fix: accurate midi scheduling on chromium

Reviewed-on: https://codeberg.org/uzu/strudel/pulls/2090

CONTRIBUTING.md

@@ -52,7 +52,17 @@ Strudel is a project handmade by humans, with thought and nuance.
 
 If you have used LLMs (so called 'AI'), please detail that in the pull request. We are still developing our response to the onslaught of LLM technology, but for practical and legal reasons are currently not accepting wholly LLM-generated code. We are also not accepting PRs that add LLM features to strudel itself.
 
-There are #llm-chat and #llm-share channels on our discord. Please do not discuss or share LLM-related things outside of those channels.
+There are #llm-chat and #llm-share channels on [our discord](https://discord.com/invite/HGEdXmRkzT). Please do not discuss or share LLM-related things outside of those channels.
+
+## Creating and sharing a new project using strudel
+
+Strudel is free/open source software, and we are also happy to see people making use of it within the following terms. 
+
+Please don't use 'strudel' in the name of your project, so people don't assume it's official strudel project. (If you'd like it to be an official strudel project, please check in with the community, e.g. on [the discord](https://discord.com/invite/HGEdXmRkzT).) 
+
+Please respect our AGPL license, which e.g. requires you to share/link to the source code of strudel, any modifications you've made to it, and the source code for the rest of your project if it integrates with strudel. You are also required to maintain Strudel's copyright notices in the source code, and include Strudel's copyright notice in your user interface. This is an ad-hoc summary - please [refer to the license](https://codeberg.org/uzu/strudel/src/branch/main/LICENSE) for full details.
+
+You are also encouraged to connect with the community and understand our aims and values.
 
 ## Report a Bug
 

packages/core/pattern.mjs

@@ -4132,3 +4132,59 @@ Pattern.prototype.worklet = function (src, ...inputs) {
 };
 
 export const worklet = (...args) => pure({}).worklet(...args);
+
+/**
+ * Creates a pattern of numbers in base b from a number or pattern of numbers
+ * limited to d digits long from the right
+ *
+ * @name base
+ * @tags generators
+ * @param {number} n - number to convert (can be a pattern or array)
+ * @param {number} b - base to convert to (defaults to 10) (can be a pattern)
+ * @param {number} d - max number of digits to produce for each n (defaults to 0 for all) (can be a pattern)
+ * @example
+ * $: note(base("7175 543", 10, 3)).scale("c:major").s("saw")
+ * // $: note("1 7 5 5 4 3").scale("c:major").s("saw")
+ */
+export const base = (n, b = 10, d = 0) => {
+  if (Array.isArray(n)) {
+    n = sequence(n);
+  }
+  n = reify(n);
+  b = reify(b);
+  d = reify(d);
+
+  return d
+    .withValue((e) => {
+      return b
+        .withValue((c) => {
+          return n
+            .withValue((v) => {
+              let digits = [];
+              let value = v;
+              while (value > 0) {
+                digits.unshift(value % c);
+                value = Math.floor(value / c);
+              }
+              if (e) {
+                const l = digits.length;
+                if (l > e) {
+                  digits = digits.slice(-1 * e);
+                }
+                /* 
+          if (l < e){
+            for (let i = l; i < e; i++) {
+              digits.unshift("~");//0); //Would like to be padding this but ~- doesn't work
+            }
+            console.log("digits", digits);
+          }
+          */
+              }
+              return sequence(digits);
+            })
+            .squeezeJoin();
+        })
+        .squeezeJoin();
+    })
+    .squeezeJoin();
+};

packages/midi/midi.mjs

@@ -171,6 +171,21 @@ function normalize(value = 0, min = 0, max = 1, exp = 1) {
   return Math.pow(normalized, exp);
 }
 
