mix

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Version: v0.0.4 Latest Latest
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Published: Mar 30, 2016 License: MIT Imports: 6 Imported by: 0

README

Mix

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https://gopkg.in/mix.v0

Sequence-based Go-native audio mixer for music apps

See demo/demo.go:

package main

import (
  "fmt"
  "os"
  "time"
  
  "gopkg.in/mix.v0"
  "gopkg.in/mix.v0/bind"
)

var (
  sampleHz   = float64(48000)
  spec = bind.AudioSpec{
    Freq:     sampleHz,
    Format:   bind.AudioF32,
    Channels: 2,
    }
  bpm        = 120
  step       = time.Minute / time.Duration(bpm*4)
  loops      = 16
  prefix     = "sound/808/"
  kick1      = "kick1.wav"
  kick2      = "kick2.wav"
  marac      = "maracas.wav"
  snare      = "snare.wav"
  hitom      = "hightom.wav"
  clhat      = "cl_hihat.wav"
  pattern    = []string{
    kick2,
    marac,
    clhat,
    marac,
    snare,
    marac,
    clhat,
    kick2,
    marac,
    marac,
    hitom,
    marac,
    snare,
    kick1,
    clhat,
    marac,
  }
)

func main() {
  defer mix.Teardown()    
  
  mix.Debug(true)
  mix.Configure(spec)
  mix.SetSoundsPath(prefix)
  mix.StartAt(time.Now().Add(1 * time.Second))

  t := 2 * time.Second // padding before music
  for n := 0; n < loops; n++ {
    for s := 0; s < len(pattern); s++ {
      mix.SetFire(pattern[s], t+time.Duration(s)*step, 0, 1.0, 0)
    }
    t += time.Duration(len(pattern)) * step
  }

  fmt.Printf("Mix, pid:%v, spec:%v\n", os.Getpid(), spec)
  for mix.FireCount() > 0 {
    time.Sleep(1 * time.Second)
  }
}

Play this Demo from the root of the project, using SDL 2.0 for hardware audio playback:

make demo

Or export WAV via stdout > demo/output.wav:

make demo.wav
What?

Game audio mixers are designed to play audio spontaneously, but when the timing is known in advance (e.g. sequence-based music apps) there is a demand for much greater accuracy in playback timing.

Read the API documentation at godoc.org/gopkg.in/mix.v0

Mix seeks to solve the problem of audio mixing for the purpose of the playback of sequences where audio files and their playback timing is known in advance.

Mix stores and mixes audio in native Go []float64 and natively implements Paul Vögler's "Loudness Normalization by Logarithmic Dynamic Range Compression" (details below)

Author: Charney Kaye

NOTICE: THIS PROJECT IS IN ALPHA STAGE, AND THE API MAY BE SUBJECT TO CHANGE.

Best efforts will be made to preserve each API version in a release tag that can be parsed, e.g. gopkg.in/mix.v0

Why?

Even after selecting a hardware interface library such as PortAudio or C++ SDL 2.0, there remains a critical design problem to be solved.

This design is a music application mixer. Most available options are geared towards Game development.

Game audio mixers offer playback timing accuracy +/- 2 milliseconds. But that's totally unacceptable for music, specifically sequence-based sample playback.

The design pattern particular to Game design is that the timing of the audio is not know in advance- the timing that really matters is that which is assembled in near-real-time in response to user interaction.

In the field of Music development, often the timing is known in advance, e.g. a sequencer, the composition of music by specifying exactly how, when and which audio files will be played relative to the beginning of playback.

Ergo, mix seeks to solve the problem of audio mixing for the purpose of the playback of sequences where audio files and their playback timing is known in advance. It seeks to do this with the absolute minimal logical overhead on top of the audio interface.

Mix takes maximum advantage of Go by storing and mixing audio in native Go []float64 and natively implementing Paul Vögler's "Loudness Normalization by Logarithmic Dynamic Range Compression"

Time

To the Mix API, time is specified as a time.Duration-since-epoch, where the epoch is the moment that mix.Start() was called.

Internally, time is tracked as samples-since-epoch at the master out playback frequency (e.g. 48000 Hz). This is most efficient because source audio is pre-converted to the master out playback frequency, and all audio maths are performed in terms of samples.

The Mixing Algorithm

Inspired by the theory paper "Mixing two digital audio streams with on the fly Loudness Normalization by Logarithmic Dynamic Range Compression" by Paul Vögler, 2012-04-20. A .PDF has been included here, from the paper originally published here.

