Batch-oriented MPEG generation with GMV in background mode
Contents
1. Next we can use the batch mode of GMV together with this attribute file to visualize all files of our sequence The images we get are finally passed to an MPEG encoder to create a video But there is one annoying peculiarity about the visualization process for each file it processes GMV pops up a window on your screen and takes a screenshot of it There is at least for us no way to tell GMV to do the visualization in background Therefore we avail ourselves in this program of a virtual framebuffer X server called Xvfb The output of GMV is side tracked to this X server which emulates a dumb framebuffer using virtual memory Hence we have no more windows popping up disturbing our work In fact the complete MPEG generation of one or several videos can be transferred to an arbitrary computer in a network This means you can even log in via modem and start this visualization process in a VT100 emulation Installation and configuration The installation process is as simple as copying this script which can be obtained from the FEATFLOW Homepage to a directory you like But you probably have to adjust a few variables within it The script needs to know the location of the following programs e GMV for the visualization process can be downloaded from the GMV Homepage see below e sgitopnm and ppmtoyuvsplit from the netpbm package for converting the GMV images into a format the MPEG encoder can handle e Xvfb if you want to generate2. warn nWarning host n is taken because of tmp X n lock n warn Remove this file if there is no X server host n n return 0 if e tmp X11 unix X n warn nWarning host n is taken because of tmp X11 unix X n n warn Remove this file if there is no X server host n n return 0 return 1 exit End of gmvmpeg References 1 Finite element software for the incompressible Navier Stokes equations User Manual Release 1 1 1998 see also http www iwr uni heidelberg de featflow 2 J F Acker Working with GMV under FEATFLOW Preprint 98 50 SFB 359 October 1998 3 J F Acker S Turek 3D Presentation of FEATFLOW Data with GMV Preprint 99 19 SFB 359 April 1999 All these papers are available at http www iwr uni heidelberg de featflow d1l html 11
3. gmvmpeg i u fls 1 99 2 x 400 y 320 invisible a streamfunction attr o streamfunction gmvmpeg i u fls 1 99 2 x 400 y 320 invisible a temperature attr o temperature End sample sh Program listing usr local bin perl by Sven H M Buijssen 99 06 14 gmvmpeg script to automate generation of mpeg movies with GMV use I0 Handle Location of programs needed local gmvGL usr local bin gmv OpenGL version of gmv local gmvMesa usr local bin gmv mesa Mesa version of gmv used in invisible mode use of Xvfb local Xvfb usr local bin Xvfb local sgitopnm usr freeware bin sgitopnm local ppmtoyuvsplit usr freeware bin ppmtoyuvsplit local mpegEncoder usr local bin mpeg Parameter for used programs local gmvToUse gmvGL Typical Xvfb parameter on SGI font path from var X11 xfs config Make sure that every path listed in the font path does really exist Otherwise Xvfb won t start local XvfbParams ac terminate fp usr lib X11 fonts 100dpi usr lib X11 fonts 75dpi usr lib X11 fonts misc usr 1lib X11 fonts Type1 usr 1lib X11 fonts Speedo _sp usr lib X11 xserver SecurityPolicy _screen 1 1028x768x32 On Sun s we use following parameters local XvfbParams ac terminate fp usr openwin lib X11 fonts misc usr openwin lib X11 fonts Speedo usr openwin lib X1
4. 1 fonts Type1 usr openwin lib X11 fonts 100dpi usr openwin lib X11 fonts 75dpi _sp usr openwin lib X11 xserver SecurityPolicy screen 1 1028x768x32 co usr openwin lib X11 rgb Some default values local version 1 0 0 local default_bitrate 5000000 local progname 0 s 1 sub usage print Usage progname a attribute_file fls first last stride i filename_prefix m size o output_filename verbose x xres y yres invisible a path for gmv attribute file to use fls two or three comma separated digits that specify first and last index of gmv input file as well as the stride If stride is omitted or set to 0 time step is adaptive h help this help screen i prefix of gmv input files followed by a dot and anumber without zero fills postfix gmv is assumed e g u for u 2 gmv u 3 gmv u 4 gmv I invisible use X server Xvfb for rendering process k keep files don t delete temporary YUV frames m max maximum size of mpeg movie in MB if omitted no limitation o name of output file without extension mpeg V verbose verbose mode version print version information x resolution in x direction if omitted set to 800 y resolution in y direction if omitted set to 600 Arguments marked with have to be specified Example progname a gmv_example attr o ex
