Add midi-file for MIDI manipulations

package.json

@@ -1,6 +1,6 @@
 {
   "name": "musicxml-midi",
-  "version": "2.8.5",
+  "version": "2.9.0",
   "description": "MusicXML to MIDI converter",
   "type": "module",
   "directories": {
@@ -9,6 +9,7 @@
   "bin": {
     "musicxml-midi": "src/js/server.js",
     "midi-timemap": "src/js/midi-timemap.js",
+    "midi-file": "src/js/midi-file.js",
     "musicxml-examples": "src/js/musicxml-examples.js",
     "musicxml-grooves": "src/js/musicxml-grooves.js"
   },
@@ -30,7 +31,7 @@
     "develop": "nodemon -e js,json src/js/server.js",
     "start": "node src/js/server.js",
     "test:xsl": "test/libs/bats/bin/bats test/*.bats",
-    "test:js": "cross-env PORT=1331 NODE_OPTIONS=--experimental-vm-modules NODE_ENV=test jest",
+    "test:js": "cross-env PORT=1331 NODE_OPTIONS=--experimental-vm-modules NODE_ENV=test jest -t ${TEST:-''}",
     "test": "npm run test:xsl && npm run test:js",
     "server": "PORT=8085 npm run start",
     "postinstall": "./postinstall.sh"
@@ -51,6 +52,7 @@
     "cors": "^2.8.5",
     "express": "^4.21.1",
     "express-fileupload": "^1.5.1",
+    "get-stdin": "^9.0.0",
     "morgan": "^1.10.0",
     "node-fetch": "^3.3.2",
     "node-jq": "^6.0.1",

src/js/midi-file.js

@@ -0,0 +1,24 @@
+#!/usr/bin/env node
+
+/**
+ * Parse a MIDI file into JSON and back.
+ *
+ * Usage: midi-file.js < source.mid | jq [..] | midi-file.js > target.mid
+ */
+
+import { parseMidi, writeMidi } from 'midi-file'
+import fs from 'fs'
+import process from 'process'
+import { buffer } from 'stream/consumers'
+
+const input = await buffer(process.stdin)
+try {
+  const midi = JSON.parse(input)
+  const buffer = Buffer.from(writeMidi(midi))
+  fs.writeFileSync(1, buffer)
+}
+catch {
+  const midi = parseMidi(input)
+  const buffer = Buffer.from(JSON.stringify(midi))
+  process.stdout.write(buffer)
+}

test/midi-file.test.js

@@ -0,0 +1,18 @@
+import util from 'util'
+import { createRequire } from 'module'
+import fs from 'fs'
+const require = createRequire(import.meta.url)
+const exec = util.promisify(require('child_process').exec)
+
+describe('midi-file', () => {
+  test('should convert incoming MIDI files to JSON', async () => {
+    const execResult = await exec('node src/js/midi-file.js < test/data/midi-timemap.test.mid')
+    const json = JSON.parse(execResult.stdout)
+    expect(json.header.numTracks).toEqual(3)
+  })
+  test('should convert incoming JSON to MIDI files', async () => {
+    const execResult = await exec('cat test/data/midi-timemap.test.mid | node src/js/midi-file.js | node src/js/midi-file.js', { encoding: 'buffer' })
+    const original = fs.readFileSync('test/data/midi-timemap.test.mid')
+    expect(execResult.stdout).toEqual(original)
+  })
+})

test/midi-timemap.test.js

@@ -3,7 +3,7 @@ import { createRequire } from 'module'
 const require = createRequire(import.meta.url)
 const exec = util.promisify(require('child_process').exec)
 
-describe('MIDI to timemap conversion cli', () => {
+describe('midi-timemap', () => {
   test('should run successfully', async () => {
     const execResult = await exec('node src/js/midi-timemap.js test/data/midi-timemap.test.mid')
     const timemap = JSON.parse(execResult.stdout);