mpgwrite.doc

多种基于内容的视频检索镜头分割算法matlab程序

MPGWRITE

Purpose

	Translate a Matlab movie into an MPEG file.

Synopsis

	mpgwrite(movie, map, 'filename', options)
		Matrix movie;
		Matrix map;
		String filename;
		Vector options;

Arguments

	movie 		a matrix containing a Matlab movie.
	map 		matrix containing a Matlab colormap.
	'filename' 	string containing the name of the MPEG
				file to be created.
	options 	(optional) vector of options for the MPEG encoder.
			Default Value: [1, 0, 1, 0, 10, 8, 10, 25]

Description

	This routine takes a Matlab movie and converts it into an MPEG
	movie which is placed in the specified output file "mpeg_file".
	The MPEG file can be viewed with an MPEG player such as mpeg_play.
	MPEG compression is lossy and the quality of the movie's 
	reproduction can be controlled by several parameters.  The MPEG
	encoder creates frames utilizing three types of interpolation.
	I-Frames are encoded completely without interpolation from past or
	future frames.  P-Frames are encoded relative to the previous
	frame and B-Frames (bi-directional) are interpolated using
	both the previous and the following frame.
	
	The options argument is a vector of integers.  Each interger
	determines the value of one option depending on its position in
	the vector.  No options in the vector may be skipped, but
	options may be ommitted from the end of the list.  The repeat 
	option directs mpgwrite to encode a specified number of copies of
	the Matlab movie and place them into the MPEG file.  The P-Search
	algorithm option controls how P-Frames are encoded.  Similarly, 
	the B-Search algorithm controls B-Frame encoding.  The reference
	frame can be either the original or the decoded image.  Using
	the decoded image is slower but results in better quality.
	The MPEG encoder divides each frame into blocks and expects that
	many of these blocks will remain the same between frames except
	for translation within the frame.  A range parameter provides 
	the encoder with a search radius in pixels.  Higher values will
	slow compression but improve the compression ratio.  The last
	three parameters that may be specified control the quantization
	scale.  Higher numbers result in better compression at the
	expense of image quality.  The following is a list of parameters
	and their allowed values:

	1. REPEAT:
		An integer number of times to repeat the movie
		(default is 1).
	2. P-SEARCH ALGORITHM:
		0 = logarithmic	(fastest, default value)
		1 = subsample
		2 = exhaustive	(better, but slow)
	3. B-SEARCH ALGORITHM:
		0 = simple	(fastest)
		1 = cross2	(slightly slower, default value)
		2 = exhaustive	(very slow)
	4. REFERENCE FRAME:
		0 = original	(faster, default)
		1 = decoded	(slower, but results in better quality)
	5. RANGE IN PIXELS:
		An integer search radius.  Default is 10.
	6. I-FRAME Q-SCALE:
		An integer between 1 and 31.  Default is 8.
	7. P-FRAME Q-SCALE:
		An integer between 1 and 31.  Default is 10.
	8. B-FRAME Q-SCALE:
		An integer between 1 and 31.  Default is 25.

See Also

	mpgread

	
Copyright (c) 1994 The MathWorks Inc.