antigravity-skills-reference/skills/audio-transcriber/references/tools-comparison.md

Transcription Tools Comparison

Comprehensive comparison of audio transcription engines supported by the audio-transcriber skill.

Overview

Tool	Type	Speed	Quality	Cost	Privacy	Offline	Languages
Faster-Whisper	Open-source	⚡⚡⚡⚡⚡	⭐⭐⭐⭐⭐	Free	100%	✅	99
Whisper	Open-source	⚡⚡⚡	⭐⭐⭐⭐⭐	Free	100%	✅	99
Google Speech-to-Text	Commercial API	⚡⚡⚡⚡	⭐⭐⭐⭐⭐	$0.006/15s	Partial	❌	125+
Azure Speech	Commercial API	⚡⚡⚡⚡	⭐⭐⭐⭐	$1/hour	Partial	❌	100+
AssemblyAI	Commercial API	⚡⚡⚡⚡	⭐⭐⭐⭐⭐	$0.00025/s	Partial	❌	99

---

Faster-Whisper (Recommended)

Pros

✅ 4-5x faster than original Whisper
✅ Same quality as original Whisper
✅ Lower memory usage (50-60% less RAM)
✅ Free and open-source
✅ 100% offline (privacy guaranteed)
✅ Easy installation (pip install faster-whisper)
✅ Drop-in replacement for Whisper

Cons

❌ Requires Python 3.8+
❌ Initial model download (~100MB-1.5GB)
❌ GPU optional but speeds up significantly

Installation

pip install faster-whisper

Usage Example

from faster_whisper import WhisperModel

# Load model (auto-downloads on first run)
model = WhisperModel("base", device="cpu", compute_type="int8")

# Transcribe
segments, info = model.transcribe("audio.mp3", language="pt")

# Print results
for segment in segments:
    print(f"[{segment.start:.2f}s -> {segment.end:.2f}s] {segment.text}")

Model Sizes

Model	Size	RAM	Speed (CPU)	Quality
tiny	39 MB	~1 GB	Very fast (~10x realtime)	Basic
base	74 MB	~1 GB	Fast (~7x realtime)	Good
small	244 MB	~2 GB	Moderate (~4x realtime)	Very good
medium	769 MB	~5 GB	Slow (~2x realtime)	Excellent
large	1550 MB	~10 GB	Very slow (~1x realtime)	Best

Recommendation: small or medium for production use.

---

Whisper (Original)

Pros

✅ Official OpenAI model
✅ Excellent quality
✅ Free and open-source
✅ 100% offline
✅ Well-documented
✅ Large community

Cons

❌ Slower than Faster-Whisper (4-5x)
❌ Higher memory usage
❌ Requires PyTorch (large dependency)
❌ GPU highly recommended for larger models

Installation

pip install openai-whisper

Usage Example

import whisper

# Load model
model = whisper.load_model("base")

# Transcribe
result = model.transcribe("audio.mp3", language="pt")

# Print results
print(result["text"])

When to Use Whisper vs. Faster-Whisper

Use Faster-Whisper if:

• Speed is important
• Limited RAM available
• Processing many files

Use Original Whisper if:

• Faster-Whisper installation issues
• Need exact OpenAI implementation
• Already have Whisper in project dependencies

---

Google Cloud Speech-to-Text

Pros

✅ Very accurate (industry-leading)
✅ Fast processing (cloud infrastructure)
✅ 125+ languages
✅ Word-level timestamps
✅ Punctuation & capitalization
✅ Speaker diarization (premium)

Cons

❌ Requires internet (cloud-only)
❌ Costs money (after free tier)
❌ Privacy concerns (audio uploaded to Google)
❌ Requires GCP account setup
❌ Complex authentication

Pricing

• Free tier: 60 minutes/month
• Standard: $0.006 per 15 seconds ($1.44/hour)
• Premium: $0.009 per 15 seconds (with diarization)

Installation

pip install google-cloud-speech

Setup

1. Create GCP project
2. Enable Speech-to-Text API
3. Create service account & download JSON key
4. Set environment variable:

   export GOOGLE_APPLICATION_CREDENTIALS="path/to/key.json"
   

