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Re: Reading various HDF files [message #46297 is a reply to message #46199]

Wed, 09 November 2005 05:36

peter.albert@gmx.de is currently offline

peter.albert@gmx.de
Messages: 108
Registered: July 2005

Senior Member

Well, it took me a while to create MPEGs, too, but here is my recipe:
First of all, I let mpeg_put read the individual frames from a direct
graphics window. So you have to subsequently display each frame in a
window.

; In order to get the dimensions right, I'd suggest to display the
first image e.g. like

window, 1, xsize = 600, ysize = 400
tv, data

; First, open the mpeg_file:

mpegID = mpeg_open( $
[!d.x_size, !d.y_s
filename = filename
motion_vec_length = 1, $
iframe_gap = 3, $
quality = 75 $
)

; With the images I wanted to put together, simply specifying
; QUALITY brought horrible results full of
; jpeg artefacts. With MOTION_VEC_LENGTH and
; IFRAME_GAP, everything is just fine. Increasing
; IFRAME_GAP gives better results, but you pay with longer processing
time.

; O.k., now for the individual frames, assuming that you have some code
for
; reading the i-th dataset

for i = 0, n do begin
data = read_the_data(i)
tv, data
mpeg_put, mpegID, $
window = !d.window, $
/color, $
frame = i, $
/order
endfor

; After all this, you have to close the file and let IDL do a lot of
compression:

mpeg_save, mpegID
mpeg_close, mpegID

That's it. In case you have only a small number of images to show, the
MPEG file will be short, given a framerate of 24 frames per second. In
that case you can just repeatedly add one and the same frame with a
second loop, but make sure to correctly count the frame number as
provided via FRAME = i. (i.e. use something like

for j = 0, nframes-1 do begin
f = i * (nframes) + j
...
... FRAMES = f, $
...
endfor

Cheers,

Peter

)

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[Message index]

		Re: Reading various HDF files By: David Fanning on Wed, 09 November 2005 05:35
		Re: Reading various HDF files By: Nicola on Wed, 09 November 2005 05:19
		Re: Reading various HDF files By: peter.albert@gmx.de on Wed, 09 November 2005 05:11
		Re: Reading various HDF files By: Nicola on Wed, 09 November 2005 04:35
		Re: Reading various HDF files By: peter.albert@gmx.de on Wed, 09 November 2005 03:37
		Re: Reading various HDF files By: Rick Towler on Thu, 10 November 2005 11:46
		Re: Reading various HDF files By: peter.albert@gmx.de on Wed, 09 November 2005 05:36

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