YLC

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Revision as of 01:14, 20 August 2009 Alex (Talk | contribs) ← Previous diff		Current revision Kostya (Talk | contribs)
Line 1:		Line 1:
	* Website: http://spring-fragrance.mints.ne.jp/aviutl/ (Japanese)		* Website: http://spring-fragrance.mints.ne.jp/aviutl/ (Japanese)
	* FourCC: YLC0		* FourCC: YLC0
		+	* Sample: http://samples.libav.org/V-codecs/ylc0.avi
	The website names it as "YUY2 Lossless Codec".		The website names it as "YUY2 Lossless Codec".
		+
		+	=== Format ===
		+
		+	bytes 0- 3 'YLC0'
		+	bytes 4- 7 zero
		+	bytes 8-11 offset to luma plane (should be 16)
		+	bytes 12-15 offset to chroma plane
		+
		+	Bitstream is read as 32-bit little-endian words MSB.
		+
		+	Luma plane contains residues stored as exp-Golomb codes (unary-coded exponent + N bits of mantiss).
		+
		+	Chroma plane contains chroma values coded in groups and uses static Huffman trees:
		+
		+	if (get_bit()) {
		+	val = decode_sym(tree1);
		+	if (val < 0xE1) {
		+	output chroma_table[val];
		+	} else {
		+	for (i = 0; i < (val - 0xDF); i++)
		+	output {0, 0, 0, 0}
		+	}
		+	} else {
		+	u0 = decode_sym(tree2);
		+	v0 = decode_sym(tree3);
		+	u1 = decode_sym(tree2);
		+	v1 = decode_sym(tree4);
		+
		+	output { u0, v0, u0 + u1, v1 }
		+	}
		+
		+	Looks like for luma plane median prediction is used and for chroma only left prediction is used.
	[[Category:Video Codecs]]		[[Category:Video Codecs]]
	[[Category:Lossless Video Codecs]]		[[Category:Lossless Video Codecs]]
-	[[Category:Undiscovered Video Codecs]]	+	[[Category:Incomplete Video Codecs]]

---

Current revision

• Website: http://spring-fragrance.mints.ne.jp/aviutl/ (Japanese)
• FourCC: YLC0
• Sample: http://samples.libav.org/V-codecs/ylc0.avi

The website names it as "YUY2 Lossless Codec".

Format

bytes  0- 3 'YLC0'
bytes  4- 7 zero
bytes  8-11 offset to luma plane (should be 16)
bytes 12-15 offset to chroma plane

Bitstream is read as 32-bit little-endian words MSB.

Luma plane contains residues stored as exp-Golomb codes (unary-coded exponent + N bits of mantiss).

Chroma plane contains chroma values coded in groups and uses static Huffman trees:

 if (get_bit()) {
     val = decode_sym(tree1);
     if (val < 0xE1) {
         output chroma_table[val];
     } else {
         for (i = 0; i < (val - 0xDF); i++)
             output {0, 0, 0, 0}
     }
 } else {
     u0 = decode_sym(tree2);
     v0 = decode_sym(tree3);
     u1 = decode_sym(tree2);
     v1 = decode_sym(tree4);

     output { u0, v0, u0 + u1, v1 }
 }

Looks like for luma plane median prediction is used and for chroma only left prediction is used.