Don't encode on copy

test/server/utils/ffmpegHelpers_merge.test.js

@@ -0,0 +1,112 @@
+const { expect } = require('chai')
+const sinon = require('sinon')
+const EventEmitter = require('events')
+const fs = require('../../../server/libs/fsExtra')
+const { mergeAudioFiles } = require('../../../server/utils/ffmpegHelpers')
+
+describe('mergeAudioFiles', () => {
+  let ffmpegStub
+  let audioTracks
+  let encodingOptions
+  let itemCachePath
+  let outputFilePath
+
+  beforeEach(() => {
+    ffmpegStub = new EventEmitter()
+    ffmpegStub.input = sinon.stub().returnsThis()
+    ffmpegStub.inputOptions = sinon.stub().returnsThis()
+    ffmpegStub.outputOptions = sinon.stub().returnsThis()
+    ffmpegStub.output = sinon.stub().returnsThis()
+    ffmpegStub.run = sinon.stub().callsFake(() => {
+      ffmpegStub.emit('end')
+    })
+
+    audioTracks = [
+      {
+        index: 0,
+        ino: 'ino1',
+        metadata: { path: '/path/to/track1.mp3', ext: '.mp3' },
+        duration: 100
+      },
+      {
+        index: 1,
+        ino: 'ino2',
+        metadata: { path: '/path/to/track2.mp3', ext: '.mp3' },
+        duration: 120
+      }
+    ]
+
+    encodingOptions = {
+      codec: 'aac',
+      bitrate: '128k',
+      channels: 2
+    }
+
+    itemCachePath = '/path/to/cache'
+    outputFilePath = '/path/to/output.m4b'
+
+    sinon.stub(fs, 'writeFile').resolves()
+    sinon.stub(fs, 'remove').resolves()
+  })
+
+  afterEach(() => {
+    sinon.restore()
+  })
+
+  it('should use re-encoding by default (codec aac)', async () => {
+    await mergeAudioFiles(audioTracks, 220, itemCachePath, outputFilePath, encodingOptions, null, ffmpegStub)
+
+    const calls = ffmpegStub.outputOptions.getCalls()
+    const allArgs = calls.flatMap(call => call.args[0])
+    
+    expect(allArgs).to.include('-acodec aac')
+    expect(allArgs).to.include('-ac 2')
+    expect(allArgs).to.include('-b:a 128k')
+  })
+
+  it('should use stream copy when codec is copy', async () => {
+    encodingOptions.codec = 'copy'
+
+    await mergeAudioFiles(audioTracks, 220, itemCachePath, outputFilePath, encodingOptions, null, ffmpegStub)
+
+    // Should hit the 'else' block which uses '-c:a copy'
+    expect(ffmpegStub.outputOptions.calledWith(['-c:a copy'])).to.be.true
+    
+    // Should NOT contain bitrate or channels or acodec
+    const outputOptionsCalls = ffmpegStub.outputOptions.getCalls()
+    outputOptionsCalls.forEach(call => {
+      const args = call.args[0]
+      if (Array.isArray(args)) {
+        expect(args.some(arg => arg.includes('-b:a'))).to.be.false
+        expect(args.some(arg => arg.includes('-ac '))).to.be.false // space to avoid matching '-acodec'
+        expect(args.some(arg => arg.includes('-acodec'))).to.be.false
+      }
+    })
+  })
+
+  it('should handle single track with copy', async () => {
+    encodingOptions.codec = 'copy'
+    const singleTrack = [audioTracks[0]]
+
+    await mergeAudioFiles(singleTrack, 100, itemCachePath, outputFilePath, encodingOptions, null, ffmpegStub)
+
+    expect(ffmpegStub.outputOptions.calledWith(['-c:a copy'])).to.be.true
+  })
+
+  it('should handle single track m4b with copy', async () => {
+    encodingOptions.codec = 'copy'
+    const singleTrack = [
+      {
+        index: 0,
+        ino: 'ino1',
+        metadata: { path: '/path/to/track1.m4b', ext: '.m4b' },
+        duration: 100
+      }
+    ]
+
+    await mergeAudioFiles(singleTrack, 100, itemCachePath, outputFilePath, encodingOptions, null, ffmpegStub)
+
+    // Code says: if (isOneTrack && firstTrackIsM4b) ffmpeg.outputOptions(['-c copy'])
+    expect(ffmpegStub.outputOptions.calledWith(['-c copy'])).to.be.true
+  })
+})