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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_FRAME_HEADER_H_
#define LIB_JXL_FRAME_HEADER_H_
// Frame header with backward and forward-compatible extension capability and
// compressed integer fields.
#include <algorithm>
#include <array>
#include <cstddef>
#include <cstdint>
#include <string>
#include <vector>
#include "lib/jxl/base/common.h"
#include "lib/jxl/base/compiler_specific.h"
#include "lib/jxl/base/status.h"
#include "lib/jxl/coeff_order_fwd.h"
#include "lib/jxl/common.h" // kMaxNumPasses
#include "lib/jxl/dec_bit_reader.h"
#include "lib/jxl/field_encodings.h"
#include "lib/jxl/fields.h"
#include "lib/jxl/frame_dimensions.h"
#include "lib/jxl/image_metadata.h"
#include "lib/jxl/loop_filter.h"
namespace jxl {
// TODO(eustas): move to proper place?
// Also used by extra channel names.
static inline Status VisitNameString(Visitor* JXL_RESTRICT visitor,
std::string* name) {
uint32_t name_length = static_cast<uint32_t>(name->length());
// Allows layer name lengths up to 1071 bytes
JXL_QUIET_RETURN_IF_ERROR(visitor->U32(Val(0), Bits(4), BitsOffset(5, 16),
BitsOffset(10, 48), 0, &name_length));
if (visitor->IsReading()) {
name->resize(name_length);
}
for (size_t i = 0; i < name_length; i++) {
uint32_t c = static_cast<uint8_t>((*name)[i]);
JXL_QUIET_RETURN_IF_ERROR(visitor->Bits(8, 0, &c));
(*name)[i] = static_cast<char>(c);
}
return true;
}
enum class FrameEncoding : uint32_t {
kVarDCT,
kModular,
};
enum class ColorTransform : uint32_t {
kXYB, // Values are encoded with XYB. May only be used if
// ImageBundle::xyb_encoded.
kNone, // Values are encoded according to the attached color profile. May
// only be used if !ImageBundle::xyb_encoded.
kYCbCr, // Values are encoded according to the attached color profile, but
// transformed to YCbCr. May only be used if
// !ImageBundle::xyb_encoded.
};
inline std::array<int, 3> JpegOrder(ColorTransform ct, bool is_gray) {
if (is_gray) {
return {{0, 0, 0}};
}
if (ct == ColorTransform::kYCbCr) {
return {{1, 0, 2}};
} else if (ct == ColorTransform::kNone) {
return {{0, 1, 2}};
} else {
JXL_DEBUG_ABORT("Internal logic error");
return {{0, 1, 2}};
}
}
struct YCbCrChromaSubsampling : public Fields {
YCbCrChromaSubsampling();
JXL_FIELDS_NAME(YCbCrChromaSubsampling)
size_t HShift(size_t c) const { return maxhs_ - kHShift[channel_mode_[c]]; }
size_t VShift(size_t c) const { return maxvs_ - kVShift[channel_mode_[c]]; }
Status VisitFields(Visitor* JXL_RESTRICT visitor) override {
// TODO(veluca): consider allowing 4x downsamples
for (uint32_t& ch : channel_mode_) {
JXL_QUIET_RETURN_IF_ERROR(visitor->Bits(2, 0, &ch));
}
Recompute();
return true;
}
uint8_t MaxHShift() const { return maxhs_; }
uint8_t MaxVShift() const { return maxvs_; }
uint8_t RawHShift(size_t c) const { return kHShift[channel_mode_[c]]; }
uint8_t RawVShift(size_t c) const { return kVShift[channel_mode_[c]]; }
// Uses JPEG channel order (Y, Cb, Cr).
