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- /*
- * Copyright (c) 2021, Hunter Salyer <thefalsehonesty@gmail.com>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
- #include "Decoder.h"
- namespace Video::VP9 {
- #define RESERVED_ZERO \
- if (m_bit_stream->read_bit() != 0) \
- return false
- Decoder::Decoder()
- {
- m_probability_tables = make<ProbabilityTables>();
- }
- bool Decoder::parse_frame(const ByteBuffer& frame_data)
- {
- m_bit_stream = make<BitStream>(frame_data.data(), frame_data.size());
- m_syntax_element_counter = make<SyntaxElementCounter>();
- m_start_bit_pos = m_bit_stream->get_position();
- if (!uncompressed_header())
- return false;
- dbgln("Finished reading uncompressed header");
- if (!trailing_bits())
- return false;
- if (m_header_size_in_bytes == 0) {
- // FIXME: Do we really need to read all of these bits?
- // while (m_bit_stream->get_position() < m_start_bit_pos + (8 * frame_data.size()))
- // RESERVED_ZERO;
- dbgln("No header");
- return true;
- }
- m_probability_tables->load_probs(m_frame_context_idx);
- m_probability_tables->load_probs2(m_frame_context_idx);
- m_syntax_element_counter->clear_counts();
- return true;
- }
- bool Decoder::uncompressed_header()
- {
- auto frame_marker = m_bit_stream->read_f(2);
- if (frame_marker != 2)
- return false;
- auto profile_low_bit = m_bit_stream->read_bit();
- auto profile_high_bit = m_bit_stream->read_bit();
- m_profile = (profile_high_bit << 1u) + profile_low_bit;
- if (m_profile == 3)
- RESERVED_ZERO;
- auto show_existing_frame = m_bit_stream->read_bit();
- if (show_existing_frame) {
- m_frame_to_show_map_index = m_bit_stream->read_f(3);
- m_header_size_in_bytes = 0;
- m_refresh_frame_flags = 0;
- m_loop_filter_level = 0;
- return true;
- }
- m_last_frame_type = m_frame_type;
- m_frame_type = read_frame_type();
- m_show_frame = m_bit_stream->read_bit();
- m_error_resilient_mode = m_bit_stream->read_bit();
- if (m_frame_type == KeyFrame) {
- if (!frame_sync_code())
- return false;
- if (!color_config())
- return false;
- if (!frame_size())
- return false;
- if (!render_size())
- return false;
- m_refresh_frame_flags = 0xFF;
- m_frame_is_intra = true;
- } else {
- m_frame_is_intra = !m_show_frame && m_bit_stream->read_bit();
- if (!m_error_resilient_mode) {
- m_reset_frame_context = m_bit_stream->read_f(2);
- } else {
- m_reset_frame_context = 0;
- }
- if (m_frame_is_intra) {
- if (!frame_sync_code())
- return false;
- if (m_profile > 0) {
- if (!color_config())
- return false;
- } else {
- m_color_space = Bt601;
- m_subsampling_x = true;
- m_subsampling_y = true;
- m_bit_depth = 8;
- }
- m_refresh_frame_flags = m_bit_stream->read_f8();
- if (!frame_size())
- return false;
- if (!render_size())
- return false;
- } else {
- m_refresh_frame_flags = m_bit_stream->read_f8();
- for (auto i = 0; i < 3; i++) {
- m_ref_frame_idx[i] = m_bit_stream->read_f(3);
- m_ref_frame_sign_bias[LastFrame + i] = m_bit_stream->read_bit();
- }
- frame_size_with_refs();
- m_allow_high_precision_mv = m_bit_stream->read_bit();
- read_interpolation_filter();
- }
- }
- if (!m_error_resilient_mode) {
- m_refresh_frame_context = m_bit_stream->read_bit();
- m_frame_parallel_decoding_mode = m_bit_stream->read_bit();
- } else {
- m_refresh_frame_context = false;
- m_frame_parallel_decoding_mode = true;
- }
- m_frame_context_idx = m_bit_stream->read_f(2);
- if (m_frame_is_intra || m_error_resilient_mode) {
- setup_past_independence();
