FAAC 2.2

[ Robert Kausch ]

• build: honor an explicit b_lto=false; drop __stdcall on x86 Windows

[ Nils Schimmelmann ]

• Bump the ABI to 2: faac_params_init() takes the caller's struct size
• HE-AAC auto range 8-32 kbps per channel at 44.1 and 48 kHz (was
  12-28), narrowing to 8-12 at 32 kHz; VBR up to -q 75 (was 60);
  HE-AAC v1 for multichannel layouts up to 8 channels, with one SBR
  fill element per SCE/CPE instead of one per frame
• Rate control: signed bit account for ABR; a real bit reservoir for CBR
  behind --cbr
• Refit the ABR bandwidth curve from a sweep: a wider core at 24-56 kbps
  stereo and every cutoff on the band grid reachable, where a double
  snap had left seven
• VBR codes at the top of the bandwidth curve (18750 Hz) instead of the
  full band; -q and -b are exclusive; -q documented as a constant
  quantizer quality, 1..5000, without bitrate anchors that drift
• SBR: reconstruction toward 20 kHz; noise floor -18 dB; log-spaced band
  table by rate; bs_stop_freq signals a k2 decoders actually accept;
  envelopes measured over the slots the decoder applies them to, coded
  in 3 dB steps, with two per frame without a transient from 17 kbps
  per channel
• Stereo: joint-stereo policy by rate; intensity on long windows below
  40 kbps per channel, L/R on short windows below the crossover from 80;
  short-window grouping and masking targets reworked; the sparsity mute
  that zeroed a quiet unjoined channel's bands is gone; M/S codes the
  side channel instead of dropping it and quantizes both halves against
  the L/R level; long windows take it on every band from 32 kbps per
  channel (24 on HE-AAC), short windows and HE-AAC at 20-24 kbps per
  channel only below 1-2 kHz
• A right-channel intensity band over a left PNS band is coded as PNS,
  so decoders that apply intensity first don't play it silent
• TNS on by default; frames screened before LPC analysis
• Block switching: the HE core runs its own transient detector instead
  of following SBR's, and both cores judge a sub-block's attack against
  a running level instead of only its neighbour, so dense stationary
  material stops defaulting to short windows
• Quantizer: short blocks take the same loudness target as long ones
  instead of 0.45x coarser, so transient frames stop losing bands to
  PNS; from 56 kbps per channel the treble de-emphasis is steeper, so
  the low bands get the margin; bands far below the frame's energy
  are allowed coarser targets; kernels take band widths in quads and
  vectorize fully, and grouping band energy is summed in four lanes
• HUFF2: choose section codebooks jointly across each window group,
  accounting for both codeword and section-header costs
• Enforce the ISO/IEC 14496-3 per-channel frame ceiling and bitrate
  limits; map channel counts to the standard AudioSpecificConfig/ADTS
  channel configurations and reject non-standard counts
• PNS and the MPEG version are now resolved by the encoder instead of
  the caller: faac_params drops pns_level for a use_pns flag,
  faac_encoder_info reports the resolved mpeg_version, and an
  explicit MPEG-2 request silently upgrades to MPEG-4 for HE-AAC;
  faac takes --no-pns in place of --pns <0..10>
• frontend: MP4 output by default with detection from the extension;
  24-bit packed PCM input; 64-bit mdat and duration; track language;
  UTF-8 and wide-character paths on CLI and Win32 GUI; iTunes gapless
  metadata (iTunSMPB); shared encoding engine and MP4 output in the GUI;
  GUI opens on ABR at 128 kbps; optional end-of-encode diagnostics;
  a PCM WAV could be read as float from an uninitialised header field;
  endian conversion utilities unified, fixing a WORDS_BIGENDIAN check
  that only worked because the macro happened to be undefined rather
  than 0; help text and the man page corrected throughout
• mp4write: container timing, HE-AAC sample rate declaration and gapless
  fixes; GUI PCM clipping fix
• HE-AAC: pad the pipeline delay to an even multiple of the core frame,
  so gapless-aware decoders trim the right sample count at both ends
• SBR: parameter resolution in VBR, tail drained on flush, psPresentFlag
  for mono, less per-frame work in the writer
• Pipeline draining during flush on short streams
• Fix a 64 kHz short-window scalefactor band width table that summed
  to 124 spectral lines instead of 128
• Build the lookup tables and FFT twiddle factors shared between
  encoder handles once per process instead of per open, so independent
  handles can be opened concurrently without racing each other's tables
• fft: replace the bit-reversed DIF kernel and its reorder pass with a
  self-sorting Stockham kernel that lands in natural order directly
• filtbank/channels: inline the window dispatch and simplify grouping
  bit accounting for vectorization
• Drop the never-selected KBD window from the filter bank
• Drop dead count mode from bitstream writer
• build: force-include config.h instead of per-file guards; drop the
  cold/noinline hints on the HE-AAC frame path so PGO and -Os/-O3
  make the call instead of a fixed attribute
• frontend: show the git commit hash in -h, the GUI, verbose logging,
  and the MP4 tag; -h reports the runtime libfaac version, not the
  compile-time one

