Digital audio processing of Swiss Army Knife Sox sound algorithm and usage

Sox can clearly write the required audio processing effect, can be easily reused, under the current conditions is a more convenient use of the project. However, I believe that with the development of audacity, it is possible to gradually replace the function of Sox in the future.

The main concern for Sox is her audio effects feature, as file format conversion, playback, and recording functions have been implemented to a greater extent in ffmpeg. A list of Sox effects is as follows:

Tone/filter effects [Filters]

allpass: RBJ all-pass biquad IIR filterbandpass: RBJ band-pass biquad IIR filterbandreject: RBJ band-reject biquad IIR filterband: SPKit resonator band-pass IIR filterbass: Tone control: RBJ shelving biquad IIR filterequalizer: RBJ peaking equalisation biquad IIR filterfirfit+: FFT convolution FIR filter using given freq. response (W.I.P.)highpass: High-pass filter: Single pole or RBJ biquad IIRhilbert: Hilbert transform filter (90 degrees phase shift)lowpass: Low-pass filter: single pole or RBJ biquad IIRsinc: Sinc-windowed low/high-pass/band-pass/reject FIRtreble: Tone control: RBJ shelving biquad IIR filter

example：

1 play file.wav bass -20
2 play file.wav bass +20

Production effects [Synthetic effects]

chorus: Make a single instrument sound like manydelay: Delay one or more channelsecho: Add an echoechos: Add a sequence of echosflanger: Stereo flangeroverdrive: Non-linear distortionphaser: Phase shifterrepeat: Loop the audio a number of timesreverb: Add reverberationreverse: Reverse the audio (to search for Satanic messages ;-)tremolo: Sinusoidal volume modulation

example：
1 play file.wav tremolo 3.5 60 //颤抖音效果
2 play file.xxx echo 0.8 0.88 60 0.4 //回音效果

Volume/level effects [Volume effect]

compand: Signal level compression/expansion/limitingcontrast: Phase contrast volume enhancementdcshift: Apply or remove DC offsetfade: Apply a fade-in and/or fade-out to the audiogain: Apply gain or attenuation; normalise/equalise/balance/headroomloudness: Gain control with ISO 226 loudness compensationmcompand: Multi-band compression/expansion/limiting norm: Normalise to 0dB (or other)vol: Adjust audio volume

examle：
1 play *.wav fade t 00:00:50.09 00:01:00 00:00:06 //设置淡入淡出效果

Editing effects [Audio editing effects, mainly adding, removing a class of functions]

pad: Pad (usually) the ends of the audio with silencesilence: Remove portions of silence from the audiosplice: Perform the equivalent of a cross-faded tape splicetrim: Cuts portions out of the audiovad: Voice activity detector

Mixing effects [Mixing effect]

channels: Auto mix or duplicate to change number of channelsdivide+: Divide sample values by those in the 1st channel (W.I.P.)remix: Produce arbitrarily mixed output channelsswap: Swap stereo channels

Pitch/tempo effects [The function of rhythm and pitch, Pitch is the algorithm of the legendary pitch.]

bend: Bend pitch at given times without changing tempopitch: Adjust pitch (= key) without changing tempospeed: Adjust pitch & tempo togetherstretch: Adjust tempo without changing pitch (simple alg.)tempo: Adjust tempo without changing pitch (WSOLA alg.)

example：
1 sox file1.wav file2.wav speed 1.29

Mastering effects [This does not know what it means, the following two effects, one is to add jitter to enhance the signal-to-noise ratio, an effect sampling rate. The first one works well]

dither: Add dither noise to increase quantisation SNRrate: Change audio sampling rate

Example

Specialised filters/mixers [more strange effect]

deemph: ISO 908 CD de-emphasis (shelving) IIR filterearwax: Process CD audio to best effect for headphone usenoisered: Filter out noise from the audiooops: Out Of Phase Stereo (or `Karaoke`) effectriaa: RIAA vinyl playback equalisation

effectsanalysis [the function used to display statistical information]

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`

example：
1 sox 杨望.wav -n stat //统计信息

Miscellaneous effects [Additional functions, more interesting]

ladspa: Apply LADSPA plug-in effects e.g. CMT (Computer Music Toolkit)synth: Synthesise/modulate audio tones or noise signalsnewfile: Create a new output file when an effects chain ends.restart: Restart 1st effects chain when multiple chains exist.

Low-level signal processing effects [underlying processing function, sensory and filter that group is more like it]

biquad: 2nd-order IIR filter using externally provided coefficientsdownsample: Reduce sample rate by discarding samplesfir: FFT convolution FIR filter using externally provided coefficientsupsample: Increase sample rate by zero stuffing

Digital audio processing of Swiss Army Knife Sox sound algorithm and usage