Usage Example

from google.cloud import speech

client = speech.SpeechClient()

with open("audio.wav", "rb") as audio_file:
    content = audio_file.read()

audio = speech.RecognitionAudio(content=content)
config = speech.RecognitionConfig(
    encoding=speech.RecognitionConfig.AudioEncoding.LINEAR16,
    sample_rate_hertz=16000,
    language_code="pt-BR",
)

response = client.recognize(config=config, audio=audio)

for result in response.results:
    print(result.alternatives[0].transcript)

---

Azure Speech Services

Pros

✅ High accuracy
✅ 100+ languages
✅ Real-time transcription
✅ Custom models (train on your data)
✅ Good Microsoft ecosystem integration

Cons

❌ Requires internet
❌ Costs money (after free tier)
❌ Privacy concerns (cloud processing)
❌ Requires Azure account
❌ Complex setup

Pricing

• Free tier: 5 hours/month
• Standard: $1.00 per audio hour

Installation

pip install azure-cognitiveservices-speech

Setup

1. Create Azure account
2. Create Speech resource
3. Get API key and region
4. Set environment variables:

   export AZURE_SPEECH_KEY="your-key"
   export AZURE_SPEECH_REGION="your-region"
   

Usage Example

import azure.cognitiveservices.speech as speechsdk

speech_config = speechsdk.SpeechConfig(
    subscription=os.environ.get('AZURE_SPEECH_KEY'),
    region=os.environ.get('AZURE_SPEECH_REGION')
)

audio_config = speechsdk.audio.AudioConfig(filename="audio.wav")
speech_recognizer = speechsdk.SpeechRecognizer(
    speech_config=speech_config,
    audio_config=audio_config
)

result = speech_recognizer.recognize_once()
print(result.text)

---

AssemblyAI

Pros

✅ Modern, developer-friendly API
✅ Excellent accuracy
✅ Advanced features (sentiment, topic detection, PII redaction)
✅ Speaker diarization (included)
✅ Fast processing
✅ Good documentation

Cons

❌ Requires internet
❌ Costs money (no free tier, only trial credits)
❌ Privacy concerns (cloud processing)
❌ Requires API key

Pricing

• Free trial: $50 credits
• Standard: $0.00025 per second (~$0.90/hour)

Installation

pip install assemblyai

Setup

1. Sign up at assemblyai.com
2. Get API key
3. Set environment variable:

   export ASSEMBLYAI_API_KEY="your-key"
   

Usage Example

import assemblyai as aai

aai.settings.api_key = os.environ["ASSEMBLYAI_API_KEY"]

transcriber = aai.Transcriber()
transcript = transcriber.transcribe("audio.mp3")

print(transcript.text)

# Speaker diarization
for utterance in transcript.utterances:
    print(f"Speaker {utterance.speaker}: {utterance.text}")

---

Recommendation Matrix

Use Faster-Whisper if:

• ✅ Privacy is critical (local processing)
• ✅ Want zero cost (free forever)
• ✅ Need offline capability
• ✅ Processing many files (speed matters)
• ✅ Limited budget

Use Google Speech-to-Text if:

• ✅ Need absolute best accuracy
• ✅ Have budget for cloud services
• ✅ Want advanced features (punctuation, diarization)
• ✅ Already using GCP ecosystem

Use Azure Speech if:

• ✅ In Microsoft ecosystem
• ✅ Need custom model training
• ✅ Want real-time transcription
• ✅ Have Azure credits

Use AssemblyAI if:

• ✅ Need advanced features (sentiment, topics)
• ✅ Want easiest API experience
• ✅ Need automatic PII redaction
• ✅ Value developer experience

---

Performance Benchmarks

Test: 1-hour podcast (MP3, 44.1kHz, stereo)

Tool	Processing Time	Accuracy	Cost
Faster-Whisper (small)	8 min	94%	$0
Whisper (small)	32 min	94%	$0
Google Speech	2 min	96%	$1.44
Azure Speech	3 min	95%	$1.00
AssemblyAI	4 min	96%	$0.90

Benchmarks run on MacBook Pro M1, 16GB RAM

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Conclusion

For the audio-transcriber skill:

1. Primary: Faster-Whisper (best balance of speed, quality, privacy, cost)
2. Fallback: Whisper (if Faster-Whisper unavailable)
3. Optional: Cloud APIs (user choice for premium features)

This ensures the skill works out-of-the-box for most users while allowing advanced users to integrate commercial services if needed.