Release Originally Created on: September 29, 2026 at 09:01:37 CST
Release Originally Published on: September 29, 2026 at 09:03:11 CST

FAAC 2.1

[ Nils Schimmelmann ]

• Honor ABI backward compatibility for faac_params
• SBR: align payload timing with core audio frames
• Add optional hard per-frame peak-bitrate limiter (--cap-rate)
• HUFF2: size both books of a codebook pair in one pass

Release Originally Created on: August 18, 2026 at 08:55:41 CST
Release Originally Published on: August 18, 2026 at 08:56:11 CST

FAAC 2.0

[ Nils Schimmelmann ]

• Harden input parsing and guard against allocation failures.
• Replace the classic faacEnc* C API with a new faac_* API in
  faac.h: parameters supplied once to faac_encoder_open(), uniform
  faac_status error reporting, resolved-property queries, and
  library-owned AudioSpecificConfig. The legacy faacEnc* surface and
  faaccfg.h are removed; the encoder core they exposed is now internal.
  SONAME bumped to 1 (libfaac.so.1). faac.h now defines
  FAAC_VERSION_MAJOR/MINOR/PATCH, tracking the SONAME, so callers
  can detect the new API at compile time (FAAC_VERSION_MAJOR >= 1).
• frontend: Port faac and the Win32 GUI to the new API; this fixes the
  AudioSpecificConfig memory leak on the MP4 output path.
• Add HE-AAC v1 (AAC-LC core + Spectral Band Replication) encoding via
  FAAC_OBJ_HE_AAC_V1, or FAAC_OBJ_AUTO, which picks LC or HE-AAC from
  the bitrate. The SBR core runs dual-rate (half-rate core, 2048-sample
  frame); faac_encoder_get_info() reports the full output rate and frame
  size so callers need no SBR-specific handling. CLI:
  --object-type lc|he-aac-v1|auto.
• stereo: Add Mixed Mode joint stereo (--joint 3) as the new default:
  per scale-factor band, picks IS above 5.5 kHz, M/S where channels are
  correlated, or L/R otherwise. Fix a midside band-silencing bug that
  produced L=R=0 on decode, guard against negative rounding before
  sqrt, and keep IS available at low sample rates.
• quantize: Restore short-window masking penalty, floor masking
  targets in quiet bands, drop stale tonal scaling in bmask, and keep
  global_gain a valid regular scalefactor -- fixing energy drops,
  quiet-band artifacts, and a decoder out-of-range error.
• tns: Cap TNS filter order to 12 to fix AAC-LC decoder rejections and
  audio dropouts in FFmpeg/FAAD.
• Retire the never-implemented MAIN/SSR/LTP object types across
  filtbank, frame, and the frontend, and collapse the single-model
  psychoacoustic vtable into direct calls.
• Fix a lookahead regression that had truncated the encoder's
  lookahead to an effective 1-frame delay, causing pre-echo artifacts
  and broken stereo coherence; then simplify the lookahead into a
  unified per-channel FIFO and energy timeline, replacing the ad hoc
  sampleBuff/next*SampleBuff/overlapBuff/prevSamples buffers.
• Relicense: rewrite stereo, quantize, channels, bitstream, filtbank,
  tns, huffdata, huff2, and the MP4 output code as original work under
  LGPL-2.1-or-later, and drop the matching MPEG reference-code preamble
  from README.md, --license, and docs/. Every source file is now free
  software. Update the license header itself from GNU Library GPL to
  Lesser GPL wording.
• fft: Replace the radix-2 FFT with radix-4 decimation-in-frequency as
  the sole implementation and precompute MDCT twiddles, for ~18%
  faster encode versus the radix-2 baseline.
• Standardize libfaac on single-precision floating point: drop the
  floating-point Meson build option and faac_real.h, and use
  float/sinf/cosf/sqrtf directly throughout the per-sample hot
  path. One-time init-time table generators (FFT/MDCT/SBR twiddles,
  window shapes, quantizer limits) keep double precision, where it's
  free. Benchmarked MOS-neutral versus the prior double-precision path.
• blockswitch: Move short-window detection to the time domain.
• Performance passes: reuse a shared work buffer for filtbank's MDCT
  scratch, and optimize TNS and stereo IS-gate hot paths.
• frame: Buffer encoder input so any input chunk size works.
• bitstream: Stop embedding the libfaac version string.
• build: Fix compiler warnings and transition to C11.
• frontend: Add a --creation-time flag for configurable MP4
  timestamps, vendor mingw-w64 wingetopt as a minimal-diff getopt
  fallback for MSVC builds, and keep TNS off by default in the GUI to
  match the CLI.

