Io_lib: Version 1.15.1

Io_lib is a library of file reading and writing code to provide a general purpose SAM/BAM/CRAM, trace file (and Experiment File) reading interface. Programmatically {S,B,CR}AM can be manipulated using the scram_*() API functions while DNA Chromatogram (“trace”) files can be read using the read_reading() function.

It has been compiled and tested on a variety of unix systems, MacOS X and MS Windows.

The directories below here contain the io_lib code. These support the following file formats:

SAM/BAM sequence files
CRAM sequence files
SCF trace files
ABI trace files
ALF trace files
ZTR trace files
SFF trace archives
SRF trace archives
Experiment files
Plain text files

These link together to form a single “libstaden-read” library supporting all the file formats via a single read_reading (or fread_reading or mfread_reading) function call and analogous write_reading functions too. See the file include/Read.h for the generic ‘Read’ structure.

See the CHANGES for a summary of older updates or git logs for the full details.

Version 1.15.1 (14th July 2025)

This is simply a change to the build infrastructure, with newer versions of the htscodecs submodule and an updated configure/libtool script to help MacOS builds.

Version 1.15.0 (14th April 2023)

The first release that no longer warns about CRAM 3.1 being draft. No changes have been made to the format and it is fully compatible with the 1.14.x releases.

Technology Demo: 4.0

The current official GA4GH CRAM version is 3.1.

The current default CRAM output is 3.0, for maximum compatibility with other tools. Use the -V3.1 option to select CRAM 3.1 if needed.

For purposes of EVALUATION ONLY this release of io_lib also includes an experimental CRAM version 4.0. The format very likely to change and should not be used for production data. CRAM 4.0 includes format modifications, such as 64-bit sizes, deduplication of read names, orientation changes of quality strings and a revised variable sized integer encoding. It can be enabled using scramble -V4.0

Enabling CRAM 3.1 or 4.0 will also enable the new codecs. Which codecs are used also depends on the profile specified (eg via “-X small”). Some of the new codecs are considerably slower, especially at decompression, but by default CRAM 3.1 aims to be comparable speed to 3.0. Note the profiles also change the granularity of random access (1k, 10k, 25k, 100k for fast, normal, small and archive respectively).

Here are some example file sizes and timings with different codecs and levels on 10 million 150bp NovaSeq reads, single threaded. Decode timing is checked using “scram_flagstat -b”.

Table produced with Io_lib 1.15.0 on a laptop with Intel i7-1185G7 CPU running Ubuntu 20.04 under Microsoft’s WSL2.

Scramble opts.	Size(MB)	Enc(s)	Dec(s)	Codecs used
-O bam (default)	518.2	65.8	5.7	bgzf(zlib)
-O bam -1	584.5	17.4	3.5	bgzf(libdeflate)
-O bam (default)	524.6	27.8	2.9	bgzf(libdeflate)
-O bam -9	486.5	810.4	3.0	bgzf(libdeflate)

-V2.0 -X fast	294.5	23.1	7.8	(default, level 1)
-V2.0 (default)	252.3	32.9	8.0	(default)
-V2.0 -X small	208.0	85.2	23.5	bzip2
-V2.0 -X archive	206.0	88.1	24.3	bzip2

-V3.0 -X fast	241.1	19.7	8.5	(default, level 1)
-V3.0 (default)	208.5	23.0	8.8	(default)
-V3.0 -X small	201.7	60.0	14.5	bzip2
-V3.0 -X archive	199.9	61.7	13.6	bzip2

-V3.1 -X fast	237.1	22.1	7.9	rANS++
-V3.1 (default)	175.8	26.7	8.9	rANS++,tok3
-V3.1 -X small	166.9	47.9	24.6	rANS++,tok3,fqz
-V3.1 -X archive	162.2	72.5	20.5	rANS++,tok3,fqz,bzip2,arith

-V4.0 -X fast	227.5	16.6	6.2	rANS++
-V4.0 (default)	172.8	19.7	6.3	rANS++,tok3
-V4.0 -X small	162.3	34.8	20.2	rANS++,tok3,fqz
-V4.0 -X archive	157.9	82.2	26.2	rANS++,tok3,fqz,bzip2,arith

gantt
    title 10 million Illumina NovaSeq records
    todayMarker off
    dateFormat  X
    axisFormat %s

    section BAM
    -5 zlib   66s / 6s   : 0,518
    -1,       17s / 3s   : 0,584
    -5,       28s / 3s   : 0,525
    -9,      810s / 3s   : 0,486
    - : 0,0