Usage

There's a demo implementation of mix included in the demo/ folder in this repository. Run it using the defaults:

go run 808.go

Or specify options, e.g. using SDL for playback

go run 808.go --playback sdl

To show the help screen:

go run 808.go --help
Dependencies
SDL2

Ubuntu:

sudo apt-get install libsdl2-dev

Mac OS X:

brew install sdl2

More details for Linux, Mac and Windows: "Setting up SDL" by Lazy Foo' Productions

Portaudio

Ubuntu:

sudo apt-get install portaudio19-dev

Mac OS X:

brew install portaudio

Windows: "Building and Installing PortAudio on Windows" by GNU Radio.

Documentation

Overview

Sequence-based Go-native audio mixer for music apps

Go-native audio mixer for Music apps

See `demo/demo.go`:

package main

import (
  "fmt"
  "os"
  "time"

  "gopkg.in/mix.v0"
  "gopkg.in/mix.v0/bind"
)

var (
  sampleHz   = float64(48000)
  spec = bind.AudioSpec{
    Freq:     sampleHz,
    Format:   bind.AudioF32,
    Channels: 2,
    }
  bpm        = 120
  step       = time.Minute / time.Duration(bpm*4)
  loops      = 16
  prefix     = "sound/808/"
  kick1      = "kick1.wav"
  kick2      = "kick2.wav"
  marac      = "maracas.wav"
  snare      = "snare.wav"
  hitom      = "hightom.wav"
  clhat      = "cl_hihat.wav"
  pattern    = []string{
    kick2,
    marac,
    clhat,
    marac,
    snare,
    marac,
    clhat,
    kick2,
    marac,
    marac,
    hitom,
    marac,
    snare,
    kick1,
    clhat,
    marac,
  }
)

func main() {
  defer mix.Teardown()

  mix.Debug(true)
  mix.Configure(spec)
  mix.SetSoundsPath(prefix)
  mix.StartAt(time.Now().Add(1 * time.Second))

  t := 2 * time.Second // padding before music
  for n := 0; n < loops; n++ {
    for s := 0; s < len(pattern); s++ {
      mix.SetFire(pattern[s], t+time.Duration(s)*step, 0, 1.0, 0)
    }
    t += time.Duration(len(pattern)) * step
  }

  fmt.Printf("Mix, pid:%v, spec:%v\n", os.Getpid(), spec)
  for mix.FireCount() > 0 {
    time.Sleep(1 * time.Second)
  }
}

Play this Demo from the root of the project, using SDL 2.0 for hardware audio playback:

make demo

Or export WAV via stdout `> demo/output.wav`:

make demo.wav

What

Game audio mixers are designed to play audio spontaneously, but when the timing is known in advance (e.g. sequence-based music apps) there is a demand for much greater accuracy in playback timing.

Read the API documentation at https://godoc.org/gopkg.in/mix.v0

Mix seeks to solve the problem of audio mixing for the purpose of the playback of sequences where audio files and their playback timing is known in advance.

Mix stores and mixes audio in native Go `[]float64` and natively implements Paul Vögler's "Loudness Normalization by Logarithmic Dynamic Range Compression" (details below)

Author: Charney Kaye <hiya@charney.io>

Why

Even after selecting a hardware interface library such as http://www.portaudio.com/ or https://www.libsdl.org/, there remains a critical design problem to be solved.

This design is a music application mixer. Most available options are geared towards Game development.

Game audio mixers offer playback timing accuracy +/- 2 milliseconds. But that's totally unacceptable for music, specifically sequence-based sample playback.

The design pattern particular to Game design is that the timing of the audio is not know in advance- the timing that really matters is that which is assembled in near-real-time in response to user interaction.

In the field of Music development, often the timing is known in advance, e.g. a sequencer, the composition of music by specifying exactly how, when and which audio files will be played relative to the beginning of playback.

Ergo, mix seeks to solve the problem of audio mixing for the purpose of the playback of sequences where audio files and their playback timing is known in advance. It seeks to do this with the absolute minimal logical overhead on top of the audio interface.

Mix takes maximum advantage of Go by storing and mixing audio in native Go `[]float64` and natively implementing Paul Vögler's "Loudness Normalization by Logarithmic Dynamic Range Compression" (see The Mixing Algorithm below)

Time

To the Mix API, time is specified as a time.Duration-since-epoch, where the epoch is the moment that mix.Start() was called.

Internally, time is tracked as samples-since-epoch at the master out playback frequency (e.g. 48000 Hz). This is most efficient because source audio is pre-converted to the master out playback frequency, and all audio maths are performed in terms of samples.