[ Fabian Greffrath ]

• Remove obsolete pkg-config template
• Restrict LTO to the shared library only

[ Orbis Security AI ]

• filtbank: Fix an out-of-bounds memcpy in FilterBank() that used
  FRAME_LEN instead of BLOCK_LEN_LONG for the overlap buffer copies

Release Originally Created on: July 20, 2026 at 06:52:15 CST
Release Originally Published on: July 20, 2026 at 06:52:37 CST

FAAC 1.50

[ Fabian Greffrath ]

• Build quantize_sse library with hidden symbols
• Don't call exit() from the library
• Define some more default_options in Meson build
• Fix some warnings in frontend/maingui.c
• Default to buildtype=release in Meson build
• Initialize data variable in huffcode()
• Remove the faulty HAVE_STRCASECMP check and other pointless header checks
• CI: Let Meson build set CFLAGS

[ Nils Schimmelmann ]

• Disallow PNS in MPEG-2 mode to match spec
• frontend: Change default to MPEG-4 as MPEG-2 is obsolete
• Add max-channels option to change MAX_CHANNELS from 64
• Fix PNS to stay on in JOINT_MS for low-bitrate accuracy
• Replace redundant cpe, sce, and lfe boolean flags in ChannelInfo with an enum
• Reduce MAX_CHANNELS to 8 for ADTS compliance
• tns: Prevent division-by-zero or instability on highly correlated signals
• Implement MOS-optimized bandwidth calculation
• Fine-tune rate controller to restore bitrate accuracy
• Fix channel-specific group metadata in joint-stereo
• Enable link-time optimization (LTO) in Meson build
• stereo: Fix undefined behaviour in intensity stereo for degenerate bands
• Fix scalefactor delta overflows to comply with AAC spec (ISO 14496-3)
• quantize: Pre-clamp scalefactor deltas to fix encoder/decoder mismatch

Release Originally Created on: April 16, 2026 at 06:58:28 CST
Release Originally Published on: April 16, 2026 at 06:58:53 CST

FAAC 1.40

[ tatsuz ]

• Fix compilation with Visual Studio

[ enWILLYado ]

• Fix SIMD calls

[ David Fort ]

• Add meson as build system

[ KokonoeTooru ]

• Meson: Install faac executable

[ Fabian Greffrath ]

