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LibVideo/VP9: Index inter-frame references with named fields or an enum

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Previously, we were using size_t, often coerced from bool or u8, to
index reference pairs. Now, they must either be taken directly from
named fields or indexed using the `ReferenceIndex` enum with options
`primary` and `secondary`. With a more explicit method of indexing
these, the compiler can aid in using reference pairs correctly, and
fuzzers may be able to detect undefined behavior more easily.
This commit is contained in:
Zaggy1024 2022-11-25 03:03:22 -06:00 • committed by Andreas Kling
parent 3af4deba6d
commit f4761dab09
8 changed files with 174 additions and 157 deletions
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120
Userland/Libraries/LibVideo/VP9/Parser.cpp
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@ -1151,23 +1151,25 @@ DecoderErrorOr<void> Parser::intra_block_mode_info(BlockContext& block_context)
return {};
}
static void select_best_reference_motion_vectors(BlockContext& block_context, MotionVectorPair reference_motion_vectors, BlockMotionVectorCandidates& candidates, u8 ref_list);
static void select_best_reference_motion_vectors(BlockContext& block_context, MotionVectorPair reference_motion_vectors, BlockMotionVectorCandidates& candidates, ReferenceIndex);
DecoderErrorOr<void> Parser::inter_block_mode_info(BlockContext& block_context, FrameBlockContext above_context, FrameBlockContext left_context)
{
TRY(read_ref_frames(block_context, above_context, left_context));
VERIFY(block_context.is_inter_predicted());
BlockMotionVectorCandidates motion_vector_candidates;
for (auto j = 0; j < 2; j++) {
if (block_context.reference_frame_types[j] > IntraFrame) {
auto reference_motion_vectors = find_reference_motion_vectors(block_context, block_context.reference_frame_types[j], -1);
select_best_reference_motion_vectors(block_context, reference_motion_vectors, motion_vector_candidates, j);
}
auto reference_motion_vectors = find_reference_motion_vectors(block_context, block_context.reference_frame_types.primary, -1);
select_best_reference_motion_vectors(block_context, reference_motion_vectors, motion_vector_candidates, ReferenceIndex::Primary);
if (block_context.is_compound()) {
auto reference_motion_vectors = find_reference_motion_vectors(block_context, block_context.reference_frame_types.secondary, -1);
select_best_reference_motion_vectors(block_context, reference_motion_vectors, motion_vector_candidates, ReferenceIndex::Secondary);
}
if (seg_feature_active(block_context, SEG_LVL_SKIP)) {
block_context.y_prediction_mode() = PredictionMode::ZeroMv;
} else if (block_context.size >= Block_8x8) {
block_context.y_prediction_mode() = TRY_READ(TreeParser::parse_inter_mode(*m_bit_stream, *m_probability_tables, *m_syntax_element_counter, m_mode_context[block_context.reference_frame_types[0]]));
block_context.y_prediction_mode() = TRY_READ(TreeParser::parse_inter_mode(*m_bit_stream, *m_probability_tables, *m_syntax_element_counter, m_mode_context[block_context.reference_frame_types.primary]));
}
if (block_context.frame_context.interpolation_filter == Switchable)
block_context.interpolation_filter = TRY_READ(TreeParser::parse_interpolation_filter(*m_bit_stream, *m_probability_tables, *m_syntax_element_counter, above_context, left_context));
@ -1177,10 +1179,11 @@ DecoderErrorOr<void> Parser::inter_block_mode_info(BlockContext& block_context,
auto size_in_4x4_blocks = block_context.get_size_in_4x4_blocks();
for (auto idy = 0; idy < 2; idy += size_in_4x4_blocks.height()) {
for (auto idx = 0; idx < 2; idx += size_in_4x4_blocks.width()) {
block_context.y_prediction_mode() = TRY_READ(TreeParser::parse_inter_mode(*m_bit_stream, *m_probability_tables, *m_syntax_element_counter, m_mode_context[block_context.reference_frame_types[0]]));
block_context.y_prediction_mode() = TRY_READ(TreeParser::parse_inter_mode(*m_bit_stream, *m_probability_tables, *m_syntax_element_counter, m_mode_context[block_context.reference_frame_types.primary]));
if (block_context.y_prediction_mode() == PredictionMode::NearestMv || block_context.y_prediction_mode() == PredictionMode::NearMv) {
for (auto j = 0; j < 1 + block_context.is_compound(); j++)
select_best_sub_block_reference_motion_vectors(block_context, motion_vector_candidates, idy * 2 + idx, j);
select_best_sub_block_reference_motion_vectors(block_context, motion_vector_candidates, idy * 2 + idx, ReferenceIndex::Primary);
if (block_context.is_compound())
select_best_sub_block_reference_motion_vectors(block_context, motion_vector_candidates, idy * 2 + idx, ReferenceIndex::Secondary);
}
auto new_motion_vector_pair = TRY(get_motion_vector(block_context, motion_vector_candidates));
for (auto y = 0; y < size_in_4x4_blocks.height(); y++) {
@ -1211,27 +1214,28 @@ DecoderErrorOr<void> Parser::read_ref_frames(BlockContext& block_context, FrameB
if (compound_mode == ReferenceModeSelect)
compound_mode = TRY_READ(TreeParser::parse_comp_mode(*m_bit_stream, *m_probability_tables, *m_syntax_element_counter, fixed_reference, above_context, left_context));
if (compound_mode == CompoundReference) {
auto secondary_reference = block_context.frame_context.variable_reference_types;
auto fixed_reference_index = block_context.frame_context.reference_frame_sign_biases[fixed_reference];
auto variable_reference_index = !fixed_reference_index;
auto variable_references = block_context.frame_context.variable_reference_types;
// FIXME: Create an enum for compound frame references using names Primary and Secondary.