- if (m_frame_type == KeyFrame || m_error_resilient_mode || m_reset_frame_context == 3) {
- for (auto i = 0; i < 4; i++) {
- m_probability_tables->save_probs(i);
- }
- } else if (m_reset_frame_context == 2) {
- m_probability_tables->save_probs(m_frame_context_idx);
- }
- m_frame_context_idx = 0;
- }
- loop_filter_params();
- quantization_params();
- segmentation_params();
- tile_info();
- m_header_size_in_bytes = m_bit_stream->read_f16();
- return true;
- }
- bool Decoder::frame_sync_code()
- {
- if (m_bit_stream->read_byte() != 0x49)
- return false;
- if (m_bit_stream->read_byte() != 0x83)
- return false;
- return m_bit_stream->read_byte() == 0x42;
- }
- bool Decoder::color_config()
- {
- if (m_profile >= 2) {
- m_bit_depth = m_bit_stream->read_bit() ? 12 : 10;
- } else {
- m_bit_depth = 8;
- }
- auto color_space = m_bit_stream->read_f(3);
- if (color_space > RGB)
- return false;
- m_color_space = static_cast<ColorSpace>(color_space);
- if (color_space != RGB) {
- m_color_range = read_color_range();
- if (m_profile == 1 || m_profile == 3) {
- m_subsampling_x = m_bit_stream->read_bit();
- m_subsampling_y = m_bit_stream->read_bit();
- RESERVED_ZERO;
- } else {
- m_subsampling_x = true;
- m_subsampling_y = true;
- }
- } else {
- m_color_range = FullSwing;
- if (m_profile == 1 || m_profile == 3) {
- m_subsampling_x = false;
- m_subsampling_y = false;
- RESERVED_ZERO;
- }
- }
- return true;
- }
- bool Decoder::frame_size()
- {
- m_frame_width = m_bit_stream->read_f16() + 1;
- m_frame_height = m_bit_stream->read_f16() + 1;
- compute_image_size();
- return true;
- }
- bool Decoder::render_size()
- {
- if (m_bit_stream->read_bit()) {
- m_render_width = m_bit_stream->read_f16() + 1;
- m_render_height = m_bit_stream->read_f16() + 1;
- } else {
- m_render_width = m_frame_width;
- m_render_height = m_frame_height;
- }
- return true;
- }
- bool Decoder::frame_size_with_refs()
- {
- bool found_ref;
- for (auto i = 0; i < 3; i++) {
- found_ref = m_bit_stream->read_bit();
- if (found_ref) {
- // TODO:
- // - FrameWidth = RefFrameWidth[ref_frame_idx[ i] ];
- // - FrameHeight = RefFrameHeight[ref_frame_idx[ i] ];
- break;
- }
- }
- if (!found_ref)
- frame_size();
- else
- compute_image_size();
- render_size();
- return true;
- }
- bool Decoder::compute_image_size()
- {
- m_mi_cols = (m_frame_width + 7u) >> 3u;
- m_mi_rows = (m_frame_height + 7u) >> 3u;
- m_sb64_cols = (m_mi_cols + 7u) >> 3u;
- m_sb64_rows = (m_mi_rows + 7u) >> 3u;
- return true;
- }
- bool Decoder::read_interpolation_filter()
- {
- if (m_bit_stream->read_bit()) {
- m_interpolation_filter = Switchable;
- } else {
- m_interpolation_filter = literal_to_type[m_bit_stream->read_f(2)];
- }
- return true;
- }
- bool Decoder::loop_filter_params()
- {
- m_loop_filter_level = m_bit_stream->read_f(6);
- m_loop_filter_sharpness = m_bit_stream->read_f(3);
- m_loop_filter_delta_enabled = m_bit_stream->read_bit();
- if (m_loop_filter_delta_enabled) {
- if (m_bit_stream->read_bit()) {
- for (auto i = 0; i < 4; i++) {
- if (m_bit_stream->read_bit()) {
- // TODO: loop_filter_ref_deltas[i] = s(6);
- }
- }
- for (auto i = 0; i < 2; i++) {
- if (m_bit_stream->read_bit()) {
- // TODO: loop_filter_mode_deltas[i] = s(6);
- }
- }
- }
- }
- return true;
- }
- bool Decoder::quantization_params()
- {
- auto base_q_idx = m_bit_stream->read_byte();
- auto delta_q_y_dc = read_delta_q();
- auto delta_q_uv_dc = read_delta_q();
- auto delta_q_uv_ac = read_delta_q();
