$ mencoder mf:///tmp/*.png -mf w=1024:h=768:fps=30:type=png  -oac copy -ovc x264 -o /tmp/marathon-mencoder-x264.avi
MEncoder 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: Type: 15 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 SSE SSE2

success: format: 16  data: 0x0 - 0x0
MF file format detected.
[mf] search expr: /tmp/*.png
[mf] number of files: 16377 (131016)
VIDEO:  [MPNG]  1024x768  24bpp  30.000 fps    0.0 kbps ( 0.0 kbyte/s)
[V] filefmt:16  fourcc:0x474E504D  size:1024x768  fps:30.00  ftime:=0.0333
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffpng] vfm: ffmpeg (FFmpeg PNG decoder)
==========================================================================
VDec: vo config request - 1024 x 768 (preferred colorspace: RGB 24-bit)
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
VDec: using RGB 24-bit as output csp (no 5)
Movie-Aspect is undefined - no prescaling applied.
SwScaler: reducing / aligning filtersize 1 -> 4
SwScaler: reducing / aligning filtersize 1 -> 4
SwScaler: reducing / aligning filtersize 1 -> 1
SwScaler: reducing / aligning filtersize 9 -> 8
[swscaler @ 0xbcf4f0]SwScaler: BICUBIC scaler, from rgb24 to yuv420p using MMX2
[swscaler @ 0xbcf4f0]SwScaler: using 4-tap MMX scaler for horizontal luminance scaling
[swscaler @ 0xbcf4f0]SwScaler: using 4-tap MMX scaler for horizontal chrominance scaling
[swscaler @ 0xbcf4f0]SwScaler: using 1-tap MMX "scaler" for vertical scaling (YV12 like)
[swscaler @ 0xbcf4f0]SwScaler: 1024x768 -> 1024x768
x264 [info]: using SAR=1/1
x264 [info]: using cpu capabilities MMX MMXEXT SSE SSE2 3DNow! 
New_Face failed. Maybe the font path is wrong.
Please supply the text font file (~/.mplayer/subfont.ttf).
subtitle font: load_sub_face failed.
New_Face failed. Maybe the font path is wrong.
Please supply the text font file (~/.mplayer/subfont.ttf).
subtitle font: load_sub_face failed.
Writing header...
ODML: vprp aspect is 4:3.
Writing header...
ODML: vprp aspect is 4:3.
Pos:  19.7s    592f ( 0%)  7.08fps Trem:   0min   0mb  A-V:0.000 [680:0]]
Flushing video frames.
Writing index...
Writing header...
ODML: vprp aspect is 4:3.

Video stream:  680.217 kbit/s  (85027 B/s)  size: 1677869 bytes  19.733 secs  592 frames
x264 [info]: slice I:3     Avg QP:23.00  size: 35817
x264 [info]: slice P:589   Avg QP:26.00  size:  2663
x264 [info]: mb I  I16..4: 69.1%  0.0% 30.9%
x264 [info]: mb P  I16..4:  3.6%  0.0%  1.2%  P16..4:  7.4%  2.4%  0.6%  0.0%  0.0%    skip:84.9%
x264 [info]: kb/s:679.4