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diff --git a/common/dct.h b/common/dct.h
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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+// Based on eos' (I)RDFT code which is in turn
+// Based upon the (I)DCT code in FFmpeg
+// Copyright (c) 2009 Peter Ross <pross@xvid.org>
+// Copyright (c) 2010 Alex Converse <alex.converse@gmail.com>
+// Copyright (c) 2010 Vitor Sessak
+
+#ifndef COMMON_DCT_H
+#define COMMON_DCT_H
+
+#include "common/scummsys.h"
+#include "common/math.h"
+#include "common/rdft.h"
+
+namespace Common {
+
+/**
+ * (Inverse) Discrete Cosine Transforms.
+ *
+ * Used in engines:
+ *  - scumm
+ */
+class DCT {
+public:
+	enum TransformType {
+		DCT_II,
+		DCT_III,
+		DCT_I,
+		DST_I
+	};
+
+	DCT(int bits, TransformType trans);
+	~DCT();
+
+	void calc(float *data);
+
+private:
+	int _bits;
+	TransformType _trans;
+
+	const float *_tCos;
+
+	float *_csc2;
+
+	RDFT *_rdft;
+
+	void calcDCTI  (float *data);
+	void calcDCTII (float *data);
+	void calcDCTIII(float *data);
+	void calcDSTI  (float *data);
+};
+
+} // End of namespace Common
+
+#endif // COMMON_DCT_H