Dawn Remembers Again

The note that produced it

On this track: Good overall, not very listenable.

“I want each to be a mosaic assemblage of the tracks, never the whole track. Each a separate video experiment to see the samples, get the groove. Aim for 1–2 minutes per track.”

“A different attempt and technology for each Afterlight song / music video experiment”: readable as embers from their spectrograms, as Gaussian splats of places.

What was made

Spectrogram terrain: each past moment of sound is a ridge further back, newest at the front, and an archive sun rises behind the ridges.

0:30–1:02 at half speed, an octave down · five swells with twelve-second tails

On the cut before

Good overall, not very listenable.

On this cut

Many nice moments and samples to find.

Sample map

Every sound placed in the 1:20 study, 13 events by layer, coloured by the track it was cut from. The bars under the map are the whole source tracks; the lit spans are the parts actually used (approximate: stretched and frozen samples are counted by where they start).

The recipe

The function that composed this study, exactly as it ran.

def dawn():
    """made listenable by slowing it: the swells at half speed and an octave down, smeared, with the bright moments let through"""
    n = 'dawn'; m = Mix(80)
    slow = resample(cut(n, 30, 62), 0.5)                     # 32 s -> 64 s, an octave lower
    slow = lp(slow, 5000) * np.minimum(np.linspace(0, 1, len(slow)) * 4, 1)[:, None]
    m.put('slow', slow, 2, 0.8, n, 30, 'halfspeed')
    m.put('freeze', freeze(cut(n, 12, 16), 30, grain=0.4, dens=16), 0, 0.5, n, 12, 'freeze')
    P = 2.564
    for k, a in enumerate([33.2, 45.0, 55.5, 70.4, 82.0]):
        a = snap(n, a); x = cut(n, a, a + P)
        m.put('swell', x, 12 + k * 12.5, 0.7, n, a, 'swell'); m.put('ember', ember(x, 12, 0.6), 12 + k * 12.5, 1.0, n, a, 'tail')
    m.put('ember', ember(cut(n, 86, 92), 18, 0.7), 66, 1.0, n, 86, 'tail')
    return m

The picture technique

class Terrain:
    """the mosaic's spectrum laid out as land: each past moment a ridge further away, the newest at the front; a sun from the archive rises behind it"""
    def __init__(s, ctx, cats=('sun',), seed=6):
        s.c = ctx; s.sky = [clip_frames(i, 320, 180, 12, 8) for i in footage(cats, 3, seed)]; s.emb = Embers(15000, 8)
    def frame(s, t, dt):
        c = s.c; rise = sm(0, c.dur * 0.8, t)
        sk = s.sky[int(t / 25) % len(s.sky)]; f = up(sk[int(t * 12) % len(sk)].astype(np.float32))
        grad = np.clip(1 - YY / (H * 0.62), 0, 1)[..., None]
        img = (f * np.array([1.0, 0.7, 0.45]) * 0.35 * (0.3 + 0.7 * rise)) * grad
        sy = H * (0.70 - 0.32 * rise); img += (np.exp(-((XX - W * 0.5) ** 2 + (YY - sy) ** 2) / 2600) * 1.4 + np.exp(-((XX - W * 0.5) ** 2 + (YY - sy) ** 2) / 60000) * 0.35)[..., None] * np.array([1.0, 0.62, 0.3]) * (0.3 + 0.7 * rise)
        canvas = (img * 255).clip(0, 255).astype(np.uint8).copy()
        glow = np.zeros((H, W), np.float32)
        R = 46; xs = np.linspace(-0.2, 1.2, 128)
        for i in range(R - 1, -1, -1):                          # back to front
            tt = t - i * 0.18
            if tt < 0: continue
            col = c.melcol(tt); d = 1 + i * 0.09; base = H * 0.52 + 300 / d
            hts = (gaussian_filter(col, 1.2) ** 1.8) * 260 / d
            px = (W / 2 + (xs - 0.5) * W * 1.6 / d).astype(np.int32); py = (base - hts).astype(np.int32)
            pts = np.concatenate([np.stack([px, py], 1), [[px[-1], H], [px[0], H]]]).astype(np.int32)
            shade = int(8 + 10 * (1 - i / R))
            cv2.fillPoly(canvas, [pts], (shade, shade // 2, shade // 3))
            cv2.polylines(glow, [np.stack([px, py], 1).reshape(-1, 1, 2)], False, float(1.2 * (1 - i / R) ** 1.5 + 0.05), 1, cv2.LINE_AA)
            if i == 0:
                pk = np.nonzero((col > 0.75) & (np.r_[0, np.diff(col)] > 0))[0]
                if len(pk): s.emb.emit(px[pk].astype(np.float32), py[pk].astype(np.float32), vx=10, vy=-50, T=0.9, life=3.0, spread=15)
        img = canvas.astype(np.float32) / 255
        g = glow + gaussian_filter(glow, 2) * 1.5
        img += g[..., None] * thermal(np.full(1, 0.7))[0]
        s.emb.step(t, dt, wind=(20, -15)); img += s.emb.draw(t, 0.8)
        return img

Files

The scripts that made this version, as plain text.

• compose.py254 linesthe nine mosaics: every cut, loop and freeze
• sampler.py154 linesloop, stretch, reverb, echo, freeze, tape stop
• mix.py85 linesthe 178-second set
• sound_design.py91 linesneedle drop, inhales, risers, sub, tape bus
• engines.py367 linesthe ten picture techniques
• vis_common.py106 linesshared embers, archive frames, the finish
• render.py41 linesrenders frames and encodes
• analyze.py21 linestempo and onsets of each source track