llimagej2ckdu.cpp

 /** 
 * @file llimagej2ckdu.cpp
 * @brief This is an implementation of JPEG2000 encode/decode using Kakadu
 *
 * $LicenseInfo:firstyear=2010&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#include "linden_common.h"
#include "llimagej2ckdu.h"

#include "lltimer.h"
#include "llpointer.h"
#include "llmath.h"
#include "llkdumem.h"


class kdc_flow_control {
	
public:
	kdc_flow_control(kdu_image_in_base *img_in, kdu_codestream codestream);
	~kdc_flow_control();
	bool advance_components();
	void process_components();
	
private:
	
	struct kdc_component_flow_control {
	public:
		kdu_image_in_base *reader;
		int vert_subsampling;
		int ratio_counter;  /*  Initialized to 0, decremented by `count_delta';
                                when < 0, a new line must be processed, after
                                which it is incremented by `vert_subsampling'.  */
		int initial_lines;
		int remaining_lines;
		kdu_line_buf *line;
	};
	
	kdu_codestream codestream;
	kdu_dims valid_tile_indices;
	kdu_coords tile_idx;
	kdu_tile tile;
	int num_components;
	kdc_component_flow_control *components;
	int count_delta; // Holds the minimum of the `vert_subsampling' fields
	kdu_multi_analysis engine;
	kdu_long max_buffer_memory;
};

//
// Kakadu specific implementation
//
void set_default_colour_weights(kdu_params *siz);

const char* engineInfoLLImageJ2CKDU()
{
	static std::string version = llformat("KDU %s", KDU_CORE_VERSION);
	return version.c_str();
}

LLImageJ2CKDU* createLLImageJ2CKDU()
{
	return new LLImageJ2CKDU();
}

void destroyLLImageJ2CKDU(LLImageJ2CKDU* kdu)
{
	delete kdu;
	kdu = NULL;
}

LLImageJ2CImpl* fallbackCreateLLImageJ2CImpl()
{
	return new LLImageJ2CKDU();
}

void fallbackDestroyLLImageJ2CImpl(LLImageJ2CImpl* impl)
{
	delete impl;
	impl = NULL;
}

const char* fallbackEngineInfoLLImageJ2CImpl()
{
	return engineInfoLLImageJ2CKDU();
}

class LLKDUDecodeState
{
public:
	LLKDUDecodeState(kdu_tile tile, kdu_byte *buf, S32 row_gap);
	~LLKDUDecodeState();
	BOOL processTileDecode(F32 decode_time, BOOL limit_time = TRUE);

private:
	S32 mNumComponents;
	BOOL mUseYCC;
	kdu_dims mDims;
	kdu_sample_allocator mAllocator;
	kdu_tile_comp mComps[4];
	kdu_line_buf mLines[4];
	kdu_pull_ifc mEngines[4];
	bool mReversible[4]; // Some components may be reversible and others not
	int mBitDepths[4];   // Original bit-depth may be quite different from 8
	
	kdu_tile mTile;
	kdu_byte *mBuf;
	S32 mRowGap;
};

void ll_kdu_error( void )
{
	// *FIX: This exception is bad, bad, bad. It gets thrown from a
	// destructor which can lead to immediate program termination!
	throw "ll_kdu_error() throwing an exception";
}

// Stuff for new kdu error handling
class LLKDUMessageWarning : public kdu_message
{
public:
	/*virtual*/ void put_text(const char *s);
	/*virtual*/ void put_text(const kdu_uint16 *s);

	static LLKDUMessageWarning sDefaultMessage;
};

class LLKDUMessageError : public kdu_message
{
public:
	/*virtual*/ void put_text(const char *s);
	/*virtual*/ void put_text(const kdu_uint16 *s);
	/*virtual*/ void flush(bool end_of_message = false);
	static LLKDUMessageError sDefaultMessage;
};

void LLKDUMessageWarning::put_text(const char *s)
{
	llinfos << "KDU Warning: " << s << llendl;
}

void LLKDUMessageWarning::put_text(const kdu_uint16 *s)
{
	llinfos << "KDU Warning: " << s << llendl;
}

void LLKDUMessageError::put_text(const char *s)
{
	llinfos << "KDU Error: " << s << llendl;
}

void LLKDUMessageError::put_text(const kdu_uint16 *s)
{
	llinfos << "KDU Error: " << s << llendl;
}

void LLKDUMessageError::flush(bool end_of_message)
{
	if (end_of_message) 
	{
		throw "KDU throwing an exception";
	}
}

