2/24/93 (MPEG Version 1.1)

CODE:

(transform.c) The encoding non-intra quantizer function has been
changed to reflect the reference encoder.  This is not to say that the
previous quantizer was incorrect, significantly different, or even
worse; there are advantages (statistical) and disadvantages (biased).
The short.mpg and short.trace have been modified accordingly.

(mpeg.c) The default output name is componentfile0.mpg rather than
componentfile0.M

(stat.c) The statistics now include mean-removed squared error. 
MRSNR calculated based on (E[X^2]-E[X]^2)/E[error^2]
SNR calculated based on E[X^2]/E[error^2].
PSNR calculated based on 255*255/E[error^2].

DOCUMENTATION:

The colorspace section was edited to include more precise matrices and
a description of CCIR-601 versus JFIF style YUV->RGB conversion.

The description on motion estimation is increased, for example, it
describes telescopic motion estimation.  The motion estimation search
window for frame distances greater than one is anchored on the
location of the previous frame's motion vector.

Some printers (non-laserwriters) have been unable to cope with the
doc.ps files, specifically problems occurred in the postscript include
files.  For some reason, Apple laserwriters and ghostscript do not
seem to be afflicted by the above problem.  We have found a change in
the dvi2ps postscript header that seems to fix this problem for Sun
newsprint (and probably other) printers as well.  If this still is a
problem, the raw tex and .ps files are available in the file
MPEGDOCv1.1.tar.Z.  Caution: the special scaling command has different
relative scales for different dvi2ps, dvips programs - can be a factor
of 100 off depending on the version of the header file.

3/15/93

Changed extend_mask[8] to extend{mask[7] in the codec.c.
Changed 0x3fff to 0x3ffff in the variable rate buffer read/save in marker.c.

5/29/93

Added a greater motion search window through the searchlimit command.
This requires a scan of the motion vector field for the greatest
displacements.  We use the variable flag DynamicMVBound to indicate
that the motion vector field is searched.  Then the procedure
MVBoundIndex is called to calculate the forward and backward indices.

Added a new flag MVTelescope which enables telescopic motion
estimation if set.  In general MVTelescope is always set, though can
be disabled if desired.

Added XING compatibility, or what I hope is XING compatible.  Changes
made to mpeg.c marker.c.

6/13/93

Completed changes to XING compatibility.  Tested on a short sequence.
Added the changes to the documentation, along with clarification of
MPEG sampled 4:2:0 versus CCIR sampled 4:1:1, along with the issues of
YUV versus YCbCr.  The library function rint which rounds a floating
point value to the nearest integer has been replaced by a macro
expansion to improve compatibility.

8/16/93

Changed a small line in me.c that was incorrect even though it was
never actually used (bounds checking).

*IMPORTANT* Changed a line in the skipped blocks to reset the DC
prediction.  May cause slight problems with old files (a bit of block
flicker), but shouldn't happen very often - the precise anamoly is
when a motion compensated block is coded, followed by skipped blocks,
the next block - if intra-coded - has an incorrect DC prediction.

Changed default Brate from 0x3fff to 0x3ffff in mpeg.c; a small change
that does not affect software decoding.

(9/6/93 version 1.2 released)

9/30/93 Version 1.2.1

marker.c: Changed the loading of non-default MPEG quantization
matrices into a zig-zag fashion.

