MPEG_STAT(1) MPEG_STAT(1)
1 December 1994
NAME
mpeg_stat - analyzes MPEG-1 encoded bitstreams
SYNOPSIS
mpeg_stat [ -all basename ] [ -block_info filename ] [ -dct ] [ -end N
] [ -histogram filename ] [ -offsets filename ] [ -qscale filename ] [
-quiet ] [ -rate filename ] [ -ratelength N ] [ -time ] [ -size
filename ] [ -start N ] [ -syslog filename ] [ -userdata filename ] [
-verify ] [ file_name ]
DESCRIPTION
mpeg_stat decodes mpeg-1 encoded bitstreams collecting varying amounts
of statistics. Errors are sent to stderr, basic statistics to stdout.
The basic information is the pattern of frames used, number of bytes
for each frame type, the specified parameters, and lengths of vectors.
For each frame type, the average size, compression rate, Q-factor, and
time to decode are given. Wherever a filename is requested - can be
used to denote stdin/out.
OPTIONS
-all basename : records information from all options (qscale,
block_info, etc.) into files with basenames of basename (For
wizards, -all foo -block_info bar will record all options BUT
-block_info into files of the form foo.*).
-block_info filename : records information about every block into file
filename. Useful for detailed analysis and to make specifics
files for re-encoding (see block2spec). The format is:
frame frame# IPB-type mv-scale temporal_ref
slice slice# q-scale
block block# IPB-type Q-scale bits block-type <vectors-if-any>
<cbp> <dct decode>
Numbering starts at 0 (except slices) and all motion vectors are in
half-pel units <X Y>.
-dct : enables the decoded dct values to be output into the block
file.
-end N : causes mpeg_stat to finish collecting statistics at frame N.
-histogram filename : summaries the overall statisitcs for each frame
type into the file.
-offsets filename : record the offset of every picture, GOP, and slice
into file filename.
-quiet : toggles the display of the frame-types as they are parsed
(and custom quantization matrices) [default: on].
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MPEG_STAT(1) MPEG_STAT(1)
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-qscale filename : writes Q factor and custom quantization matrix
information into file filename. The Q-factor and number of
blocks of that quality (ignoring skipped blocks) for each type of
frame is recorded.
-rate filename : record the bit rate at every picture (after the first
second) into the file filename. Also collect minimum and maximum
bit rate encountered in the summary information. (Rate is the
number of bits used per second, at every frame).
-ratelength N : Change the measurement period for rate to N, so it
will measure the total rate required over any N frame period
(after the first N, of course).
-size filename : stores information about the type (I,P,B) and size of
each frame in file filename (one frame per line).
-start N : causes mpeg_stat to begin collecting statistics at frame N.
(Preceding frames will be parsed, but few statistics are
collected (the system layer counters will sill be running).) -
syslog filename : describes the parsing of the system layer into
the file filename. Note this option is not turned on by -all.
-time : prints the amount of time total and per-frame type
averages to decode. This will give an estimate of time in a
software player, but is not generally useful, so it is off by
default. -userdata filename : dumps user data fields into a
file. Can be read in ASCII. -verify : does more work to check
the validity of the sequence. Slows down the statistics, so it
is optional.
EXAMPLE
Decoding the flowergarden sequence (mpeg_stat -quiet flower.mpg)
should produce the following statistics:
Reading /u/smoot/mpg/flower.mpg
Frame sequence as to be displayed:
BBPBBPBBPBBPBBIBBPBBPBBPBBPBBIBBPBBPBBPBBPBBIBBPBBPBBPBBPBBIBBPBBPBBPBBPBBI
BBPBBPBBPBBPBBIBBPBBPBBPBBPBBIBBPBBPBBPBBPBBIBBPBBPBBPBBPBBIBBPBBPBBPBBPBB
Searching for constant frame type sequence...pattern detected:
IBBPBBPBBPBBPBB
SUMMARY:
Total Bytes read: 0. Total number of frames: 150. Length is 5.01 sec
Width: 352 Height: 240 Avg. Frame Size: 4786 bytes + 6 bits
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MPEG_STAT(1) MPEG_STAT(1)
1 December 1994
(average rate 1147692.76 bits/sec)
Total Compression Rate: 1.89 % of uncompressed 24 bit images
= 0.45 bits per pixel
Number of Macroblocks [width * height = sum]: 22 x 15 = 330 per frame
Skipped Macroblocks = 4389 (9.46%), Coded Macroblocks = 41992 (90.54%)
Total Time Decoding: 8.611 secs. 0.05721 sec/frame or 17.11
frames/sec.