The Mixing Algorithm

Inspired by the theory paper "Mixing two digital audio streams with on the fly Loudness Normalization by Logarithmic Dynamic Range Compression" by Paul Vögler, 2012-04-20. This paper is published at http://www.voegler.eu/pub/audio/digital-audio-mixing-and-normalization.html.

Usage

There's a demo implementation of mix included in the `demo/` folder in this repository. Run it using the defaults:

go run 808.go

Or specify options, e.g. using SDL for playback

go run 808.go --playback sdl

To show the help screen:

go run 808.go --help

Dependencies

SDL2

Ubuntu:

sudo apt-get install libsdl2-dev

Mac OS X:

brew install sdl2

More details for Linux, Mac and Windows: http://lazyfoo.net/SDL_tutorials/lesson01/index.php

Portaudio

Ubuntu:

sudo apt-get install portaudio19-dev

Mac OS X:

brew install portaudio

Windows: https://gnuradio.org/redmine/projects/gnuradio/wiki/PortAudioInstall.

This project is in Alpha and the API is subject to change

Best efforts will be made to preserve each API version in a release tag that can be parsed, e.g. http://gopkg.in/mix.v0

Mix in good health!

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func ClearAllFires added in v0.0.3

func ClearAllFires()

ClearAllFires to clear all fires currently ready, or live

func Configure

func Configure(s spec.AudioSpec)

Configure the mixer frequency, format, channels & sample rate.

func Debug

func Debug(isOn bool)

Debug ON/OFF (ripples down to all sub-modules)

func FireCount added in v0.0.3

func FireCount() int

FireCount to check the number of fires currently scheduled for playback

func GetNowAt added in v0.0.4

func GetNowAt() time.Duration

GetNowAt returns current mix position

func GetStartTime added in v0.0.2

func GetStartTime() time.Time

GetStartTime the mixer was started at

func OutputClose added in v0.0.4

func OutputClose()

OutputBegin to output WAV closer as []byte via stdout

func OutputContinueTo added in v0.0.4

func OutputContinueTo(t time.Duration)

OutputContinueTo output as []byte via stdout, up to a specified duration-since-start

func OutputStart added in v0.0.4

func OutputStart(length time.Duration)

OutputStart requires a known length

func SetFire

func SetFire(source string, begin time.Duration, sustain time.Duration, volume float64, pan float64) *fire.Fire

SetFire to represent a single audio source playing at a specific time in the future (in time.Duration from play start), with sustain time.Duration, volume from 0 to 1, and pan from -1 to +1

func SetMixCycleDuration added in v0.0.3

func SetMixCycleDuration(d time.Duration)

Set the duration between "mix cycles", wherein garbage collection is performed.

func SetSoundsPath added in v0.0.2

func SetSoundsPath(prefix string)

SetSoundsPath prefix

func Spec

func Spec() *spec.AudioSpec

Spec for the mixer, which may include callback functions, e.g. portaudio

func Start

func Start()

Start the mixer now

func StartAt

func StartAt(t time.Time)

StartAt a specific time in the future

func Teardown

func Teardown()

Teardown everything and release all memory.

Types

This section is empty.

Source Files

Directories

Path Synopsis
Package bind is for modular binding of mix to audio interface
Package bind is for modular binding of mix to audio interface
debug
Package debug for debugging
Package debug for debugging
hardware/null
Package null is for modular binding of mix to a null (mock) audio interface
Package null is for modular binding of mix to a null (mock) audio interface
hardware/portaudio
Package portaudio is for modular binding of mix to audio interface via PortAudio
Package portaudio is for modular binding of mix to audio interface via PortAudio
hardware/sdl
Package sdl is for modular binding of mix to audio interface via SDL2
Package sdl is for modular binding of mix to audio interface via SDL2
opt
Package opt specifies valid options
Package opt specifies valid options
sample
Package sample models an audio sample Package sample models an audio sample
Package sample models an audio sample Package sample models an audio sample
spec
Package spec specifies valid audio formats
Package spec specifies valid audio formats
wav
Package wav is direct WAV filo I/O Package wav is direct WAV filo I/O Package wav is direct WAV filo I/O Package wav is direct WAV filo I/O
Package wav is direct WAV filo I/O Package wav is direct WAV filo I/O Package wav is direct WAV filo I/O Package wav is direct WAV filo I/O
lib
fire
Package fire model an audio source playing at a specific time
Package fire model an audio source playing at a specific time
mix
Package mix combines sources into an output audio stream
Package mix combines sources into an output audio stream
source
Package source models a single audio source Package source models a single audio source
Package source models a single audio source Package source models a single audio source

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