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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#ifndef LIB_JXL_HEADERS_H_
#define LIB_JXL_HEADERS_H_
// Codestream headers, also stored in CodecInOut.
#include <stddef.h>
#include <stdint.h>
#include "lib/jxl/aux_out_fwd.h"
#include "lib/jxl/base/compiler_specific.h"
#include "lib/jxl/base/status.h"
#include "lib/jxl/dec_bit_reader.h"
#include "lib/jxl/enc_bit_writer.h"
#include "lib/jxl/field_encodings.h"
namespace jxl {
// Reserved by ISO/IEC 10918-1. LF causes files opened in text mode to be
// rejected because the marker changes to 0x0D instead. The 0xFF prefix also
// ensures there were no 7-bit transmission limitations.
static constexpr uint8_t kCodestreamMarker = 0x0A;
// Compact representation of image dimensions (best case: 9 bits) so decoders
// can preallocate early.
class SizeHeader : public Fields {
public:
// All fields are valid after reading at most this many bits. WriteSizeHeader
// verifies this matches Bundle::MaxBits(SizeHeader).
static constexpr size_t kMaxBits = 78;
SizeHeader();
JXL_FIELDS_NAME(SizeHeader)
Status VisitFields(Visitor* JXL_RESTRICT visitor) override;
Status Set(size_t xsize, size_t ysize);
size_t xsize() const;
size_t ysize() const {
return small_ ? ((ysize_div8_minus_1_ + 1) * 8) : ysize_;
}
private:
bool small_; // xsize and ysize <= 256 and divisible by 8.
uint32_t ysize_div8_minus_1_;
uint32_t ysize_;
uint32_t ratio_;
uint32_t xsize_div8_minus_1_;
uint32_t xsize_;
};
// (Similar to SizeHeader but different encoding because previews are smaller)
class PreviewHeader : public Fields {
public:
PreviewHeader();
JXL_FIELDS_NAME(PreviewHeader)
Status VisitFields(Visitor* JXL_RESTRICT visitor) override;
Status Set(size_t xsize, size_t ysize);
size_t xsize() const;
size_t ysize() const { return div8_ ? (ysize_div8_ * 8) : ysize_; }
private:
bool div8_; // xsize and ysize divisible by 8.
uint32_t ysize_div8_;
uint32_t ysize_;
uint32_t ratio_;
uint32_t xsize_div8_;
uint32_t xsize_;
};
struct AnimationHeader : public Fields {
AnimationHeader();
JXL_FIELDS_NAME(AnimationHeader)
Status VisitFields(Visitor* JXL_RESTRICT visitor) override;
// Ticks per second (expressed as rational number to support NTSC)
uint32_t tps_numerator;
uint32_t tps_denominator;
uint32_t num_loops; // 0 means to repeat infinitely.
bool have_timecodes;
};
Status ReadSizeHeader(BitReader* JXL_RESTRICT reader,
SizeHeader* JXL_RESTRICT size);
Status WriteSizeHeader(const SizeHeader& size, BitWriter* JXL_RESTRICT writer,
size_t layer, AuxOut* aux_out);
} // namespace jxl
#endif // LIB_JXL_HEADERS_H_
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