Files
squoosh/codecs/jxl/enc/jxl_enc.cpp

131 lines
3.7 KiB
C++

#include <emscripten/bind.h>
#include <emscripten/val.h>
#include "lib/jxl/base/thread_pool_internal.h"
#include "lib/jxl/enc_file.h"
#include "lib/jxl/external_image.h"
using namespace emscripten;
thread_local const val Uint8Array = val::global("Uint8Array");
struct JXLOptions {
// 1 = slowest
// 7 = fastest
int speed;
float quality;
bool progressive;
int epf;
int nearLossless;
bool lossyPalette;
};
val encode(std::string image, int width, int height, JXLOptions options) {
jxl::CompressParams cparams;
jxl::PassesEncoderState passes_enc_state;
jxl::CodecInOut io;
jxl::PaddedBytes bytes;
jxl::ImageBundle* main = &io.Main();
jxl::ThreadPoolInternal* pool_ptr = nullptr;
#ifdef __EMSCRIPTEN_PTHREADS__
jxl::ThreadPoolInternal pool;
pool_ptr = &pool;
#endif
cparams.epf = options.epf;
cparams.speed_tier = static_cast<jxl::SpeedTier>(options.speed);
cparams.near_lossless = options.nearLossless;
if (options.lossyPalette) {
cparams.lossy_palette = true;
cparams.palette_colors = 0;
cparams.options.predictor = jxl::Predictor::Zero;
}
// Reduce memory usage of tree learning for lossless data.
// TODO(veluca93): this is a mitigation for excessive memory usage in the JXL encoder.
float megapixels = width * height * 0.000001;
if (megapixels > 8) {
cparams.options.nb_repeats = 0.1;
} else if (megapixels > 4) {
cparams.options.nb_repeats = 0.3;
} else {
// default is OK.
}
float quality = options.quality;
// Quality settings roughly match libjpeg qualities.
if (quality < 7 || quality == 100) {
cparams.modular_mode = true;
// Internal modular quality to roughly match VarDCT size.
cparams.quality_pair.first = cparams.quality_pair.second =
std::min(35 + (quality - 7) * 3.0f, 100.0f);
} else {
cparams.modular_mode = false;
if (quality >= 30) {
cparams.butteraugli_distance = 0.1 + (100 - quality) * 0.09;
} else {
cparams.butteraugli_distance = 6.4 + pow(2.5, (30 - quality) / 5.0f) / 6.25f;
}
}
if (options.progressive) {
cparams.qprogressive_mode = true;
cparams.responsive = 1;
if (!cparams.modular_mode) {
cparams.progressive_dc = 1;
}
}
if (cparams.modular_mode) {
if (cparams.quality_pair.first != 100 || cparams.quality_pair.second != 100) {
cparams.color_transform = jxl::ColorTransform::kXYB;
} else {
cparams.color_transform = jxl::ColorTransform::kNone;
}
}
if (cparams.near_lossless) {
// Near-lossless assumes -R 0
cparams.responsive = 0;
cparams.modular_mode = true;
}
io.metadata.m.SetAlphaBits(8);
if (!io.metadata.size.Set(width, height)) {
return val::null();
}
uint8_t* inBuffer = (uint8_t*)image.c_str();
auto result = jxl::ConvertImage(
jxl::Span<const uint8_t>(reinterpret_cast<const uint8_t*>(image.data()), image.size()), width,
height, jxl::ColorEncoding::SRGB(/*is_gray=*/false), /*has_alpha=*/true,
/*alpha_is_premultiplied=*/false, /*bits_per_alpha=*/8, /*bits_per_sample=*/8,
/*big_endian=*/false, /*flipped_y=*/false, pool_ptr, main);
if (!result) {
return val::null();
}
auto js_result = val::null();
if (EncodeFile(cparams, &io, &passes_enc_state, &bytes, /*aux=*/nullptr, pool_ptr)) {
js_result = Uint8Array.new_(typed_memory_view(bytes.size(), bytes.data()));
}
return js_result;
}
EMSCRIPTEN_BINDINGS(my_module) {
value_object<JXLOptions>("JXLOptions")
.field("speed", &JXLOptions::speed)
.field("quality", &JXLOptions::quality)
.field("progressive", &JXLOptions::progressive)
.field("nearLossless", &JXLOptions::nearLossless)
.field("lossyPalette", &JXLOptions::lossyPalette)
.field("epf", &JXLOptions::epf);
function("encode", &encode);
}