comp.lang.idl-pvwave archive - RDF feed
type: channel
description: Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
items: mpeg creation problem
items: Re: mpeg creation problem

mpeg creation problem
type: item
description: I have a 3d plot which i want to save as an mpeg video of 2000 frames (a lot) x[ i ] , y[ i ] , z[ i ] are arrays (dimension=2000) of numbers properly defined I use the following code: ; number of frames nfr=2000 ; spatial size in pixels xsize=300 ysize=300 ; open the mpeg mpegID=MPEG_OPEN([xsize,ysize]) ; loop over the frames for f=0,nfr-2 do begin ; create a 3d environment .................................................... ; plot the line of a frame using the arrays in the environment for i=0,f plots, [ x[i] , x[i+1] ], [ y[i] , y[i+1] ], [ z[i], z[i +1] ], /T3D, /DATA endfor ; put a frame into the mpeg MPEG_PUT,mpegID,WINDOW=0,FRAME=f endfor ; save and close MPEG_SAVE,mpegID,FILENAME='vid.mpg' MPEG_CLOSE,mpegID Comments: I run IDL in a remote pc (through linux ssh). Each frame is first plotted to my screen and then inserted to the mpg. It takes almost 10minutes for each frame so i should wait a very long time for my 2000 frame..!! I think that the screen plotting delays the whole process. There must be a better way since they say IDL is the top graphics tool... Questions: 1. Can I do the same job without each frame appearing on my screen?? How should I change the code?? 2. Do U have any other suggestions to improve this ?? Thanx for ur patience
creator: kostis
date: 2007-02-28T14:26:43-00:00

Re: mpeg creation problem
type: item
description: kostis wrote: [...] > Questions: > > 1. Can I do the same job without each frame appearing on my screen?? > How should I change the code?? You could try plotting into the z-buffer if nothing else. The way you're doing it now, you're transporting every pixel over your network. > 2. Do U have any other suggestions to improve this ?? I create mpegs with a couple thousand frames of data fairly regularly. it takes a while when you hit the mpeg_close, but each frame shouldn't take as long as you're indicating. How large is the window that you're using (I didn't see the window,xsize=..., ysize=... statement). If it is anything other than 300x300, then you're not only transmitting unnecessarily large bitmaps around, but you incur some rebinning penalty at each frame. You might consider doing a tvrd() "by hand" for each frame and then handing the resulting bitmaps to mpeg_put individually - if only to see whether that makes a difference (that's how I usually do it). - S -- http://www.sgeier.net My real email address does not contain any "Z"s.
creator: Sven Geier
date: 2007-03-13T07:35:55-00:00