Move cmd module to internal

internal/ffmpeg/hardware_darwin.go

@@ -0,0 +1,21 @@
+package ffmpeg
+
+func ProbeHardware(name string) string {
+	switch name {
+	case "h264":
+		if run(
+			"-f", "lavfi", "-i", "testsrc2", "-t", "1",
+			"-c", "h264_videotoolbox", "-f", "null", "-") {
+			return EngineVideoToolbox
+		}
+
+	case "h265":
+		if run(
+			"-f", "lavfi", "-i", "testsrc2", "-t", "1",
+			"-c", "hevc_videotoolbox", "-f", "null", "-") {
+			return EngineVideoToolbox
+		}
+	}
+
+	return EngineSoftware
+}