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.\" @(#)mpeg_bits.1 1.0 95/01/21 SMI;
.TH MPEG_BITS 1 "21 January 1995"
.SH NAME
mpeg_bits \- monitors and modifies bitrate in encoded streams
.SH SYNOPSIS
.B mpeg_bits
[
.B -edits edit_file_name
] [
.B -dither dither_option
] [
.B file_name
]
.SH DESCRIPTION
.B mpeg_bits
provides a GUI for the monitoring and modification of MPEG streams.
As it displays an MPEG bitstream, it gives feedback on how bits are
being allocated on a macroblock-by-macroblock level. It also enables
the user to specify block-level q-scale changes, which are then
compiled into a specifics file which can be used in later encodings.
.SH OPTIONS
.HP
.B -edits edit_file_name
: loads the edits made in a previous mpeg_bits session
.HP
.B -dither dither_option
: selects from a variety of dither options. The possible values are:
.RS
.HP
ordered - ordered dither.
.HP
ordered2 - a faster ordered dither. This is the default.
.HP
mbordered - ordered dithering at the macroblock level. Although there
is a noticeable decrease in dither quality, this is the fastest dither
available.
.HP
fs4 - Floyd-Steinberg dithering with 4 error values propogated.
.HP
fs2 - Floyd-Steinberg dithering with 2 error values propogated.
.HP
fs2fast - Fast Floyd-Steinberg dithering with 2 error values propogated.
.HP
hybrid - Hybrid dithering, a combination of ordered dithering for the luminance
channel and Floyd-Steinberg 2 error dithering for the chrominance channels. Errors
are NOT propogated properly and are dropped all togethor every two pixels in either
direction.
.HP
hybrid2 - Hybrid dithering as above, but with error propogation among pixels.
.HP
2x2 - A dithering technique using a 2x2 pixel area for each pixel. The image displayed
is 4 times larger than the original image encoded. Random error terms are added to
each pixel to break up contours and gradients.
.HP
gray - Grayscale dithering. The image is dithered into 128 grayscales. Chrominance
information is thrown away.
.HP
gray256 - Grayscale dithering. The image is dithered into 256 grayscales
(requires private colormap). Chrominance information is thrown away.
.HP
color - Full color display (only available on 24 bit color displays).
.HP
none - no dithering is done, no image is displayed. Used to time decoding process.
.HP
mono - Floyd-Steinberg dithering for monochrome displays.
.HP
threshold - Floyd-simple dithering for monochrome displays.
.HP
.RE
.SH NOTES
The tool expects video streams only. It can handle multiplexed MPEG streams
(video+audio streams) by discarding the audio. It uses the paris entropy coding
table set (which we believe to be the MPEG-1 standard), but can not handle any bitstreams
that use the "berlin" entropy coding table set. Berlin data is relatively rare so there
shouldn't be too much to worry about here, but be aware of the difference when looking
for streams to work with.
.LP
Some streams do not end with the proper sequence end code and will probably generate
an "Improper sequence end code." error when done playing.
.LP
This player can play XING data files. Be aware that XING makes no use of temporal
redundancy or motion vector information. In other words, they do not use any P or
B frames in their streams. Instead, XING data is simply a sequence of I frames. Since
I frames take significantly longer to decode, performance of the application using XING
data is not representative of its ability.
.SH VERSION
This is the first public release, version 1.0.
.SH AUTHORS
.HP
Doug Banks - University of California, Berkeley, dbanks@cs.berkeley.edu
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