[Chimera-users] Chimera movies in PowerPoint

[Thomas Goddard]

Hi Xinchao,

  Several people have asked exactly your question of how to get a
Chimera movie to play in PowerPoint on Windows without being jerky.
I don't have a Windows machine to test on today but I investigated on
the web and have a theory.  I believe the jerky playback is because
Chimera is encoding the movie using the -qscale option to the ffmpeg
encoder causing variable bit rate (VBR) encoding.  When you play the
movie it becomes jerky because the player software does not handle
the variable bit rate well -- it doesn't buffer up enough data and
then can't handle the passages when alot is changing in the video.
Another issue is choosing a format that PowerPoint on Windows accepts.

  Here are two suggestions.  The first is to reencode the movie using
the ffmpeg program included in Chimera:

  chimera/bin/ffmpeg -i mymovie.qt -f avi -vcodec msmpeg4 -b 2000 mymovie.avi

This command produces an AVI file using msmpeg4 encoding at a bit rate
of 2000 Kbits / sec (about 12 Mbytes / minute) from a quicktime file
created by Chimera.  You can increase the bit rate to get better
quality or lower it to get smaller file size and worse quality.  From
what I read on the web Windows XP will be happy with AVI format and
msmpeg4 encoding.  You may find it hard to run this command unless you
are familiar with running command-line programs on Windows.  You could
use a Windows Command Prompt window or Run Command, but you may need
to provide full paths to the ffmpeg program and movie file.

  An alternative is to modify the Chimera Movie Recorder code

	chimera/share/MovieRecorder/ffmpeg_encoder.py

putting comment characters (#) in front of lines 106-111:

        arg_list.append('-qscale')
        qsc = param_dict['Q_SCALE']
        if qsc:
            arg_list.append(str(qsc))
        else:
            arg_list.append('1')

so they become

#        arg_list.append('-qscale')
#        qsc = param_dict['Q_SCALE']
#        if qsc:
#            arg_list.append(str(qsc))
#        else:
#            arg_list.append('1')

This change is eliminating the -qscale option when Chimera runs ffmpeg
to encode your movie.  Instead we will explicitly request the encoding
bit rate with the -b ffmpeg option.  Now restart Chimera and record a
movie with the Movie Recorder using "Custom" video format to select
bit rate (which controls movie quality and file size).  The Custom
video format settings are under the Movie Options panel, swich on "Use
preset video format" and select "Custom" from the Presets menu.  Then
set the resolution to match your Chimera window size (shown in the
upper right corner of the Movie Recorder dialog, choose the encoding
format and set the bit rate (in kilobits per second).  If you don't
make these Custom settings then Movie Recorder will use ffmpeg's
standard very low bit rate of 200 kbits/second making a very low
quality and small file size movie.

  Let me know if you found either of these suggestions to produce usable
movies for PowerPoint on Windows.  Then I can change Chimera Movie Recorder
to make it easy to use such settings.

	Tom



> To: goddard at cgl.ucsf.edu
> Subject: Chimera Movie format
> Date: Fri, 16 Jun 2006 15:33:52 -0400
> From: Xinchao Yu <yxinchao at bu.edu>
> 
> Dear Tom:
>     I am a graduate student working with Dr. Christopher Akey at Boston 
> University. Recently, I have been trying to make some movies for large 
> compplexes with multiple domains. My problem is that if I use MPEG as the 
> output movie format, the movement can get very jerky in the movie. While I 
> don't have this problem with .mov format (compressed to the same extent as 
> the .MPEG files). But .mov file is not readily incorporated into powerpoint 
> presentations. Did you have similar observations? Or do you have some 
> suggestions concenning this problem. Thanks a lot! 
>  
> 
>               Xinchao Yu
> Department of Physiology & Biophysics
> Boston University, School of Medicine
> 700 Albany Str., Boston, MA, 02118 
>