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The current release handles the following audio file formats:

  • Raw files in various binary formats
  • Raw textual data
  • Amiga 8svx files
  • Apple/SGI AIFF files
  • SUN .au files
    • PCM, u-law, A-law
    • G7xx ADPCM files (read only)
    • mutant DEC .au files
    • NeXT .snd files
  • AVR files
  • CDDA (Compact Disc Digital Audio format)
  • CVS and VMS files (continuous variable slope)
  • Grandstream ring-tone files
  • GSM files
  • HTK files
  • LPC-10 files
  • Macintosh HCOM files
  • Amiga MAUD files
  • AMR-WB & AMR-NB (with optional libamrwb & libamrnb libraries)
  • MP2/MP3 (with optional libmad, libtwolame and libmp3lame libraries)
  • MP4, AAC, AC3, WAVPACK, AMR-NB files (with optional ffmpeg library)
  • AVI, WMV, Ogg Theora, MPEG video files (with optional ffmpeg library)
  • Ogg Vorbis files (with optional Ogg Vorbis libraries)
  • FLAC files (with optional libFLAC)
  • IRCAM SoundFile files
  • NIST SPHERE files
  • Turtle beach SampleVision files
  • Sounder & Soundtool (DOS) files
  • Yamaha TX-16W sampler files
  • SoundBlaster .VOC files
  • Dialogic/OKI ADPCM files (.VOX)
  • Microsoft .WAV files
    • PCM, floating point
    • u-law, A-law, MS ADPCM, IMA (DMI) ADPCM
    • GSM
    • RIFX (big endian)
  • WavPack files (with optional libwavpack library)
  • Psion (palmtop) A-law WVE files and Record voice notes
  • Maxis XA Audio files
    • EA ADPCM (read support only, for now)
  • Pseudo formats that allow direct playing/recording from most audio devices
  • The "null" pseudo-file that reads and writes from/to nowhere

The audio effects/tools included in this release are as follows:

  • Tone/filter effects
    • allpass: RBJ all-pass biquad IIR filter
    • bandpass: RBJ band-pass biquad IIR filter
    • bandreject: RBJ band-reject biquad IIR filter
    • band: SPKit resonator band-pass IIR filter
    • bass: Tone control: RBJ shelving biquad IIR filter
    • equalizer: RBJ peaking equalisation biquad IIR filter
    • firfit+: FFT convolution FIR filter using given freq. response (W.I.P.)
    • highpass: High-pass filter: Single pole or RBJ biquad IIR
    • hilbert: Hilbert transform filter (90 degrees phase shift)
    • lowpass: Low-pass filter: single pole or RBJ biquad IIR
    • sinc: Sinc-windowed low/high-pass/band-pass/reject FIR
    • treble: Tone control: RBJ shelving biquad IIR filter
  • Production effects
    • chorus: Make a single instrument sound like many
    • delay: Delay one or more channels
    • echo: Add an echo
    • echos: Add a sequence of echos
    • flanger: Stereo flanger
    • overdrive: Non-linear distortion
    • phaser: Phase shifter
    • repeat: Loop the audio a number of times
    • reverb: Add reverberation
    • reverse: Reverse the audio (to search for Satanic messages ;-)
    • tremolo: Sinusoidal volume modulation
  • Volume/level effects
    • compand: Signal level compression/expansion/limiting
    • contrast: Phase contrast volume enhancement
    • dcshift: Apply or remove DC offset
    • fade: Apply a fade-in and/or fade-out to the audio
    • gain: Apply gain or attenuation; normalise/equalise/balance/headroom
    • loudness: Gain control with ISO 226 loudness compensation
    • mcompand: Multi-band compression/expansion/limiting
    • norm: Normalise to 0dB (or other)
    • vol: Adjust audio volume
  • Editing effects
    • pad: Pad (usually) the ends of the audio with silence
    • silence: Remove portions of silence from the audio
    • splice: Perform the equivalent of a cross-faded tape splice
    • trim: Cuts portions out of the audio
    • vad: Voice activity detector
  • Mixing effects
    • channels: Auto mix or duplicate to change number of channels
    • divide+: Divide sample values by those in the 1st channel (W.I.P.)
    • remix: Produce arbitrarily mixed output channels
    • swap: Swap stereo channels
  • Pitch/tempo effects
    • bend: Bend pitch at given times without changing tempo
    • pitch: Adjust pitch (= key) without changing tempo
    • speed: Adjust pitch & tempo together
    • stretch: Adjust tempo without changing pitch (simple alg.)
    • tempo: Adjust tempo without changing pitch (WSOLA alg.)
  • Mastering effects
    • dither: Add dither noise to increase quantisation SNR
    • rate: Change audio sampling rate
  • Specialised filters/mixers
    • deemph: ISO 908 CD de-emphasis (shelving) IIR filter
    • earwax: Process CD audio to best effect for headphone use
    • noisered: Filter out noise from the audio
    • oops: Out Of Phase Stereo (or `Karaoke') effect
    • riaa: RIAA vinyl playback equalisation
  • Analysis `effects'
    • noiseprof: Produce a DFT profile of the audio (use with noisered)
    • spectrogram: graph signal level vs. frequency & time (needs `libpng')
    • stat: Enumerate audio peak & RMS levels, approx. freq., etc.
    • stats: Multichannel aware `stat'
  • Miscellaneous effects
    • ladspa: Apply LADSPA plug-in effects e.g. CMT (Computer Music Toolkit)
    • synth: Synthesise/modulate audio tones or noise signals
    • newfile: Create a new output file when an effects chain ends.
    • restart: Restart 1st effects chain when multiple chains exist.
  • Low-level signal processing effects
    • biquad: 2nd-order IIR filter using externally provided coefficients
    • downsample: Reduce sample rate by discarding samples
    • fir: FFT convolution FIR filter using externally provided coefficients
    • upsample: Increase sample rate by zero stuffing
    + Experimental or incomplete effect; may change in future.

Multiple audio files can be combined (and then further processed with effects) using any one of the following combiner methods:

  • concatenate
  • mix
  • merge: E.g. two mono files to one stereo file
  • sequence: For playing multiple audio files/streams
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