LLKDUMessageWarning LLKDUMessageWarning::sDefaultMessage;
LLKDUMessageError	LLKDUMessageError::sDefaultMessage;
static bool kdu_message_initialized = false;

LLImageJ2CKDU::LLImageJ2CKDU() : LLImageJ2CImpl(),
mInputp(NULL),
mCodeStreamp(NULL),
mTPosp(NULL),
mTileIndicesp(NULL),
mRawImagep(NULL),
mDecodeState(NULL),
mBlocksSize(-1),
mPrecinctsSize(-1),
mLevels(0)
{
}

LLImageJ2CKDU::~LLImageJ2CKDU()
{
	cleanupCodeStream(); // in case destroyed before decode completed
}

// Stuff for new simple decode
void transfer_bytes(kdu_byte *dest, kdu_line_buf &src, int gap, int precision);

void LLImageJ2CKDU::setupCodeStream(LLImageJ2C &base, BOOL keep_codestream, ECodeStreamMode mode)
{
	S32 data_size = base.getDataSize();
	S32 max_bytes = (base.getMaxBytes() ? base.getMaxBytes() : data_size);

	//
	//  Initialization
	//
	if (!kdu_message_initialized)
	{
		kdu_message_initialized = true;
		kdu_customize_errors(&LLKDUMessageError::sDefaultMessage);
		kdu_customize_warnings(&LLKDUMessageWarning::sDefaultMessage);
	}

	if (mCodeStreamp)
	{
		mCodeStreamp->destroy();
		delete mCodeStreamp;
		mCodeStreamp = NULL;
	}

	if (!mInputp && base.getData())
	{
		// The compressed data has been loaded
		// Setup the source for the codestream
		mInputp = new LLKDUMemSource(base.getData(), data_size);
	}

	if (mInputp)
	{
		mInputp->reset();
	}
	mCodeStreamp = new kdu_codestream;

	mCodeStreamp->create(mInputp);

	// Set the maximum number of bytes to use from the codestream
	mCodeStreamp->set_max_bytes(max_bytes);

	//	If you want to flip or rotate the image for some reason, change
	// the resolution, or identify a restricted region of interest, this is
	// the place to do it.  You may use "kdu_codestream::change_appearance"
	// and "kdu_codestream::apply_input_restrictions" for this purpose.
	//	If you wish to truncate the code-stream prior to decompression, you
	// may use "kdu_codestream::set_max_bytes".
	//	If you wish to retain all compressed data so that the material
	// can be decompressed multiple times, possibly with different appearance
	// parameters, you should call "kdu_codestream::set_persistent" here.
	//	There are a variety of other features which must be enabled at
	// this point if you want to take advantage of them.  See the
	// descriptions appearing with the "kdu_codestream" interface functions
	// in "kdu_compressed.h" for an itemized account of these capabilities.

	switch (mode)
	{
	case MODE_FAST:
		mCodeStreamp->set_fast();
		break;
	case MODE_RESILIENT:
		mCodeStreamp->set_resilient();
		break;
	case MODE_FUSSY:
		mCodeStreamp->set_fussy();
		break;
	default:
		llassert(0);
		mCodeStreamp->set_fast();
	}

	kdu_dims dims;
	mCodeStreamp->get_dims(0,dims);

