The subtractive synth's amplitude-envelope release decremented at
`(dt / r) * s` — the rate was multiplied by the sustain level, floored
at 0.001. For any percussive patch (sustain≈0: Square Bass, Pulse Pluck,
Noise Perc), release ran ~1000× too slow, so a 0.2 s tail took minutes.
Since a voice's isActive follows its amp envelope, the voice never freed
and kept rendering (3 osc + filter) indefinitely.
That one bug produced all three reported symptoms:
* missed note-offs / stuck notes needing panic — the note-off fires but
the voice takes minutes to go silent, reading as ignored;
* fast-tapping dropouts on every instrument — released-mid-envelope
voices pile up (whole pool + 8 live audition voices) and CPU climbs
until the audio callback overruns → xruns;
* audition-then-play dropouts — audition notes are already stuck on the
live pool before the sequencer stacks track voices on top.
Release now ramps to zero at a constant 1/r rate, reaching silence
within r seconds from any level (matching SampleVoice's behaviour). The
Sampler/SoundFont path already captured its release rate at note-off, so
it was less affected — but the shared synth voice pinned the CPU budget,
which is why the stutter showed across all instruments.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
On-device profiling (worst case: 4 channels x 3 oscillators + cutoff & pitch
modulation, dense pattern at 200 BPM) showed the render callback averaging 2.8ms
against a 2.0ms budget with continuous xruns — the hiccups. The cost was the
per-sample Math.pow used for pitch modulation across 3 oscillators x many voices.
Recompute modulated oscillator pitch at control rate (every 16 samples, like the
filter cutoff) instead of per sample; LFO/envelopes move slowly enough that this
is inaudible. Render dropped to ~1.27ms avg with zero new xruns. No crashes under
load (the ConcurrentHashMap + stable SVF filter fixes from 0.4.3 hold).
Patch bump to 0.4.4 (versionCode 11).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Address three issues introduced with the 3-oscillator synth:
- Crashes: ToolboxSlot.values was a plain HashMap read on the audio thread while
the UI wrote it (knob drags vs. the synth's ~40-param-per-note reads). Made it a
ConcurrentHashMap so get/put are atomic and reads are lock-free (RT-safe).
- Filter cutoff not affecting the sound: (a) the cheap ladder went unstable at high
cutoff (f > 1 -> NaN -> silent voice) — replaced with a stable Cytomic TPT
state-variable low-pass (with NaN recovery); (b) a voice captured its patch only
at note-on, so live knob turns were inaudible — the engine now refreshes active
voices' patches every block, so cutoff/level/mod changes affect held & playing
notes.
- Hiccups: every note allocated a SynthPatch (+arrays) causing GC dropouts — the
patch is now cached per bus and reparsed only on param/tempo change, so steady
playback allocates nothing on the audio thread.
Patch bump to 0.4.3 (versionCode 10).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Add fling/drag vertical scrolling to the pattern grid via Modifier.scrollable
(fractional pixel offset for smooth, non-snapping motion). The view still follows
the playhead during playback (and the cursor when stopped) by default; a finger
flick detaches it into free inertial scrolling, and switching to another block
re-attaches the follow (the scroll state is keyed on the active pattern).
Tap-to-focus is unchanged. Patch bump to 0.4.2 (versionCode 9).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Two changes that landed together (the note-off work was uncommitted when the synth
rewrite began):
Synth rewrite — replace the simple NES tone generator with a classic Minimoog-style
voice: 3 oscillators (+ noise) → mixer → resonant 4-pole ladder low-pass (own
contour envelope + key tracking) → amplifier (own envelope), plus a tempo-synced
LFO and a 4-slot modulation matrix.
- DSP: SynthVoice rewritten (PolyBLEP oscillators, ladder filter, two ADSRs, LFO,
mod matrix); new SynthPatch parses a slot into an immutable snapshot per note.
PolyBLEP + control-rate cutoff + precomputed osc tuning keep the RT cost down.
- Model: SynthDefs (shared option lists/defaults), rewritten NES_SYNTH params,
NesSynthPresets (8 chiptune factory presets) seeded into the preset library.
