Fix stale references in ASR documentation

[Alex-Wengg]

Summary

• DirectoryStructure.md: Update "New Structure" tree to match post-PR ASR tech debt cleanup: remove dead code, fix bugs, add benchmark script 28/03/2026 #460 state — remove ANEOptimizer.swift (deleted), MLArrayCache.swift, PerformanceMetrics.swift, ProgressEmitter.swift (moved to Shared/), rename NemotronPipeline.swift → NemotronStreamingAsrManager+Pipeline.swift
• GettingStarted.md: Fix EOU model name from parakeet-eou-1.1b-coreml to parakeet-realtime-eou-120m-coreml

Test plan

• Verify directory tree in DirectoryStructure.md matches Sources/FluidAudio/ASR/Parakeet/
• Verify model name in GettingStarted.md matches Models.md and ModelNames.swift

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[claude]

Claude finished @Alex-Wengg's task —— View job

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PR Review Complete ✅

Reviewed PR #462: Fix stale references in ASR documentation

Todo List

• Create pending PR review
• Analyze PR diff and changes
• Verify directory structure updates
• Verify model name fixes
• Add inline review comments if needed
• Submit review

Analysis

✅ Directory structure changes verified - All removed files (ANEOptimizer.swift, MLArrayCache.swift, PerformanceMetrics.swift, ProgressEmitter.swift) have indeed been moved to Sources/FluidAudio/Shared/ and NemotronPipeline.swift has been renamed to NemotronStreamingAsrManager+Pipeline.swift.

✅ Model name fix verified - The correction from parakeet-eou-1.1b-coreml to parakeet-realtime-eou-120m-coreml is accurate and consistent with all other references in the codebase.

Review Summary

All documentation updates are accurate and properly reflect the current codebase state. The PR correctly fixes stale references that would have confused developers. No issues found - ready to merge.

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[claude]

✅ Documentation updates look good!

This PR correctly fixes the stale references in the ASR documentation:

1. DirectoryStructure.md: Accurately removes the deleted/moved files and reflects the current state post-PR #460
2. GettingStarted.md: Correctly updates the EOU model name to match the actual model used throughout the codebase

All changes have been verified against the current source code structure and model references. No issues found.

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 1 additional finding.

[github-actions]

PocketTTS Smoke Test ✅

Check	Result
Build	✅
Model download	✅
Model load	✅
Synthesis pipeline	✅
Output WAV	✅ (153.8 KB)

_{Runtime: 0m32s}

_{Note: PocketTTS uses CoreML MLState (macOS 15) KV cache + Mimi streaming state. CI VM lacks physical GPU — audio quality may differ from Apple Silicon.}

[github-actions]

Parakeet EOU Benchmark Results ✅

Status: Benchmark passed
Chunk Size: 320ms
Files Tested: 100/100

Performance Metrics

Metric	Value	Description
WER (Avg)	7.03%	Average Word Error Rate
WER (Med)	4.17%	Median Word Error Rate
RTFx	11.46x	Real-time factor (higher = faster)
Total Audio	470.6s	Total audio duration processed
Total Time	42.0s	Total processing time

Streaming Metrics

Metric	Value	Description
Avg Chunk Time	0.042s	Average chunk processing time
Max Chunk Time	0.084s	Maximum chunk processing time
EOU Detections	0	Total End-of-Utterance detections

_{Test runtime: 1m0s • 03/29/2026, 01:16 AM EST}

_{RTFx = Real-Time Factor (higher is better) • Processing includes: Model inference, audio preprocessing, state management, and file I/O}

[github-actions]

Qwen3-ASR int8 Smoke Test ✅

Check	Result
Build	✅
Model download	✅
Model load	✅
Transcription pipeline	✅
Decoder size	571 MB (vs 1.1 GB f32)

Performance Metrics

Metric	CI Value	Expected on Apple Silicon
Median RTFx	0.06x	~2.5x
Overall RTFx	0.06x	~2.5x

_{Runtime: 3m27s}

_{Note: CI VM lacks physical GPU — CoreML MLState (macOS 15) KV cache produces degraded results on virtualized runners. On Apple Silicon: ~1.3% WER / 2.5x RTFx.}

[github-actions]

Speaker Diarization Benchmark Results

Speaker Diarization Performance

Evaluating "who spoke when" detection accuracy

Metric	Value	Target	Status	Description
DER	15.1%	<30%	✅	Diarization Error Rate (lower is better)
JER	24.9%	<25%	✅	Jaccard Error Rate
RTFx	18.69x	>1.0x	✅	Real-Time Factor (higher is faster)

Diarization Pipeline Timing Breakdown

Time spent in each stage of speaker diarization

Stage	Time (s)	%	Description
Model Download	12.772	22.7	Fetching diarization models
Model Compile	5.474	9.7	CoreML compilation
Audio Load	0.077	0.1	Loading audio file
Segmentation	16.834	30.0	Detecting speech regions
Embedding	28.056	50.0	Extracting speaker voices
Clustering	11.222	20.0	Grouping same speakers
Total	56.150	100	Full pipeline

Speaker Diarization Research Comparison

Research baselines typically achieve 18-30% DER on standard datasets

Method	DER	Notes
FluidAudio	15.1%	On-device CoreML
Research baseline	18-30%	Standard dataset performance

