Initial commit: Go driver for the Lian Li Galahad II LCD

Streams H.264 to the Galahad II LCD via USB (gousb) with:
- ffmpeg CLI transcoding (no fragile FFmpeg C-ABI bindings)
- pure-Go Annex-B access-unit splitting
- framerate pacing with graceful shutdown and USB reconnect
- TOML config, cobra CLI, structured slog logging, unit tests

internal/transcoder/transcoder_test.go

@@ -0,0 +1,123 @@
+package transcoder
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"galahad2lcd/internal/config"
+)
+
+func TestBuildFilter(t *testing.T) {
+	tests := []struct {
+		rotate int
+		fps    float64
+		want   string
+	}{
+		{0, 30, "scale=480:480:flags=lanczos,format=yuv420p"},
+		{90, 30, "scale=480:480:flags=lanczos,transpose=1,format=yuv420p"},
+		{180, 30, "scale=480:480:flags=lanczos,transpose=1,transpose=1,format=yuv420p"},
+		{270, 30, "scale=480:480:flags=lanczos,transpose=2,format=yuv420p"},
+	}
+	for _, tt := range tests {
+		if got := buildFilter(tt.rotate, tt.fps); got != tt.want {
+			t.Errorf("buildFilter(%d, %v) = %q, want %q", tt.rotate, tt.fps, got, tt.want)
+		}
+	}
+}
+
+func TestParseFPSRational(t *testing.T) {
+	tests := []struct {
+		in   string
+		want float64
+		err  bool
+	}{
+		{"30000/1001", 30000.0 / 1001, false},
+		{"25", 25, false},
+		{"0/0", 0, true},
+		{"", 0, true},
+		{"bogus", 0, true},
+		{"10/2", 5, false},
+	}
+	for _, tt := range tests {
+		got, err := parseFPSRational(tt.in)
+		if (err != nil) != tt.err {
+			t.Errorf("parseFPSRational(%q) error = %v, wantErr = %v", tt.in, err, tt.err)
+			continue
+		}
+		if !tt.err && got != tt.want {
+			t.Errorf("parseFPSRational(%q) = %v, want %v", tt.in, got, tt.want)
+		}
+	}
+}
+
+func TestClampFPS(t *testing.T) {
+	if got := clampFPS(0); got != defaultFPS {
+		t.Errorf("clampFPS(0) = %v, want %v", got, defaultFPS)
+	}
+	if got := clampFPS(300); got != 120 {
+		t.Errorf("clampFPS(300) = %v, want 120", got)
+	}
+	if got := clampFPS(24); got != 24 {
+		t.Errorf("clampFPS(24) = %v, want 24", got)
+	}
+}
+
+// TestTranscodeIntegration exercises the real ffmpeg path when available.
+func TestTranscodeIntegration(t *testing.T) {
+	if _, err := exec.LookPath("ffmpeg"); err != nil {
+		t.Skip("ffmpeg not installed")
+	}
+
+	dir := t.TempDir()
+	input := filepath.Join(dir, "src.gif")
+	cache := filepath.Join(dir, "out.h264")
+
+	// Build a tiny valid GIF with ffmpeg's testsrc2 source.
+	if err := run(context.Background(), "ffmpeg",
+		"-y", "-v", "error",
+		"-f", "lavfi", "-i", "testsrc2=size=480x480:rate=10:duration=1",
+		input); err != nil {
+		t.Fatalf("generate source gif: %v", err)
+	}
+
+	tc := NewWithBinaries("ffmpeg", "ffprobe")
+	cfg := config.Default()
+	cfg.Display.Input = input
+	cfg.Display.Rotate = 90
+	cfg.Stream.CachePath = cache
+
+	fps, err := tc.Transcode(context.Background(), cfg)
+	if err != nil {
+		t.Fatalf("Transcode error = %v", err)
+	}
+	if fps != 10 {
+		t.Errorf("fps = %v, want 10", fps)
+	}
+
+	st, err := os.Stat(cache)
+	if err != nil {
+		t.Fatalf("cache file missing: %v", err)
+	}
+	if st.Size() == 0 {
+		t.Error("cache file empty")
+	}
+	if !strings.HasPrefix(readFirstBytes(t, cache), "\x00\x00\x00\x01") {
+		t.Error("cache file does not start with an Annex-B start code")
+	}
+}
+
+func readFirstBytes(t *testing.T, path string) string {
+	t.Helper()
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read cache: %v", err)
+	}
+	if len(data) < 4 {
+		return string(data)
+	}
+	return string(data[:4])
+}