+const isFirefox = navigator?.userAgent?.includes('Firefox');
+// call fn either directly with given time (non-firefox) or after scheduleAtTime with undefined (firefox)
+// the scheduleAtTime approach is still jittery, but the best we can be on firefox
+// firefox bug: https://bugzilla.mozilla.org/show_bug.cgi?id=2062997
+function timedSend(timeMs, fn) {
+  if (isFirefox) {
+    const audioTime = getAudioContext().currentTime + (timeMs - performance.now()) / 1000;
+    scheduleAtTime(() => {
+      fn(undefined);
+    }, audioTime);
+  } else {
+    fn(timeMs);
+  }
+}
+
 function mapCC(mapping, value) {
   return Object.keys(value)
     .filter((key) => !!mapping[getControlName(key)])
@@ -182,7 +197,7 @@ function mapCC(mapping, value) {
 }
 
 // sends a cc message to the given device on the given channel
-function sendCC(ccn, ccv, device, midichan, targetTime) {
+function sendCC(ccn, ccv, device, midichan, timeMs) {
   if (typeof ccv !== 'number' || ccv < 0 || ccv > 1) {
     throw new Error('expected ccv to be a number between 0 and 1');
   }
@@ -190,23 +205,19 @@ function sendCC(ccn, ccv, device, midichan, targetTime) {
     throw new Error('expected ccn to be a number or a string');
   }
   const scaled = Math.round(ccv * 127);
-  scheduleAtTime(() => {
+  timedSend(timeMs, (timeMs) => device.sendControlChange(ccn, scaled, { channels: midichan, time: timeMs }));
-    device.sendControlChange(ccn, scaled, midichan);
-  }, targetTime);
 }
 
 // sends a program change message to the given device on the given channel
-function sendProgramChange(progNum, device, midichan, targetTime) {
+function sendProgramChange(progNum, device, midichan, timeMs) {
   if (typeof progNum !== 'number' || progNum < 0 || progNum > 127) {
     throw new Error('expected progNum (program change) to be a number between 0 and 127');
   }
-  scheduleAtTime(() => {
+  timedSend(timeMs, (timeMs) => device.sendProgramChange(progNum, { channels: midichan, time: timeMs }));
-    device.sendProgramChange(progNum, midichan);
-  }, targetTime);
 }
 
 // sends a sysex message to the given device on the given channel
-function sendSysex(sysexid, sysexdata, device, targetTime) {
+function sendSysex(sysexid, sysexdata, device, timeMs) {
   if (Array.isArray(sysexid)) {
     if (!sysexid.every((byte) => Number.isInteger(byte) && byte >= 0 && byte <= 255)) {
       throw new Error('all sysexid bytes must be integers between 0 and 255');
@@ -221,13 +232,11 @@ function sendSysex(sysexid, sysexdata, device, targetTime) {
   if (!sysexdata.every((byte) => Number.isInteger(byte) && byte >= 0 && byte <= 255)) {
     throw new Error('all sysex bytes must be integers between 0 and 255');
   }
-  scheduleAtTime(() => {
+  timedSend(timeMs, (timeMs) => device.sendSysex(sysexid, sysexdata, { time: timeMs }));
-    device.sendSysex(sysexid, sysexdata);
-  }, targetTime);
 }
 
 // sends a NRPN message to the given device on the given channel
-function sendNRPN(nrpnn, nrpv, device, midichan, targetTime) {
+function sendNRPN(nrpnn, nrpv, device, midichan, timeMs) {
   if (Array.isArray(nrpnn)) {
     if (!nrpnn.every((byte) => Number.isInteger(byte) && byte >= 0 && byte <= 255)) {
       throw new Error('all nrpnn bytes must be integers between 0 and 255');
@@ -235,34 +244,29 @@ function sendNRPN(nrpnn, nrpv, device, midichan, targetTime) {
   } else if (!Number.isInteger(nrpv) || nrpv < 0 || nrpv > 255) {
     throw new Error('A:sysexid must be an number between 0 and 255 or an array of such integers');
   }
-  scheduleAtTime(() => {
+
-    device.sendNRPN(nrpnn, nrpv, midichan);
+  timedSend(timeMs, (timeMs) => device.sendNrpnValue(nrpnn, nrpv, { channels: midichan, time: timeMs }));
-  }, targetTime);
 }
 