Note: RTFx shown above is from GitHub Actions runner. On Apple Silicon with ANE:

• M2 MacBook Air (2022): Runs at 150 RTFx real-time
• Performance scales with Apple Neural Engine capabilities

_{🎯 Speaker Diarization Test • AMI Corpus ES2004a • 1049.0s meeting audio • 56.1s diarization time • Test runtime: 3m 18s • 03/29/2026, 01:19 AM EST}

[github-actions]

Sortformer High-Latency Benchmark Results

ES2004a Performance (30.4s latency config)

Metric	Value	Target	Status
DER	33.4%	<35%	✅
Miss Rate	24.4%	-	-
False Alarm	0.2%	-	-
Speaker Error	8.8%	-	-
RTFx	10.5x	>1.0x	✅
Speakers	4/4	-	-

_{Sortformer High-Latency • ES2004a • Runtime: 3m 12s • 2026-03-29T05:20:47.189Z}

[github-actions]

VAD Benchmark Results

Performance Comparison

Dataset	Accuracy	Precision	Recall	F1-Score	RTFx	Files
MUSAN	92.0%	86.2%	100.0%	92.6%	746.2x faster	50
VOiCES	92.0%	86.2%	100.0%	92.6%	731.7x faster	50

Dataset Details

• MUSAN: Music, Speech, and Noise dataset - standard VAD evaluation
• VOiCES: Voices Obscured in Complex Environmental Settings - tests robustness in real-world conditions

✅: Average F1-Score above 70%

[github-actions]

Offline VBx Pipeline Results

Speaker Diarization Performance (VBx Batch Mode)

Optimal clustering with Hungarian algorithm for maximum accuracy

Metric	Value	Target	Status	Description
DER	14.5%	<20%	✅	Diarization Error Rate (lower is better)
RTFx	4.57x	>1.0x	✅	Real-Time Factor (higher is faster)

Offline VBx Pipeline Timing Breakdown

Time spent in each stage of batch diarization

Stage	Time (s)	%	Description
Model Download	14.849	6.5	Fetching diarization models
Model Compile	6.364	2.8	CoreML compilation
Audio Load	0.051	0.0	Loading audio file
Segmentation	27.039	11.8	VAD + speech detection
Embedding	228.587	99.6	Speaker embedding extraction
Clustering (VBx)	0.743	0.3	Hungarian algorithm + VBx clustering
Total	229.490	100	Full VBx pipeline

Speaker Diarization Research Comparison

Offline VBx achieves competitive accuracy with batch processing

Method	DER	Mode	Description
FluidAudio (Offline)	14.5%	VBx Batch	On-device CoreML with optimal clustering
FluidAudio (Streaming)	17.7%	Chunk-based	First-occurrence speaker mapping
Research baseline	18-30%	Various	Standard dataset performance

Pipeline Details:

• Mode: Offline VBx with Hungarian algorithm for optimal speaker-to-cluster assignment
• Segmentation: VAD-based voice activity detection
• Embeddings: WeSpeaker-compatible speaker embeddings
• Clustering: PowerSet with VBx refinement
• Accuracy: Higher than streaming due to optimal post-hoc mapping

_{🎯 Offline VBx Test • AMI Corpus ES2004a • 1049.0s meeting audio • 256.4s processing • Test runtime: 4m 21s • 03/29/2026, 01:25 AM EST}

[github-actions]

ASR Benchmark Results ✅

Status: All benchmarks passed

Parakeet v3 (multilingual)

Dataset	WER Avg	WER Med	RTFx	Status
test-clean	0.57%	0.00%	4.54x	✅
test-other	1.19%	0.00%	2.45x	✅

Parakeet v2 (English-optimized)

Dataset	WER Avg	WER Med	RTFx	Status
test-clean	0.80%	0.00%	5.37x	✅
test-other	1.00%	0.00%	3.53x	✅

Streaming (v3)

Metric	Value	Description
WER	0.00%	Word Error Rate in streaming mode
RTFx	0.60x	Streaming real-time factor
Avg Chunk Time	1.511s	Average time to process each chunk
Max Chunk Time	2.137s	Maximum chunk processing time
First Token	1.853s	Latency to first transcription token
Total Chunks	31	Number of chunks processed

Streaming (v2)

Metric	Value	Description
WER	0.00%	Word Error Rate in streaming mode
RTFx	0.62x	Streaming real-time factor
Avg Chunk Time	1.452s	Average time to process each chunk
Max Chunk Time	1.622s	Maximum chunk processing time
First Token	1.455s	Latency to first transcription token
Total Chunks	31	Number of chunks processed

_{Streaming tests use 5 files with 0.5s chunks to simulate real-time audio streaming}

_{25 files per dataset • Test runtime: 6m55s • 03/29/2026, 01:31 AM EST}

_{RTFx = Real-Time Factor (higher is better) • Calculated as: Total audio duration ÷ Total processing time
Processing time includes: Model inference on Apple Neural Engine, audio preprocessing, state resets between files, token-to-text conversion, and file I/O
Example: RTFx of 2.0x means 10 seconds of audio processed in 5 seconds (2x faster than real-time)}

Expected RTFx Performance on Physical M1 Hardware:

• M1 Mac: ~28x (clean), ~25x (other)
• CI shows ~0.5-3x due to virtualization limitations

_{Testing methodology follows HuggingFace Open ASR Leaderboard}