CHANGES

 libmad - MPEG audio decoder library
 Copyright (C) 2000-2004 Underbit Technologies, Inc.

 $Id: CHANGES,v 1.14 2004/02/17 02:02:03 rob Exp $

===============================================================================

Version 0.15.1 (beta)

  * Updated to autoconf 2.59, automake 1.8.2, libtool 1.5.2.

  * Replaced Layer III IMDCT routine with one based on a faster algorithm,
    improving both speed and accuracy.

  * Improved portability of the Huffman table initialization.

  * Fixed a problem that could result in an assertion failure in layer3.c
    due to an invalid Layer III free format bitrate.

  * Improved the robustness of Layer II bitrate/mode combinations, and added
    a new MAD_ERROR_BADMODE error enum. The allowability of low-bitrate
    stereo streams is influenced by the --enable-strict-iso option to
    `configure'.

Version 0.15.0 (beta)

  * Updated to autoconf 2.57, automake 1.7.5, libtool 1.4.3.

  * Added new mad_f_div() API routine.

  * Added a 64th entry to the Layer I/Layer II scalefactor table, for better
    compatibility with existing streams. The --enable-strict-iso option to
    `configure' can be used to disable use of this entry.

  * Modified the header decoding routine to allow the reserved emphasis
    value, for better compatibility with existing streams. The
    --enable-strict-iso option to `configure' can be used to restore the
    previous behavior of reporting this value as an error.

  * Added new MAD_EMPHASIS_RESERVED enumeration constant.

  * Fixed a bug in the ARM version of mad_f_scale64() discovered by Andre
    McCurdy.

  * Rewrote PowerPC assembly for minor gains.

  * Modified mad_timer_fraction() to avoid the possibility of division by
    zero when 0 is passed as the second argument.

  * Fixed a non-fatal problem caused by attempting to designate ancillary
    bits in Layer III after a decoding error.

  * Changed to build a shared library by default.

  * Changed to use native Cygwin build by default; give --host=mingw32 to
    `configure' to use MinGW (and avoid a dependency on the Cygwin DLL).

Version 0.14.2 (beta)

  * Changed Cygwin builds to use MinGW; resulting Win32 executables no
    longer have a dependency on Cygwin DLLs.

  * Added a new mad_stream_errorstr() API function to libmad for retrieving
    a string description of the current error condition.

Version 0.14.1 (beta)

  * Updated config.guess and config.sub to latest upstream versions.

  * Enabled libtool versioning rather than release numbering.

  * Improved the documentation in minimad.c.

  * Several other small fixes.

Version 0.14.0 (beta)

  * Added a 64-bit FPM negation operation to improve performance of subband
    synthesis on some platforms.

  * Improved MSVC++ portability and added MSVC++ project files.

  * Added rounding to Layer III requantization for slightly better accuracy.

Version 0.13.0 (beta)

  * Ancillary data is now properly extracted from Layer III streams.

  * Rewrote the Layer III joint stereo decoding routine to correct a major
    MPEG-2 problem and a minor MPEG-1 problem decoding intensity stereo.

  * Eliminated the dependency on sign-extending right shifts for Layer I and
    Layer II.

  * Renamed `private' field to `private_bits' for better C++ compatibility.

  * Gratuitously renamed `sfreq' field to `samplerate' and
    MAD_ERROR_BADSAMPLEFREQ constant to MAD_ERROR_BADSAMPLERATE.

  * Added `samplerate' and `channels' fields to synth.pcm struct to allow
    these to be different from the decoded frame, and for simpler access.

  * Added new mad_stream_options() and mad_decoder_options() API entries for
    special runtime decoding options.

  * Added new MAD_OPTION_IGNORECRC and MAD_OPTION_HALFSAMPLERATE options.

  * Added new MAD_FLAG_FREEFORMAT indicator flag.

  * Fixed some bugs in the async decoder.

  * Added a new mad_timer_multiply() API routine.

  * Eliminated `+' from asm constraints under Intel for better compatibility
    with some compilers.

  * Fixed a PIC-related problem in imdct_l_arm.S.

  * Eliminated a static variable to make libmad thread-safe.

Version 0.12.5 (beta)

  * Modified Layer III requantization to occur during Huffman decoding for
    significant performance gains.

  * Optimized short block IMDCT by eliminating redundant calculations.

  * Made several other Layer III performance improvements; added
    ASO_INTERLEAVE1, ASO_INTERLEAVE2, and ASO_ZEROCHECK
    architecture-specific options for best performance on various
    architectures.

  * Optimized synthesis DCT to store result values as soon as they are
    calculated.

Version 0.12.4 (beta)

  * New PowerPC fixed-point assembly courtesy of David Blythe.

  * Reorganized fixed-point assembly routines for easier maintenance and
    better performance.

  * Improved performance of subband synthesis through better indexing and
    fewer local variables.

  * Added alias reduction for the lower two subbands of mixed short blocks,
    per a report of ambiguity with ISO/IEC 11172-3 and for uniformity with
    most other implementations. Also improved alias reduction performance
    using multiply/accumulate.

  * Added --enable-strict-iso option to `configure' to override best
    accepted practices such as the alias reduction for mixed short blocks.

  * Improved performance of Layer III IMDCT by using longer
    multiply/accumulate runs where possible.

