Commit 19657291 for libheif
commit 196572916866867515ba623503377dfaba998b5c
Author: Dirk Farin <dirk.farin@gmail.com>
Date: Mon Feb 9 18:38:31 2026 +0100
unci: implement decoder for component interleaving with blocks
diff --git a/libheif/CMakeLists.txt b/libheif/CMakeLists.txt
index ef4aa42a..fa00815c 100644
--- a/libheif/CMakeLists.txt
+++ b/libheif/CMakeLists.txt
@@ -303,6 +303,8 @@ if (WITH_UNCOMPRESSED_CODEC)
codecs/uncompressed/unc_decoder_pixel_interleave.cc
codecs/uncompressed/unc_decoder_block_pixel_interleave.h
codecs/uncompressed/unc_decoder_block_pixel_interleave.cc
+ codecs/uncompressed/unc_decoder_block_component_interleave.h
+ codecs/uncompressed/unc_decoder_block_component_interleave.cc
codecs/uncompressed/unc_decoder_mixed_interleave.h
codecs/uncompressed/unc_decoder_mixed_interleave.cc
codecs/uncompressed/unc_decoder_row_interleave.h
diff --git a/libheif/codecs/uncompressed/unc_decoder.cc b/libheif/codecs/uncompressed/unc_decoder.cc
index 6e85cbd2..c77ba4a3 100644
--- a/libheif/codecs/uncompressed/unc_decoder.cc
+++ b/libheif/codecs/uncompressed/unc_decoder.cc
@@ -28,6 +28,7 @@
#include "unc_decoder_mixed_interleave.h"
#include "unc_decoder_row_interleave.h"
#include "unc_decoder_block_pixel_interleave.h"
+#include "unc_decoder_block_component_interleave.h"
#include "unc_codec.h"
#include "unc_boxes.h"
#include "compression.h"
@@ -337,13 +338,14 @@ Result<std::unique_ptr<unc_decoder>> unc_decoder_factory::get_unc_decoder(
const std::shared_ptr<const Box_uncC>& uncC)
{
static unc_decoder_factory_component_interleave dec_component;
+ static unc_decoder_factory_block_component_interleave dec_block_component;
static unc_decoder_factory_pixel_interleave dec_pixel;
static unc_decoder_factory_block_pixel_interleave dec_block_pixel;
static unc_decoder_factory_mixed_interleave dec_mixed;
static unc_decoder_factory_row_interleave dec_row;
static const unc_decoder_factory* decoders[]{
- &dec_component, &dec_pixel, &dec_block_pixel, &dec_mixed, &dec_row
+ &dec_block_component, &dec_component, &dec_pixel, &dec_block_pixel, &dec_mixed, &dec_row
};
for (const unc_decoder_factory* dec : decoders) {
diff --git a/libheif/codecs/uncompressed/unc_decoder_block_component_interleave.cc b/libheif/codecs/uncompressed/unc_decoder_block_component_interleave.cc
new file mode 100644
index 00000000..60a3e0d6
--- /dev/null
+++ b/libheif/codecs/uncompressed/unc_decoder_block_component_interleave.cc
@@ -0,0 +1,224 @@
+/*
+ * HEIF codec.
+ * Copyright (c) 2026 Dirk Farin <dirk.farin@gmail.com>
+ *
+ * This file is part of libheif.