auto secondary_reference_selection = TRY_READ(TreeParser::parse_comp_ref(*m_bit_stream, *m_probability_tables, *m_syntax_element_counter, fixed_reference, secondary_reference, variable_reference_index, above_context, left_context));
auto fixed_reference_index = ReferenceIndex::Primary;
auto variable_reference_index = ReferenceIndex::Secondary;
if (block_context.frame_context.reference_frame_sign_biases[fixed_reference])
swap(fixed_reference_index, variable_reference_index);
auto variable_reference_selection = TRY_READ(TreeParser::parse_comp_ref(*m_bit_stream, *m_probability_tables, *m_syntax_element_counter, fixed_reference, variable_references, variable_reference_index, above_context, left_context));
block_context.reference_frame_types[fixed_reference_index] = fixed_reference;
block_context.reference_frame_types[variable_reference_index] = secondary_reference[secondary_reference_selection];
block_context.reference_frame_types[variable_reference_index] = variable_references[variable_reference_selection];
return {};
}
// FIXME: Maybe consolidate this into a tree. Context is different between part 1 and 2 but still, it would look nice here.
ReferenceFrameType primary_type = ReferenceFrameType::LastFrame;
auto single_ref_p1 = TRY_READ(TreeParser::parse_single_ref_part_1(*m_bit_stream, *m_probability_tables, *m_syntax_element_counter, above_context, left_context));
if (single_ref_p1) {
auto single_ref_p2 = TRY_READ(TreeParser::parse_single_ref_part_2(*m_bit_stream, *m_probability_tables, *m_syntax_element_counter, above_context, left_context));
block_context.reference_frame_types[0] = single_ref_p2 ? AltRefFrame : GoldenFrame;
} else {
block_context.reference_frame_types[0] = LastFrame;
primary_type = single_ref_p2 ? ReferenceFrameType::AltRefFrame : ReferenceFrameType::GoldenFrame;
}
block_context.reference_frame_types[1] = None;
block_context.reference_frame_types = { primary_type, ReferenceFrameType::None };
return {};
}
@ -1239,22 +1243,26 @@ DecoderErrorOr<void> Parser::read_ref_frames(BlockContext& block_context, FrameB
DecoderErrorOr<MotionVectorPair> Parser::get_motion_vector(BlockContext const& block_context, BlockMotionVectorCandidates const& candidates)
{
MotionVectorPair result;
for (auto i = 0; i < 1 + block_context.is_compound(); i++) {
auto read_one = [&](ReferenceIndex index) -> DecoderErrorOr<void> {
switch (block_context.y_prediction_mode()) {
case PredictionMode::NewMv:
result[i] = TRY(read_motion_vector(block_context, candidates, i));
result[index] = TRY(read_motion_vector(block_context, candidates, index));
break;
case PredictionMode::NearestMv:
result[i] = candidates[i].nearest_vector;
result[index] = candidates[index].nearest_vector;
break;
case PredictionMode::NearMv:
result[i] = candidates[i].near_vector;
result[index] = candidates[index].near_vector;
break;
default:
result[i] = {};
result[index] = {};
break;
}
}
return {};
};
TRY(read_one(ReferenceIndex::Primary));
if (block_context.is_compound())
TRY(read_one(ReferenceIndex::Secondary));
return result;
}
@ -1265,7 +1273,7 @@ static bool should_use_high_precision_motion_vector(MotionVector const& delta_ve
}
// read_mv( ref ) in the spec.
