Origin Xan Codec - Revision history

Matt at 12:25, 17 March 2021

2021-03-17T12:25:21Z

← Older revision		Revision as of 05:25, 17 March 2021
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	Chroma values use the 16-bit symbol lookup table prior to the packed data for storing possible chroma values.		Chroma values use the 16-bit symbol lookup table prior to the packed data for storing possible chroma values.

	* The table entries are either 5-bit precision for WCIV (xxxUUUUU ~~VVVVVVxxx~~), or 8-bit precision (UUUUUUUU VVVVVVVV) for Crusader.		* The table entries are either 5-bit precision for WCIV (xxxUUUUU VVVVVxxx), or 8-bit precision (UUUUUUUU VVVVVVVV) for Crusader.
	* After the table is a packed list of 8-bit values, each representing a 1-indexed table offset (0 means do not change the previous frame's chroma). The unpacking algorithm for this data is the same as the [[Wing Commander III MVE Video Codec]].		* After the table is a packed list of 8-bit values, each representing a 1-indexed table offset (0 means do not change the previous frame's chroma). The unpacking algorithm for this data is the same as the [[Wing Commander III MVE Video Codec]].

Matt at 07:54, 13 March 2021

2021-03-13T07:54:29Z

← Older revision		Revision as of 00:54, 13 March 2021
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	Frame type 1 luma employs the same principle of coding as frame type 0, but the previous frame's luma values are used for prediction.		Frame type 1 luma employs the same principle of coding as frame type 0, but the previous frame's luma values are used for prediction.

	Type 1 frames also optionally include a second luma refinement block (offset is 0 if this block is not present). The values in this block are simply added to the values in the first block, also multiplied by 2.		Type 1 frames also optionally include a second luma refinement block (offset is 0 if this block is not present). The values in this block are simply added to the values in the first block, also multiplied by 2. '''Note:''' this second block is not supported by the ffmpeg implementation, which causes it to often look blockier than the original game.

	== Games Using Xan Video ==		== Games Using Xan Video ==

Matt: Lots of updates based on No Regret reversing.

2021-03-02T12:25:24Z

Lots of updates based on No Regret reversing.

← Older revision		Revision as of 05:25, 2 March 2021
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	== Format ==		== Format ==

	This codec is similar to [[Wing Commander III MVE Video Codec]] and employs the same packing algorithm. The main difference is that this codec stores information in YUV colorspace ~~(6 bits for~~ Y component~~, 5~~ bits ~~for~~ U and V components).		This codec is similar to [[Wing Commander III MVE Video Codec]] and employs the same packing algorithm. The main difference is that this codec stores information in YUV colorspace.
			* Y component is stored at 6 bits
			* U and V components are 5 bits in Wing Commander 4 videos, and 8 bits in Crusader: No Regret.

	Frame format:		Frame format:

	header:		header:
	bytes 0-3 - frame type		bytes 0-3 - frame type (0 or 1)
	bytes 4-7 - offset to chroma data		bytes 4-7 - offset to chroma data
	bytes 8-11 - offset to luma refinements		bytes 8-11 - offset to luma refinements (or 0 if not present)

			type 0:
	bytes 12-? - luma Huffman-coded data for frame type 0		bytes 12-? - luma Huffman-coded data for frame type 0
	or		or type 1:
	bytes 12-15 - offset to ~~chroma differences~~		bytes 12-15 - offset to second luma refinements (or 0 if not present)
	bytes 16-? - luma Huffman-coded data for frame type 1		bytes 16-? - luma Huffman-coded data for frame type 1

	chroma data:		chroma data:
	bytes 0-1 - chroma data is YUV420 or YUV410		bytes 0-1 - chroma mode: 0 = data is YUV420 (4 luma pixels to 2 chroma pixels), 1 = data is YUV410
	bytes 2-3 - ~~offset to Huffman~~-~~coded~~ chroma ~~indexes~~		bytes 2-3 - chroma value table size (entries)
	bytes 4-? - ~~possible~~ chroma ~~values~~		bytes 4-x - chroma value lookup table (16 bits per entry, as U,V values)
			bytes x+1-? - packed chroma table entry numbers

	Luma data is packed with left-to-right Huffman codes, chroma data is packed with the same <code>wc3_unpack</code>.		Luma data is packed with left-to-right Huffman codes, chroma data is packed with the same <code>wc3_unpack</code> as the [[Wing Commander III MVE Video Codec]].