 // sends a pitch bend message to the given device on the given channel
-function sendPitchBend(midibend, device, midichan, targetTime) {
+function sendPitchBend(midibend, device, midichan, timeMs) {
   if (typeof midibend !== 'number' || midibend < -1 || midibend > 1) {
     throw new Error('expected midibend to be a number between -1 and 1');
   }
-  scheduleAtTime(() => {
+  timedSend(timeMs, (timeMs) => device.sendPitchBend(midibend, { channels: midichan, time: timeMs }));
-    device.sendPitchBend(midibend, midichan);
-  }, targetTime);
 }
 
 // sends a channel aftertouch message to the given device on the given channel
-function sendAftertouch(miditouch, device, midichan, targetTime) {
+function sendAftertouch(miditouch, device, midichan, timeMs) {
   if (typeof miditouch !== 'number' || miditouch < 0 || miditouch > 1) {
     throw new Error('expected miditouch to be a number between 0 and 1');
   }
 
-  scheduleAtTime(() => {
+  timedSend(timeMs, (timeMs) => device.sendChannelAftertouch(miditouch, { channels: midichan, time: timeMs }));
-    device.sendChannelAftertouch(miditouch, midichan);
-  }, targetTime);
 }
 
 // sends a note message to the given device on the given channel
-function sendNote(note, velocity, duration, device, midichan, targetTime) {
+function sendNote(note, velocity, duration, device, midichan, timeMs) {
   if (note == null || note === '') {
     throw new Error('note cannot be null or empty');
   }
@@ -273,11 +277,10 @@ function sendNote(note, velocity, duration, device, midichan, targetTime) {
     throw new Error('duration must be a positive number');
   }
   const midiNumber = typeof note === 'number' ? note : noteToMidi(note);
-  const midiNote = new Note(midiNumber, { attack: velocity, duration });
+  const midiNote = new Note(midiNumber, { attack: velocity });
 
-  scheduleAtTime(() => {
+  timedSend(timeMs, (timeMs) => device.sendNoteOn(midiNote, { channels: midichan, time: timeMs }));
-    device.playNote(midiNote, midichan);
+  timedSend(timeMs + duration, (timeMs) => device.sendNoteOff(midiNote, { channels: midichan, time: timeMs }));
-  }, targetTime);
 }
 
 /**
@@ -287,8 +290,6 @@ function sendNote(note, velocity, duration, device, midichan, targetTime) {
  * @param {object} options Additional MIDI configuration options
  * @example
  * note("c4").midichan(1).midi('IAC Driver Bus 1')
- * @example
- * note("c4").midichan(1).midi('IAC Driver Bus 1', { controller: true, latency: 50 })
  */
 
 Pattern.prototype.midi = function (midiport, options = {}) {
@@ -337,11 +338,28 @@ Pattern.prototype.midi = function (midiport, options = {}) {
       logger(`Midi device disconnected! Available: ${getMidiDeviceNamesString(outputs)}`),
   });
 
-  return this.onTrigger((hap, _currentTime, cps, targetTime) => {
+  let p; // filtered clock offset
+  let lastOffset;
+
+  return this.sortHapsByPart().onTrigger((hap, _currentTime, cps, targetTime) => {
     if (!WebMidi.enabled) {
       logger('Midi not enabled');
       return;
     }
+    const { contextTime, performanceTime } = getAudioContext().getOutputTimestamp();
+    if (!contextTime || !performanceTime) {
+      logger('[midi] skip midi event: not ready yet?');
+      return;
+    }
+    const cutoff = 0.01;
+    const offset = performanceTime - contextTime * 1000;
+    p ??= offset; // first input is initial offset
+    if (offset !== lastOffset) {
+      // update filter only when offset changes
+      p = offset * cutoff + p * (1 - cutoff); // onepole iir filter to smooth drift :)
+    }
+    lastOffset = offset;
+    const timeMs = targetTime * 1000 + p; // this is now correct in performance time
     hap.ensureObjectValue();
 