DecoderErrorOr<MotionVector> Parser::read_motion_vector(BlockContext const& block_context, BlockMotionVectorCandidates const& candidates, u8 reference_index)
DecoderErrorOr<MotionVector> Parser::read_motion_vector(BlockContext const& block_context, BlockMotionVectorCandidates const& candidates, ReferenceIndex reference_index)
{
m_use_hp = block_context.frame_context.high_precision_motion_vectors_allowed && should_use_high_precision_motion_vector(candidates[reference_index].best_vector);
MotionVector diff_mv;
@ -1503,22 +1511,22 @@ static void add_motion_vector_to_list_deduped(MotionVector const& vector, Vector
}
// get_block_mv( candidateR, candidateC, refList, usePrev ) in the spec.
MotionVectorCandidate Parser::get_motion_vector_from_current_or_previous_frame(BlockContext const& block_context, MotionVector candidate_vector, u8 ref_list, bool use_prev)
MotionVectorCandidate Parser::get_motion_vector_from_current_or_previous_frame(BlockContext const& block_context, MotionVector candidate_vector, ReferenceIndex reference_index, bool use_prev)
{
if (use_prev) {
auto const& prev_context = m_previous_block_contexts.at(candidate_vector.row(), candidate_vector.column());
return { prev_context.ref_frames[ref_list], prev_context.primary_motion_vector_pair[ref_list] };
return { prev_context.ref_frames[reference_index], prev_context.primary_motion_vector_pair[reference_index] };
}
auto const& current_context = block_context.frame_block_contexts().at(candidate_vector.row(), candidate_vector.column());
return { current_context.ref_frames[ref_list], current_context.primary_motion_vector_pair()[ref_list] };
return { current_context.ref_frames[reference_index], current_context.primary_motion_vector_pair()[reference_index] };
}
// if_same_ref_frame_add_mv( candidateR, candidateC, refFrame, usePrev ) in the spec.
void Parser::add_motion_vector_if_reference_frame_type_is_same(BlockContext const& block_context, MotionVector candidate_vector, ReferenceFrameType ref_frame, Vector<MotionVector, 2>& list, bool use_prev)
{
for (auto ref_list = 0u; ref_list < 2; ref_list++) {
auto candidate = get_motion_vector_from_current_or_previous_frame(block_context, candidate_vector, ref_list, use_prev);
for (auto i = 0u; i < 2; i++) {
auto candidate = get_motion_vector_from_current_or_previous_frame(block_context, candidate_vector, static_cast<ReferenceIndex>(i), use_prev);
if (candidate.type == ref_frame) {
add_motion_vector_to_list_deduped(candidate.vector, list);
return;
@ -1536,13 +1544,13 @@ static void apply_sign_bias_to_motion_vector(FrameContext const& frame_context,
// if_diff_ref_frame_add_mv( candidateR, candidateC, refFrame, usePrev ) in the spec.
void Parser::add_motion_vector_if_reference_frame_type_is_different(BlockContext const& block_context, MotionVector candidate_vector, ReferenceFrameType ref_frame, Vector<MotionVector, 2>& list, bool use_prev)
{
auto first_candidate = get_motion_vector_from_current_or_previous_frame(block_context, candidate_vector, 0, use_prev);
auto first_candidate = get_motion_vector_from_current_or_previous_frame(block_context, candidate_vector, ReferenceIndex::Primary, use_prev);
if (first_candidate.type > ReferenceFrameType::IntraFrame && first_candidate.type != ref_frame) {
apply_sign_bias_to_motion_vector(block_context.frame_context, first_candidate, ref_frame);
add_motion_vector_to_list_deduped(first_candidate.vector, list);
}
auto second_candidate = get_motion_vector_from_current_or_previous_frame(block_context, candidate_vector, 1, use_prev);
auto second_candidate = get_motion_vector_from_current_or_previous_frame(block_context, candidate_vector, ReferenceIndex::Secondary, use_prev);
auto mvs_are_same = first_candidate.vector == second_candidate.vector;
if (second_candidate.type > ReferenceFrameType::IntraFrame && second_candidate.type != ref_frame && !mvs_are_same) {
apply_sign_bias_to_motion_vector(block_context.frame_context, second_candidate, ref_frame);
@ -1588,8 +1596,9 @@ MotionVectorPair Parser::find_reference_motion_vectors(BlockContext const& block
auto context = block_context.frame_block_contexts().at(candidate.row(), candidate.column());
context_counter += mode_2_counter[to_underlying(context.y_mode)];
for (auto ref_list = 0u; ref_list < 2; ref_list++) {
if (context.ref_frames[ref_list] == reference_frame) {
for (auto i = 0u; i < 2; i++) {
auto reference_index = static_cast<ReferenceIndex>(i);
if (context.ref_frames[reference_index] == reference_frame) {
// This section up until add_mv_ref_list() is defined in spec as get_sub_block_mv().