    section CRAM 2.0
    fast,     23s /  8s  : 0,294
    normal,   33s /  8s  : 0,253
    small,    85s / 23s  : 0,208
    archive,  88s / 24s  : 0,206
    - : 0,0

    section CRAM 3.0
    fast,     20s /  8s  : 0,241
    normal,   23s /  9s  : 0,208
    small,    60s / 14s  : 0,202
    archive,  62s / 14s  : 0,200
    - : 0,0

    section CRAM 3.1
    fast,     22s /  8s  : 0,237
    normal,   27s /  9s  : 0,176
    small,    48s / 25s  : 0,167
    archive,  72s / 21s  : 0,162
    - : 0,0

    section CRAM 4.0
    fast,     17s /  6s  : 0,227
    normal,   20s /  6s  : 0,173
    small,    35s / 20s  : 0,162
    archive,  82s / 26s  : 0,158

With 1 million aligned PacBio Revio records, on the same system. Also using one thread only:

Scramble opts.	Size(MB)	Enc(s)	Dec(s)	Codecs used
-O bam -1	3061	97.5	16.0	bgzf(libdeflate)
-O bam (default)	2891	128.4	15.3	bgzf(libdeflate)
-O bam -9	2651	2314.7	16.4	bgzf(libdeflate)

-V2.0 -X fast	1334	80.3	23.9	(default, level 1)
-V2.0 (default)	1206	111.2	25.1	(default)
-V2.0 -X small	1048	276.3	98.7	bzip2
-V2.0 -X archive	1042	294.2	98.5	bzip2

-V3.0 -X fast	1164	67.3	18.5	(default, level 1)
-V3.0 (default)	1016	64.5	26.4	(default)
-V3.0 -X small	1003	124.8	32.2	bzip2
-V3.0 -X archive	997	162.4	34.7	bzip2

-V3.1 -X fast	1161	56.8	17.6	rANS++
-V3.1 (default)	943	66.0	18.5	rANS++,tok3
-V3.1 -X small	892	142.7	81.8	rANS++,tok3,fqz
-V3.1 -X archive	875	288.9	97.6	rANS++,tok3,fqz,bzip2,arith

-V4.0 -X fast	1160	53.6	17.6	rANS++
-V4.0 (default)	941	60.9	17.7	rANS++,tok3
-V4.0 -X small	892	137.6	78.8	rANS++,tok3,fqz
-V4.0 -X archive	874	283.6	87.9	rANS++,tok3,fqz,bzip2,arith

gantt
    title 1 million PacBio Revio records
    todayMarker off
    dateFormat  X
    axisFormat %s

    section BAM
    -1,       97s / 16s  : 0,3061
    -5,      128s / 15s  : 0,2981
    -9,     2315s / 16s  : 0,2651
    - : 0,0

    section CRAM 2.0
    fast,     80s / 24s  : 0,1334
    normal,  111s / 25s  : 0,1206
    small,   276s / 32s  : 0,1048
    archive, 294s / 35s  : 0,1042
    - : 0,0

    section CRAM 3.0
    fast,     67s / 18s  : 0,1164
    normal,   64s / 26s  : 0,1016
    small,   125s / 32s  : 0,1003
    archive, 162s / 35s  : 0, 997
    - : 0,0

    section CRAM 3.1
    fast,     57s / 18s  : 0,1161
    normal,   66s / 18s  : 0, 943
    small,   143s / 82s  : 0, 892
    archive, 289s / 97s  : 0, 875
    - : 0,0

    section CRAM 4.0
    fast,     54s / 18s  : 0,1160
    normal,   61s / 18s  : 0, 941
    small,   128s / 79s  : 0, 892
    archive, 284s / 88s  : 0, 874

Building

Prerequisites

You will need a C compiler, a Unix “make” program plus zlib, bzip2 and lzma libraries and associated development packages (including C header files). The appropriate operating system package names and comands differ per system. On Debian Linux derived systems use the command below (or build and install your own copies from source):

sudo apt-get install make zlib1g-dev libbz2-dev liblzma-dev

On RedHat derived systems the package names differ:

sudo yum install make zlib-devel bzip2-devel xz-devel

Zlib

This code makes heavy use of the Deflate algorithm, assuming a Zlib interface. The native Zlib bundled with most systems is now rather old and better optimised versions exist for certain platforms (e.g. using the SSE instructions on Intel and AMD CPUs).

Therefore the –with-zlib=/path/to/zlib configure option may be used to point to a different Zlib. I have tested it with the vanilla zlib, Intel’s zlib and CloudFlare’s Zlib. Of the three it appears the CloudFlare one has the quickest implementation, but mileage may vary depending on OS and CPU.