• CI: fix artifact path
• Remove autoconf/automake build system
• Remove plugins stuff, unmaintained for decades
• Remove MSVC projects, deprecated in favour of meson
• Do not check for unused headers
• Generalize OS check in CI rule
• Remove redundant defines
• Make faacgui usable again
• Report library version on version mismatch
• Maintain library SONAME version 0.0.0
• Build both static and shared library by default
• Properly declare symbol visibility as hidden

[ Nils Schimmelmann ]

• Add options to disable DRM and opt for single floating-point precision
• CI: add native MSVC build and fix Windows compatibility
• Remove dead code
• Optimize FFT reordering by combining real and imaginary passes
• Optimize FFT performance
• CI: update GitHub Actions and add Dependabot configuration
• Refactor quantizer for portable C and extensible SIMD dispatch
• Optimize memory allocation and unify MDCT implementation
• Optimize MDCT by removing conditional branches and hoisting logic
• Rrefactor the hot path for writing bits to the output stream
• Remove Digital Radio Mondiale (DRM) support

Release Originally Created on: March 17, 2026 at 07:01:30 CST
Release Originally Published on: March 17, 2026 at 07:01:45 CST

FAAC 1.31.1

[ Fabian Greffrath ]

• Reduce autoconf requirement back down to 2.69
• Reformat configure.ac for the ac2ver.exe hack to work
• Upload Windows artifacts

Release Originally Created on: March 3, 2025 at 07:56:35 CST
Release Originally Published on: March 3, 2025 at 07:57:56 CST

FAAC 1.31

[ Tatsuya Suzuki ]

• updated Visual Studio projects to VS 2019
• main.c : progress report keeps alignment when encoding a large file
• project/msvc : cleanup, fixes and changes

[ Christopher Degawa ]

• frontend: fix out-of-root build

[ Fabian Greffrath ]

• add a pkg-config file
• avoid division by zero
• Remove #pragma pack from faacEncStruct (thanks Locutus of Borg)
• Reduce memory (thanks xnvi)
  • Remove BwpInfo bwpInfo from struct CoderInfo
  • Remove nextSampleBuff[] and next2SampleBuff[] from struct faacEncStruct
• tns: Initialize rArray[] variable
• update autoconf.ac and friends
• do not pass add-stdcall-alias option to clang
• always build both the regular and the DRM library
• fix cppcheck warnings
• add some basic CI
• fix compilation with clang on Windows
• Append INSTALL to README

[ Steve Fosdick ]

• Add album artist and various sort order MP4 tags

[ Aaron Boxer ]

• set libfaac library name to "faac" rather than "libfaac"

[ Frank ]

• Error C2065 (add #define _USE_MATH_DEFINES)

[ pine3ree ]

• Allow genre-id up to 255

Release Originally Created on: February 28, 2025 at 14:24:39 CST
Release Originally Published on: February 28, 2025 at 14:25:51 CST

FAAC 1.30

[ Robert Kausch ]

• Fix Joint Stereo coding

[ Krzysztof Nikiel ]

• Code cleanup and compilation fixes
• Fix endianness conversion functions

[ Takashi Yoshi ]

• Fix compilation with GCC < 4.6
• Fix compilation on big endian systems

[ Fabian Greffrath ]

• Fix division by zero errors
• Fix compilation with GCC <= 4.7.3
• Change pointer type for proper arithmetics
• Fix logic error in compiler detection
• Revert back to some more generic SSE2 code
• Fix a memory leak
• Fix some cppcheck warnings in the Cfaac code
• Check index ranges before dereferencing book arrays (CVE-2018-19886)
• Clean up stdint.h header inclusions
• Consistently use stdint.h types

[ Michael Fink ]

• Update Visual Studio 2017 projects
• Add stdint.h header inclusions
• Port over ac2ver tool from faad2 to generate PACKAGE_VERSION
  when compiling with Visual Studio

[ Eugène Filin ]

• Memory allocations redefined

Release Originally Created on: October 16, 2019 at 10:52:19 CST
Release Originally Published on: October 16, 2019 at 10:56:39 CST