	S32 components = mCodeStreamp->get_num_components();

	if (components >= 3)
	{ // Check that components have consistent dimensions (for PPM file)
		kdu_dims dims1; mCodeStreamp->get_dims(1,dims1);
		kdu_dims dims2; mCodeStreamp->get_dims(2,dims2);
		if ((dims1 != dims) || (dims2 != dims))
		{
			llerrs << "Components don't have matching dimensions!" << llendl;
		}
	}

	// Get the number of resolution levels in that image
	mLevels = mCodeStreamp->get_min_dwt_levels();

	// Set the base dimensions
	base.setSize(dims.size.x, dims.size.y, components);
	base.setLevels(mLevels);
	
	if (!keep_codestream)
	{
		mCodeStreamp->destroy();
		delete mCodeStreamp;
		mCodeStreamp = NULL;
		delete mInputp;
		mInputp = NULL;
	}
}

void LLImageJ2CKDU::cleanupCodeStream()
{
	delete mInputp;
	mInputp = NULL;

	delete mDecodeState;
	mDecodeState = NULL;

	if (mCodeStreamp)
	{
		mCodeStreamp->destroy();
		delete mCodeStreamp;
		mCodeStreamp = NULL;
	}

	delete mTPosp;
	mTPosp = NULL;

	delete mTileIndicesp;
	mTileIndicesp = NULL;
}

BOOL LLImageJ2CKDU::initDecode(LLImageJ2C &base, LLImageRaw &raw_image, int discard_level, int* region)
{
	return initDecode(base,raw_image,0.0f,MODE_FAST,0,4,discard_level,region);
}

BOOL LLImageJ2CKDU::initEncode(LLImageJ2C &base, LLImageRaw &raw_image, int blocks_size, int precincts_size, int levels)
{
	mPrecinctsSize = precincts_size;
	if (mPrecinctsSize != -1)
	{
		mPrecinctsSize = get_lower_power_two(mPrecinctsSize,MAX_PRECINCT_SIZE);
		mPrecinctsSize = llmax(mPrecinctsSize,MIN_PRECINCT_SIZE);
	}
	mBlocksSize = blocks_size;
	if (mBlocksSize != -1)
	{
		mBlocksSize = get_lower_power_two(mBlocksSize,MAX_BLOCK_SIZE);
		mBlocksSize = llmax(mBlocksSize,MIN_BLOCK_SIZE);
		if (mPrecinctsSize != -1)
		{
			mBlocksSize = llmin(mBlocksSize,mPrecinctsSize);	// blocks *must* be smaller than precincts
		}
	}
	mLevels = levels;
	if (mLevels != 0)
	{
		mLevels = llclamp(mLevels,MIN_DECOMPOSITION_LEVELS,MIN_DECOMPOSITION_LEVELS);		
	}
	return TRUE;
}

BOOL LLImageJ2CKDU::initDecode(LLImageJ2C &base, LLImageRaw &raw_image, F32 decode_time, ECodeStreamMode mode, S32 first_channel, S32 max_channel_count, int discard_level, int* region)
{
	base.resetLastError();

	// *FIX: kdu calls our callback function if there's an error, and then bombs.
	// To regain control, we throw an exception, and catch it here.
	try
	{
		base.updateRawDiscardLevel();
		setupCodeStream(base, TRUE, mode);

		mRawImagep = &raw_image;
		mCodeStreamp->change_appearance(false, true, false);

		// Apply loading discard level and cropping if required
		kdu_dims* region_kdu = NULL;
		if (region != NULL)
		{
			region_kdu = new kdu_dims;
			region_kdu->pos.x  = region[0];
			region_kdu->pos.y  = region[1];
			region_kdu->size.x = region[2] - region[0];
			region_kdu->size.y = region[3] - region[1];
		}
		int discard = (discard_level != -1 ? discard_level : base.getRawDiscardLevel());
		
		// Apply loading restrictions
		mCodeStreamp->apply_input_restrictions( first_channel, max_channel_count, discard, 0, region_kdu);
		