+ *
+ * libheif 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, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * libheif 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 libheif. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "unc_decoder_block_component_interleave.h"
+#include "unc_decoder_legacybase.h" // for skip_to_alignment
+#include "unc_codec.h"
+#include "unc_types.h"
+#include "error.h"
+
+#include <bit>
+#include <cassert>
+#include <cstring>
+#include <vector>
+
+
+unc_decoder_block_component_interleave::unc_decoder_block_component_interleave(
+ uint32_t width, uint32_t height,
+ std::shared_ptr<const Box_cmpd> cmpd,
+ std::shared_ptr<const Box_uncC> uncC)
+ : unc_decoder(width, height, cmpd, uncC)
+{
+}
+
+
+std::vector<uint64_t> unc_decoder_block_component_interleave::get_tile_data_sizes() const
+{
+ const uint32_t block_size = m_uncC->get_block_size();
+ assert(block_size > 0);
+
+ uint64_t total_tile_size = 0;
+
+ for (const auto& component : m_uncC->get_components()) {
+ (void) component;
+ uint32_t bytes_per_row = block_size * m_tile_width;
+ skip_to_alignment(bytes_per_row, m_uncC->get_row_align_size());
+ total_tile_size += static_cast<uint64_t>(bytes_per_row) * m_tile_height;
+ }
+
+ if (m_uncC->get_tile_align_size() != 0) {
+ skip_to_alignment(total_tile_size, m_uncC->get_tile_align_size());
+ }
+
+ return {total_tile_size};
+}
+
+
+Error unc_decoder_block_component_interleave::decode_tile(const std::vector<uint8_t>& tile_data,
+ std::shared_ptr<HeifPixelImage>& img,
+ uint32_t out_x0, uint32_t out_y0)
+{
+ const uint32_t block_size = m_uncC->get_block_size();
+ const bool little_endian = m_uncC->is_block_little_endian();
+ const bool pad_lsb = m_uncC->is_block_pad_lsb();
+
+ // Build per-component info
+ struct ComponentInfo {
+ uint32_t shift;
+ uint64_t mask;
+ uint32_t bytes_per_sample;
+ bool use;
+ uint8_t* dst_plane;
+ size_t dst_plane_stride;
+ };
+
+ const auto& components = m_uncC->get_components();
+ const uint32_t num_components = static_cast<uint32_t>(components.size());
+ std::vector<ComponentInfo> comp(num_components);
+
+ for (uint32_t i = 0; i < num_components; i++) {
+ const auto& c = components[i];
+ comp[i].bytes_per_sample = (c.component_bit_depth + 7) / 8;
+ comp[i].mask = (uint64_t{1} << c.component_bit_depth) - 1;
+
+ // Each component is alone in its block, so shift depends only on padding.
+ if (pad_lsb) {
+ comp[i].shift = block_size * 8 - c.component_bit_depth;
+ }
+ else {
+ comp[i].shift = 0;
+ }
+
+ heif_channel channel;
+ comp[i].use = map_uncompressed_component_to_channel(m_cmpd, c, &channel);
+ if (comp[i].use) {
+ comp[i].dst_plane = img->get_plane(channel, &comp[i].dst_plane_stride);
+ }
+ else {
+ comp[i].dst_plane = nullptr;
+ comp[i].dst_plane_stride = 0;
+ }
+ }
+
+ const uint8_t* src = tile_data.data();
+ const uint8_t* src_end = src + tile_data.size();
+
+ // Process components sequentially (component interleave)
+ for (uint32_t c = 0; c < num_components; c++) {
+ uint32_t bytes_per_row = block_size * m_tile_width;
+ skip_to_alignment(bytes_per_row, m_uncC->get_row_align_size());
+
+ for (uint32_t tile_y = 0; tile_y < m_tile_height; tile_y++) {
+ for (uint32_t tile_x = 0; tile_x < m_tile_width; tile_x++) {
+ if (src + block_size > src_end) {
+ return {heif_error_Invalid_input, heif_suberror_Unspecified,
+ "Block-component interleave: insufficient data"};
+ }
+
+ if (comp[c].use) {
+ // Read block_size bytes into a uint64_t.
+ uint64_t block_val = 0;
+ if (little_endian) {
+ for (uint32_t b = 0; b < block_size; b++) {
+ block_val |= static_cast<uint64_t>(src[b]) << (b * 8);
+ }
+ }
+ else {
+ for (uint32_t b = 0; b < block_size; b++) {
+ block_val = (block_val << 8) | src[b];
+ }
+ }
+
+ uint32_t value = static_cast<uint32_t>((block_val >> comp[c].shift) & comp[c].mask);
+ uint32_t dst_x = out_x0 + tile_x;
+ uint32_t dst_y = out_y0 + tile_y;
+ uint64_t dst_offset = static_cast<uint64_t>(dst_y) * comp[c].dst_plane_stride
+ + static_cast<uint64_t>(dst_x) * comp[c].bytes_per_sample;
+ uint8_t* dst = comp[c].dst_plane + dst_offset;
+
+ if (comp[c].bytes_per_sample == 1) {
+ *dst = static_cast<uint8_t>(value);
+ }
+ else {
+ // Store in native endian (2 bytes).