	==== Huffman codes for luma ====		==== Huffman codes for luma ====
Line 48:		Line 52:
	==== Luma reconstruction ====		==== Luma reconstruction ====

	Only every second pixel value is coded, the other half is interpolated as an average of their right and left neighbours.		Only every second pixel value is coded, the other half is interpolated as an average of their right and left neighbours. Coded values are 5-bit delta coded and expanded to 6-bit range.
	~~An optional enhancement for interpolated pixels can be present as a separate chunk (called luma refinement previously).~~
	Coded values are 5-bit delta coded and ~~then~~ expanded to 6-bit range.
	~~Top line uses deltas between current and left neighbour, the rest of lines use top neighbour for prediction~~.

	For details please refer <code>libavcodec/xxan.c</code>		The top row uses deltas between current and left neighbour, the rest of lines use top neighbour for prediction.

			After interpolation, an optional delta enhancement block may exist be present to refine interpolated pixels (called luma refinements above). The block is half-size, as it only adjusts the interpolated pixels. The values in this block are multiplied by 2 before adding to the interpolated values, which are then clamped via (val & 0x3f).

			For details please refer to ffmpeg's <code>libavcodec/xxan.c</code>

	==== Chroma reconstruction ====		==== Chroma reconstruction ====

	Chroma values use 16-bit symbol table prior to packed data for storing possible chroma values.		Chroma values use the 16-bit symbol lookup table prior to the packed data for storing possible chroma values.

			* The table entries are either 5-bit precision for WCIV (xxxUUUUU VVVVVVxxx), or 8-bit precision (UUUUUUUU VVVVVVVV) for Crusader.
			* After the table is a packed list of 8-bit values, each representing a 1-indexed table offset (0 means do not change the previous frame's chroma). The unpacking algorithm for this data is the same as the [[Wing Commander III MVE Video Codec]].

	=== Inter frame (type 1) ===		=== Inter frame (type 1) ===
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	==== Luma reconstruction ====		==== Luma reconstruction ====

	It employs the same principle of coding but previous frame luma values are used for prediction.		Frame type 1 luma employs the same principle of coding as frame type 0, but the previous frame's luma values are used for prediction.

			Type 1 frames also optionally include a second luma refinement block (offset is 0 if this block is not present). The values in this block are simply added to the values in the first block, also multiplied by 2.

	== Games Using Xan Video ==		== Games Using Xan Video ==

	* [http://www.mobygames.com/game/dos/crusader-no-regret Crusader: No Regret (DOS)]		* [http://www.mobygames.com/game/dos/crusader-no-regret Crusader: No Regret (DOS)]
	* [http://www.mobygames.com/game/windows/pandemonium Pandemonium!] (note: not an Origin's game!)		* [http://www.mobygames.com/game/windows/pandemonium Pandemonium!] (note: not an Origin game!)
	* [http://www.mobygames.com/game/wing-commander-iv-the-price-of-freedom Wing Commander IV]		* [http://www.mobygames.com/game/wing-commander-iv-the-price-of-freedom Wing Commander IV]

	[[Category:Game Formats]]		[[Category:Game Formats]]
	[[Category:Video Codecs]]		[[Category:Video Codecs]]

Multimedia Mike: /* Games Using Xan Video */ not on No Remorse game

2012-02-14T07:23:29Z

Games Using Xan Video: not on No Remorse game

← Older revision		Revision as of 00:23, 14 February 2012
Line 68:		Line 68:

