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- Description
-
All the programs that access trace files can uncompress on-the-fly. This module
maybe used to compress existing trace files. No compression programs are
supplied with the package, although there are several good public domain
compression programs available.
Note that using the ZTR trace format will typically yield better compression
than using any of the supported compression programs on an SCF
file. Attempting to compress a ZTR file using this module will not decrease
the size (and may even increase the file size). Also see
section Trace Format Conversion.
- Option: Compression method
-
This selects the algorithm used for compressing trace files. The choices are
None, Compress (the standard UNIX compression program), Gzip (from GNU) and
Bzip versions 1 and 2. These are listed in ascending order of compression
ratios, with Bzip (either version) giving the best compression. Generally Gzip
is the best supported program and is not too far behind Bzip.
The following table provides comparisons with compression sizes on ABI and SCF
files. (Note that the ABI file typically holds 12 bit trace data data.) The
sizes listed are the average length, in bytes, of the 96 (originally ABI 3700
trace) files that the tests were performed on. The SCF and ZTR files were
recalled using phred, so also contain confidence values. For comparison, the
ZTR file sizes are also shown.
File type Size in bytes
abi 189150
compressed abi 104681
gzipped abi 87789
bzipped abi 62032
16-bit scf 82124
compress 16-bit scf 26574
gzipped 16-bit scf 25957
bzipped 16-bit scf 18877
16-bit ztr 17185
8-bit scf 45967
compress 8-bit scf 15000
gzipped 8-bit scf 14718
bzipped 8-bit scf 12659
8-bit ztr 11155
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Last generated on 22 October 2002.
URL: http://www.mrc-lmb.cam.ac.uk/pubseq/manual/pregap4_unix_21.html