     // midi event values from hap with configurable defaults
@@ -379,7 +397,7 @@ Pattern.prototype.midi = function (midiport, options = {}) {
     // if midimap is set, send a cc messages from defined controls
     if (midicontrolMap.has(midimap)) {
       const ccs = mapCC(midicontrolMap.get(midimap), hap.value);
-      ccs.forEach(({ ccn, ccv }) => sendCC(ccn, ccv, device, midichan, targetTime));
+      ccs.forEach(({ ccn, ccv }) => sendCC(ccn, ccv, device, midichan, timeMs));
     } else if (midimap !== 'default') {
       // Add warning when a non-existent midimap is specified
       logger(`[midi] midimap "${midimap}" not found! Available maps: ${[...midicontrolMap.keys()].join(', ')}`);
@@ -388,15 +406,17 @@ Pattern.prototype.midi = function (midiport, options = {}) {
     // Handle note
     if (note !== undefined && !midiConfig.isController) {
       // note off messages will often a few ms arrive late,
-      // try to prevent glitching by subtracting noteOffsetMs from the duration length
+      // try to prevent glitching by subtracting at max noteOffsetMs from the duration length
-      const duration = (hap.duration.valueOf() / cps) * 1000 - midiConfig.noteOffsetMs;
+      const hapDuration = (hap.duration.valueOf() / cps) * 1000;
+      const offset = Math.min(midiConfig.noteOffsetMs, hapDuration / 2);
+      const duration = hapDuration - offset;
 
-      sendNote(note, velocity, duration, device, midichan, targetTime);
+      sendNote(note, velocity, duration, device, midichan, timeMs);
     }
 
     // Handle program change
     if (progNum !== undefined) {
-      sendProgramChange(progNum, device, midichan, targetTime);
+      sendProgramChange(progNum, device, midichan, timeMs);
     }
 
     // Handle sysex
@@ -406,63 +426,53 @@ Pattern.prototype.midi = function (midiport, options = {}) {
     // if sysexid is an array the first byte is 0x00
 
     if (sysexid !== undefined && sysexdata !== undefined) {
-      sendSysex(sysexid, sysexdata, device, targetTime);
+      sendSysex(sysexid, sysexdata, device, timeMs);
     }
 
     // Handle control change
     if (ccv !== undefined && ccn !== undefined) {
-      sendCC(ccn, ccv, device, midichan, targetTime);
+      sendCC(ccn, ccv, device, midichan, timeMs);
     }
 
     // Handle NRPN non-registered parameter number
     if (nrpnn !== undefined && nrpv !== undefined) {
-      sendNRPN(nrpnn, nrpv, device, midichan, targetTime);
+      sendNRPN(nrpnn, nrpv, device, midichan, timeMs);
     }
 
     // Handle midibend
     if (midibend !== undefined) {
-      sendPitchBend(midibend, device, midichan, targetTime);
+      sendPitchBend(midibend, device, midichan, timeMs);
     }
 
     // Handle miditouch
     if (miditouch !== undefined) {
-      sendAftertouch(miditouch, device, midichan, targetTime);
+      sendAftertouch(miditouch, device, midichan, timeMs);
     }
 
