nanovt

Transcribe video or audio files with OpenAI or Volcengine speech-to-text.

The script extracts audio with ffmpeg, converts it to mono 16 kHz, transcribes it, and writes a single text file. The OpenAI provider splits the audio into short chunks; the Volcengine provider submits the whole file to an asynchronous job.

Requirements

• Python 3.13+
• ffmpeg
• OPENAI_API_KEY in your environment (OpenAI provider, the default)
• VOLC_ASR_API_KEY in your environment (Volcengine provider)

Installation

From PyPI:

pip install nanovt

Or install it as an isolated uv tool:

uv tool install nanovt

Usage

nanovt input.mp4

By default, input.mp4 writes input.txt.

To force a language, pass an optional language code. For example, English:

nanovt input.mp4 --language en

If --language is omitted, the model detects the language automatically.

Other useful options:

nanovt input.mp4 --chunk-seconds 180 --retries 3
nanovt input.mp4 --output transcript.txt
nanovt input.mp4 --keep-temp

For speaker-labeled dialogue transcription, enable diarization:

nanovt input.mp4 --diarize

This uses gpt-4o-transcribe-diarize by default and writes dialogue lines such as A: ..., B: ..., and C: ....

Volcengine provider

Volcengine's big-model ASR handles Chinese and code-switched speech well. Set VOLC_ASR_API_KEY and select the provider:

nanovt input.mp4 --provider volc --language zh --diarize

The audio is compressed to a mono 16 kHz MP3 and submitted inline, so no public URL is needed. --model defaults to bigmodel; override the resource id with VOLC_ASR_RESOURCE_ID (default volc.seedasr.auc). --chunk-seconds is unused for this provider. Diarized output uses the same A: ... / B: ... lines.

Development

uv sync --group dev
uv run pytest
uv run nanovt input.mp4