README
¶
Ontomix
Go-native audio mixer for Music apps
See example/808.go:
package main
import (
"fmt"
"os"
"math/rand"
"time"
"gopkg.in/ontomix.v0"
"gopkg.in/ontomix.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 ontomix.Teardown()
ontomix.Debug(true)
ontomix.Configure(spec)
ontomix.SetSoundsPath(prefix)
ontomix.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++ {
ontomix.SetFire(pattern[s], t+time.Duration(s)*step, 0, 1.0, rand.Float64() * 2 - 1)
}
t += time.Duration(len(pattern)) * step
}
fmt.Printf("Ontomix, pid:%v, spec:%v\n", os.Getpid(), spec)
for ontomix.FireCount() > 0 {
time.Sleep(1 * time.Second)
}
}
Run the above from the root of the project with:
make example
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/ontomix.v0
Ontomix 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.
Ontomix 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/ontomix.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 matterns 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, ontomix 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.
Ontomix 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 Ontomix API, time is specified as a time.Duration-since-epoch, where the epoch is the moment that ontomix.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
Insipired 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 an example implementation of ontomix included in the example/ 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
Portaudio
Ubuntu:
sudo apt-get install portaudio19-dev
Documentation
¶
Overview ¶
Package ontomix is a sequence-based Go-native audio mixer
Package ontomix is a sequence-based Go-native audio mixer ¶
Package ontomix is a sequence-based Go-native audio mixer ¶
Package ontomix is a sequence-based Go-native audio mixer
Index ¶
- Constants
- func ClearAllFires()
- func Configure(spec bind.AudioSpec)
- func Debug(isOn bool)
- func FireCount() int
- func GetStartTime() time.Time
- func SetMixCycleDuration(d time.Duration)
- func SetSoundsPath(prefix string)
- func Spec() *bind.AudioSpec
- func Start()
- func StartAt(t time.Time)
- func Teardown()
- type Fire
- type Source
- type Tz
Constants ¶
const VERSION = "0.0.3"
VERSION # of this ontomix source code
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 FireCount ¶ added in v0.0.3
func FireCount() int
FireCount to check the number of fires currently scheduled for playback
func GetStartTime ¶ added in v0.0.2
GetStartTime the mixer was started at
func SetMixCycleDuration ¶ added in v0.0.3
Set the duration between "mix cycles", wherein garbage collection is performed.
Types ¶
type Fire ¶
type Fire struct {
/* setup */
BeginTz Tz
EndTz Tz
Source string
Volume float64 // 0 to 1
Pan float64 // -1 to +1
// contains filtered or unexported fields
}
Fire represents a single audio source playing at a specific time in the future.
func SetFire ¶
func SetFire(source string, begin time.Duration, sustain time.Duration, volume float64, pan float64) *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
type Source ¶
type Source struct {
URL string
// contains filtered or unexported fields
}
Source stores a series of Samples in Channels across Time, for audio playback.
Source Files
Directories
¶
| Path | Synopsis |
|---|---|
|
Package bind is for modular binding of ontomix to audio interface Package bind has native Go WAV I/O Package bind is for modular binding of ontomix to audio interface Package bind is for modular binding of ontomix to audio interface Package bind is for modular binding of ontomix to audio interface Package bind is for modular binding of ontomix to audio interface
|
Package bind is for modular binding of ontomix to audio interface Package bind has native Go WAV I/O Package bind is for modular binding of ontomix to audio interface Package bind is for modular binding of ontomix to audio interface Package bind is for modular binding of ontomix to audio interface Package bind is for modular binding of ontomix to audio interface |