CloudFlare: https://github.com/cloudflare/zlib Intel: https://github.com/jtkukunas/zlib Zlib-ng: https://github.com/Dead2/zlib-ng

The Zlib-ng one needs configuring with –zlib-compat and when you build Io_lib you will need to define -DWITH_GZFILEOP too. It also doesn’t work well when used in conjunction with LD_PRELOAD. Therefore I wouldn’t recommend it for now.

If you are using the CloudFlare implementation, you may also want to disable the CRC implementation in this code if your CloudFlare zlib was built with PCLMUL support as their implementation is faster. Otherwise the CRC here is quicker than Zlib’s own version. Building io_lib with the internal CRC code disabled is done with ./configure –disable-own-crc (or CFLAGS=-UIOLIB_CRC).

Libdeflate

The BAM reading and writing also has optional support for the libdeflate library (https://github.com/ebiggers/libdeflate). This can be used instead of an optimised zlib (see above), and generally is slightly faster. Build using:

./configure --with-libdeflate=/path

Git clone

We recommend building from a release tarball, which has the configure script already created for you. However if you wish to build from the latest code then use “git clone -r” to clone recursively to get the htscodecs submodule (or follow up a normal “git clone” with “git submodule update –init –recursive”). You will then need to create the configure script using autoreconf in both io_lib and htscodecs directories. This is easiest achieved using the supply bootstrap script.

./bootstrap

The autotools programs may not be on your system. If it fails, then install autoconf, automake and libtool packages; see above for example OS-specific installation commands.

Linux

We use the GNU autoconf build mechanism.

To build:

./configure

“./configure –help” will give a list of the options for GNU autoconf. For modifying the compiler options or flags you may wish to redefine the CC or CFLAGS variable.

Eg (in sh or bash): CC=cc CFLAGS=-g ./configure

make (or gmake)

This will build the sources.

CFLAGS may also be changed a build time using (eg): make ‘CFLAGS=-g …’

make install

The default installation location is /usr/local/bin and /usr/local/lib. These can be changed with the –prefix option to “configure”.

Windows

Under Microsoft Windows we recommend the use of MSYS and MINGW as a build environment.

These contain enough tools to build using the configure script as per Linux. The latest msys can be downloaded here:

http://repo.msys2.org/distrib/msys2-x86_64-latest.exe

Once installed and setup (“pacman -Syu”; close window & relaunch msys; “pacman -Syu” again), install mingw64 compilers via “pacman -S –needed man base-devel git mingw-w64-x86_64-toolchain”.

This should then be sufficient to configure and compile. However note that you may need to use “./configure –disable-shared” for the test harness to work due to deficiences in the libtool wrapper script.

If you wish to use Microsoft Visual Studio you may need to add the MSVC_includes subdirectory to your C include search path. This adds several missing header files (eg unistd.h and sys/time.h) needed to build this software. We do not have a MSVC project file available and have not tested the build under this environment for a number of years.

In this case you will also need to copy io_lib/os.h.in to io_lib/os.h and either remove the @SET_ENDIAN@ and adjacent @ lines (as these are normally filled out for you by autoconf) or add -DNO_AUTOCONF to your compiler options.

The code should also build cleanly under a cross-compiler. This has not been tested recently, but a past successful invocation was:

./configure \
        --host=x86_64-w64-mingw32 \
        --prefix=$DIST \
        --with-io_lib=$DIST \
        --with-tcl=$DIST/lib \
        --with-tk=$DIST/lib \
        --with-tklib=$DIST/lib/tklib0.5 \
        --with-zlib=$DIST \
        LDFLAGS=-L$DIST/lib

with $DIST being pre-populated with already built and installed 3rd party dependencies, some from MSYS mentioned above.

Libbsc

This is experimental, just to see what we can get with a high quality compression engine in CRAM. It’s hard to build right now, especially given it’s a C++ library and our code is C. The hacky solution now is (linux) e.g.:

../configure
CPPFLAGS=-I $HOME/ftp/compression/libbsc \ LDFLAGS="-L$ HOME/ftp/compression/libbsc -fopenmp”
LIBS=-lstdc++

Enable it using scramble -J, but note this requires experimental CRAM versions 3.1 or 4.0.

** Neither of these should be used for production data. **

MacOS X

The configure script should work by default, but if you are attempting to build FAT binaries to work on both i386 and ppc targets you’ll need to disable dependency tracking. Ie:

CFLAGS="-arch i386 -arch ppc" LDFLAGS="-arch i386 -arch ppc" \
  ../configure --disable-dependency-tracking