Add "Speech Recognition" condition

Allows checking for speech patterns on a given OBS audio source

plugins/speech/speech-recognizer.hpp

@@ -0,0 +1,86 @@
+#pragma once
+#include "message-buffer.hpp"
+#include "message-dispatcher.hpp"
+
+#include <obs.hpp>
+
+#include <atomic>
+#include <condition_variable>
+#include <mutex>
+#include <string>
+#include <thread>
+#include <vector>
+
+struct whisper_context;
+struct audio_data;
+
+namespace advss {
+
+// Captures audio from one OBS source, resamples to 16 kHz mono, runs
+// whisper.cpp inference on a background thread, and dispatches the resulting
+// transcript text to registered MessageBuffers.
+class SpeechRecognizer {
+public:
+	SpeechRecognizer();
+	~SpeechRecognizer();
+
+	bool LoadModel(const std::string &modelPath);
+
+	bool StartCapture(obs_source_t *source);
+	void StopCapture();
+
+	void SetBufferDuration(double seconds);
+	void SetNThreads(int n);
+	void SetLanguage(const std::string &lang);
+	void SetTranslate(bool translate);
+	void SetVadEnergyThreshold(float threshold);
+	void SetSuppressNonSpeechTokens(bool suppress);
+	void SetNoContext(bool noContext);
+	void SetListenWhenMuted(bool listen);
+	void SetUseGpu(bool useGpu);
+
+	[[nodiscard]] std::shared_ptr<MessageBuffer<std::string>>
+	RegisterClient();
+
+private:
+	static void AudioCaptureCallback(void *param, obs_source_t *source,
+					 const struct audio_data *audio,
+					 bool muted);
+	void AppendResampledAudio(const struct audio_data *audio);
+	void InferenceLoop();
+
+	// Held during whisper_full and when freeing/replacing _ctx.
+	std::mutex _ctxMutex;
+	whisper_context *_ctx = nullptr;
+	// Stored as void* to avoid pulling <media-io/audio-resampler.h> into
+	// this header. Cast to audio_resampler_t* in the .cpp.
+	void *_resampler = nullptr;
+
+	std::vector<float> _audioBuffer;
+	std::mutex _audioMutex;
+	double _bufferDurationSeconds = 5.0;
+	float _vadEnergyThreshold = 1e-4f;
+	size_t _framesSinceLastStep = 0;
+
+	std::vector<float> _inferenceBuffer;
+	std::thread _inferenceThread;
+	std::atomic_bool _stopThread{false};
+	std::condition_variable _inferenceCV;
+	std::mutex _inferenceMutex;
+	bool _bufferReady = false;
+	int _nThreads = 4;
+	std::string _language = "auto";
+	bool _translate = false;
+	bool _suppressNonSpeechTokens = true;
+	bool _noContext = true;
+	bool _listenWhenMuted = false;
+	bool _useGpu = true;
+
+	OBSWeakSource _captureSource;
+	int _sourceSampleRate = 44100;
+	int _sourceChannelCount = 2;
+
+	MessageDispatcher<std::string> _dispatcher;
+};
+
+} // namespace advss