diff --git a/imgui.ini b/imgui.ini
index dd9f37e..a71e8e8 100644
--- a/imgui.ini
+++ b/imgui.ini
@@ -14,7 +14,7 @@ Size=200,200
 Collapsed=0
 
 [Window][Connection]
-Pos=177,324
-Size=640,354
+Pos=911,549
+Size=640,352
 Collapsed=0
 
diff --git a/internal/playback/sync_slot.go b/internal/playback/sync_slot.go
new file mode 100644
index 0000000..3f4bc06
--- /dev/null
+++ b/internal/playback/sync_slot.go
@@ -0,0 +1,122 @@
+package playback
+
+import (
+	"context"
+	"errors"
+	"fmt"
+)
+
+type SyncPairConfig struct {
+	Video FeedConfig
+	Audio FeedConfig
+}
+
+var (
+	ErrSyncWorkerRequired   = errors.New("sync worker is required")
+	ErrSyncActivityMismatch = errors.New(
+		"synchronized video and audio must have matching active states",
+	)
+)
+
+func (c SyncPairConfig) Validate() error {
+	if err := c.Video.Validate(); err != nil {
+		return fmt.Errorf("video: %w", err)
+	}
+	if err := c.Audio.Validate(); err != nil {
+		return fmt.Errorf("audio: %w", err)
+	}
+	if c.Video.Active != c.Audio.Active {
+		return ErrSyncActivityMismatch
+	}
+	return nil
+}
+
+func (c SyncPairConfig) Active() bool {
+	return c.Video.Active && c.Audio.Active
+}
+
+type SyncSlot struct {
+	worker *SyncWorker
+}
+
+func NewSyncSlot(worker *SyncWorker) (*SyncSlot, error) {
+	if worker == nil {
+		return nil, ErrSyncWorkerRequired
+	}
+	return &SyncSlot{
+		worker: worker,
+	}, nil
+}
+
+func (s *SyncSlot) Run(
+	ctx context.Context,
+	initial SyncPairConfig,
+	commands <-chan SyncPairConfig,
+) error {
+	if err := initial.Validate(); err != nil {
+		return fmt.Errorf("validate initial sync config: %w", err)
+	}
+
+	var (
+		workerCancel context.CancelFunc
+		workerDone   chan error
+	)
+
+	start := func(config SyncPairConfig) {
+		workerCtx, cancel := context.WithCancel(ctx)
+		done := make(chan error, 1)
+
+		workerCancel = cancel
+		workerDone = done
+
+		go func() {
+			done <- s.worker.Run(workerCtx, config.Video, config.Audio)
+		}()
+	}
+
+	stop := func() {
+		if workerCancel == nil {
+			return
+		}
+
+		workerCancel()
+		<-workerDone
+
+		workerCancel = nil
+		workerDone = nil
+	}
+
+	if initial.Active() {
+		start(initial)
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			stop()
+			return ctx.Err()
+
+		case config, ok := <-commands:
+			if !ok {
+				stop()
+				return nil
+			}
+
+			if err := config.Validate(); err != nil {
+				// Ignore invalid commands without disturbing the current worker.
+				continue
+			}
+
+			stop()
+			if config.Active() {
+				start(config)
+			}
+
+		case <-workerDone:
+			// The worker stopped naturally or exhausted its retries.
+			workerCancel()
+			workerCancel = nil
+			workerDone = nil
+		}
+	}
+}
diff --git a/internal/playback/sync_slot_test.go b/internal/playback/sync_slot_test.go
new file mode 100644
index 0000000..b8e9129
--- /dev/null
+++ b/internal/playback/sync_slot_test.go
@@ -0,0 +1,231 @@
+package playback
+
+import (
+	"context"
+	"errors"
+	"sync"
+	"testing"
+	"time"
+)
+
+type slotSyncFactory struct {
+	opened chan SyncPairConfig
+
+	mu         sync.Mutex
+	active     int
+	maxActive  int
+	closeCount int
+}
+
+func newSlotSyncFactory() *slotSyncFactory {
+	return &slotSyncFactory{opened: make(chan SyncPairConfig, 8)}
+}
+
+func (f *slotSyncFactory) OpenSync(
+	_ context.Context,
+	video FeedConfig,
+	audio FeedConfig,
+) (SyncReader, error) {
+	f.mu.Lock()
+	f.active++
+	if f.active > f.maxActive {
+		f.maxActive = f.active
+	}
+	f.mu.Unlock()
+	f.opened <- SyncPairConfig{Video: video, Audio: audio}
+	return &slotSyncReader{factory: f}, nil
+}
+
+func (f *slotSyncFactory) counts() (active, maxActive, closeCount int) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return f.active, f.maxActive, f.closeCount
+}
+
+type slotSyncReader struct {
+	factory *slotSyncFactory
+}
+
+func (r *slotSyncReader) ReadSync(ctx context.Context) (SyncFrame, error) {
+	<-ctx.Done()
+	return SyncFrame{}, ctx.Err()
+}
+
+func (r *slotSyncReader) Close() error {
+	r.factory.mu.Lock()
+	defer r.factory.mu.Unlock()
+	r.factory.active--
+	r.factory.closeCount++
+	return nil
+}
+
+func newSlotTestSyncWorker(t *testing.T, factory SyncReaderFactory) *SyncWorker {
+	t.Helper()
+	worker, err := NewSyncWorker(
+		factory,
+		&fakeVideoSink{},
+		&fakeAudioSink{},
+		testRetryPolicy(1),
+		func(error) bool { return false },
+		nil,
+	)
+	if err != nil {
+		t.Fatalf("NewSyncWorker() error = %v", err)
+	}
+	return worker
+}
+
+func receiveSyncSlotOpen(t *testing.T, opened <-chan SyncPairConfig) SyncPairConfig {
+	t.Helper()
+	select {
+	case config := <-opened:
+		return config
