dsp: violins and horns, four players a note

[mishan]

Item 6 of the instrument list: ensembles. Stacked on #333, since both graphs use osc::blep.

strings.dsp and section.dsp widen one voice with a chorus. These are four discrete players per note, each with its own:

• detune (Detune) and slow wander (Drift, seeded from the note so pieces replay exactly)

• vibrato rate, coming in after Vibrato Delay

• entry time (Stagger)

• seat across the stereo field (Width)

• dsp/violins.dsp: saw players through a note-tracking tone filter that opens with velocity. A violin-body resonance (290 Hz and 2.8 kHz, Body) is applied once per side of the summed section.

• dsp/horns.dsp: each player scoops up from Scoop cents flat over Scoop Time, with a filter that opens with its own envelope by Bite × velocity. The cutoff is a multiple of the note, so the timbre holds up the range.

Testing

• ctest -R "dsp|fx|catalog|gencheck|nodes": 18/18 pass.
• Rendered a phrase on each: no clipping or NaN; peaks are 0.43 and 0.36 at channel amp 90.

[Copilot]

Copilot review overview

🟡 Changes recommended

Fixed sustain levels erase velocity dynamics, while Stagger changes attack and scoop duration rather than delaying player entry.

Review effort: Balanced
Findings: 5

Open (5)

• Scale horn sustain by velocity · New
• Keep scoop time fixed and apply entry delay · New
• Delay player two signal instead of its attack · New
• Scale sustain by velocity to preserve note dynamics · New
• Delay player entry instead of lengthening attack · New

What changed in this PR

Adds two four-player ensemble instruments using osc::blep, deterministic drift, vibrato, and stereo seating.

Changes:

• Adds a resonant violin-section graph.
• Adds a velocity-sensitive horn-section graph with pitch scoops.

File	Description
dsp/​violins.dsp	Defines the four-player violin ensemble.
dsp/​horns.dsp	Defines the four-player horn ensemble.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[mishan]

Addressed in 055387b: sustain now scales with velocity, and Stagger delays each player's entry through a gate rather than stretching its attack and scoop. The delayed gate needs env::adsr to wait for a wired trigger, which is #337; merge that first. With it applied, player 4 at Stagger = 200 ms is silent until 180 ms and enters then, while player 1 starts at once.

[Copilot]

Copilot review overview

🟡 Changes recommended

The ADSR trigger semantics prevent the staggered players from starting at their intended delayed entry times.

Review effort: Balanced
Findings: 2

Open (2)

• Player 2 envelopes bypass stagger gate and late-open after note-off · New
• Player 2 starts before stagger gate and ignores early note-off · New

Resolved since last review (5)

• Delay player entry instead of lengthening attack
• Scale sustain by velocity to preserve note dynamics
• Delay player two signal instead of its attack
• Keep scoop time fixed and apply entry delay
• Scale horn sustain by velocity

[Copilot]

Copilot review overview

🔵 Needs a closer look

The staggered gates rely on the behavioral changes in unmerged PR #337.

Review effort: Balanced
Findings: None

Resolved since last review (2)

• Player 2 starts before stagger gate and ignores early note-off
• Player 2 envelopes bypass stagger gate and late-open after note-off