID_VIDEO_BITRATE=0
ID_VIDEO_WIDTH=320
ID_VIDEO_HEIGHT=240
ID_VIDEO_FPS=29.970
ID_VIDEO_ASPECT=0.0000
ID_AUDIO_FORMAT=mp4a
ID_AUDIO_BITRATE=128000
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=2
ID_LENGTH=148.31
xscreensaver_disable: xscreensaver wid=10485761.
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
==========================================================================
ID_VIDEO_CODEC=ffh264
==========================================================================
Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio Coding)
AUDIO: 48000 Hz, 2 ch, s16le, 128.0 kbit/8.33% (ratio: 16000->192000)
ID_AUDIO_BITRATE=128000
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=2
Selected audio codec: [faad] afm: faad (FAAD AAC (MPEG-2/MPEG-4 Audio) decoder)
==========================================================================
AO: [oss] 48000Hz 2ch s16le (2 bytes per sample)
ID_AUDIO_CODEC=faad
Starting playback...


Exiting... (End of file)