fr3fou / beep

synthesizing raw pcm music using go from scratch

beep

Synthesizing raw PCM music using Go from scratch.

TODO

• Refactor to idiomatic go code

• Rename to a proper name

• Make examples

• Make note durations methods on beep.Melody (as they are dependant on the note length and BPM)

• Implement a simple format - mp3 / wav

• Define all notes in all octaves a seperate file

• GUI + keybinds - Will be a separate project

• Play multiple notes at once (chords)

  • f(x) + g(x) where f and g produce different notes, should result in them playing at the same time
  • Note -> SingleNote, add Chord (multiple notes). Both implement new Note interface

  type Note interface {
      Samples(sampleRate float64, generator Generator, adsr ADSR) []float64
  }

• Support for merging melodies (playing 2 melodies at the same time)

  g := beep.NewMelody(...)
  g.AddNotes(...)
  
  // or
  g.Runs[0].AddNotes(...)
  
  // more runs, i.e. staves
  g.NewRun(notes...)

• Support for concatenating melodies / have melodies with differing BPM

  g := beep.NewMelody(...)
  g.AddNotes(...)
  n := beep.NewMelody(...)
  n.AddNotes(...)
  o := g.Concat(n) // combines both melodies and makes a longer one

• Dual Channel support (left and right ear)

• Fix clipping in release of linear ADSR (theoretically negligible)

• Implement logarithmic / exp ADSR

• Support for dotted notes

• Overtones

• Fix periods for generators that aren't sin (?)

How to play music

ffplay megolovania.bin -autoexit -showmode 1 -f f64le -ar 48000

References

• https://pages.mtu.edu/~suits/NoteFreqCalcs.html
• https://medium.com/@MicroPyramid/understanding-audio-quality-bit-rate-sample-rate-14286953d71f
• https://www.youtube.com/watch?v=FYTZkE5BZ-0
• https://www.reddit.com/r/explainlikeimfive/comments/4d4krv/eli5_what_is_the_difference_between_sample_rate/
• https://www.geogebra.org/graphing
• https://golang.org/pkg/encoding/binary
• https://www.wikiwand.com/en/A440_(pitch_standard)
• https://www.wikiwand.com/en/Envelope_(music)
• https://mathbitsnotebook.com/Algebra1/FunctionGraphs/FNGContinuousDiscrete.html
• https://xiph.org/video/vid2.shtml
• https://wiki.multimedia.cx/index.php/PCM
• https://stackoverflow.com/questions/1073606/is-there-a-one-line-function-that-generates-a-triangle-wave
• https://www.desmos.com/calculator/nduy9l2pez
• https://dsp.stackexchange.com/questions/2555/help-with-equations-for-exponential-adsr-envelope
• http://web.mit.edu/6.111/www/f2004/projects/ghs_report.pdf
• http://www.martin-finke.de/blog/articles/audio-plugins-011-envelopes/
• https://www.geogebra.org/graphing/ehmusxyd
• https://zipcpu.com/dsp/2017/12/09/nco.html

Contributors ✨

Thanks goes to these wonderful people (emoji key):

Simo Aleksandrov 💻 🚇

Viktor Danov 💻 🚇

This project follows the all-contributors specification. Contributions of any kind welcome!