Status Set(const uint8_t* hsample, const uint8_t* vsample) {
for (size_t c = 0; c < 3; c++) {
size_t cjpeg = c < 2 ? c ^ 1 : c;
size_t i = 0;
for (; i < 4; i++) {
if (1 << kHShift[i] == hsample[cjpeg] &&
1 << kVShift[i] == vsample[cjpeg]) {
channel_mode_[c] = i;
break;
}
}
if (i == 4) {
return JXL_FAILURE("Invalid subsample mode");
}
}
Recompute();
return true;
}
bool Is444() const {
return HShift(0) == 0 && VShift(0) == 0 && // Cb
HShift(2) == 0 && VShift(2) == 0 && // Cr
HShift(1) == 0 && VShift(1) == 0; // Y
}
bool Is420() const {
return HShift(0) == 1 && VShift(0) == 1 && // Cb
HShift(2) == 1 && VShift(2) == 1 && // Cr
HShift(1) == 0 && VShift(1) == 0; // Y
}
bool Is422() const {
return HShift(0) == 1 && VShift(0) == 0 && // Cb
HShift(2) == 1 && VShift(2) == 0 && // Cr
HShift(1) == 0 && VShift(1) == 0; // Y
}
bool Is440() const {
return HShift(0) == 0 && VShift(0) == 1 && // Cb
HShift(2) == 0 && VShift(2) == 1 && // Cr
HShift(1) == 0 && VShift(1) == 0; // Y
}
std::string DebugString() const {
if (Is444()) return "444";
if (Is420()) return "420";
if (Is422()) return "422";
if (Is440()) return "440";
return "cs" + std::to_string(channel_mode_[0]) +
std::to_string(channel_mode_[1]) + std::to_string(channel_mode_[2]);
}
private:
void Recompute() {
maxhs_ = 0;
maxvs_ = 0;
for (uint32_t ch : channel_mode_) {
maxhs_ = std::max(maxhs_, kHShift[ch]);
maxvs_ = std::max(maxvs_, kVShift[ch]);
}
}
static const uint8_t kHShift[4];
static const uint8_t kVShift[4];
uint32_t channel_mode_[3];
uint8_t maxhs_;
uint8_t maxvs_;
};
// Indicates how to combine the current frame with a previously-saved one. Can
// be independently controlled for color and extra channels. Formulas are
// indicative and treat alpha as if it is in range 0.0-1.0. In descriptions
// below, alpha channel is the extra channel of type alpha used for blending
// according to the blend_channel, or fully opaque if there is no alpha channel.
// The blending specified here is used for performing blending *after* color
// transforms - in linear sRGB if blending a XYB-encoded frame on another
// XYB-encoded frame, in sRGB if blending a frame with kColorSpace == kSRGB, or
// in the original colorspace otherwise. Blending in XYB or YCbCr is done by
// using patches.
enum class BlendMode {
// The new values (in the crop) replace the old ones: sample = new
kReplace = 0,
// The new values (in the crop) get added to the old ones: sample = old + new
kAdd = 1,
// The new values (in the crop) replace the old ones if alpha>0:
// For the alpha channel that is used as source:
// alpha = old + new * (1 - old)
// For other channels if !alpha_associated:
// sample = ((1 - new_alpha) * old * old_alpha + new_alpha * new) / alpha
// For other channels if alpha_associated:
// sample = (1 - new_alpha) * old + new
// The alpha formula applies to the alpha used for the division in the other
// channels formula, and applies to the alpha channel itself if its
// blend_channel value matches itself.
kBlend = 2,
// The new values (in the crop) are added to the old ones if alpha>0:
// For the alpha channel that is used as source:
// sample = sample = old + new * (1 - old)
// For other channels: sample = old + alpha * new
kAlphaWeightedAdd = 3,
// The new values (in the crop) get multiplied by the old ones:
// sample = old * new
// The range of the new value matters for multiplication purposes, and its
// nominal range of 0..1 is computed the same way as this is done for the
// alpha values in kBlend and kAlphaWeightedAdd.
// If using kMul as a blend mode for color channels, no color transform is
// performed on the current frame.
kMul = 4,
};
struct BlendingInfo : public Fields {
BlendingInfo();
JXL_FIELDS_NAME(BlendingInfo)
Status VisitFields(Visitor* JXL_RESTRICT visitor) override;
BlendMode mode;
// Which extra channel to use as alpha channel for blending, only encoded
// for blend modes that involve alpha and if there are more than 1 extra
// channels.
uint32_t alpha_channel;
// Clamp alpha or channel values to 0-1 range.
bool clamp;
// Frame ID to copy from (0-3). Only encoded if blend_mode is not kReplace.
uint32_t source;
std::string DebugString() const;
size_t nonserialized_num_extra_channels = 0;
bool nonserialized_is_partial_frame = false;
};
// Origin of the current frame. Not present for frames of type
// kOnlyPatches.
struct FrameOrigin {
int32_t x0, y0; // can be negative.