MPEG-Viewer requirements:
Pixel aspect ratio of 0.6735
Required display speed: 29.97 frames/sec
Specified bit rate is 1.00 MBits/sec (2500 * 400bits/sec)
Requested buffer size is 8K ints (16 bits).
And the constrained parameter flag is on. The stream
meets the constrained parameter requirements.
Length of vectors in pixels:
Horizontal forward vectors, maximum : 39 average: 6
Vertical forward vectors, maximum : 22 average: 1
Horizontal backward vectors, maximum: 29 average: 5
Vertical backward vectors, maximum : 16 average: 1
Frame specific information:
10 I FRAMES, average is:
Size: 17323 bytes + 1 bits (24.13%)
Compression Rate: 6.84%
Q Factor [scales quantization matrix]: 11.15
Time to Decode: 0.114039 secs.
40 P FRAMES, average is:
Size: 8031 bytes + 0 bits (44.74%)
Compression Rate: 3.17%
Q Factor [scales quantization matrix]: 10.85
Time to Decode: 0.075342 secs.
100 B FRAMES, average is:
Size: 2235 bytes + 4 bits (31.13%)
Compression Rate: 0.88%
Q Factor [scales quantization matrix]: 15.01
50.59% interpolated Macro Blocks
Time to Decode: 0.044516 secs.
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MPEG_STAT(1) MPEG_STAT(1)
1 December 1994
NOTES
The analyzer expects MPEG-1 video streams only. It can handle
multiplexed MPEG streams (video+audio streams), but mostly analyzes
the video portion. Some streams do not end with the proper sequence
end code and will probably generate an "Improper sequence end code."
error when done. In general mpeg_stat attempts to catch and alert its
user to errors in the stream. Such errors are glossed over in
mpeg_play. Be aware that errors can disturb statistics gathering,
generating odd results. This player can handle 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.
HISTORY
The analyzer is based on the UC Berkeley mpeg_play player by Ketan
Patel, Brian Smith, Henry Chi-To Ma, and Kim Man Liu. It was modified
at the Technical University of Berlin, Germany, Dept. of Computer
Science by Tom Pfeifer, Jens Brettin, Harald Masche, Alexander
Schulze, and Dirk Schubert. It has been further modified to collect
much more information by Steve Smoot (UC Berkeley).
BUGS
No statistics should be collected before the start frame. Sometimes
system layer streams will indicate that they lack proper end codes,
when they have them. VBV size conformance is not checked.
Verification is not complete. Frame numbers should probably be in
display numbering not stream numbering. Other bugs? Send mail to
<mpeg-bugs@plateau.cs.berkeley.edu>.
VERSION
This is version 2.2, contining some new features since 2.1, and
several bug fixes. It is a major change since version 1.0.
AUTHORS
Ketan Patel - University of California, Berkeley,
kpatel@cs.berkeley.edu
Brian Smith - University of California, Berkeley,
bsmith@cs.berkeley.edu
Henry Chi-To Ma - University of California, Berkeley,
cma@cs.berkeley.edu
Kim Man Liu - University of California, Berkeley, kliu@cs.berkeley.edu
Tom Pfeifer - Multimedia systems project - pfeifer@fokus.gmd.de
Steve Smoot - University of California, Berkeley,
smoot@cs.berkeley.edu
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1 December 1994
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