5. Batch oriented MPEG generation with GMV in background mode Sven H M Buijssen Stefan Turek Institute of Applied Mathematics University of Heidelberg Im Neuenheimer Feld 294 69120 Heidelberg Germany Email featflow gaia iwr uni heidelberg de Homepage www iwr uni heidelberg de featflow June 1999 Abstract For automatisation purposes we developed a perl script called gmvmpeg that simplifies the generation of MPEG movies with GMV the General Mesh Viewer of the Los Alamos group Particularly the possibility to do this in background on remote computers might be of general interest What it does There are numerous software packages for the visualization of numerical data Within the FEATFLOW software GMV General Mesh Viewer of Los Alamos National Laboratory belongs to our favourite tools For an overview of the features of this program please see documentation Mainly two features of GMV are exploited by the script gmvmpeg GMV comes with the possibility to save an arbitrary configuration into an attribute file Thus all you need to do to generate an MPEG movie out of a sequence of files containing data from a numerical simulation is the following 1 load a more or less arbitrary file from your sequence 2 make a decision on the subset of data to be displayed and 3 save this configuration into a so called attribute file See also the other GMV reports at our homepage which describe the use of GMV for FEATFLOW data
6. ImageMagick html e Xvfb http www xfree org e mpeg http www mpeg org MPEG video html video software or visit the MPEG homepage at http www cselt stet it mpeg For convenience reasons gmvmpeg autonomously determines the next free socket on a computer This function ality was taken from the perl script vncserver a wrapper script to start an X VNC server This package which is not needed for gmvmpeg is published under the terms of the GNU General Public License and can be obtained from e Virtual Network Computing VNC http www uk research att com vnc index html Example Finally we want to show an invocation of gmvmpeg We will give the same example as in 2 where we visualized a pressure distribution e Start GMV and adjust its settings for displaying a pressure distribution e Save your adjustments in an attribute file named pressure attr e To create an MPEG movie called pressure mpeg with a 400x320 resolution from the data files u 1 gmv to u 99 gmv just type gmvmpeg a pressure attr i u fls 1 99 o pressure x 400 y 320 e If you have prepared additional attribute files streamfunction attr and temperature attr the batch oriented MPEG generation in invisible mode i e with exploitation of Xvfb can be started with the following shell script only every second file is processed bin sh gmvmpeg i u fls 1 99 2 x 400 y 320 invisible a pressure attr 0 pressure
7. MPEG movies in background which comes with the Xfree86 package which is distributed for free see below e mpeg for the encoding process see below Command line options gmvmpeg has the following command line options to control the noninteractive generation of MPEG movies They are partially explained in the GMV reports from our homepage see also the references attribute file a filename Path of the GMV attribute file to be used prefix of input files i prefix gmvmpeg assumes the following structure for the input files containing the data to be visualized lt prefix gt lt number gt gmv where lt number gt is supposed to have no additional prefix zeros file name of MPEG movie output o filename Basename of MPEG output i e without the extension mpeg indices of input files fls number1 number2 number3 The sequence of input files starts with number lt number1 gt and ends with lt number2 gt with a stride of lt number3 gt If lt number3 gt is omitted or zero time stepping is adaptive and all files available are taken fls stands for first last stride These command line options are imperative Optional are the following invisible mode I invisible By default GMV will pop up a window for each file processed and make a snapshot of it Due to the use of Xvfb you will not notice the generation process gmvmpeg finds out the lowest available display number on the host concerning and starts Xvfb at th
8. ame No such file or directory n exit If at least one input file has been processed generate a mpeg movie if j gt 0 Reset DISPLAY environment variable ENV DISPLAY originalDisplay if useXvfb 1 Compute bitrate for mpeg encoder if maxmb lt 0 max_bits default_bitrate j 25 else max_bits maxmb 1024 1024 8 Generate mpeg print Generating movie outfile mpeg print n mpegEncoder PF p 3 a 1 b j h xres v yres _x max_bits s outfile mpeg outfile verbose n if verbose eq system mpegEncoder PF p 3 a 1 b j h xres v yres x max_bits s outfile mpeg outfile verbose print if verbose eq print done n Clean up working directory if keepfiles 0 print xxx Removing temporary files system rm AzsnapgmvAz verbose system rm outfile Y system rm outfile U system rm outfile V print done n else print progname No input files found Nothing done n HHEFHHHHHEHHHEHHAEHHHEHHHREHHHAHHHEAHHREHH HAHAHAHAHA HEH HHRHHH HEEB EH RE Stuff taken from vncserver wrapper script to start an X VNC server http www uk research att com vnc index html HEHEHEHEHHEHEHRHHEH AEH HEHEHREHARHE REE REHAEHEH RHE HAH HEHE HRAE REHASH HH HH HH H OH Find socket constants use Socket is a perl5 ism so we wrap it in an eval and if it fails we
