Offline Audio Transcriber
Transcribe audio files (.mp3, .wav, .m4a) completely offline in your browser using AI via Transformers.js. No audio is ever sent to a server.
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MP3 Audio Transcription
MP3 (MPEG-1 Audio Layer III) is the most common compressed audio format. Transcription converts the speech in an MP3 into written text using automatic speech recognition (ASR) technology.
How MP3 Transcription Works
- The MP3 file is decoded to raw PCM audio data in your browser
- Audio is segmented into manageable chunks for recognition
- The Web Speech API or a local AI model processes each chunk
- Text segments are assembled into a complete transcript
Supported Audio Formats
- MP3 — most universal compressed format, 64–320 kbps
- WAV — uncompressed, highest quality, larger files
- M4A/AAC — Apple's format, used by iPhone voice memos
- OGG Vorbis — open-source compressed format
- FLAC — lossless compression, very high quality
What MP3 bitrate gives the best transcription results?
For speech transcription, 64 kbps mono is typically sufficient — speech doesn't require the full frequency range music needs. Transcription accuracy improves very little above 128 kbps. What matters more is sample rate (at least 16 kHz for speech) and minimizing background noise during recording.
Can this transcribe podcasts with multiple speakers?
Basic transcription converts all speech to text without distinguishing speakers (diarization). For podcast transcription with labeled speakers, tools like AssemblyAI, Whisper with speaker diarization, or Rev.com support speaker identification. This tool provides accurate text output; post-processing can attribute speech manually.
How long does it take to transcribe an MP3?
Browser-based transcription typically runs at 1–3× real time (a 10-minute recording takes 3–10 minutes). Server-side models like Whisper run faster on GPU hardware — under 1 minute for a 10-minute recording. Transcription speed depends on audio length, quality, and the processing hardware available.