cpython/Demo/sgi/video/README

CMIF video tools
================

This directory contains Python and C programs to manipulate files
containing digitized video in the "CMIF video format".


History
-------

We started this in October 1991, when we had a large framegrabber
board on loan from SGI for a few weeks: we developed a movie recording
program and added numerous features, including still frame capture and
synchronous sound recording using a second machine (the machine
holding the framegrabber board didn't have audio).

During the following months, when we started using and processing the
recorded film fragments, the "CMIF video format" was revised several
times, and we eventually created an object-oriented interface for
reading and writing various incarnations of these files, called VFile.
(This module is also used by our flagship application, the CMIF
editor, not in this directory but in /ufs/guido/mm/.)

When we got our own Indigo entry-level video board (in June 1992) and
a version of the Irix video library that supported capturing PAL
format (in August 1992), Sjoerd added an interface to the video
library to Python (sv) and Guido wrote Vrec.py (based upon a still
frame grabber by Sjoerd, in turn based upon SGI demo code in C) to
record a movie using it.  Vrec was soon followed by modernized
versions of the other programs (Vinfo, Vplay, Vtime) and an
interactive editor (Vedit).  Finally, VFile was rewritten for more
modularity, functionality and robustness, and various other tools were
added as needed.  Also, new options were added to existing tools, and
several new video file formats were added.

	Guido van Rossum
	Jack Jansen
	Sjoerd Mullender


Overview of files
-----------------

cmif-film.ms	description of the CMIF video file format (more than a
		little out of date -- read the source for VFile for
		more info about new file formats)


These are programs with a command line interface:

Vrec.py		record video movies using the Indigo video library and
		board

Vplay.py	play video movies

Vinfo.py	show statistics on movies

Vtime.py	Copy a video file, manipulating the time codes (e.g.
		faster/slower, or regenerate time codes, or drop
		frames too close apart)

Vcopy.py	selectively write frames from one movie file to another
		usage: Vcopy [-t type] [-m treshold] [-a] infile outfile
		commands: 'n' gets next frame; 'w' writes current frame

Vmkjpeg.py	compress an rgb or grey video file to jpeg[grey] format

Vunjpeg.py	expand a jpeg[grey] video file to rgb or grey format

Vfix.py		truncate the scan line width of a video file to
		a multiple of 4 ('grey' images only)

Vedit.py	interactive video editing program (uses the FORMS library)

Vsend.py	unicast or multicast live video as UDP packets

Vreceive.py	receive transmissions from Vsend

Vaddcache.py	add a "cached index" to a video file, for faster playing

Vrecb.py	like Vrec.py but uses "burst capture" -- somewhat specialized

Dsend.py	like Vsend.py but sends screen snapshots (to Vreceive.py)

DisplayVideoIn.py	Like LiveVideoIn.py but reads screen snapshots

rgb2video.py	combine a sequence of rgb image files into a CMIF video file

video2rgb.py	split a CMIF video file into a sequence of rgb image files


These modules and files are used by the above programs:

VFile.py	classes that read and write CMIF video files

Viewer.py	two viewer classes used by Vedit

LiveVideoIn.py	live video input class, used by Vsend

LiveVideoOut.py	live video output class, used by Vsend and Vreceive

imgconv.py	Image conversion subroutines for rgb2video.py

senddefs.py	Defaults shared by Vsend and Vreceice

watchcursor.py	Generally useful module to define a watch cursor in GL

VeditForm.fd	FORMS' fdesign definition for Vedit's form