};
// Size of the current frame.
struct FrameSize {
uint32_t xsize, ysize;
};
// AnimationFrame defines duration of animation frames.
struct AnimationFrame : public Fields {
explicit AnimationFrame(const CodecMetadata* metadata);
JXL_FIELDS_NAME(AnimationFrame)
Status VisitFields(Visitor* JXL_RESTRICT visitor) override;
// How long to wait [in ticks, see Animation{}] after rendering.
// May be 0 if the current frame serves as a foundation for another frame.
uint32_t duration;
uint32_t timecode; // 0xHHMMSSFF
// Must be set to the one ImageMetadata acting as the full codestream header,
// with correct xyb_encoded, list of extra channels, etc...
const CodecMetadata* nonserialized_metadata = nullptr;
};
// For decoding to lower resolutions. Only used for kRegular frames.
struct Passes : public Fields {
Passes();
JXL_FIELDS_NAME(Passes)
Status VisitFields(Visitor* JXL_RESTRICT visitor) override;
void GetDownsamplingBracket(size_t pass, int& minShift, int& maxShift) const {
maxShift = 2;
minShift = 3;
for (size_t i = 0;; i++) {
for (uint32_t j = 0; j < num_downsample; ++j) {
if (i == last_pass[j]) {
if (downsample[j] == 8) minShift = 3;
if (downsample[j] == 4) minShift = 2;
if (downsample[j] == 2) minShift = 1;
if (downsample[j] == 1) minShift = 0;
}
}
if (i == num_passes - 1) minShift = 0;
if (i == pass) return;
maxShift = minShift - 1;
}
}
uint32_t GetDownsamplingTargetForCompletedPasses(uint32_t num_p) const {
if (num_p >= num_passes) return 1;
uint32_t retval = 8;
for (uint32_t i = 0; i < num_downsample; ++i) {
if (num_p > last_pass[i]) {
retval = std::min(retval, downsample[i]);
}
}
return retval;
}
std::string DebugString() const;
uint32_t num_passes; // <= kMaxNumPasses
uint32_t num_downsample; // <= num_passes
// Array of num_downsample pairs. downsample=1/last_pass=num_passes-1 and
// downsample=8/last_pass=0 need not be specified; they are implicit.
uint32_t downsample[kMaxNumPasses];
uint32_t last_pass[kMaxNumPasses];
// Array of shift values for each pass. It is implicitly assumed to be 0 for
// the last pass.
uint32_t shift[kMaxNumPasses];
};
enum FrameType {
// A "regular" frame: might be a crop, and will be blended on a previous
// frame, if any, and displayed or blended in future frames.
kRegularFrame = 0,
// A DC frame: this frame is downsampled and will be *only* used as the DC of
// a future frame and, possibly, for previews. Cannot be cropped, blended, or
// referenced by patches or blending modes. Frames that *use* a DC frame
// cannot have non-default sizes either.
kDCFrame = 1,
// A PatchesSource frame: this frame will be only used as a source frame for
// taking patches. Can be cropped, but cannot have non-(0, 0) x0 and y0.
kReferenceOnly = 2,
// Same as kRegularFrame, but not used for progressive rendering. This also
// implies no early display of DC.
kSkipProgressive = 3,
};
// Image/frame := one of more of these, where the last has is_last = true.
// Starts at a byte-aligned address "a"; the next pass starts at "a + size".
struct FrameHeader : public Fields {
// Optional postprocessing steps. These flags are the source of truth;
// Override must set/clear them rather than change their meaning. Values
// chosen such that typical flags == 0 (encoded in only two bits).
enum Flags {
// Often but not always off => low bit value:
// Inject noise into decoded output.
kNoise = 1,
// Overlay patches.
kPatches = 2,
// 4, 8 = reserved for future sometimes-off
// Overlay splines.
kSplines = 16,
kUseDcFrame = 32, // Implies kSkipAdaptiveDCSmoothing.
// 64 = reserved for future often-off
// Almost always on => negated:
kSkipAdaptiveDCSmoothing = 128,
};
explicit FrameHeader(const CodecMetadata* metadata);
JXL_FIELDS_NAME(FrameHeader)
Status VisitFields(Visitor* JXL_RESTRICT visitor) override;
// Sets/clears `flag` based upon `condition`.
void UpdateFlag(const bool condition, const uint64_t flag) {
if (condition) {
flags |= flag;
} else {
flags &= ~flag;
}
}
// Returns true if this frame is supposed to be saved for future usage by
// other frames.
bool CanBeReferenced() const {
// DC frames cannot be referenced. The last frame cannot be referenced. A
// duration 0 frame makes little sense if it is not referenced. A
// non-duration 0 frame may or may not be referenced.
return !is_last && frame_type != FrameType::kDCFrame &&
(animation_frame.duration == 0 || save_as_reference != 0);
}
mutable bool all_default;
// Always present
FrameEncoding encoding;
// Some versions of UBSAN complain in VisitFrameType if not initialized.