+ if constexpr (std::endian::native == std::endian::little) {
+ dst[0] = static_cast<uint8_t>(value & 0xFF);
+ dst[1] = static_cast<uint8_t>((value >> 8) & 0xFF);
+ }
+ else {
+ dst[0] = static_cast<uint8_t>((value >> 8) & 0xFF);
+ dst[1] = static_cast<uint8_t>(value & 0xFF);
+ }
+ }
+ }
+
+ src += block_size;
+ }
+
+ // Skip row alignment padding
+ uint32_t pixel_bytes = block_size * m_tile_width;
+ src += bytes_per_row - pixel_bytes;
+ }
+ }
+
+ return Error::Ok;
+}
+
+
+// --- Factory ---
+
+bool unc_decoder_factory_block_component_interleave::can_decode(const std::shared_ptr<const Box_uncC>& uncC) const
+{
+ if (uncC->get_interleave_type() != interleave_mode_component) {
+ return false;
+ }
+
+ if (uncC->get_block_size() == 0 || uncC->get_block_size() > 8) {
+ return false;
+ }
+
+ if (uncC->get_pixel_size() != 0) {
+ return false;
+ }
+
+ if (uncC->get_sampling_type() != sampling_mode_no_subsampling) {
+ return false;
+ }
+
+ uint32_t block_bits = uncC->get_block_size() * 8;
+
+ for (const auto& component : uncC->get_components()) {
+ if (component.component_bit_depth > 16) {
+ return false;
+ }
+ if (component.component_format != component_format_unsigned) {
+ return false;
+ }
+ // Each component must fit in the block, and must be larger than half the
+ // block so that exactly one component occupies each block.
+ // Each component must be larger than half the block so that exactly one
+ // component occupies each block, and must fit within the block.
+ if (component.component_bit_depth > block_bits ||
+ component.component_bit_depth <= block_bits / 2) {
+ return false;
+ }
+ }
+
+ return true;
+}
+
+
+std::unique_ptr<unc_decoder> unc_decoder_factory_block_component_interleave::create(
+ uint32_t width, uint32_t height,
+ const std::shared_ptr<const Box_cmpd>& cmpd,
+ const std::shared_ptr<const Box_uncC>& uncC) const
+{
+ return std::make_unique<unc_decoder_block_component_interleave>(width, height, cmpd, uncC);
+}
diff --git a/libheif/codecs/uncompressed/unc_decoder_block_component_interleave.h b/libheif/codecs/uncompressed/unc_decoder_block_component_interleave.h
new file mode 100644
index 00000000..597f1d74
--- /dev/null
+++ b/libheif/codecs/uncompressed/unc_decoder_block_component_interleave.h
@@ -0,0 +1,55 @@
+/*
+ * HEIF codec.
+ * Copyright (c) 2026 Dirk Farin <dirk.farin@gmail.com>
+ *
+ * This file is part of libheif.
+ *
+ * libheif 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, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * libheif 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 libheif. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIBHEIF_UNC_DECODER_BLOCK_COMPONENT_INTERLEAVE_H
+#define LIBHEIF_UNC_DECODER_BLOCK_COMPONENT_INTERLEAVE_H
+
+#include "unc_decoder.h"
+#include <memory>
+#include <vector>
+
+
+class unc_decoder_block_component_interleave : public unc_decoder
+{
+public:
+ unc_decoder_block_component_interleave(uint32_t width, uint32_t height,
+ std::shared_ptr<const Box_cmpd> cmpd,
+ std::shared_ptr<const Box_uncC> uncC);
+
+ std::vector<uint64_t> get_tile_data_sizes() const override;
+
+ Error decode_tile(const std::vector<uint8_t>& tile_data,
+ std::shared_ptr<HeifPixelImage>& img,
+ uint32_t out_x0, uint32_t out_y0) override;
+};
+
+
+class unc_decoder_factory_block_component_interleave : public unc_decoder_factory
+{
+private:
+ bool can_decode(const std::shared_ptr<const Box_uncC>& uncC) const override;
+
+ std::unique_ptr<unc_decoder> create(
+ uint32_t width, uint32_t height,
+ const std::shared_ptr<const Box_cmpd>& cmpd,
+ const std::shared_ptr<const Box_uncC>& uncC) const override;
+};
+
+#endif // LIBHEIF_UNC_DECODER_BLOCK_COMPONENT_INTERLEAVE_H