	* [http://www.mobygames.com/game/dos/crusader-no-regret Crusader: No Regret (DOS)]		* [http://www.mobygames.com/game/dos/crusader-no-regret Crusader: No Regret (DOS)]
	* [http://www.mobygames.com/game/dos/crusader-no-remorse Crusader: No Remorse (DOS)]
	* [http://www.mobygames.com/game/windows/pandemonium Pandemonium!] (note: not an Origin's game!)		* [http://www.mobygames.com/game/windows/pandemonium Pandemonium!] (note: not an Origin's game!)
	* [http://www.mobygames.com/game/wing-commander-iv-the-price-of-freedom Wing Commander IV]		* [http://www.mobygames.com/game/wing-commander-iv-the-price-of-freedom Wing Commander IV]

Kostya: /* Games Using Xan Video */

2011-03-15T09:07:09Z

Games Using Xan Video

← Older revision		Revision as of 02:07, 15 March 2011
Line 74:		Line 74:
	[[Category:Game Formats]]		[[Category:Game Formats]]
	[[Category:Video Codecs]]		[[Category:Video Codecs]]
	~~[[Category:Incomplete Video Codecs]]~~

Kostya at 10:52, 7 March 2011

2011-03-07T10:52:51Z

Show changes

Kostya: /* Format */

2009-12-09T06:39:56Z

Format

← Older revision		Revision as of 23:39, 8 December 2009
Line 93:		Line 93:
	byte_l &= 0x3F;		byte_l &= 0x3F;
	mem2C[0] = byte_l;		mem2C[0] = byte_l;

	byte_l = ((current_values >> 8) & 0xFF);		byte_l = ((current_values >> 8) & 0xFF);
	byte_l += mem2C[2];		byte_l += mem2C[2];
Line 113:		Line 113:
	byte_l &= 0x3F;		byte_l &= 0x3F;
	*mem2C++ = byte_l;		*mem2C++ = byte_l;

	width_counter = (s->avctx->width - 1) / 2;		width_counter = (s->avctx->width - 1) / 2;

	while (width_counter--) {		while (width_counter--) {
	byte_h = *mem34++;		byte_h = *mem34++;
Line 127:		Line 127:
	byte_l = byte_h;		byte_l = byte_h;
	}		}

	*mem2C++ = byte_l;		*mem2C++ = byte_l;
	}		}

Kostya: Mike, will you ever complete this?

2009-12-09T06:38:48Z

Mike, will you ever complete this?

@@ Line 22: / Line 22: @@
     bytes 12-? - luma Huffman-coded data for frame type 0
    or
-    bytes 12-15 - offset to some chroma differences?
+    bytes 12-15 - offset to chroma differences
     bytes 16-? - luma Huffman-coded data for frame type 1
@@ Line 30: / Line 30: @@
     bytes 4-? - possible chroma values
-=== Luma reconstruction for  frame type 0 ===
+Luma data is packed with left-to-right Huffman codes, chroma data is packed with the same <code>wc3_unpack</code>.
 Reconstruction of the first line:
@@ Line 78: / Line 82: @@
+         }
          *out++ = byte_l;
+     }

Kostya: /* Luma reconstruction for frame type 0 */

2007-10-08T06:14:14Z

Luma reconstruction for frame type 0

← Older revision		Revision as of 23:14, 7 October 2007
Line 32:		Line 32:
	=== Luma reconstruction for frame type 0 ===		=== Luma reconstruction for frame type 0 ===

	Reconstruction ~~for~~ the first line:		Reconstruction of the first line:

	byte_l = *unpacked++;		byte_l = *unpacked++;
Line 52:		Line 52:
	*out++ = byte_l;		*out++ = byte_l;

	Reconstruction of the rest of the lines:		Reconstruction of the rest of the lines:

	while (height_counter--) {		while (height_counter--) {

Kostya: This is already known

2007-10-08T06:12:49Z

This is already known

@@ Line 8: / Line 8: @@
 '''Trivia:''' All Xan-encoded AVI files contain very interesting comment string inside. 'Xxan video stream, Blue Mu Productions.' What could possible that Blue Mu be? A subdivision of Origin or real codec authors?
 == Games Using Xan Video ==
@@ Line 19: / Line 90: @@
 [[Category:Game Formats]]
 [[Category:Video Codecs]]
-[[Category:Undiscovered Video Codecs]]
+[[Category:Incomplete Video Codecs]]