     // Handle midicmd
     if (hap.whole.begin + 0 === 0) {
       // we need to start here because we have the timing info
-      scheduleAtTime(() => {
+      timedSend(timeMs, (timeMs) => device.sendStart({ time: timeMs }));
-        device.sendStart();
-      }, targetTime);
     }
     if (['clock', 'midiClock'].includes(midicmd)) {
-      scheduleAtTime(() => {
+      timedSend(timeMs, (timeMs) => device.sendClock({ time: timeMs }));
-        device.sendClock();
-      }, targetTime);
     } else if (['start'].includes(midicmd)) {
-      scheduleAtTime(() => {
+      timedSend(timeMs, (timeMs) => device.sendStart({ time: timeMs }));
-        device.sendStart();
-      }, targetTime);
     } else if (['stop'].includes(midicmd)) {
-      scheduleAtTime(() => {
+      timedSend(timeMs, (timeMs) => device.sendStop({ time: timeMs }));
-        device.sendStop();
-      }, targetTime);
     } else if (['continue'].includes(midicmd)) {
-      scheduleAtTime(() => {
+      timedSend(timeMs, (timeMs) => device.sendContinue({ time: timeMs }));
-        device.sendContinue();
-      }, targetTime);
     } else if (Array.isArray(midicmd)) {
       if (midicmd[0] === 'progNum') {
-        sendProgramChange(midicmd[1], device, midichan, targetTime);
+        sendProgramChange(midicmd[1], device, midichan, timeMs);
       } else if (midicmd[0] === 'cc') {
         if (midicmd.length === 2) {
-          sendCC(midicmd[0], midicmd[1] / 127, device, midichan, targetTime);
+          sendCC(midicmd[0], midicmd[1] / 127, device, midichan, timeMs);
         }
       } else if (midicmd[0] === 'sysex') {
         if (midicmd.length === 3) {
           const [_, id, data] = midicmd;
-          sendSysex(id, data, device, targetTime);
+          sendSysex(id, data, device, timeMs);
         }
       }
     }

packages/mqtt/mqtt.mjs

@@ -4,7 +4,7 @@ Copyright (C) 2022 Strudel contributors - see <https://codeberg.org/uzu/strudel/
 This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
-import { Pattern, isPattern } from '@strudel/core';
+import { Pattern, isPattern, createParams } from '@strudel/core';
 import Paho from 'paho-mqtt';
 
 const connections = {};
@@ -118,3 +118,12 @@ Pattern.prototype.mqtt = function (
     return hap.setContext({ ...hap.context, onTrigger, dominantTrigger: true });
   });
 };
+
+// This adds the 'move' and 'motor' commands to strudel
+export const { move, motor } = createParams('move', 'motor');
+window.move = move;
+window.motor = motor;
+// This adds the 'robot' command
+Pattern.prototype.robot = function (robot_id, address = 'ws://192.168.8.248:9001/mqtt') {
+  return this.mqtt(undefined, undefined, '/move/' + robot_id, address);
+};

test/__snapshots__/examples.test.mjs.snap

@@ -1242,6 +1242,35 @@ exports[`runs examples > example "bank" example index 0 1`] = `
 ]
 `;
 
+exports[`runs examples > example "base" example index 0 1`] = `
+[
+  "[ 0/1 → 1/6 | note:D3 s:saw ]",
+  "[ 1/6 → 1/3 | note:C4 s:saw ]",
+  "[ 1/3 → 1/2 | note:A3 s:saw ]",
+  "[ 1/2 → 2/3 | note:A3 s:saw ]",
+  "[ 2/3 → 5/6 | note:G3 s:saw ]",
+  "[ 5/6 → 1/1 | note:F3 s:saw ]",
+  "[ 1/1 → 7/6 | note:D3 s:saw ]",
+  "[ 7/6 → 4/3 | note:C4 s:saw ]",
+  "[ 4/3 → 3/2 | note:A3 s:saw ]",
+  "[ 3/2 → 5/3 | note:A3 s:saw ]",
+  "[ 5/3 → 11/6 | note:G3 s:saw ]",
+  "[ 11/6 → 2/1 | note:F3 s:saw ]",
+  "[ 2/1 → 13/6 | note:D3 s:saw ]",
+  "[ 13/6 → 7/3 | note:C4 s:saw ]",
+  "[ 7/3 → 5/2 | note:A3 s:saw ]",
+  "[ 5/2 → 8/3 | note:A3 s:saw ]",
+  "[ 8/3 → 17/6 | note:G3 s:saw ]",
+  "[ 17/6 → 3/1 | note:F3 s:saw ]",
+  "[ 3/1 → 19/6 | note:D3 s:saw ]",
+  "[ 19/6 → 10/3 | note:C4 s:saw ]",
+  "[ 10/3 → 7/2 | note:A3 s:saw ]",
+  "[ 7/2 → 11/3 | note:A3 s:saw ]",
+  "[ 11/3 → 23/6 | note:G3 s:saw ]",
+  "[ 23/6 → 4/1 | note:F3 s:saw ]",
+]
+`;
+
 exports[`runs examples > example "beat" example index 0 1`] = `
 [
   "[ 0/1 → 1/16 | s:bd ]",

