handle clipping move osc&gain to the user side

Changes

2 changed files (+48/-31)

• music.nim
  • @@ -1,7 +1,7 @@
    - import musiclib, std/math + import musiclib, std/[math, sugar] # Number of times to sample each second - let bitrate = 44100 + const bitrate = 44100 func osc_piano*(f, t: float): float = ## Returns the intensity of a tone of frequency f sampled at time t
  • @@ -20,14 +20,27 @@ Y += Y * Y * Y
    Y *= 1 + 16 * t * math.exp(-6 * t) Y + func osc_pulse*(f,t:float):float = + let width = (1.0 / f) / 2 + let phase: float = t mod (width * 2) + if phase < width: 1.0 else: -1.0 + func freq*(octave, step: float): float = ## Returns the frequency of a note 55 * pow(2, (octave + step / 12 - 1)) - func p*(len, octave, step, vol: float = 1): Note = + var osc: OscFn = (f, t: float) => 0.0 + + proc p*(len, octave, step, vol: float = 1): Note = ## Note helper constructor - let osc: OscFn = osc_piano (len, freq(octave, step), vol, osc) + + + #------- song region ------- + + const GAIN_NORMAL = 0.24 + + osc = (f, t: float) => osc_piano(f, t) * GAIN_NORMAL let intro = [ p(1,3,3),
  • @@ -50,6 +63,8 @@ p(1,3,0),
    p(1,3,3), p(8,3,7), ] + + # osc = osc_pulse let melody = [ p(1,3,3),
  • @@ -119,17 +134,6 @@ p(1,4,8),
    p(2,4,10), ] - let bass = [ - p(1,1,3), - p(1,1,10), - p(1,1,1), - p(1,1,8), - p(1,1,3), - p(1,2,3), - p(1,1,1), - p(1,1,10), - ] - let melody2 = [ p(1,0,0), p(1,5,10),
  • @@ -273,6 +277,19 @@ p(2,3,3),
    p(16,3,7,2), ] + osc = (f, t: float) => osc_piano(f, t) * GAIN_NORMAL * 1.5 + + let bass = [ + p(1,1,3), + p(1,1,10), + p(1,1,1), + p(1,1,8), + p(1,1,3), + p(1,2,3), + p(1,1,1), + p(1,1,10), + ] + from std/algorithm import sort # Process all lists of notes
  • @@ -280,16 +297,16 @@ var music: seq[ProcessedNote] = @[]
    music.process(intro, 0, 4) music.process(melody, 8, 4) music.process(melody, 24, 4) - music.process(bass, 24, gain=1.5) - music.process(bass, 32, gain=1.5) + music.process(bass, 24) + music.process(bass, 32) music.process(melody, 40, 4) music.process(melody2, 40, 4) - music.process(bass, 40, gain=1.5) - music.process(bass, 48, gain=1.5) + music.process(bass, 40) + music.process(bass, 48) music.process(melody, 56, 4) music.process(melody3, 56, 4) - music.process(bass, 56, gain=1.5) - music.process(bass, 64, gain=1.5) + music.process(bass, 56) + music.process(bass, 64) music.process(outro, 72, 4) music.sortByStart()
• musiclib.nim
  • @@ -16,12 +16,9 @@ freq: float
    vol: float osc: OscFn - ## give some seconds for the note to fade out - const HACK_DROPOFF_DELAY = 2.0 - const HACK_LONGEST_NOTE = 16.0 - func process*(music: var seq[ProcessedNote], notes: openArray[Note]; start_init: float, speed: float=1, gain:float = 1) = + func process*(music: var seq[ProcessedNote], notes: openArray[Note]; start_init: float, speed: float=1) = ## Adds a list of notes to the music list ## ## `notes` sequence of notes with no rests in between
  • @@ -32,7 +29,7 @@ assert note.len >= 0.0
    assert note.len <= HACK_LONGEST_NOTE, &"note too long: {note.len}" start = t let stop = t + note.len / speed - music &= (start, stop, note.freq, note.vol * gain, note.osc) + music &= (start, stop, note.freq, note.vol, note.osc) t = stop func sortByStart*(music: var seq[ProcessedNote]) =
  • @@ -45,7 +42,7 @@ ## assumes `music` is sorted by `.start`
    music.lowerBound(x, (m, key) => cmp(m.start, key)) - const GAIN_BIAS: float = pow(2.0, 28.0) + const GAIN_BIAS: float = pow(2.0, 31.0) proc at*(music: openArray[ProcessedNote], t: float): int32 = ## Returns the total intensity of music sampled at time t
  • @@ -59,10 +56,13 @@
    while i >= 0: let m = music[i] assert m.start <= t - if m.stop + HACK_DROPOFF_DELAY >= t: + if m.start + HACK_LONGEST_NOTE < t: + break + else: ret += m.vol * m.osc(m.freq, t - m.start) - if m.start + HACK_LONGEST_NOTE + HACK_DROPOFF_DELAY < t: - break i -= 1 - int32(ret * GAIN_BIAS) + ret *= GAIN_BIAS + + # clip sample + clamp(ret, int32.low.float..int32.high.float).int32