- m_lossless = base_q_idx == 0 && delta_q_y_dc == 0 && delta_q_uv_dc == 0 && delta_q_uv_ac == 0;
- return true;
- }
- i8 Decoder::read_delta_q()
- {
- if (m_bit_stream->read_bit())
- return m_bit_stream->read_s(4);
- return 0;
- }
- bool Decoder::segmentation_params()
- {
- auto segmentation_enabled = m_bit_stream->read_bit();
- if (!segmentation_enabled)
- return true;
- auto segmentation_update_map = m_bit_stream->read_bit();
- if (segmentation_update_map) {
- for (auto i = 0; i < 7; i++) {
- m_segmentation_tree_probs[i] = read_prob();
- }
- auto segmentation_temporal_update = m_bit_stream->read_bit();
- for (auto i = 0; i < 3; i++) {
- m_segmentation_pred_prob[i] = segmentation_temporal_update ? read_prob() : 255;
- }
- }
- if (!m_bit_stream->read_bit())
- return true;
- m_segmentation_abs_or_delta_update = m_bit_stream->read_bit();
- for (auto i = 0; i < MAX_SEGMENTS; i++) {
- for (auto j = 0; j < SEG_LVL_MAX; j++) {
- auto feature_value = 0;
- auto feature_enabled = m_bit_stream->read_bit();
- m_feature_enabled[i][j] = feature_enabled;
- if (feature_enabled) {
- auto bits_to_read = segmentation_feature_bits[j];
- feature_value = m_bit_stream->read_f(bits_to_read);
- if (segmentation_feature_signed[j]) {
- if (m_bit_stream->read_bit())
- feature_value = -feature_value;
- }
- }
- m_feature_data[i][j] = feature_value;
- }
- }
- return true;
- }
- u8 Decoder::read_prob()
- {
- if (m_bit_stream->read_bit())
- return m_bit_stream->read_byte();
- return 255;
- }
- bool Decoder::tile_info()
- {
- auto min_log2_tile_cols = calc_min_log2_tile_cols();
- auto max_log2_tile_cols = calc_max_log2_tile_cols();
- m_tile_cols_log2 = min_log2_tile_cols;
- while (m_tile_cols_log2 < max_log2_tile_cols) {
- if (m_bit_stream->read_bit())
- m_tile_cols_log2++;
- else
- break;
- }
- m_tile_rows_log2 = m_bit_stream->read_bit();
- if (m_tile_rows_log2) {
- m_tile_rows_log2 += m_bit_stream->read_bit();
- }
- return true;
- }
- u16 Decoder::calc_min_log2_tile_cols()
- {
- auto min_log_2 = 0;
- while ((MAX_TILE_WIDTH_B64 << min_log_2) < m_sb64_cols)
- min_log_2++;
- return min_log_2;
- }
- u16 Decoder::calc_max_log2_tile_cols()
- {
- u16 max_log_2 = 1;
- while ((m_sb64_cols >> max_log_2) >= MIN_TILE_WIDTH_B64)
- max_log_2++;
- return max_log_2 - 1;
- }
- bool Decoder::setup_past_independence()
- {
- for (auto i = 0; i < 8; i++) {
- for (auto j = 0; j < 4; j++) {
- m_feature_data[i][j] = 0;
- m_feature_enabled[i][j] = false;
- }
- }
- m_segmentation_abs_or_delta_update = false;
- for (auto row = 0; row < m_mi_rows; row++) {
- for (auto col = 0; col < m_mi_cols; col++) {
- // TODO: m_prev_segment_ids[row][col] = 0;
- }
- }
- m_loop_filter_delta_enabled = true;
- m_loop_filter_ref_deltas[IntraFrame] = 1;
- m_loop_filter_ref_deltas[LastFrame] = 0;
- m_loop_filter_ref_deltas[GoldenFrame] = -1;
- m_loop_filter_ref_deltas[AltRefFrame] = -1;
- for (auto i = 0; i < 2; i++) {
- m_loop_filter_mode_deltas[i] = 0;
- }
- m_probability_tables->reset_probs();
- return true;
- }
- bool Decoder::trailing_bits()
- {
- while (m_bit_stream->get_position() & 7u)
- RESERVED_ZERO;
- return true;
- }
- void Decoder::dump_info()
- {
- dbgln("Frame dimensions: {}x{}", m_frame_width, m_frame_height);
- dbgln("Render dimensions: {}x{}", m_render_width, m_render_height);
- dbgln("Bit depth: {}", m_bit_depth);
- dbgln("Interpolation filter: {}", (u8)m_interpolation_filter);
- }
- }
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