website/astro.config.mjs

@@ -78,6 +78,7 @@ export default defineConfig({
             urlPattern: ({ url }) =>
               [
                 /^https:\/\/raw\.githubusercontent\.com\/.*/i,
+                /^https:\/\/strudel\.b-cdn\.net\/.*/i,
                 /^https:\/\/freesound\.org\/.*/i,
                 /^https:\/\/cdn\.freesound\.org\/.*/i,
                 /^https:\/\/shabda\.ndre\.gr\/.*/i,

website/src/pages/learn/faq.mdx

@@ -52,6 +52,15 @@ There are multiple ways to load your sample collection. Some methods are good fo
 - Serve a folder of samples locally using the [strudel 'sampler' commandline tool](https://strudel.cc/learn/samples/#from-disk-via-strudelsampler). This can be most reliable method, but requires [nodejs](https://nodejs.org) to be installed.
 - Host your sound library online on the web and [load them from an URL](/learn/samples/#loading-custom-samples)
 
+## Can I create a new project based on Strudel?
+
+Strudel is free/open source software, and we are always happy to see people making use of it within the following terms:
+
+- Please don't use 'strudel' in the name of your project (e.g. strudel2000, foo-strudel), so people don't assume it's official strudel project. (If you'd like it to be an official strudel project, please check in with the community, e.g. on the [discord chat](https://discord.com/invite/HGEdXmRkzT).)
+- Please respect our AGPL license, which e.g. requires you to share/link to the source code of strudel, any modifications you've made to it, and the source code for the rest of your project if it integrates with strudel. You are also required to maintain Strudel's copyright notices in the source code, and include Strudel's copyright notice in your user interface. This is an ad-hoc summary - please [refer to the license](https://codeberg.org/uzu/strudel/src/branch/main/LICENSE) for full details.
+
+You are also encouraged to connect with [the community](https://discord.com/invite/HGEdXmRkzT) to understand our aims and values.
+
 ## Can I use Strudel with AI/LLM tools?
 
 You are free to do what you like with Strudel, within the terms of the free/open source AGPLv3 license.

