Whisper Transcription for Video Editors: Costs, Word Timestamps and Setup

Whisper - OpenAI's open-source speech recognition model - is what powers most modern caption tools, and using it through an API costs video editors almost nothing: $0.006 per audio minute on OpenAI (about 36 cents for an hour of audio), with Groq running the same whisper-large-v3 model faster at comparably tiny prices. Here's what editors actually need to know: word timestamps, the 25 MB limit, privacy, and where it fits in a caption workflow.

Why Whisper took over captioning

Whisper was released by OpenAI in late 2022 and open-sourced, which did two things: set a new accuracy bar for messy real-world audio (accents, music beds, crosstalk), and let every provider host it. The version that matters for captions is whisper-large-v3 with word-level timestamps- each word comes back with start and end times, which is precisely what per-word caption animation needs. Sentence-level timing (what basic subtitle tools use) can't drive a highlight that follows the voice.

What it costs, in editor terms

Groq prices its hosted whisper-large-v3 similarly low (fractions of a cent per audio minute, metered per second) and is dramatically faster - often transcribing a clip in a few seconds. Prices drift; check platform.openai.com and console.groq.com for current numbers. The takeaway doesn't drift: transcription is a rounding error next to literally any subscription.

OpenAI vs Groq for caption work

• Groq: runs whisper-large-v3 (the strongest open Whisper), very fast, generous on names and proper nouns. Our default recommendation for captions.
• OpenAI: the reference implementation, rock-solid availability, same API shape. The whisper-1 endpoint is slightly weaker on unusual names than large-v3.

The 25 MB limit (and the MP3 trick)

Both providers cap each upload at 25 MB. That sounds small until you realize it's an audio limit: a 96 kbps mono MP3 fits roughly 35 minutes in 25 MB. The standard workflow is exporting MP3 audio rather than WAV (a 10-minute WAV is ~100 MB; the same audio as MP3 is ~7 MB) and splitting anything longer than ~30 minutes. Tools with ffmpeg available can compress automatically.

Privacy: what leaves your machine

With a direct API integration, the audio goes from your machine to the provider you chose - nobody else's servers in between. OpenAI and Groq both state API data isn't used for model training by default (check their current policies). Contrast that with upload-your-video caption services, where your full footage sits in someone else's render pipeline. For client work under NDA, audio-only to a no-training API is a much easier conversation.

How this plugs into Premiere

Caption Plug now uses a bundled local Whisper model by default, so no API key, upload, or per-minute fee is required. OpenAI and Groq remain optional for editors who prefer the direct API workflow described above. Either route turns word timestamps into animated captions rendered frame-accurately on your timeline. Transcripts are cached, so restyling or toggling the censor never re-uploads anything. With the local model, the audio never leaves the machine at all.