9. ample i u fls 1 99 2 sub parseargv local o0k 0 xres 800 yres 600 attrfile default attr inbasename u outfile movie first 1 last 1 stride 1 g adaptive 0 keepfiles 0 maxmb 0 verbose gt dev null useXvfb 0 for i 0 i lt ARGV i arg ARGV i if arg eq a attrfile ARGV it 1 ok elsif arg eq fls list split ARGV i 1 if list lt 1 list gt 3 print progname Syntax error in argument fls specifying n first and last index as well as stride n n Syntax has to be n first last stride n n exit first list 0 last list 1 if list 2 stride list 2 else stride 0 adaptive time stepping if stride 0 if stride 0 adaptive 1 stride 1 ok elsif arg eq help arg eq help usage exit elsif arg eq i inbasename ARGV i 1 ok elsif arg eq I arg eq invisible useXvfb 1 gmvToUse gmvMesa elsif arg eq k arg eq keep files keepfiles 1 elsif arg eq m arg eq max maxmb ARGV i 1 elsif arg eq o outfile ARGV it1 ok elsif arg eq V arg eq verbose verbose elsif arg eq version print progname version version n use progname h for a list of options n exit elsif arg eq x xres ARGV i 1 elsif ar
10. at display keep YUV frames k keep files The snapshots are converted to YUV3 format and are by default deleted when the MPEG encoding has finished If you want to play with different bitrates specify this option to avoid unnecessary regeneration With the program mkmpeg mentioned in 2 you can then play around with different movie file sizes maximum size of MPEG movie m number max number Tells the MPEG encoder to limit the file size to lt number gt MB By default there is no limitation lWe successfully compiled Xvfb under SGI Irix 6 5 as well as under SunOS 5 5 and 5 6 However we observed a latent instability Xvfb crashes when GMV has processed approximately a dozen input files Therefore we have chosen to relaunch it for every input file The program mkyuv which is also introduced in 2 is obsolete upon availability of gmvmpeg verbose V verbose Verbose mode By default gmvmpeg will swallow all output from GMV and the MPEG encoder version information version Prints version information window size x number y number Resolution in x and y direction of the movie to be generated Default values are 800x600 Where to get the programs mentioned see also our homepage e gmvmpeg http www iwr uni heidelberg de featflow dl html e GMV http www xdiv lanl gov XCM gmv GMVHome html e NetPBM http wuarchive wustl edu graphics graphics packages NetPBM e ImageMagick http www wizards dupont com cristy
11. g eq y yres ARGV i 1 if 0ok lt 4 usage exit parseargv STDOUT gt autoflush 1 Check whether attrib file exists and is readable if r attrfile print progname Attribute file attrfile does not exist or is not readable nNothing done n exit if useXvfb 1 originalDisplay ENV DISPLAY amp GetSocketConstants XvfibDisplayNumber amp GetDisplayNumber XvfbDisplay originalDisplay s 1 XvfbDisplayNumber 0 ENV DISPLAY XvfbDisplay local j 0 for i first i lt last it stride local filename inbasename i gmv Process when file exists if r filename j If specified start Xvfb if useXvfb 1 system Xvfb XvfbDisplayNumber XvfbParams verbose 2 gt dev null amp print Processing filename print n gmvToUse m a attrfile w 0 0 xres yres i filename _s verbose n if verbose eq system emvToUse m a attrfile w 0 0 xres yres i filename s verbose if verbose eq system sgitopnm AzsnapgmvAz ppmtoyuvsplit outfile j verbose print kkk Ms else system sgitopnm AzsnapgmvAz 2 gt dev null ppmtoyuvsplit outfile j verbose print done n If file does not exist and we don t have an adaptive time stepping print error message and exit elsif adaptive print progname filen
12. try require sys socket ph If this fails we just guess at the values If you find perl moaning here just hard code the values of AF_INET and SOCK_STREAM You can find these out for your platform by looking in usr include sys socket h and related files sub GetSocketConstants chop os uname chop osrev uname r eval use Socket if 0 eval require sys socket ph if 0 if os eq Sun0S amp amp osrev 74 AF_INET 2 SOCK_STREAM else AF_INET 2 SOCK_STREAM else AF_INET amp AF_INET SOCK_STREAM amp SOCK_STREAM 2 1 else AF_INET amp AF_INET SOCK_STREAM amp SOCK_STREAM GetDisplayNumber gets the lowest available display number sub GetDisplayNumber chop host uname n foreach n 1 99 if amp CheckDisplayNumber n return n die prog no free display number on host n CheckDisplayNumber checks if the given display number is available sub CheckDisplayNumber local n _ socket S AF_INET SOCK_STREAM 0 die prog socket failed n if bind S pack S n x12 AF_INET 6000 n 10 close S return 0 close S socket S AF_INET SOCK_STREAM 0 die prog socket failed n if bind S pack S n x12 AF_INET 5900 n close S return 0 close S if e tmp X n lock
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