stretch

stretch is a skill for Claude Code, Codex from Generous-Corp/pulp. It costs 50 tokens per session (5,130 once invoked), scanned A, original, MIT.

A guide to using an offline audio processor for changing playback speed, pitch, or timing. It covers sound modes, presets, comparisons, and the limits of current quality.

In plain words
What is it for?
It helps configure offline processing, prepare real-time pitch and time stretching, compare modes, save presets, and check invalid processing settings.
Why use it?
Audio time and pitch changes can sound different depending on the settings and sample format, so developers need a consistent way to choose and compare them.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/generous-corp/pulp/stretch
Any agent
npx skills add Generous-Corp/pulp --skill stretch
Clone the repo
git clone --depth 1 https://github.com/Generous-Corp/pulp

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for stretch

README.md
[![agentmods](https://agentmods.dev/badge/skills/generous-corp/pulp/stretch.svg)](https://agentmods.dev/skills/generous-corp/pulp/stretch)
Your own site
<a href="https://agentmods.dev/skills/generous-corp/pulp/stretch"><img src="https://agentmods.dev/badge/skills/generous-corp/pulp/stretch.svg" alt="Measured on agentmods" height="20"></a>
Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,130 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00050 $0.05130
Opus 5 $0.00025 $0.02565
Sonnet 5 $0.00010 $0.01026
Haiku 4.5 $0.00005 $0.00513

Measured today against content hash 99fb60a80e5f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

stretch scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/stretch/SKILL.md · 313 lines

How it starts

The opening of the file, as written. The whole thing — 313 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Stretch (offline time-stretch / pitch / varispeed)

pulp::signal::OfflineStretch is the non-realtime, max-quality stretch/pitch engine. This skill is the agent-facing guide: which character mode to use, how to fine-tune and share a preset, how to A/B measure, and what's genuinely good vs. still cooking. Headers: core/signal/include/pulp/signal/{offline_stretch,stretch_preset}.hpp. Dev CLI: examples/offline-stretch/stretchcli. Eval toolkit: examples/offline-stretch/eval/.

Most DSP helpers now expose *64 aliases when the underlying class is templated, including OfflineStretch64 and RealtimePitchTimeProcessor64. The offline stretch public config remains control-plane double regardless of sample type; only the sample buffers and internal DSP storage widen for the f64 aliases. Keep quality comparisons explicit about which sample type is under test.

Finite streaming contract

For clip-ready streaming, prepare RealtimePitchTimeProcessor in PitchTimeMode::time_stretch and check its PitchTimePrepareStatus. Non-positive sample rates, channel counts outside the prepared ceiling, and non-positive max_block capacities are rejected before processor state changes. Time-stretch sizing also requires a finite max_time_ratio >= 1; pitch sizing requires a finite, non-negative semitone bound whose derived ratio is finite. Preparation rejects any otherwise-valid bound whose synthesis hop, power-of-two ring, or typed backing-buffer byte size is not representable in the target address space; never rely on a later float-to-int conversion or allocation failure to police capacity. Optional FFT overrides must satisfy the spectral engine's 256–16384 power-of-two window and analysis_hop <= fft_size/2 invariants or preparation rejects them without changing prior state. The realtime processor also stages its spectral-envelope analyzer before it publishes any new configuration or retained processing state. Keep that prepare transactional: an analyzer capacity failure must leave the previously prepared processor usable rather than half-adopting the new geometry. feed() is all-or-nothing: on backpressure, drain available_stretched() with read_stretched() and retry the identical input block. Never advance a decoder on a rejected feed.

Read the full file on GitHub · 313 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. today First seen · 313 lines · 50 tokens per session scan A 99fb60a80e5f

Subscribe to this mod's changes

stretch is a skill published in the GitHub repository Generous-Corp/pulp (16 stars, last pushed today), licensed MIT. It adds 50 tokens to every session and 5,130 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-04.

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