How to transcribe audio and video files to text with one API call (MP3, MP4, Google Drive, Dropbox)

Description and use

An automated recipe for transcribing audio and video files via a single API call, combining audio extraction, chunking, share‑link handling, and returning text and SRT.

Problem

Transcribing large or remote audio/video files is cumbersome due to size limits, format requirements, and share‑link handling.

Outcome

A 50‑minute MP3 from Dropbox was transcribed in ~40 s for $0.15 (≈$0.003 per minute).

Workflow

• Provide file URLs (direct or share links) or upload a file
• API extracts audio from video if needed
• Splits large files into 10‑minute chunks
• Transcribes each chunk with Whisper large‑v3
• Adjusts timestamps for each chunk
• Combines text and segments
• Returns JSON with status, fileName, language, duration, text, segments, and optional SRT

Evidence

A 50-minute MP3 shared through Dropbox was transcribed in about 40 seconds and cost $0.15.

Source

Whisper wants audio. Pull the audio track out with ffmpeg first, and shrink it while you are there, since speech models work on 16 kHz mono anyway:

Source

A Google Drive or Dropbox share link opens a preview page, not the file. You need the direct-download form:

Source