constexpr u8 idx_n_column_to_subblock[4][2] = {
{ 1, 2 },
@ -1599,7 +1608,7 @@ MotionVectorPair Parser::find_reference_motion_vectors(BlockContext const& block
};
auto index = block >= 0 ? idx_n_column_to_subblock[block][offset_vector.column() == 0] : 3;
add_motion_vector_to_list_deduped(context.sub_block_motion_vectors[index][ref_list], list);
add_motion_vector_to_list_deduped(context.sub_block_motion_vectors[index][reference_index], list);
break;
}
}
@ -1634,41 +1643,42 @@ MotionVectorPair Parser::find_reference_motion_vectors(BlockContext const& block
MotionVectorPair result;
for (auto i = 0u; i < list.size(); i++)
result[i] = list[i];
result[static_cast<ReferenceIndex>(i)] = list[i];
return result;
}
// find_best_ref_mvs( refList ) in the spec.
static void select_best_reference_motion_vectors(BlockContext& block_context, MotionVectorPair reference_motion_vectors, BlockMotionVectorCandidates& candidates, u8 reference_index)
static void select_best_reference_motion_vectors(BlockContext& block_context, MotionVectorPair reference_motion_vectors, BlockMotionVectorCandidates& candidates, ReferenceIndex reference_index)
{
for (auto i = 0u; i < MAX_MV_REF_CANDIDATES; i++) {
auto delta = reference_motion_vectors[i];
auto delta_row = delta.row();
auto delta_column = delta.column();
if (!block_context.frame_context.high_precision_motion_vectors_allowed || !should_use_high_precision_motion_vector(delta)) {
auto adjust_and_clamp_vector = [&](MotionVector& vector) {
auto delta_row = vector.row();
auto delta_column = vector.column();
if (!block_context.frame_context.high_precision_motion_vectors_allowed || !should_use_high_precision_motion_vector(vector)) {
if ((delta_row & 1) != 0)
delta_row += delta_row > 0 ? -1 : 1;
if ((delta_column & 1) != 0)
delta_column += delta_column > 0 ? -1 : 1;
}
delta = { delta_row, delta_column };
reference_motion_vectors[i] = clamp_motion_vector(block_context, delta, (BORDERINPIXELS - INTERP_EXTEND) << 3);
}
vector = { delta_row, delta_column };
vector = clamp_motion_vector(block_context, vector, (BORDERINPIXELS - INTERP_EXTEND) << 3);
};
adjust_and_clamp_vector(reference_motion_vectors.primary);
adjust_and_clamp_vector(reference_motion_vectors.secondary);
candidates[reference_index].nearest_vector = reference_motion_vectors[0];
candidates[reference_index].near_vector = reference_motion_vectors[1];
candidates[reference_index].best_vector = reference_motion_vectors[0];
candidates[reference_index].nearest_vector = reference_motion_vectors.primary;
candidates[reference_index].near_vector = reference_motion_vectors.secondary;
candidates[reference_index].best_vector = reference_motion_vectors.primary;
}
// append_sub8x8_mvs( block, refList ) in the spec.
void Parser::select_best_sub_block_reference_motion_vectors(BlockContext const& block_context, BlockMotionVectorCandidates& candidates, i32 block, u8 reference_index)
void Parser::select_best_sub_block_reference_motion_vectors(BlockContext const& block_context, BlockMotionVectorCandidates& candidates, i32 block, ReferenceIndex reference_index)
{
MotionVector sub_8x8_mvs[2];
Array<MotionVector, 2> sub_8x8_mvs;
MotionVectorPair reference_motion_vectors = find_reference_motion_vectors(block_context, block_context.reference_frame_types[reference_index], block);
auto destination_index = 0;
if (block == 0) {
for (auto i = 0u; i < 2; i++)
sub_8x8_mvs[destination_index++] = reference_motion_vectors[i];
sub_8x8_mvs[destination_index++] = reference_motion_vectors.primary;
sub_8x8_mvs[destination_index++] = reference_motion_vectors.secondary;
} else if (block <= 2) {
sub_8x8_mvs[destination_index++] = block_context.sub_block_motion_vectors[0][reference_index];
} else {
@ -1681,7 +1691,7 @@ void Parser::select_best_sub_block_reference_motion_vectors(BlockContext const&
}
for (auto n = 0u; n < 2 && destination_index < 2; n++) {
auto ref_list_vector = reference_motion_vectors[n];
auto ref_list_vector = reference_motion_vectors[static_cast<ReferenceIndex>(n)];
if (ref_list_vector != sub_8x8_mvs[0])
sub_8x8_mvs[destination_index++] = ref_list_vector;
}