[MEncoder-users] Cannot achieve better picture quality with MPEG2 - help needed

[Nicolas Hesler]

Corey Hickey wrote:
> That's probably a good idea.
>   

I uploaded a number of files to incoming/rgb_conversion/

original.png (the source image, this image is single image in a sequence 
of images generated with Adobe Flash)
png_movie.mpg (the mencoder encoded mpeg2 - command line below)
bmp_from_premiere.bmp (rgb->yuy2->rgb)
shot_using_vlc.png (screenshot using vlc)
shot_using_mplayer.png (screenshot using mplayer)

if you compare the original.png with either of the screenshots, you will 
the change in color in the green. the bmp_from_premiere does not suffer 
from this problem.

See below the mencoder output  for more...


mencoder -oac lavc -ovc lavc -of mpeg -mpegopt
s format=mpeg2:muxrate=18080:tsaf -vf harddup -lavcopts 
vcodec=mpeg2video:vrc_bu
f_size=3835:vrc_maxrate=18000:vbitrate=14000:trell:mbd=2:lmin=0.01:vpass=1:aspec
t=16/9 -ofps 24 mf://*.png -mf fps=24 -o png_video.mpg


MEncoder Sherpya-SVN-r26446-4.2.3 (C) 2000-2008 MPlayer Team
CPU: Intel(R) Xeon(TM) CPU 3.73GHz (Family: 15, Model: 6, Stepping: 4)
CPUflags: Type: 15 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled with runtime CPU detection.
success: format: 16  data: 0x0 - 0x0
MF file format detected.
[mf] search expr: *.png
[mf] number of files: 60 (240)
[demux_mf] file type was not set! trying 'type=png'...
VIDEO:  [MPNG]  0x0  24bpp  24.000 fps    0.0 kbps ( 0.0 kbyte/s)
[V] filefmt:16  fourcc:0x474E504D  size:0x0  fps:24.00  ftime:=0.0417
PACKET SIZE: 2048 bytes, deltascr: 24467
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
Opening video filter: [harddup]
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffpng] vfm: ffmpeg (FFmpeg PNG decoder)
==========================================================================
Limiting audio preload to 0.4s.
Increasing audio density to 4.
VDec: vo config request - 1280 x 720 (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 @ 00D71CD4]BICUBIC scaler, from rgb24 to yuv420p using MMX2
[swscaler @ 00D71CD4]using 4-tap MMX scaler for horizontal luminance scaling
[swscaler @ 00D71CD4]using 4-tap MMX scaler for horizontal chrominance 
scaling
[swscaler @ 00D71CD4]using 1-tap MMX "scaler" for vertical scaling (YV12 
like)
[swscaler @ 00D71CD4]1280x720 -> 1280x720
videocodec: libavcodec (1280x720 fourcc=3267706d [mpg2])
[VE_LAVC] High quality encoding selected (non-realtime)!
[mpeg2video @ 00D8A3B0][lavc rc] Using all of requested bitrate is not 
necessary
 for this video with these parameters.
Writing header...
INITV: 0.200, 0.158, fps: 24.000
Pos:   2.5s     60f (100%) 19.85fps Trem:   0min   0mb  A-V:0.000 [214:0]
Flushing video frames.
Writing index...

Overhead: 7.118% (4763 / 66917)
Writing header...

Video stream:  214.134 kbit/s  (26766 B/s)  size: 66917 bytes  2.500 
secs  60 fr
ames






i dropped another file in the root of incoming, export_premiere_avisynth.mpg

(for this file, I frameserved the original png out of premiere in yuy2, 
and encoded using mencoder, only this time, mencoder doesn't have to do 
the colorspace conversion,  and the color looks as it should.


==========================================================================
Opening video decoder: [raw] RAW Uncompressed Video
VDec: vo config request - 1280 x 720 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is undefined - no prescaling applied.
videocodec: libavcodec (1280x720 fourcc=3267706d [mpg2])
[VE_LAVC] High quality encoding selected (non-realtime)!
[mpeg2video @ 00D8A3B0][lavc rc] Using all of requested bitrate is not 
necessary
 for this video with these parameters.
Selected video codec: [rawyv12] vfm: raw (RAW YV12)


Should I still take this to the ffmpeg list?  or am I doing something 
wrong?