website/src/pages/workshop/motors.mdx

@@ -0,0 +1,117 @@
+---
+title: Movement with Strudel
+layout: ../../layouts/MainLayout.astro
+---
+
+import { MiniRepl } from '@src/docs/MiniRepl';
+import Box from '@components/Box.astro';
+import QA from '@components/QA';
+
+# Controlling motors with Strudel
+
+Strudel is mainly made for making music, but it's possible to pattern other things with it, including motors.
+
+We're going to use a microcontroller for this, called an "[Inventor 2040W](https://shop.pimoroni.com/products/inventor-2040-w)", which is
+a [Pico W](https://shop.pimoroni.com/products/inventor-2040-w?variant=40053063155795) with extra ports added including some for controlling motors.
+
+![image](https://shop.pimoroni.com/cdn/shop/products/Inventor2040_1of3_1500x1500_crop_center.jpg?v=1656927927)
+
+## Technical details
+
+Feel free to gloss over these!
+
+- The Inventor 2040W connects to the internet wirelessly, and it can power from a battery or USB. Hopefully the batteries last!
+- It's running [some code](https://github.com/patternclub/alpacalab/blob/main/course/main.py) that listens for messages using an "Internet of Things" network protocol (called MQTT). When it receives a message, it moves a motor.
+- It connects to a small server (running software called 'mosquitto') on Alex's laptop.
+- Strudel can send these messages instead of triggering sounds - that's how we use it to pattern movement.
+
+## First movement
+
+Let's get a motor running!
+
+1. Note the letter drawn on a label on the back of the microcontroller.
+
+2. Plug a battery into your microcontroller.
+
+3. Plug a motor into 'servo' (not motor) plug numbered 1, with the yellow (lightest) cable closest to the '1', and the brown (darkest) cable outward
+
+4. Run the below to set up some values, changing the `x` in 'robot('x')` to the letter on your microcontroller.
+
+<MiniRepl
+  client:visible
+  tune={`
+   $: move("-60 80").motor("0").robot('x');
+  `}
+/>
+
+<Box>
+
+If you refresh the page, you'll need to change the letter to match your robot again.
+
+If your motor starts moving unexpectedly, someone else might have put your letter in by mistake!
+
+Note that in the above, we start counting motors from '0', so motor 1 on the board is motor 0 in the code.
+
+</Box>
+
+## Patterning movement
+
+Many strudel features for playing with sound patterns will work when
+playing with motor patterns. Try playing with the mininotation in the
+`move` command:
+
+<MiniRepl
+  client:visible
+  tune={`
+$: move("-10 0 10 [20 30]*2").motor("0").slow(2).robot('x')
+  `}
+/>
+
+The move instructions are in the range from -90 to 90.
+
+<box>
+  If your motors stop working at some point, and your code looks right, try pressing the 'reset' button on the
+  microcontroller.
+</box>
+
+It's possible to make smooth movements based on different 'waveforms', for example a smooth sinewave:
+
+<MiniRepl
+  client:visible
+  tune={`
+$: move(sine.range(-30, 30).segment(16)).motor("0").slow(2).robot('x');
+  `}
+/>
+
+The movement is still quite jerky, because the 'segment' command is
+only taking 16 positions from the sinewave. Try increasing it to 32 or 64. It's best not too much higher than that, as the microcontroller
+might get overwhelmed with a backlog of instructions!
+
+<box>
+  Try replacing `sine` with other waveforms: `saw` (sawtooth wave), `tri` (triangular wave) are good, and there is also
+  `rand` (random wave) and `perlin` (a kind of smoothed-out randomness).
+</box>
+
+## Patterning more than one motor
+
+You can pattern the `motor` command separately from the `move` one:
+
+<MiniRepl
+  client:visible
+  tune={`
+$: move("-10 0 10 [20 30]*2").motor("0 1").slow(2).robot('x');
+  `}
+/>
+
+Alternatively, you can pattern two motors in separate patterns. The below sends the same pattern for the first two motors, but with the second one running slower:
+
+<MiniRepl
+  client:visible
+  tune={`
+
+$: move("-10 0 10 [20 30]\*2").motor("0").slow(2).robot('x');
+
+$: move("-10 0 10 [20 30]\*2").motor("1").slow(3).robot('x');
+
+`}
+/>

website/src/repl/components/panel/WelcomeTab.jsx

@@ -36,8 +36,9 @@ export function WelcomeTab({ context }) {
         <a href="https://tidalcycles.org/" target="_blank">
           tidalcycles
         </a>
-        , which is a popular live coding language for music, written in Haskell. Strudel is free/open source software:
+        , which is a popular live coding language for music, written in Haskell. Strudel is free/open source software,
-        you can redistribute and/or modify it under the terms of the{' '}
+        with copyright owned by its [contributors](https://codeberg.org/uzu/strudel/activity/contributors). You can
+        redistribute and/or modify it under the terms of the{' '}
         <a href="https://codeberg.org/uzu/strudel/src/branch/main/LICENSE" target="_blank">
           GNU Affero General Public License
         </a>