README

Local speech-to-text for PHP, in-process.
16kHz WAV in, text + timestamped segments out — no Python sidecar, no remote API, no audio leaving the box.

What is ext-whisper?

ext-whisper is a PHP 8.3+ extension that loads a whisper.cpp model and runs speech-to-text in the PHP process, on CPU. Written in Rust on top of ext-php-rs and whisper-rs.

🎙️ Transcription with timestamps — full text plus time-aligned segments, offsets in seconds.
🧾 Contracts-shaped output — segment rows match Displace\AI\Contracts\Transcriber exactly; the adapter is two lines.
🧰 Actionable errors — a non-conforming WAV throws with the precise ffmpeg one-liner that fixes it.
🌍 Multilingual + translate — ['language' => 'de'] hints, ['translate' => true] to English (multilingual models).
🧵 Thread-safe by construction — one model handle, a fresh whisper state per call, no shared mutable state.
🤫 Quiet by default — whisper.cpp's stderr firehose is silenced; EXT_WHISPER_LOG=1 restores it.

Quick start

mkdir -p models
curl -L -o models/ggml-tiny.en.bin \
    https://huggingface.co/ggerganov/whisper.cpp/resolve/main/ggml-tiny.en.bin

make build
php -d extension=$PWD/target/debug/libwhisper.so examples/transcribe.php \
    models/ggml-tiny.en.bin tests/fixtures/jfk.wav

<?php
use Displace\Whisper\Model;

$model  = Model::load('models/ggml-tiny.en.bin');
$result = $model->transcribe('audio/meeting.wav');

echo $result->text(), PHP_EOL;

foreach ($result->segments() as $s) {
    printf("[%6.2fs → %6.2fs] %s\n", $s['start'], $s['end'], $s['text']);
}

$model->close();

Input must be 16kHz mono 16-bit PCM WAV; everything else converts in one line (ffmpeg -i in.mp3 -ar 16000 -ac 1 -c:a pcm_s16le out.wav) and the error messages carry that exact command.

Documentation

whisper.displace.tech — install, audio preparation, the full API surface. Built from docs/ with mdbook, deployed on every push to main.

Part of a stack

Transcribe (ext-whisper) → chunk (ai-toolkit) → embed (ext-infer) → search (ext-turbovec): searchable audio archives, entirely on your hardware. The ai-contracts Transcriber interface is the integration surface.

Compatibility

	macOS arm64	Linux x86_64	Linux arm64	Windows
PHP 8.3	✅	✅	✅	—
PHP 8.4	✅	✅	✅	—
PHP 8.5	✅	✅	✅	—

Deliberately out of scope (v0.1)

Audio decoding (mp3/m4a/ogg — the ffmpeg one-liner is the API; symphonia-based decoding is a v0.2 candidate) · streaming / realtime transcription · speaker diarization · word-level timestamps · GPU-default builds (CPU-first platform-wide; use_gpu exists for custom builds) · Windows.

displace / ext-whisper

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