Version 0.12.3 (beta)

  * Added MPEG 2.5 support.

  * Added preliminary support for parameterizing the binary point position
    in the fixed-point representation.

  * Added multiply/accumulate optimization to the Layer III IMDCT for long
    blocks.

  * Fixed a bug in the handling of Layer III mixed_block_flag.

  * Fixed a configure problem when multiple -O CFLAGS are present.

Version 0.12.2 (beta)

  * Rearranged the synthesis polyphase filterbank memory vector for better
    locality of reference, and rewrote mad_synth_frame() to accommodate,
    resulting in improved performance.

  * Discovered a combination of compiler optimization flags that further
    improve performance.

  * Changed some array references in layer3.c to pointer derefs.

Version 0.12.1 (beta)

  * Resolved the intensity + MS joint stereo issue (a simple bug).
    OPT_ISKLUGE is no longer considered to be a kluge.

  * Fixed another, hopefully last main_data memory bug.

  * Split part of struct mad_frame into struct mad_header for convenience
    and size.

Version 0.12.0 (alpha)

  * Changed the build environment to use automake and libtool. A libmad
    shared library can now be built using the --enable-shared option to
    `configure'.

  * Added another callback to MAD's high-level decoder API after the frame
    header has been read but before the frame's audio data is decoded.

  * Streamlined header processing so that mad_frame_decode() can be called
    with or without having already called mad_frame_header().

  * Fixed some other header reading miscellany, including CRC handling and
    free bitrate detection, and frame length verification with free
    bitrates.

  * Fixed a problem with Layer III free bitrates > 320 kbps. The main_data
    buffer size should now be large enough to handle any size frame, by
    virtue of the maximum possible part2_3_length.

  * Further developed the async API; arbitrary messages can now be passed to
    the subsidiary decoding process.

  * Streamlined timer.c and extended its interface. It now has support for
    video frame/field lengths, including output support for drop-frame
    encoding.

  * Replaced many constant integer preprocessor defines with enums.

Version 0.11.4 (beta)

  * Fixed free format bitrate discovery.

  * Changed the timer implementation and extended its interface.

  * Integrated Nicolas Pitre's patch for pre-shifting at compile-time and
    for better multiply/accumulate code output.

  * Applied Simon Burge's patch to imdct_l_arm.S for a.out compatibility.

  * Added -mtune=strongarm for all ARM targets.

Version 0.11.3 (beta)

  * Added new --enable-speed and --enable-accuracy options for `configure'
    to automatically select appropriate SSO/ASO options, et al.

  * Modified subband synthesis to use multiply/accumulate optimization (if
    available) for better speed and/or accuracy.

  * Incorporated Andre McCurdy's changes for further rounding optimizations
    in the rest of his code.

Version 0.11.2 (beta)

  * Incorporated Nicolas Pitre's ARM assembly and parameterized scaling
    changes.

  * Incorporated Andre McCurdy's ARM assembly optimization (used only if
    --enable-aso is given to `configure' to enable architecture-specific
    optimizations.)

  * Reduced FPM_INTEL assembly to two instructions.

  * Fixed accuracy problems with certain FPM modes in synth.c.

  * Improved the accuracy of FPM_APPROX.

  * Improved the accuracy of SSO.

  * Improved sync discovery by checking for a sync word in the following
    frame.

  * Minor code clean-up.

  * Added experimental rules for generating a libmad.so shared library.

Version 0.11.1 (beta)

  * Moved libmad code into a separate directory.

  * Changed SSO to be disabled by default, as output accuracy is deemed to
    be more important than speed in the general case.

  * Fixed a bug in Layer III sanity checking that could cause a crash on
    certain random data input.

  * Extended the Layer III requantization table from 8191 to 8206 as some
    encoders are known to use these values, even though ISO/IEC 11172-3
    suggests the maximum should be 8191.

Version 0.11.0 (beta)

  * Implemented MPEG-2 extension to Lower Sampling Frequencies.

  * Improved Layer III performance by avoiding IMDCT calculation when all
    input samples are zero.

  * Significantly reduced size of Layer II tables.

Version 0.10.3 (beta)

  * Improved SSO output quality.

  * Made portable to cygwin.

  * Localized memory references in III_huffdecode() for better performance.

Version 0.10.2 (beta)

  * Rewrote Layer III long block 36-point IMDCT routine for better
    performance.

  * Improved subband synthesis fixed-point games somewhat.

Version 0.10.1 (beta)

  * Added a subband synthesis optimization (SSO) which involves modifying
    the fixed-point multiplication method during windowing. This produces
    subtle differences in the output but improves performance greatly.

  * Added I_STEREO and MS_STEREO flags to frame struct.

  * Eliminated privately-used CRCFAILED flag.

  * Fixed a bug where Layer III decoding could crash on some badly-formatted
    (e.g. non-MPEG) bitstreams.

  * Miscellaneous code clean-up.

Version 0.10.0 (beta)

  * Added SPARC fixed-point math support.

  * Revamped libmad API for better high- and low-level support.

  * Documented more of the code.

  * Changed sync semantics such that new stream buffers are assumed to be
    sync-aligned.

  * Changed Layer III to dynamically allocate static memory so as not to
    waste it (about 6.4K) when only decoding Layer I or Layer II.

===============================================================================