Add the support of screenshotting using libav

go.mod

@@ -298,7 +298,7 @@ require (
 	github.com/spf13/pflag v1.0.6
 	github.com/stretchr/testify v1.10.0
 	github.com/xaionaro-go/audio v0.0.0-20250210102901-abfced9d5ef3
-	github.com/xaionaro-go/avpipeline v0.0.0-20250727184631-f13f8d149b18
+	github.com/xaionaro-go/avpipeline v0.0.0-20250809004114-8edb93a58cf2
 	github.com/xaionaro-go/datacounter v1.0.4
 	github.com/xaionaro-go/go-rtmp v0.0.0-20241009130244-1e3160f27f42
 	github.com/xaionaro-go/grpcproxy v0.0.0-20241103205849-a8fef42e72f9

go.sum

@@ -1078,6 +1078,10 @@ github.com/xaionaro-go/avmediacodec v0.0.0-20250505012527-c819676502d8 h1:FZn9+T
 github.com/xaionaro-go/avmediacodec v0.0.0-20250505012527-c819676502d8/go.mod h1:2W2Kp/HJFXcFBppQ4YytgDy/ydFL3hGc23xSB1U/Luc=
 github.com/xaionaro-go/avpipeline v0.0.0-20250727184631-f13f8d149b18 h1:OfkJnBBNbr3AUbqumbGpY78W8FoEHaz0zKdKzZMmkGc=
 github.com/xaionaro-go/avpipeline v0.0.0-20250727184631-f13f8d149b18/go.mod h1:eFxxNA50Pyp1B+snK0TlmpsnrGUtzJohbY/+J3BEvqA=
+github.com/xaionaro-go/avpipeline v0.0.0-20250808224324-1125ac2d144b h1:J+fc4WXTCnxc1LfafpRndcWOjq0NDCpToc8NPBHdSIQ=
+github.com/xaionaro-go/avpipeline v0.0.0-20250808224324-1125ac2d144b/go.mod h1:eFxxNA50Pyp1B+snK0TlmpsnrGUtzJohbY/+J3BEvqA=
+github.com/xaionaro-go/avpipeline v0.0.0-20250809004114-8edb93a58cf2 h1:xKetGyk2/9XGZwiupCYGJLoAkw2dl774Gp4afxLbZoY=
+github.com/xaionaro-go/avpipeline v0.0.0-20250809004114-8edb93a58cf2/go.mod h1:eFxxNA50Pyp1B+snK0TlmpsnrGUtzJohbY/+J3BEvqA=
 github.com/xaionaro-go/datacounter v1.0.4 h1:+QMZLmu73R5WGkQfUPwlXF/JFN+Weo4iuDZkiL2wVm8=
 github.com/xaionaro-go/datacounter v1.0.4/go.mod h1:Sf9vBevuV6w5iE6K3qJ9pWVKcyS60clWBUSQLjt5++c=
 github.com/xaionaro-go/eventbus v0.0.0-20250720144534-4670758005d9 h1:ZAm8ueMw5D85LDeV1Kboc3ANqXr3LK/eXIl9hj1BJyM=

pkg/screenshoter/cmd/screenshoter/assert.go

@@ -0,0 +1,7 @@
+package main
+
+func assertNoError(err error) {
+	if err != nil {
+		panic(err)
+	}
+}

