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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_ENC_ANS_PARAMS_H_
#define LIB_JXL_ENC_ANS_PARAMS_H_
// Encoder-only parameter needed for ANS entropy encoding methods.
#include <stdint.h>
#include <stdlib.h>
#include "lib/jxl/enc_params.h"
namespace jxl {
struct HistogramParams {
enum class ClusteringType {
kFastest, // Only 4 clusters.
kFast,
kBest,
};
enum class HybridUintMethod {
kNone, // just use kHybridUint420Config.
k000, // force the fastest option.
kFast, // just try a couple of options.
kContextMap, // fast choice for ctx map.
kBest,
};
enum class LZ77Method {
kNone, // do not try lz77.
kRLE, // only try doing RLE.
kLZ77, // try lz77 with backward references.
kOptimal, // optimal-matching LZ77 parsing.
};
enum class ANSHistogramStrategy {
kFast, // Only try some methods, early exit.
kApproximate, // Only try some methods.
kPrecise, // Try all methods.
};
HistogramParams() = default;
HistogramParams(SpeedTier tier, size_t num_ctx) {
if (tier > SpeedTier::kFalcon) {
clustering = ClusteringType::kFastest;
lz77_method = LZ77Method::kNone;
} else if (tier > SpeedTier::kTortoise) {
clustering = ClusteringType::kFast;
} else {
clustering = ClusteringType::kBest;
}
if (tier > SpeedTier::kTortoise) {
uint_method = HybridUintMethod::kNone;
}
if (tier >= SpeedTier::kSquirrel) {
ans_histogram_strategy = ANSHistogramStrategy::kApproximate;
}
}
ClusteringType clustering = ClusteringType::kBest;
HybridUintMethod uint_method = HybridUintMethod::kBest;
LZ77Method lz77_method = LZ77Method::kRLE;
ANSHistogramStrategy ans_histogram_strategy = ANSHistogramStrategy::kPrecise;
std::vector<size_t> image_widths;
size_t max_histograms = ~0;
bool force_huffman = false;
};
} // namespace jxl
#endif // LIB_JXL_ENC_ANS_PARAMS_H_
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