FrameType frame_type = FrameType::kRegularFrame;
uint64_t flags;
ColorTransform color_transform;
YCbCrChromaSubsampling chroma_subsampling;
uint32_t group_size_shift; // only if encoding == kModular;
uint32_t x_qm_scale; // only if VarDCT and color_transform == kXYB
uint32_t b_qm_scale; // only if VarDCT and color_transform == kXYB
std::string name;
// Skipped for kReferenceOnly.
Passes passes;
// Skipped for kDCFrame
bool custom_size_or_origin;
FrameSize frame_size;
// upsampling factors for color and extra channels.
// Upsampling is always performed before applying any inverse color transform.
// Skipped (1) if kUseDCFrame
uint32_t upsampling;
std::vector<uint32_t> extra_channel_upsampling;
// Only for kRegular frames.
FrameOrigin frame_origin;
BlendingInfo blending_info;
std::vector<BlendingInfo> extra_channel_blending_info;
// Animation info for this frame.
AnimationFrame animation_frame;
// This is the last frame.
bool is_last;
// ID to refer to this frame with. 0-3, not present if kDCFrame.
// 0 has a special meaning for kRegular frames of nonzero duration: it defines
// a frame that will not be referenced in the future.
uint32_t save_as_reference;
// Whether to save this frame before or after the color transform. A frame
// that is saved before the color tansform can only be used for blending
// through patches. On the contrary, a frame that is saved after the color
// transform can only be used for blending through blending modes.
// Irrelevant for extra channel blending. Can only be true if
// blending_info.mode == kReplace and this is not a partial kRegularFrame; if
// this is a DC frame, it is always true.
bool save_before_color_transform;
uint32_t dc_level; // 1-4 if kDCFrame (0 otherwise).
// Must be set to the one ImageMetadata acting as the full codestream header,
// with correct xyb_encoded, list of extra channels, etc...
const CodecMetadata* nonserialized_metadata = nullptr;
// NOTE: This is ignored by AllDefault.
LoopFilter loop_filter;
bool nonserialized_is_preview = false;
size_t default_xsize() const {
if (!nonserialized_metadata) return 0;
if (nonserialized_is_preview) {
return nonserialized_metadata->m.preview_size.xsize();
}
return nonserialized_metadata->xsize();
}
size_t default_ysize() const {
if (!nonserialized_metadata) return 0;
if (nonserialized_is_preview) {
return nonserialized_metadata->m.preview_size.ysize();
}
return nonserialized_metadata->ysize();
}
FrameDimensions ToFrameDimensions() const {
size_t xsize = default_xsize();
size_t ysize = default_ysize();
xsize = frame_size.xsize ? frame_size.xsize : xsize;
ysize = frame_size.ysize ? frame_size.ysize : ysize;
if (dc_level != 0) {
xsize = DivCeil(xsize, 1 << (3 * dc_level));
ysize = DivCeil(ysize, 1 << (3 * dc_level));
}
FrameDimensions frame_dim;
frame_dim.Set(xsize, ysize, group_size_shift,
chroma_subsampling.MaxHShift(),
chroma_subsampling.MaxVShift(),
encoding == FrameEncoding::kModular, upsampling);
return frame_dim;
}
// True if a color transform should be applied to this frame.
bool needs_color_transform() const {
return !save_before_color_transform ||
frame_type == FrameType::kRegularFrame ||
frame_type == FrameType::kSkipProgressive;
}
std::string DebugString() const;
uint64_t extensions;
};
Status ReadFrameHeader(BitReader* JXL_RESTRICT reader,
FrameHeader* JXL_RESTRICT frame);
// Shared by enc/dec. 5F and 13 are by far the most common for d1/2/4/8, 0
// ensures low overhead for small images.
static constexpr U32Enc kOrderEnc =
U32Enc(Val(0x5F), Val(0x13), Val(0), Bits(kNumOrders));
} // namespace jxl
#endif // LIB_JXL_FRAME_HEADER_H_