This repository implements a low-latency, real-time speech-to-speech conversational AI system. It provides an OpenAI Realtime API-compatible server over WebSocket and WebRTC transports, along with a CLI tool for local, talk, and serve modes. The architecture is modular, with separate handler stages for Voice Activity Detection (VAD), Speech-to-Text (STT), Large Language Model (LLM) reasoning, and Text-to-Speech (TTS), connected via typed queues. Multiple backends are supported for each stage, including local models (Whisper, Parakeet, Kokoro, Qwen3-TTS, MLX) and cloud APIs (OpenAI, vLLM, Hugging Face Inference Providers). A demo web application with HF OAuth, rate limiting, and audio worklets is included for browser-based interaction. The system is designed for production use, with emphasis on low latency through speculative turn handling, cancellation scopes, and turn latency instrumentation. Extensive test suites cover unit, integration, and protocol contract tests, including an evaluation harness for Big Bench Audio. While primarily an application, the repo also includes data/research components such as benchmarking scripts and a custom speech evaluation dataset.
Whisper is a speech recognition system that provides both a command-line interface and a Python library for transcribing and translating audio. The system processes audio by converting it to log-Mel spectrograms, then uses a Transformer-based encoder-decoder model to predict text tokens. Key components include audio processing, model architecture, decoding strategies, tokenization, and utilities for word-level timestamp alignment. The codebase is modular, well-tested, and actively maintained with recent updates supporting modern Python and PyTorch versions.
ESPnet is an end-to-end speech processing toolkit built on PyTorch, covering a wide range of tasks: automatic speech recognition (ASR), text-to-speech (TTS), speech translation (ST), speech enhancement (SE), speaker recognition, spoken language understanding (SLU), singing voice synthesis (SVS), speech language modeling (SpeechLM), and more. The repository contains both a core Python library (`espnet2/`, `espnet3/`) and a large collection of reproducible recipes (`egs2/`, `egs3/`) for dozens of public corpora and research challenges. The architecture is modular: each task defines its own model, loss, training, and inference via a `Task` class, with abstract base classes for encoders, decoders, frontends, tokenizers, and losses. Configuration is YAML-driven, and the training pipeline uses PyTorch Lightning (in ESPnet3) or a custom trainer (ESPnet2). The system provides CLI tools (`espnet` with subcommands like `transcribe`, `synthesize`, `enhance`, `translate`) and a Python API (`Speech2Text.from_pretrained()`) for inference. It also includes Docker images for deployment and Hugging Face Spaces demos. The repository is hybrid: it is primarily a software framework/library (application) with a strong research character, as evidenced by the extensive recipe collection, benchmark results, and support for state-of-the-art models (Conformer, HuBERT, Whisper, VALL-E). The recipe system follows Kaldi-style data preparation and stage-based pipelines, enabling reproducible experimentation. External dependencies include PyTorch, torchaudio, sentencepiece, and optional components like flash-attn, fairseq, and s3prl. The codebase is actively maintained with CI across multiple OS and Python versions, unit tests, and integration tests.