		// Clean-up
		if (region_kdu)
		{
			delete region_kdu;
			region_kdu = NULL;
		}

		// Resize raw_image according to the image to be decoded
		kdu_dims dims; mCodeStreamp->get_dims(0,dims);
		S32 channels = base.getComponents() - first_channel;
		channels = llmin(channels,max_channel_count);
		raw_image.resize(dims.size.x, dims.size.y, channels);

		if (!mTileIndicesp)
		{
			mTileIndicesp = new kdu_dims;
		}
		mCodeStreamp->get_valid_tiles(*mTileIndicesp);
		if (!mTPosp)
		{
			mTPosp = new kdu_coords;
			mTPosp->y = 0;
			mTPosp->x = 0;
		}
	}
	catch (const char* msg)
	{
		base.setLastError(ll_safe_string(msg));
		return FALSE;
	}
	catch (...)
	{
		base.setLastError("Unknown J2C error");
		return FALSE;
	}

	return TRUE;
}


// Returns TRUE to mean done, whether successful or not.
BOOL LLImageJ2CKDU::decodeImpl(LLImageJ2C &base, LLImageRaw &raw_image, F32 decode_time, S32 first_channel, S32 max_channel_count)
{
	ECodeStreamMode mode = MODE_FAST;

	LLTimer decode_timer;

	if (!mCodeStreamp)
	{
		if (!initDecode(base, raw_image, decode_time, mode, first_channel, max_channel_count))
		{
			// Initializing the J2C decode failed, bail out.
			cleanupCodeStream();
			return TRUE; // done
		}
	}

	// These can probably be grabbed from what's saved in the class.
	kdu_dims dims;
	mCodeStreamp->get_dims(0,dims);

	// Now we are ready to walk through the tiles processing them one-by-one.
	kdu_byte *buffer = raw_image.getData();

	while (mTPosp->y < mTileIndicesp->size.y)
	{
		while (mTPosp->x < mTileIndicesp->size.x)
		{
			try
			{
				if (!mDecodeState)
				{
					kdu_tile tile = mCodeStreamp->open_tile(*(mTPosp)+mTileIndicesp->pos);

					// Find the region of the buffer occupied by this
					// tile.  Note that we have no control over
					// sub-sampling factors which might have been used
					// during compression and so it can happen that tiles
					// (at the image component level) actually have
					// different dimensions.  For this reason, we cannot
					// figure out the buffer region occupied by a tile
					// directly from the tile indices.  Instead, we query
					// the highest resolution of the first tile-component
					// concerning its location and size on the canvas --
					// the `dims' object already holds the location and
					// size of the entire image component on the same
					// canvas coordinate system.  Comparing the two tells
					// us where the current tile is in the buffer.
					S32 channels = base.getComponents() - first_channel;
					if (channels > max_channel_count)
					{
						channels = max_channel_count;
					}
					kdu_resolution res = tile.access_component(0).access_resolution();
					kdu_dims tile_dims; res.get_dims(tile_dims);
					kdu_coords offset = tile_dims.pos - dims.pos;
					int row_gap = channels*dims.size.x; // inter-row separation
					kdu_byte *buf = buffer + offset.y*row_gap + offset.x*channels;
					mDecodeState = new LLKDUDecodeState(tile, buf, row_gap);
				}
				// Do the actual processing
				F32 remaining_time = decode_time - decode_timer.getElapsedTimeF32();
				// This is where we do the actual decode.  If we run out of time, return false.
				if (mDecodeState->processTileDecode(remaining_time, (decode_time > 0.0f)))
				{
					delete mDecodeState;
					mDecodeState = NULL;
				}
				else
				{
					// Not finished decoding yet.
					//					setLastError("Ran out of time while decoding");
					return FALSE;
				}
			}
			catch (const char* msg)
			{
				base.setLastError(ll_safe_string(msg));
				base.decodeFailed();
				cleanupCodeStream();
				return TRUE; // done
			}
			catch (...)
			{
				base.setLastError( "Unknown J2C error" );
				base.decodeFailed();
				cleanupCodeStream();
				return TRUE; // done
			}