pkg/screenshoter/cmd/screenshoter/main.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"image"
+	"time"
+
+	"github.com/xaionaro-go/streamctl/pkg/screenshot"
+	"github.com/xaionaro-go/streamctl/pkg/screenshoter"
+)
+
+func main() {
+	xMin := flag.Int("x-min", 0, "")
+	xMax := flag.Int("x-max", 100, "")
+	yMin := flag.Int("y-min", 0, "")
+	yMax := flag.Int("y-max", 100, "")
+	fps := flag.Float64("fps", 30, "")
+	flag.Parse()
+
+	ctx := context.Background()
+
+	h := screenshoter.New()
+
+	startedAt := time.Now()
+	frameCount := 0
+	err := h.Loop(
+		ctx,
+		time.Duration(float64(time.Second) / *fps),
+		screenshot.Config{
+			Bounds: image.Rectangle{
+				Min: image.Point{
+					X: *xMin,
+					Y: *yMin,
+				},
+				Max: image.Point{
+					X: *xMax,
+					Y: *yMax,
+				},
+			},
+		},
+		func(context.Context, image.Image) {
+			frameCount++
+			fps := float64(frameCount) / time.Since(startedAt).Seconds()
+			fmt.Printf("received a picture; overall FPS: %f\n", fps)
+		},
+	)
+	assertNoError(err)
+}

pkg/screenshoter/screenshoter_libav.go

@@ -0,0 +1,80 @@
+//go:build with_libav && linux
+// +build with_libav,linux
+
+package screenshoter
+
+import (
+	"context"
+	"fmt"
+	"image"
+	"time"
+
+	"github.com/asticode/go-astiav"
+	"github.com/facebookincubator/go-belt/tool/logger"
+	"github.com/xaionaro-go/avpipeline/frame"
+	"github.com/xaionaro-go/avpipeline/node"
+	"github.com/xaionaro-go/avpipeline/preset/screencapturer"
+	"github.com/xaionaro-go/observability"
+	"github.com/xaionaro-go/streamctl/pkg/screenshot"
+)
+
+type Screenshoter struct{}
+
+func New() *Screenshoter {
+	return &Screenshoter{}
+}
+
+func (s *Screenshoter) Loop(
+	ctx context.Context,
+	interval time.Duration,
+	config screenshot.Config,
+	callback func(context.Context, image.Image),
+) error {
+	fpsFloat := 1 / interval.Seconds()
+	fps := astiav.Rational{}
+	fps.SetNum(int(fpsFloat * 1000))
+	fps.SetDen(1000)
+
+	logger.Debugf(ctx, "FPS == %f", fps.Float64())
+	screenCapturer, err := screencapturer.New(ctx, screencapturer.Params{
+		Area: config.Bounds,
+		FPS:  fps,
+	})
+	if err != nil {
+		return fmt.Errorf("unable to initialize a screen capturer: %w", err)
+	}
+
+	errCh := make(chan node.Error, 100)
+	observability.Go(ctx, func(ctx context.Context) {
+		screenCapturer.Serve(ctx, node.ServeConfig{}, errCh)
+	})
+	defer screenCapturer.Close(ctx)
+
+	var img image.Image
+	for {
+		var frame frame.Output
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case err := <-errCh:
+			return fmt.Errorf("unable to serve the screenshoter node: %w", err)
+		case pkt := <-screenCapturer.OutputPacketChan():
+			return fmt.Errorf("receive a packet (of size %d), while expected a decoded frame", pkt.GetSize())
+		case frame = <-screenCapturer.OutputFrameChan():
+		}
+
+		if img == nil {
+			img, err = frame.Data().GuessImageFormat()
+			if err != nil {
+				return fmt.Errorf("unable to guess the image format: %w", err)
+			}
+		}
+
+		err := frame.Data().ToImage(img)
+		if err != nil {
+			return fmt.Errorf("unable to obtain the image: %w", err)
+		}
+
+		callback(ctx, img)
+	}
+}

pkg/screenshoter/screenshoter_nolibav.go

@@ -1,3 +1,6 @@
+//go:build !with_libav || !linux
+// +build !with_libav !linux
+
 package screenshoter
 
 import (
@@ -10,37 +13,37 @@ import (
 )
 
 type ScreenshotEngine interface {
-	Screenshot(cfg screenshot.Config) (*image.RGBA, error)
+	Screenshot(cfg screenshot.Config) (image.Image, error)
 }
 
 type Screenshoter struct {
 	ScreenshotEngine ScreenshotEngine
 }
 
-func New(
+type ScreenshotImplementation struct{}
-	engine ScreenshotEngine,
+
-) *Screenshoter {
+func (ScreenshotImplementation) Screenshot(cfg screenshot.Config) (image.Image, error) {
-	return &Screenshoter{
+	return screenshot.Implementation{}.Screenshot(cfg)
-		ScreenshotEngine: engine,
-	}
 }
 
