[MEncoder-users] Creating animated screenshots

[Marko Hyvonen]

I just did a few tests and in my case the vbitrate does have an 
effect. vbitrate=10 results in 300kb movie with poor quality and 
vbitrate=9000 in 3MB movie with quite decent quality. But it did look like 
vbitrate above 7200 or so did not make a difference any more. But is this 
simply that no higher bitrate is needed to improve quality ? I was 
under the impression that vbitrate defines maximum rate, which might not 
be needed in all cases. 

My mencoder is as follows (pre-compiled I recall?) 

MEncoder 1.0pre7try2-3.3.1 (C) 2000-2005 MPlayer Team
CPU: Intel Pentium 4/Xeon/Celeron Foster (Family: 8, Stepping: 9)
Detected cache-line size is 64 bytes
CPUflags: Type: 8 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 SSE SSE2


On Tue, 23 May 2006, Volker Poplawski wrote:

> vbitrate seems to be ignored on every codec whenever mf is used. It is 
> respected i.g. when encoding from .vob to .avi.
> 
> BTW: My mediaplayer doesn't accept mpeg4 also.
> 
> Invocation and output of mplayer below:
> > mencoder "mf://*.jpg" -mf fps=10:type=jpg -ovc lavc -lavcopts 
> vcodec=mpeg4:vbitrate=1200 -nosound -o output_mpeg4.avi
> MEncoder 1.0pre7try3-SUSE Linux 10.0 (x86_64)-Packman-4.0.2 (C) 2000-2005 
> MPlayer Team
> CPU: Advanced Micro Devices Opteron Sledgehammer (Family: 8, Stepping: 10)
> Detected cache-line size is 64 bytes
> CPUflags: Type: 8 MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 1 SSE2: 1
> Compiled for x86 CPU with extensions: MMX MMX2 3DNow 3DNowEx SSE SSE2
> 
> File not found: 'frameno.avi'
> Failed to open frameno.avi
> success: format: 16  data: 0x0 - 0x0
> [demuxer] mf support.
> [mf] search expr: *.jpg
> [mf] number of files: 3161 (25288)
> VIDEO:  [IJPG]  0x0  24bpp  10.000 fps    0.0 kbps ( 0.0 kbyte/s)
> [V] filefmt:16  fourcc:0x47504A49  size:0x0  fps:10.00  ftime:=0.1000
> Opening video filter: [expand osd=1]
> Expand: -1 x -1, -1 ; -1  (-1=autodetect) osd: 1
> ==========================================================================
> Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
> Selected video codec: [ffmjpeg] vfm:ffmpeg (FFmpeg MJPEG decoder)
> ==========================================================================
> Writing AVI header...
> ODML: Aspect information not (yet?) available or unspecified, not writing vprp 
> header.
> VDec: vo config request - 1024 x 768 (preferred csp: Planar YV12)
> VDec: using Planar YV12 as output csp (no 3)
> Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
> videocodec: libavcodec (1024x768 fourcc=34504d46 [FMP4])
> ODML: Aspect information not (yet?) available or unspecified, not writing vprp 
> header
> Pos: 316.1s   3161f ( 0%)  26fps Trem:   0min   0mb  A-V:0.000 [737:0]]
> Flushing video frames
> 
> Writing AVI index...
> Fixing AVI header...
> ODML: Aspect information not (yet?) available or unspecified, not writing vprp 
> header.
> 
> Video stream:  737.411 kbit/s  (92176 bps)  size: 29136962 bytes  316.100 secs  
> 3161 frames
> > Hi,
> >
> > On 5/23/06, Volker Poplawski <volker at openbios.org> wrote:
> > > msmpeg2v2 at least leads to playable results. But bitrate is silently
> > > ignored by mencoder. no matter what vbitrate=xxxx specified, i always end
> > > up with ca 850kbit/s.
> >
> > It obviously shouldn't ignore it. Please retry with "standard" mpeg4
> > codec (which is known to work). If it doesn't change anything, that
> > means that there's smth wrong with the options you gave to mencoder.
> >
> >
> > Guillaume
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> 

      
 ____________________________________

 Marko Hyvonen, PhD                  
 Department of Biochemistry    
 University of Cambridge        
 http://www-cryst.bioc.cam.ac.uk/~marko
 tel:  +44-(0)1223-766 044 / 760 468
 _______________________________________