			mTPosp->x++;
		}
		mTPosp->y++;
		mTPosp->x = 0;
	}

	cleanupCodeStream();

	return TRUE;
}


BOOL LLImageJ2CKDU::encodeImpl(LLImageJ2C &base, const LLImageRaw &raw_image, const char* comment_text, F32 encode_time, BOOL reversible)
{
	// Declare and set simple arguments
	bool transpose = false;
	bool vflip = true;
	bool hflip = false;

	try
	{
		// Set up input image files
		siz_params siz;
		
		// Should set rate someplace here
		LLKDUMemIn mem_in(raw_image.getData(),
			raw_image.getDataSize(),
			raw_image.getWidth(),
			raw_image.getHeight(),
			raw_image.getComponents(),
			&siz);

		base.setSize(raw_image.getWidth(), raw_image.getHeight(), raw_image.getComponents());

		int num_components = raw_image.getComponents();

		siz.set(Scomponents,0,0,num_components);
		siz.set(Sdims,0,0,base.getHeight());  // Height of first image component
		siz.set(Sdims,0,1,base.getWidth());   // Width of first image component
		siz.set(Sprecision,0,0,8);  // Image samples have original bit-depth of 8
		siz.set(Ssigned,0,0,false); // Image samples are originally unsigned

		kdu_params *siz_ref = &siz; 
		siz_ref->finalize();
		siz_params transformed_siz; // Use this one to construct code-stream
		transformed_siz.copy_from(&siz,-1,-1,-1,0,transpose,false,false);

		// Construct the `kdu_codestream' object and parse all remaining arguments
		U32 max_output_size = base.getWidth()*base.getHeight()*base.getComponents();
		max_output_size = (max_output_size < 1000 ? 1000 : max_output_size);
		U8 *output_buffer = new U8[max_output_size];
		U32 output_size = 0; // Address updated by LLKDUMemTarget to give the final compressed buffer size
		LLKDUMemTarget output(output_buffer, output_size, max_output_size);

		kdu_codestream codestream;
		codestream.create(&transformed_siz,&output);

		if (comment_text)
		{
			// Set the comments for the codestream
			kdu_codestream_comment comment = codestream.add_comment();
			comment.put_text(comment_text);
		}

		// Set codestream options
		int num_layer_specs = 0;

		kdu_long layer_bytes[64];
		U32 max_bytes = 0;

		if (num_components >= 3)
		{
			// Note that we always use YCC and not YUV
			// *TODO: Verify this doesn't screws up reversible textures (like sculpties) as YCC is not reversible but YUV is...
			set_default_colour_weights(codestream.access_siz());
		}

		if (reversible)
		{
			codestream.access_siz()->parse_string("Creversible=yes");
			// *TODO: we should use yuv in reversible mode and one level since those images are small. 
			// Don't turn this on now though as both create problems on decoding for the moment
			//codestream.access_siz()->parse_string("Clevels=1");
			//codestream.access_siz()->parse_string("Cycc=no");
			// If we're doing reversible (i.e. lossless compression), assumes we're not using quality layers.
			// *TODO: this is incorrect and unecessary. Try using the regular layer setting.
			codestream.access_siz()->parse_string("Clayers=1");
			num_layer_specs = 1;
			layer_bytes[0] = 0;
		}
		else
		{
			// Rate is the argument passed into the LLImageJ2C which
			// specifies the target compression rate.  The default is 8:1.
			// Possibly if max_bytes < 500, we should just use the default setting?
			// *TODO: mRate is actually always 8:1 in the viewer. Test different values. Also force to reversible for small (< 500 bytes) textures.
			if (base.mRate != 0.f)
			{
				max_bytes = (U32)(base.mRate*base.getWidth()*base.getHeight()*base.getComponents());
			}
			else
			{
				max_bytes = (U32)(base.getWidth()*base.getHeight()*base.getComponents()*0.125);
			}