-func (s *Screenshoter) Engine() ScreenshotEngine {
+func New() *Screenshoter {
-	return s.ScreenshotEngine
+	return &Screenshoter{
+		ScreenshotEngine: ScreenshotImplementation{},
+	}
 }
 
 func (s *Screenshoter) Loop(
 	ctx context.Context,
 	interval time.Duration,
 	config screenshot.Config,
-	callback func(context.Context, *image.RGBA),
+	callback func(context.Context, image.Image),
-) {
+) error {
 	t := time.NewTicker(interval)
 	defer t.Stop()
 	for {
 		select {
 		case <-ctx.Done():
-			return
+			return ctx.Err()
 		case <-t.C:
 		}
 		img, err := s.ScreenshotEngine.Screenshot(config)

pkg/streampanel/image.go

@@ -17,20 +17,18 @@ import (
 	"github.com/facebookincubator/go-belt/tool/logger"
 	"github.com/xaionaro-go/observability"
 	"github.com/xaionaro-go/streamctl/pkg/screenshot"
-	"github.com/xaionaro-go/streamctl/pkg/screenshoter"
 	streamdconsts "github.com/xaionaro-go/streamctl/pkg/streamd/consts"
 	"github.com/xaionaro-go/streamctl/pkg/streampanel/consts"
 	"github.com/xaionaro-go/xsync"
 )
 
 type Screenshoter interface {
-	Engine() screenshoter.ScreenshotEngine
 	Loop(
 		ctx context.Context,
 		interval time.Duration,
 		config screenshot.Config,
-		callback func(context.Context, *image.RGBA),
+		callback func(context.Context, image.Image),
-	)
+	) error
 }
 
 func (p *Panel) setImage(
@@ -313,12 +311,15 @@ func (p *Panel) reinitScreenshoter(ctx context.Context) {
 		ctx, cancelFunc := context.WithCancel(ctx)
 		p.screenshoterClose = cancelFunc
 		observability.Go(ctx, func(ctx context.Context) {
-			p.Screenshoter.Loop(
+			err := p.Screenshoter.Loop(
 				ctx,
 				200*time.Millisecond,
 				p.Config.Screenshot.Config,
-				func(ctx context.Context, img *image.RGBA) { p.setScreenshot(ctx, img) },
+				func(ctx context.Context, img image.Image) { p.setScreenshot(ctx, img) },
 			)
+			if err != nil {
+				logger.Errorf(ctx, "unable to run the screenshoter loop: %v", err)
+			}
 		})
 	})
 }

pkg/streampanel/panel.go

@@ -34,7 +34,6 @@ import (
 	"github.com/xaionaro-go/streamctl/pkg/command"
 	gconsts "github.com/xaionaro-go/streamctl/pkg/consts"
 	"github.com/xaionaro-go/streamctl/pkg/oauthhandler"
-	"github.com/xaionaro-go/streamctl/pkg/screenshot"
 	"github.com/xaionaro-go/streamctl/pkg/screenshoter"
 	"github.com/xaionaro-go/streamctl/pkg/streamcontrol"
 	"github.com/xaionaro-go/streamctl/pkg/streamcontrol/kick"
@@ -204,7 +203,7 @@ func New(
 	p := &Panel{
 		configPath:          configPath,
 		Config:              Options(opts).ApplyOverrides(cfg),
-		Screenshoter:        screenshoter.New(screenshot.Implementation{}),
+		Screenshoter:        screenshoter.New(),
 		imageLastDownloaded: map[consts.ImageID][]byte{},
 		imageLastParsed:     map[consts.ImageID]image.Image{},
 		streamStatus:        map[streamcontrol.PlatformName]*streamStatus{},