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Code Issues 2 Packages Projects Releases Wiki Activity

Update stream capture frame rate to 60 FPS and adjust encoding settings; increase audio bitrate to 256k for better quality.

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Nikita
2025-12-21 18:15:28 -08:00
parent 7d24993b08
commit b9927d9807
4 changed files with 41 additions and 18 deletions
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33
cli/stream/Sources/stream-capture/main.swift
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@@ -173,8 +173,9 @@ actor ZeroCPUCapturer: NSObject, SCStreamDelegate, SCStreamOutput {
config.width = normalizedSize.width
config.height = normalizedSize.height
// 30 FPS for streaming
config.minimumFrameInterval = CMTime(value: 1, timescale: 30)
let targetFrameRate: Int32 = 60
// 60 FPS for streaming
config.minimumFrameInterval = CMTime(value: 1, timescale: targetFrameRate)
// Queue depth for smooth delivery (like OBS)
config.queueDepth = 8
@@ -210,7 +211,7 @@ actor ZeroCPUCapturer: NSObject, SCStreamDelegate, SCStreamOutput {
// Start capture
try await stream?.startCapture()
print("Capture started: \(config.width)x\(config.height) @ 30fps")
print("Capture started: \(config.width)x\(config.height) @ \(targetFrameRate)fps")
}
func stopCapture() async {
@@ -329,10 +330,19 @@ class HardwareEncoder {
}
// Configure for streaming
let targetFrameRate: Int32 = 60
let keyframeInterval = Int(targetFrameRate) * 2
let bitrate = HardwareEncoder.recommendedBitrate(
width: width,
height: height,
frameRate: Int(targetFrameRate)
)
VTSessionSetProperty(session, key: kVTCompressionPropertyKey_RealTime, value: kCFBooleanTrue)
VTSessionSetProperty(session, key: kVTCompressionPropertyKey_ProfileLevel, value: kVTProfileLevel_H264_High_AutoLevel)
VTSessionSetProperty(session, key: kVTCompressionPropertyKey_AverageBitRate, value: 4_500_000 as CFNumber) // 4.5 Mbps
VTSessionSetProperty(session, key: kVTCompressionPropertyKey_MaxKeyFrameInterval, value: 60 as CFNumber) // Keyframe every 2s @ 30fps
VTSessionSetProperty(session, key: kVTCompressionPropertyKey_ExpectedFrameRate, value: targetFrameRate as CFNumber)
VTSessionSetProperty(session, key: kVTCompressionPropertyKey_AverageBitRate, value: bitrate as CFNumber)
VTSessionSetProperty(session, key: kVTCompressionPropertyKey_MaxKeyFrameInterval, value: keyframeInterval as CFNumber)
VTSessionSetProperty(session, key: kVTCompressionPropertyKey_MaxKeyFrameIntervalDuration, value: 2 as CFNumber)
VTSessionSetProperty(session, key: kVTCompressionPropertyKey_AllowFrameReordering, value: kCFBooleanFalse) // No B-frames for low latency
VTCompressionSessionPrepareToEncodeFrames(session)
@@ -374,6 +384,19 @@ class HardwareEncoder {
}
}
private static func recommendedBitrate(width: Int, height: Int, frameRate: Int) -> Int {
let baseWidth = 2560
let baseHeight = 1440
let baseFrameRate = 60
let baseBitrate = 30_000_000
let pixels = max(1, width) * max(1, height)
let basePixels = baseWidth * baseHeight
let fpsScale = Double(max(frameRate, 1)) / Double(baseFrameRate)
let raw = Double(baseBitrate) * (Double(pixels) / Double(basePixels)) * fpsScale
return min(max(Int(raw.rounded()), 12_000_000), 80_000_000)
}
deinit {
if let session = session {
VTCompressionSessionInvalidate(session)