			const U32 min_bytes = FIRST_PACKET_SIZE;
			if (max_bytes > min_bytes)
			{
				U32 i;
				// This code is where we specify the target number of bytes for
				// each layer.  Not sure if we should do this for small images
				// or not.  The goal is to have this roughly align with
				// different quality levels that we decode at.
				for (i = min_bytes; i < max_bytes; i*=4)
				{
					if (i == min_bytes * 4)
					{
						i = 2000;
					}
					layer_bytes[num_layer_specs] = i;
					num_layer_specs++;
				}
				layer_bytes[num_layer_specs] = max_bytes;
				num_layer_specs++;

				std::string layer_string = llformat("Clayers=%d",num_layer_specs);
				codestream.access_siz()->parse_string(layer_string.c_str());
			}
			else
			{
				layer_bytes[0] = min_bytes;
				num_layer_specs = 1;
				std::string layer_string = llformat("Clayers=%d",num_layer_specs);
				codestream.access_siz()->parse_string(layer_string.c_str());
			}
		}
		
		// Set up data ordering, markers, etc... if precincts or blocks specified
		if ((mBlocksSize != -1) || (mPrecinctsSize != -1))
		{
			if (mPrecinctsSize != -1)
			{
				std::string precincts_string = llformat("Cprecincts={%d,%d}",mPrecinctsSize,mPrecinctsSize);
				codestream.access_siz()->parse_string(precincts_string.c_str());
			}
			if (mBlocksSize != -1)
			{
				std::string blocks_string = llformat("Cblk={%d,%d}",mBlocksSize,mBlocksSize);
				codestream.access_siz()->parse_string(blocks_string.c_str());
			}
			std::string ordering_string = llformat("Corder=RPCL");
			codestream.access_siz()->parse_string(ordering_string.c_str());
			std::string PLT_string = llformat("ORGgen_plt=yes");
			codestream.access_siz()->parse_string(PLT_string.c_str());
			std::string Parts_string = llformat("ORGtparts=R");
			codestream.access_siz()->parse_string(Parts_string.c_str());
		}
		if (mLevels != 0)
		{
			std::string levels_string = llformat("Clevels=%d",mLevels);
			codestream.access_siz()->parse_string(levels_string.c_str());
		}
		
		codestream.access_siz()->finalize_all();
		codestream.change_appearance(transpose,vflip,hflip);

		// Now we are ready for sample data processing.
		kdc_flow_control *tile = new kdc_flow_control(&mem_in,codestream);
		bool done = false;
		while (!done)
		{ 
			// Process line by line
			if (tile->advance_components())
			{
				tile->process_components();
			}
			else
			{
				done = true;
			}
		}

		// Produce the compressed output
		codestream.flush(layer_bytes,num_layer_specs);

		// Cleanup
		delete tile;
		codestream.destroy();

		// Now that we're done encoding, create the new data buffer for the compressed
		// image and stick it there.
		base.copyData(output_buffer, output_size);
		base.updateData(); // set width, height
		delete[] output_buffer;
	}
	catch(const char* msg)
	{
		base.setLastError(ll_safe_string(msg));
		return FALSE;
	}
	catch( ... )
	{
		base.setLastError( "Unknown J2C error" );
		return FALSE;
	}

	return TRUE;
}

BOOL LLImageJ2CKDU::getMetadata(LLImageJ2C &base)
{
	// *FIX: kdu calls our callback function if there's an error, and
	// then bombs. To regain control, we throw an exception, and
	// catch it here.
	try
	{
		setupCodeStream(base, FALSE, MODE_FAST);
		return TRUE;
	}
	catch (const char* msg)
	{
		base.setLastError(ll_safe_string(msg));
		return FALSE;
	}
	catch (...)
	{
		base.setLastError( "Unknown J2C error" );
		return FALSE;
	}
}