- Editor: NesSynthEditor — swipeable cards (Oscillators / Filter / Amp+LFO / Mod
Matrix) with dot pagination; new rotary Knob control (absolute, fader-like
vertical drag: bottom = empty, top = full); enums via RetroDropdown. The shared
slot-audition keyboard (renamed SoundFontKeyboard -> SlotAuditionKeyboard) is
pinned at the editor bottom.
- Engine builds a SynthPatch per note. The enum id stays NES_SYNTH so existing
projects still route; the old single `wave` param is dropped (amp envelope keys
carry over).
Track-tied note-offs — a note-off ("===") is now tied to its track, not a channel:
it has no velocity/channel of its own (shown as ".." and non-editable) and simply
releases whatever that track last played, on the bus(es) that note routed to
(AudioEngine.trackLastChannel). `.sng` export writes "OFF .. ..".
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Each transport-toolbar row now distributes its elements across the full width
(Arrangement.SpaceBetween) instead of clustering at the left: dropped the
per-row horizontalScroll (which gave the row infinite width and defeated any
distribution) and the manual landscape spacer. Rows no longer scroll — elements
fill the bar edge to edge. Patch bump to 0.3.2 (versionCode 5).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Configure the release variant's output filename (via the legacy applicationVariants
API) so the unsigned release APK is stamped with its versionCode — e.g.
space.rcmd.android.sizzle_4.apk — to simplify uploading to the private F-Droid
repo. Staging keeps its app-staging.apk name.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Lay out and place the SF2/XI loader's audition keyboard like the toolbox and
tracker keyboards: extract it into SoundFontKeyboard (an octave selector above two
weighted octaves) and pin it at the bottom of the device editor, with the controls
scrolling in a weighted region above (1.7 : 1, matching the toolbox tab) — so it's
the same height and always visible instead of scrolling away. Patch bump to 0.3.1
(versionCode 4).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
- SF2/XI loader: add a Loop XFade control (ms, 0-500) next to the loop toggle.
SampleVoice crossfades the loop tail into its head for a click-free seam even
when the file's loop points don't match; 0 ms keeps the previous hard wrap.
Threaded through VoiceSample and all noteOn call sites.
- Add a reusable RepeatButton: fires on press then auto-repeats while held with
an exponentially shrinking interval (stops on release/scroll-off). Applied to
every +/- stepper (tempo, MIDI channel, arrangement repeats, audition/keyboard
octave, and the new crossfade).
- Bump version to 0.3.0 (versionCode 3) per the minor-per-change policy.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Global rename of the app/package identifier from
com.reactorcoremeltdown.sizzletracker to space.rcmd.android.sizzle:
- build.gradle.kts: applicationId + namespace.
- Move the Kotlin source tree (main + test) and rewrite every package/import.
- native_audio.cpp: JNI symbol names (Java_space_rcmd_android_sizzle_...) so the
Oboe callback still links against the relocated NativeAudioBridge.
- docs: package/file-map header.
The desktop-project GitHub URLs (github.com/reactorcoremeltdown/sizzletracker)
and the Reactorcoremeltdown copyright/SPDX author identity are intentionally left
unchanged. Note: the new applicationId installs as a separate package (existing
installs won't upgrade in place).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A retro, grid-based music tracker for Android (Kotlin + Jetpack Compose,
single Activity) with four equally-capable input methods (touch, keyboard,
gamepad, MIDI) and four tabs: tracker, mixer, toolbox, settings.
Highlights:
- Tracker: Canvas-drawn 4-track pattern grid over an 8-lane arrangement roll,
with a glyph cache and draw-phase state reads so the playhead and edits
redraw without per-frame recomposition.
- Audio: sample-accurate sequencer feeding a shared AudioEngine, driven by
either a Kotlin AudioTrack loop or native Oboe/AAudio via JNI (16 KB-aligned
native libs). media3 MediaSession for lock-screen/headset transport.
- Toolbox: 16 instrument/effect slots with a 2-octave audition keyboard;
single-tap select, double-tap edit, long-press clear.
- Note entry: long-press cell popups (piano keyboard / value steppers) plus
keyboard/gamepad stepping that resumes from the last note/channel entered.
Velocity capped at 0x7F, channel at 16.
- Selection/clipboard (cut/copy/paste/delete) and .sng import/export
compatible with the reference desktop tool.
- A `profile` build type (non-debuggable, debug-signed) for realistic
on-device performance testing.
- Developer handover documentation under docs/.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
