libacm - Library for InterPlay ACM Audio format.
================================================

Intro
-----

Decoder library for InterPlay ACM audio files.
Includes command line tool.

The format was used for games Fallout, Fallout 2 and Baldur's Gate series.
It is less efficient than the more advanced MP3, Vorbis or AAC algorithms,
but it's main feature is very fast decoding speed. 


NEWS
----

FFmpeg
~~~~~~

* This decoder was merged into FFmpeg 3.0.  Now ACM files can be played
  via ffmpeg commands or using libavcodec.

Version 1.3
~~~~~~~~~~~

* acmtool: Fix crash with libao 1.x
* plugins: drop, they do not work with any modern player.

Version 1.2
~~~~~~~~~~~

* decoder: Fix error handling in load_bits()   (Brian "Moses" Hall)
* acmtool: Show time instead number of samples.

* plugin-xmms2: New plugin for XMMS2
* plugin-audacious: Support Audacious up to 2.4
* plugin-gstreamer: Fix End-Of-Stream handling
* plugin-xmms: Drop it.  XMMS is obsolete.

Version 1.1
~~~~~~~~~~~

* acmtool: play files with libao: acmtool -p FILE
* decoder: support WAVC files, which are ACM files with additional header.
* decoder: take mono ACM as stereo, as there are lot of badly tagged files.
           Trust channel count on WAVC files, those seem to be correct,
           and WAVC is mostly used for samples.
* decoder: avoid divide-by-zero in bitrate calculation.
* plugin-audacious: Keep up with API changes in Audacious 2.x branch.
           It seems to be still compatible with 1.x, but I have not tested.

Version 1.0
~~~~~~~~~~~

* decoder: excpect EOF in more places - otherwise libacm
  complained about "unexpected eof".
* decoder: on reading assume there is additional single zero byte
  at the end of all files.  Otherwise last block on some files was
  skipped because last few bits could not be read.

Thanks to above 2 changes libacm now decodes all Fallout 1/2
files in full length and without complaining.

* License plugins under LGPL.
* New separate plugin for Audacious 1.5+
* Remove plugin for Beep Media Player
* Rewrite plugin-gstreamer.c for GStreamer "Hell On Earth" 0.10
* acmtool -d -o - writes to stdout.

Version 0.9.2
~~~~~~~~~~~~~

* License core libacm code under minimal BSD/ISC license.
  Plugins continue to be under GPL.
* Fix acmtool crash.  ([email protected])

Version 0.9.1 (unreleased)
~~~~~~~~~~~~~~~~~~~~~~~~~~

* Use autoconf/automake for build system
* Plugin for GStreamer 0.8.  (alsasink seems to be buggy for 22050 Hz
  audio.  If you hear any cracks, try to use osssink.)
* Small cleanups.

Version 0.9
~~~~~~~~~~~

* First public release.
* Includes: decoder, acmtool, plugins for XMMS, BEEP and Winamp


Installation
------------

  ./configure
  make
  make install

Command line tools usage
------------------------

    $ acmtool -h
    acmtool - libacm version 1.0
    Decode: acmtool -d [-q][-m|-s] [-r|-n] -o outfile infile
	    acmtool -d [-q][-m|-s] [-r|-n] infile [infile ...]
    Other:  acmtool -i ACMFILE [ACMFILE ...]
	    acmtool -M|-S ACMFILE [ACMFILE ...]
    Commands:
      -d     decode audio into WAV files
      -p     play audio
      -i     show info about ACM files
      -M     modify ACM header to have 1 channel
      -S     modify ACM header to have 2 channels
    Switches:
      -m     force mono wav
      -s     force stereo wav
      -r     raw output - no wav header
      -q     be quiet
      -n     no output - for benchmarking
      -o FN  output to file, can be used if single source file

The mono/stereo options are necessary because for some ACM files
the number of channels in header in wrong.  Usually those are
game samples, which contain mono audio but are tagger as stereo.


Credits
-------

All the hard work of reverse engineering the format was done
by ABel from TeamX. I simply re-implemented it in C.