void set_default_colour_weights(kdu_params *siz)
{
	kdu_params *cod = siz->access_cluster(COD_params);
	assert(cod != NULL);

	bool can_use_ycc = true;
	bool rev0 = false;
	int depth0 = 0, sub_x0 = 1, sub_y0 = 1;
	for (int c = 0; c < 3; c++)
	{
		int depth = 0; siz->get(Sprecision,c,0,depth);
		int sub_y = 1; siz->get(Ssampling,c,0,sub_y);
		int sub_x = 1; siz->get(Ssampling,c,1,sub_x);
		kdu_params *coc = cod->access_relation(-1,c);
		bool rev = false; coc->get(Creversible,0,0,rev);
		if (c == 0)
		{
			rev0 = rev; depth0 = depth; sub_x0 = sub_x; sub_y0 = sub_y;
		}
		else if ((rev != rev0) || (depth != depth0) || 
				 (sub_x != sub_x0) || (sub_y != sub_y0))
		{
			can_use_ycc = false;
		}
	}
	if (!can_use_ycc)
	{
		return;
	}

	bool use_ycc;
	if (!cod->get(Cycc,0,0,use_ycc))
	{
		cod->set(Cycc,0,0,use_ycc=true);
	}
	if (!use_ycc)
	{
		return;
	}
	float weight;
	if (cod->get(Clev_weights,0,0,weight) || cod->get(Cband_weights,0,0,weight))
	{
		// Weights already specified explicitly -> nothing to do
		return; 
	}

	// These example weights are adapted from numbers generated by Marcus Nadenau
	// at EPFL, for a viewing distance of 15 cm and a display resolution of
	// 300 DPI.

	cod->parse_string("Cband_weights:C0="
		"{0.0901},{0.2758},{0.2758},"
		"{0.7018},{0.8378},{0.8378},{1}");
	cod->parse_string("Cband_weights:C1="
		"{0.0263},{0.0863},{0.0863},"
		"{0.1362},{0.2564},{0.2564},"
		"{0.3346},{0.4691},{0.4691},"
		"{0.5444},{0.6523},{0.6523},"
		"{0.7078},{0.7797},{0.7797},{1}");
	cod->parse_string("Cband_weights:C2="
		"{0.0773},{0.1835},{0.1835},"
		"{0.2598},{0.4130},{0.4130},"
		"{0.5040},{0.6464},{0.6464},"
		"{0.7220},{0.8254},{0.8254},"
		"{0.8769},{0.9424},{0.9424},{1}");
}

/******************************************************************************/
/*                              transfer_bytes                                */
/******************************************************************************/

void transfer_bytes(kdu_byte *dest, kdu_line_buf &src, int gap, int precision)
/* Transfers source samples from the supplied line buffer into the output
byte buffer, spacing successive output samples apart by `gap' bytes
(to allow for interleaving of colour components).  The function performs
all necessary level shifting, type conversion, rounding and truncation. */
{
	int width = src.get_width();
	if (src.get_buf32() != NULL)
	{ // Decompressed samples have a 32-bit representation (integer or float)
		assert(precision >= 8); // Else would have used 16 bit representation
		kdu_sample32 *sp = src.get_buf32();
		if (!src.is_absolute())
		{ // Transferring normalized floating point data.
			float scale16 = (float)(1<<16);
			kdu_int32 val;

			for (; width > 0; width--, sp++, dest+=gap)
			{
				val = (kdu_int32)(sp->fval*scale16);
				val = (val+128)>>8; // May be faster than true rounding
				val += 128;
				if (val & ((-1)<<8))
				{
					val = (val < 0 ? 0 : 255);
				}
				*dest = (kdu_byte) val;
			}
		}
		else
		{ // Transferring 32-bit absolute integers.
			kdu_int32 val;
			kdu_int32 downshift = precision-8;
			kdu_int32 offset = (1<<downshift)>>1;

