Initial audio support

apps/LoopThroughWithOpenGLCompositing/AudioSupport.h

@@ -0,0 +1,71 @@
+#pragma once
+
+#include <array>
+#include <cstdint>
+#include <deque>
+#include <mutex>
+#include <vector>
+
+constexpr unsigned kAudioSampleRate = 48000;
+constexpr unsigned kAudioChannelCount = 2;
+constexpr unsigned kAudioTextureWidth = 64;
+constexpr unsigned kAudioTextureHeight = 2;
+
+struct AudioFrameBlock
+{
+	std::vector<int32_t> interleavedSamples;
+
+	std::size_t frameCount() const
+	{
+		return interleavedSamples.size() / kAudioChannelCount;
+	}
+};
+
+struct AudioAnalysisSnapshot
+{
+	std::array<float, 2> rms = { 0.0f, 0.0f };
+	std::array<float, 2> peak = { 0.0f, 0.0f };
+	float monoRms = 0.0f;
+	float monoPeak = 0.0f;
+	std::array<float, 4> bands = { 0.0f, 0.0f, 0.0f, 0.0f };
+	std::array<float, kAudioTextureWidth * kAudioTextureHeight * 4> texture = {};
+};
+
+struct AudioStatusSnapshot
+{
+	bool enabled = false;
+	unsigned bufferedSampleFrames = 0;
+	uint64_t underrunCount = 0;
+	AudioAnalysisSnapshot analysis;
+};
+
+class AudioDelayBuffer
+{
+public:
+	void Reset(unsigned delaySampleFrames);
+	void PushInterleaved(const int32_t* samples, std::size_t sampleFrameCount);
+	AudioFrameBlock Pop(std::size_t sampleFrameCount, bool& underrun);
+	unsigned BufferedSampleFrames() const;
+	uint64_t UnderrunCount() const;
+
+private:
+	mutable std::mutex mMutex;
+	std::deque<int32_t> mSamples;
+	uint64_t mUnderrunCount = 0;
+};
+
+class AudioAnalyzer
+{
+public:
+	void Reset();
+	AudioAnalysisSnapshot Analyze(const AudioFrameBlock& block);
+	const AudioAnalysisSnapshot& Current() const { return mCurrent; }
+
+private:
+	std::deque<float> mMonoHistory;
+	std::array<float, 4> mSmoothedBands = { 0.0f, 0.0f, 0.0f, 0.0f };
+	AudioAnalysisSnapshot mCurrent;
+};
+
+uint64_t AudioSampleTimeForVideoFrame(uint64_t videoFrameIndex, uint64_t frameDuration, uint64_t frameTimescale, uint64_t audioSampleRate = kAudioSampleRate);
+unsigned AudioSamplesForVideoFrame(uint64_t videoFrameIndex, uint64_t frameDuration, uint64_t frameTimescale, uint64_t audioSampleRate = kAudioSampleRate);