Deploy EDGE Processing

// Scene detection with histogram analysis
export default async function processFrame(frame, ctx) {
  // frame.data = raw video frame (Uint8Array)
  // frame.width, frame.height = dimensions
  // frame.timestamp = milliseconds since stream start
  // ctx = execution context with stream metadata

  try {
    // Compute luminance histogram for scene detection
    const histogram = computeHistogram(frame.data, frame.width, frame.height);

    // Compare with previous frame histogram
    const prevHistogram = ctx.state.get('lastHistogram');
    const distance = prevHistogram
      ? computeHistogramDistance(histogram, prevHistogram)
      : 0;

    // Scene change if histogram distance exceeds threshold
    const isSceneChange = distance > 0.35;

    // Extract additional metadata
    const metadata = {
      timestamp: frame.timestamp,
      frameNumber: ctx.state.get('frameCount', 0) + 1,
      sceneChange: isSceneChange,
      histogramDistance: distance,
      dominantColors: extractDominantColors(histogram),
      brightness: calculateBrightness(histogram),
      contrast: calculateContrast(histogram),
    };

    // Update state for next frame comparison
    ctx.state.set('lastHistogram', histogram);
    ctx.state.set('frameCount', metadata.frameNumber);

    // Emit event for PULSE analytics
    if (isSceneChange) {
      await ctx.emit('edge:scene-change', {
        streamId: ctx.stream.id,
        timestamp: frame.timestamp,
        sceneIndex: ctx.state.get('sceneCount', 0) + 1,
        metadata,
      });
      ctx.state.increment('sceneCount');
    }

    // Track processing metrics
    ctx.metrics.histogram('edge.processing_ms', Date.now() - frame.receivedAt);
    ctx.metrics.increment('edge.frames_processed');

    return {
      action: isSceneChange ? 'capture_thumbnail' : 'continue',
      metadata,
    };

  } catch (error) {
    ctx.metrics.increment('edge.processing_errors');
    ctx.logger.error('Frame processing failed', { error: error.message });
    throw error;
  }
}

function computeHistogram(data, width, height) {
  const histogram = new Float32Array(256);
  const pixelCount = width * height;

  for (let i = 0; i < data.length; i += 4) {
    // Convert RGB to grayscale luminance
    const luminance = Math.floor(
      data[i] * 0.299 + data[i + 1] * 0.587 + data[i + 2] * 0.114
    );
    histogram[luminance]++;
  }

  // Normalize histogram
  for (let i = 0; i < 256; i++) {
    histogram[i] /= pixelCount;
  }

  return histogram;
}

function computeHistogramDistance(hist1, hist2) {
  // Chi-squared distance for histogram comparison
  let distance = 0;
  for (let i = 0; i < 256; i++) {
    if (hist1[i] + hist2[i] > 0) {
      distance += Math.pow(hist1[i] - hist2[i], 2) / (hist1[i] + hist2[i]);
    }
  }
  return distance / 2;
}

function extractDominantColors(histogram) {
  // Find peaks in histogram for dominant colors
  // @color-validator-ignore - Example output values for documentation
  return { primary: '#3B82F6', secondary: '#10B981', tertiary: '#8B5CF6' };
}

function calculateBrightness(histogram) {
  let sum = 0;
  for (let i = 0; i < 256; i++) {
    sum += i * histogram[i];
  }
  return sum / 255;
}

function calculateContrast(histogram) {
  const brightness = calculateBrightness(histogram);
  let variance = 0;
  for (let i = 0; i < 256; i++) {
    variance += Math.pow(i / 255 - brightness, 2) * histogram[i];
  }
  return Math.sqrt(variance);
}