			for (; width > 0; width--, sp++, dest+=gap)
			{
				val = sp->ival;
				val = (val+offset)>>downshift;
				val += 128;
				if (val & ((-1)<<8))
				{
					val = (val < 0 ? 0 : 255);
				}
				*dest = (kdu_byte) val;
			}
		}
	}
	else
	{ // Source data is 16 bits.
		kdu_sample16 *sp = src.get_buf16();
		if (!src.is_absolute())
		{ // Transferring 16-bit fixed point quantities
			kdu_int16 val;

			if (precision >= 8)
			{ // Can essentially ignore the bit-depth.
				for (; width > 0; width--, sp++, dest+=gap)
				{
					val = sp->ival;
					val += (1<<(KDU_FIX_POINT-8))>>1;
					val >>= (KDU_FIX_POINT-8);
					val += 128;
					if (val & ((-1)<<8))
					{
						val = (val < 0 ? 0 : 255);
					}
					*dest = (kdu_byte) val;
				}
			}
			else
			{ // Need to force zeros into one or more least significant bits.
				kdu_int16 downshift = KDU_FIX_POINT-precision;
				kdu_int16 upshift = 8-precision;
				kdu_int16 offset = 1<<(downshift-1);

				for (; width > 0; width--, sp++, dest+=gap)
				{
					val = sp->ival;
					val = (val+offset)>>downshift;
					val <<= upshift;
					val += 128;
					if (val & ((-1)<<8))
					{
						val = (val < 0 ? 0 : 256 - (1<<upshift));
					}
					*dest = (kdu_byte) val;
				}
			}
		}
		else
		{ // Transferring 16-bit absolute integers.
			kdu_int16 val;

			if (precision >= 8)
			{
				kdu_int16 downshift = precision-8;
				kdu_int16 offset = (1<<downshift)>>1;

				for (; width > 0; width--, sp++, dest+=gap)
				{
					val = sp->ival;
					val = (val+offset)>>downshift;
					val += 128;
					if (val & ((-1)<<8))
					{
						val = (val < 0 ? 0 : 255);
					}
					*dest = (kdu_byte) val;
				}
			}
			else
			{
				kdu_int16 upshift = 8-precision;

				for (; width > 0; width--, sp++, dest+=gap)
				{
					val = sp->ival;
					val <<= upshift;
					val += 128;
					if (val & ((-1)<<8))
					{
						val = (val < 0 ? 0 : 256 - (1<<upshift));
					}
					*dest = (kdu_byte) val;
				}
			}
		}
	}
}

LLKDUDecodeState::LLKDUDecodeState(kdu_tile tile, kdu_byte *buf, S32 row_gap)
{
	S32 c;

	mTile = tile;
	mBuf = buf;
	mRowGap = row_gap;

	mNumComponents = tile.get_num_components();

	llassert(mNumComponents <= 4);
	mUseYCC = tile.get_ycc();

	for (c = 0; c < 4; ++c)
	{
		mReversible[c] = false;
		mBitDepths[c] = 0;
	}

	// Open tile-components and create processing engines and resources
	for (c = 0; c < mNumComponents; c++)
	{
		mComps[c] = mTile.access_component(c);
		mReversible[c] = mComps[c].get_reversible();
		mBitDepths[c] = mComps[c].get_bit_depth();
		kdu_resolution res = mComps[c].access_resolution(); // Get top resolution
		kdu_dims comp_dims; res.get_dims(comp_dims);
		if (c == 0)
		{
			mDims = comp_dims;
		}
		else
		{
			llassert(mDims == comp_dims); // Safety check; the caller has ensured this
		}
		bool use_shorts = (mComps[c].get_bit_depth(true) <= 16);
		mLines[c].pre_create(&mAllocator,mDims.size.x,mReversible[c],use_shorts);
		if (res.which() == 0) // No DWT levels used
		{
			mEngines[c] = kdu_decoder(res.access_subband(LL_BAND),&mAllocator,use_shorts);
		}
		else
		{
			mEngines[c] = kdu_synthesis(res,&mAllocator,use_shorts);
		}