OpenAI Charges by the Minute, So Make the Minutes Shorter

A developer discovered that speeding up audio files 2x or 3x before sending them to OpenAI's transcription APIs significantly reduces costs and processing time while maintaining transcription quality. Using ffmpeg to accelerate audio reduces the duration-based pricing for whisper-1 and token-based pricing for gpt-4o-transcribe models. Testing showed 2x speed saves about 23% on costs, while 3x speed provides even better savings. The technique works because AI models, like human brains, can handle compressed audio information effectively, though 4x speed produces unusable results.