MGHAVIWRITEFILE__DEFINE Name
Class MGHaviWriteFile Purpose
This class encapsulates an AVI file to be written using the
functions supported by the AVI DLL. Properties
BIT_RATE (Init)
Maximum video data rate in bits per second as a scalar integer.
The interpretation of this parameter depends on the codec. In my
experience it is best left at its default of 0 (unconstrained).
CODEC (Init, Get)
Video codec name as a 4-character string. This must match the
4-character descriptor (FOURCC) one of the codecs installed on
the machine. (The comparison is case-insensitive.) If the CODEC
argument to the Init function is omitted, then a dialogue will
appear offering a choice of codecs & compression options.
DIMENSIONS (Init, Get)
Image dimensions as a 2-element integer vector. Note that some
codecs impose conditions on the dimensions. These conditions
vary with the codec and its settings. For some codecs the
dimensions be a multiple of 2, 4 or 8 and some codecs in some
configurations support only a few fixed dimensions. As a
practical compromise, it is wise for the calling application to
round the dimensions to the nearest multiple of 4.
FILE_NAME (Init, Get)
The name of the AVI file wrapped by the MGHaviWriteFile object.
FRAME_RATE (Init)
Video playback rate in frames per second as a scalar integer.
Default is 15 fps.
IFRAME_GAP (Init)
Spacing between I-frames in the video stream as a scalar
integer. (I-frames, or key frames are frames that can be
reconstructed without using data from any surrounding frames in
the animation.) A large IFRAME_GAP reduces file size but makes
navigation to arbitrary positions in the animation slow. For
quick navigation set IFRAME_GAP to a smallish value like
10. Default is 0 (I-frame spacing left to the codec).
QUALITY (Init)
Video quality as a scalar integer between 0 (lowest) and 100
(highest). The interpretation of this parameter depends on the
codec.
TRUE_COLOR (Init)
A logical value specifying whether the frames are to be supplied
as [3,m,n] true-colour images (TRUE_COLOR=1) or [m,n] pseudo-colour
images (TRUE_COLOR=0). Default is 1.
AUTHORSHIP:
The IDL code in this file is based on code written by Oleg
Kornilov and provides an interface to C code also written by
Oleg.
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This software is provided subject to the following conditions:
1. NIWA makes no representations or warranties regarding the
accuracy of the software, the use to which the software may
be put or the results to be obtained from the use of the
software. Accordingly NIWA accepts no liability for any loss
or damage (whether direct of indirect) incurred by any person
through the use of or reliance on the software.
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Modification History
Mark Hadfield, 2006-05:
Written, based on routines in Oleg's movie_io.pro.