FAAC - Freeware Advanced Audio Coder


Contents

  • Usage
  • options
  • Copyrights
  • Patents
  • People


    • Usage

    faac [options] <infile> <outfile>

    Options

    Rate control. -q holds a quality and lets the bitrate follow the material (VBR); -b holds an average over the file (ABR, the default at 128 kbps); -b --cbr holds it in every frame (CBR). --cap-rate bounds any single frame in any mode, so -q --cap-rate is capped VBR: constant quality, no frame above the cap. -q and -b are exclusive.
  • -q <quality> Constant quality, 1..5000 (default: 100). Higher is better and costs more bits. The bitrate follows the material, so one quality can take twice the bits on one recording as on another, and it moves between releases as the encoder is tuned. With --object-type auto a quality up to 75 uses HE-AAC v1; from 76 it is AAC-LC at a much higher bitrate. Use -b for a predictable size.
  • -b <bitrate> Average bitrate in kbps, up to about 500 for stereo.
  • --cbr Hold the -b bitrate in every frame. A bit reservoir keeps each frame inside the decoder's input buffer and pads the ones that would leave it to overflow, so the stream lands on its rate exactly. For constant-rate channels and matched-bitrate comparisons; on a file or a packet network the padding is bytes for nothing.
  • --cap-rate <bitrate> Cap any single frame at the given kbps, for transports that drop an oversized frame rather than splitting it, and for bounding VBR. Must be at least the -b bitrate. Best effort: a frame cannot shrink below its own side information.
  • -c <freq> Cut the audio off above the given frequency. Left out, the encoder chooses the cutoff from the bitrate, between 14 and 19 kHz on most stereo settings; VBR codes up to 19 kHz. It is printed at the start of the encode. Set it as high as half the sample rate to keep everything; the bitrate rises with it. HE-AAC sets its own cutoff and ignores this.
    • Coding tools.
  • --object-type <type> lc (AAC-LC), he-aac-v1 (AAC-LC plus Spectral Band Replication) or auto (default), which picks HE-AAC v1 at low bitrates and qualities and AAC-LC above.
  • --joint <mode> Joint stereo: 0 off, 1 Mid/Side, 2 Intensity Stereo, 3 both, chosen per band (default).
  • --no-pns Disable Perceptual Noise Substitution, which codes noise-like bands as a noise level instead of spectral lines. On by default.
  • --no-tns Disable Temporal Noise Shaping, which reduces pre-echo on transients. On by default.
    • Input and output.
  • -o <filename> Output file. The format follows the extension: .m4a/.mp4/.m4b for MP4 (the default), .aac/.adts for an ADTS stream.
  • -a ADTS stream output.
  • -r Raw AAC output without headers. Rarely what you want.
  • - A hyphen in place of the input or output file reads from stdin or writes to stdout, for piping.
  • -v <level> Verbosity; -v0 is quiet.
  • -P Raw PCM input instead of WAV. -R sets the sample rate (default 44100), -B the sample size (8, 16, 24 or 32 bits, or float; default 16), -C the channel count (default 2), -X swaps the byte order.
  • -I <C[,LFE]> Positions of the centre and LFE channels in multichannel input (default 3,4, as in 5.1 WAV).
  • --ignorelength Ignore the length in the WAV header, for files over 4 GB.
  • --overwrite Overwrite an existing output file.
    • MP4 tags. --artist, --album, --title, --composer, --genre, --track, --disc, --year, --comment, --compilation, --cover-art <file> (GIF, JPEG or PNG), --albumartist, --lang, the *sort variants, and --tag <name,value> for any other iTunes tag.

    Advanced, for testing. --mpeg-vers 2|4 forces the MPEG version (default 4); --shortctl 0|1|2 forces the block type (both, no short, no long).

    faac --long-help prints all of these.


    Copyrights

    FAAC - Freeware Advanced Audio Coder
    FAAC is free software, licensed under the GNU Lesser General Public License (LGPL), version 2.1 or later: 
    FAAC - Freeware Advanced Audio Coder
Copyright © 1999-2001, Menno Bakker
Copyright © 2002-2017, Krzysztof Nikiel
Copyright © 2004, Dan Villiom P. Christiansen
Copyright © 2005-2026, Fabian Greffrath
Copyright © 2026, Nils Schimmelmann

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

    Patents

    Please note that the use of this software may require the payment of patent royalties. You need to consider this issue before you start building derivative works. We are not warranting or indemnifying you in any way for patent royalities! YOU ARE SOLELY RESPONSIBLE FOR YOUR OWN ACTIONS!



    People

    Currently maintained by M. Bakker (menno)

    Other contributors:
    Tony Lenox
    RageOMatic
    thebard
    Ivan Dimkovic
    Krzysztof Nikiel (knik)
    Janne Hyvärinen (ca5e)
    Stuart Espey (stux)
    Andrew Voznytsa
    Måns Rullgård
    Bill May


    FAAC is free software, licensed under the GNU Lesser General Public License (LGPL), version 2.1 or later.