+	case <-time.After(time.Second):
+		t.Fatal("sync worker did not open")
+		return SyncPairConfig{}
+	}
+}
+
+func testSyncPair(name string, active bool) SyncPairConfig {
+	return SyncPairConfig{
+		Video: FeedConfig{Domain: "/video", UUID: name + "-video", Active: active},
+		Audio: FeedConfig{Domain: "/audio", UUID: name + "-audio", Active: active},
+	}
+}
+
+func TestSyncPairConfigRejectsActivityMismatch(t *testing.T) {
+	config := testSyncPair("pair", true)
+	config.Audio.Active = false
+	if err := config.Validate(); !errors.Is(err, ErrSyncActivityMismatch) {
+		t.Fatalf("Validate() error = %v, want %v", err, ErrSyncActivityMismatch)
+	}
+}
+
+func TestNewSyncSlotRequiresWorker(t *testing.T) {
+	slot, err := NewSyncSlot(nil)
+	if slot != nil {
+		t.Fatalf("NewSyncSlot(nil) slot = %#v, want nil", slot)
+	}
+	if !errors.Is(err, ErrSyncWorkerRequired) {
+		t.Fatalf("NewSyncSlot(nil) error = %v, want %v", err, ErrSyncWorkerRequired)
+	}
+}
+
+func TestSyncSlotStartsInitialActivePair(t *testing.T) {
+	factory := newSlotSyncFactory()
+	slot, err := NewSyncSlot(newSlotTestSyncWorker(t, factory))
+	if err != nil {
+		t.Fatal(err)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	done := make(chan error, 1)
+	want := testSyncPair("first", true)
+	go func() { done <- slot.Run(ctx, want, make(chan SyncPairConfig)) }()
+
+	if got := receiveSyncSlotOpen(t, factory.opened); got != want {
+		t.Fatalf("opened config = %#v, want %#v", got, want)
+	}
+	cancel()
+	select {
+	case err := <-done:
+		if !errors.Is(err, context.Canceled) {
+			t.Fatalf("Run() error = %v, want context.Canceled", err)
+		}
+	case <-time.After(time.Second):
+		t.Fatal("Run() did not stop after cancellation")
+	}
+	active, _, closed := factory.counts()
+	if active != 0 || closed != 1 {
+		t.Fatalf("reader counts = active %d, closed %d; want 0, 1", active, closed)
+	}
+}
+
+func TestSyncSlotReplacesWithoutOverlappingWorkers(t *testing.T) {
+	factory := newSlotSyncFactory()
+	slot, err := NewSyncSlot(newSlotTestSyncWorker(t, factory))
+	if err != nil {
+		t.Fatal(err)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	commands := make(chan SyncPairConfig)
+	done := make(chan error, 1)
+	first := testSyncPair("first", true)
+	second := testSyncPair("second", true)
+	go func() { done <- slot.Run(ctx, first, commands) }()
+	receiveSyncSlotOpen(t, factory.opened)
+	commands <- second
+	if got := receiveSyncSlotOpen(t, factory.opened); got != second {
+		t.Fatalf("replacement = %#v, want %#v", got, second)
+	}
+	cancel()
+	<-done
+	active, maxActive, closed := factory.counts()
+	if active != 0 || maxActive != 1 || closed != 2 {
+		t.Fatalf("counts = active %d, maximum %d, closed %d; want 0, 1, 2", active, maxActive, closed)
+	}
+}
+
+func TestSyncSlotIgnoresInvalidCommand(t *testing.T) {
+	factory := newSlotSyncFactory()
+	slot, err := NewSyncSlot(newSlotTestSyncWorker(t, factory))
+	if err != nil {
+		t.Fatal(err)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	commands := make(chan SyncPairConfig)
+	done := make(chan error, 1)
+	initial := testSyncPair("first", true)
+	go func() { done <- slot.Run(ctx, initial, commands) }()
+	receiveSyncSlotOpen(t, factory.opened)
+
+	invalid := testSyncPair("invalid", true)
+	invalid.Audio.Active = false
+	commands <- invalid
+	select {
+	case config := <-factory.opened:
+		t.Fatalf("invalid command opened config %#v", config)
+	case <-time.After(20 * time.Millisecond):
+	}
+	active, _, closed := factory.counts()
+	if active != 1 || closed != 0 {
+		t.Fatalf("invalid command disturbed reader: active %d, closed %d", active, closed)
+	}
+	cancel()
+	<-done
+}
+
+func TestSyncSlotInactivePairStopsWithoutRestart(t *testing.T) {
+	factory := newSlotSyncFactory()
+	slot, err := NewSyncSlot(newSlotTestSyncWorker(t, factory))
+	if err != nil {
+		t.Fatal(err)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	commands := make(chan SyncPairConfig)
+	done := make(chan error, 1)
+	go func() { done <- slot.Run(ctx, testSyncPair("first", true), commands) }()
+	receiveSyncSlotOpen(t, factory.opened)
+	commands <- testSyncPair("first", false)
+
+	deadline := time.Now().Add(time.Second)
+	for {
+		active, _, closed := factory.counts()
+		if active == 0 && closed == 1 {
+			break
+		}
+		if time.Now().After(deadline) {
+			t.Fatal("inactive pair did not stop reader")
+		}
+		time.Sleep(time.Millisecond)
+	}
+	close(commands)
+	select {
+	case err := <-done:
+		if err != nil {
+			t.Fatalf("Run() error = %v, want nil", err)
+		}
+	case <-time.After(time.Second):
+		t.Fatal("Run() did not stop after commands closed")
+	}
+}