signed parseSEWithFallback(ABitReader *br, signed fallback) {
// NOTE: parseUE cannot normally return ~0 as the max supported value is 0xFFFE
unsigned codeNum = parseUEWithFallback(br, ~0U);
if (codeNum == ~0U) {
return fallback;
}
return (codeNum & 1) ? (codeNum + 1) / 2 : -signed(codeNum / 2);
}
status_t HevcParameterSets::parseSps(const uint8_t* data, size_t size) {
// See Rec. ITU-T H.265 v3 (04/2015) Chapter 7.3.2.2 for reference
NALBitReader reader(data, size);
// Skip sps_video_parameter_set_id
reader.skipBits(4);
uint8_t maxSubLayersMinus1 = reader.getBitsWithFallback(3, 0);
// Skip sps_temporal_id_nesting_flag;
reader.skipBits(1);
// Skip general profile
reader.skipBits(96);
if (maxSubLayersMinus1 > 0) {
bool subLayerProfilePresentFlag[8];
bool subLayerLevelPresentFlag[8];
for (int i = 0; i < maxSubLayersMinus1; ++i) {
subLayerProfilePresentFlag[i] = reader.getBitsWithFallback(1, 0);
subLayerLevelPresentFlag[i] = reader.getBitsWithFallback(1, 0);
}
// Skip reserved
reader.skipBits(2 * (8 - maxSubLayersMinus1));
for (int i = 0; i < maxSubLayersMinus1; ++i) {
if (subLayerProfilePresentFlag[i]) {
// Skip profile
reader.skipBits(88);
}
if (subLayerLevelPresentFlag[i]) {
// Skip sub_layer_level_idc[i]
reader.skipBits(8);
}
}
}
// Skip sps_seq_parameter_set_id
skipUE(&reader);
uint8_t chromaFormatIdc = parseUEWithFallback(&reader, 0);
mParams.add(kChromaFormatIdc, chromaFormatIdc);
if (chromaFormatIdc == 3) {
// Skip separate_colour_plane_flag
reader.skipBits(1);
}
// Skip pic_width_in_luma_samples
skipUE(&reader);
// Skip pic_height_in_luma_samples
skipUE(&reader);
if (reader.getBitsWithFallback(1, 0) /* i.e. conformance_window_flag */) {
// Skip conf_win_left_offset
skipUE(&reader);
// Skip conf_win_right_offset
skipUE(&reader);
// Skip conf_win_top_offset
skipUE(&reader);
// Skip conf_win_bottom_offset
skipUE(&reader);
}
mParams.add(kBitDepthLumaMinus8, parseUEWithFallback(&reader, 0));
mParams.add(kBitDepthChromaMinus8, parseUEWithFallback(&reader, 0));
// log2_max_pic_order_cnt_lsb_minus4
size_t log2MaxPicOrderCntLsb = parseUEWithFallback(&reader, 0) + (size_t)4;
bool spsSubLayerOrderingInfoPresentFlag = reader.getBitsWithFallback(1, 0);
for (uint32_t i = spsSubLayerOrderingInfoPresentFlag ? 0 : maxSubLayersMinus1;
i <= maxSubLayersMinus1; ++i) {
skipUE(&reader); // sps_max_dec_pic_buffering_minus1[i]
skipUE(&reader); // sps_max_num_reorder_pics[i]
skipUE(&reader); // sps_max_latency_increase_plus1[i]
}
skipUE(&reader); // log2_min_luma_coding_block_size_minus3
skipUE(&reader); // log2_diff_max_min_luma_coding_block_size
skipUE(&reader); // log2_min_luma_transform_block_size_minus2
skipUE(&reader); // log2_diff_max_min_luma_transform_block_size
skipUE(&reader); // max_transform_hierarchy_depth_inter
skipUE(&reader); // max_transform_hierarchy_depth_intra
if (reader.getBitsWithFallback(1, 0)) { // scaling_list_enabled_flag u(1)
// scaling_list_data
if (reader.getBitsWithFallback(1, 0)) { // sps_scaling_list_data_present_flag
for (uint32_t sizeId = 0; sizeId < 4; ++sizeId) {
for (uint32_t matrixId = 0; matrixId < 6; matrixId += (sizeId == 3) ? 3 : 1) {
if (!reader.getBitsWithFallback(1, 1)) {
// scaling_list_pred_mode_flag[sizeId][matrixId]
skipUE(&reader); // scaling_list_pred_matrix_id_delta[sizeId][matrixId]
} else {
uint32_t coefNum = std::min(64, (1 << (4 + (sizeId << 1))));
if (sizeId > 1) {
skipSE(&reader); // scaling_list_dc_coef_minus8[sizeId − 2][matrixId]
}
for (uint32_t i = 0; i < coefNum; ++i) {
skipSE(&reader); // scaling_list_delta_coef
}
}
}
}
}
}
reader.skipBits(1); // amp_enabled_flag
reader.skipBits(1); // sample_adaptive_offset_enabled_flag u(1)
if (reader.getBitsWithFallback(1, 0)) { // pcm_enabled_flag
reader.skipBits(4); // pcm_sample_bit_depth_luma_minus1
reader.skipBits(4); // pcm_sample_bit_depth_chroma_minus1 u(4)
skipUE(&reader); // log2_min_pcm_luma_coding_block_size_minus3
skipUE(&reader); // log2_diff_max_min_pcm_luma_coding_block_size
reader.skipBits(1); // pcm_loop_filter_disabled_flag
}
uint32_t numShortTermRefPicSets = parseUEWithFallback(&reader, 0);
uint32_t numPics = 0;
for (uint32_t i = 0; i < numShortTermRefPicSets; ++i) {
// st_ref_pic_set(i)
if (i != 0 && reader.getBitsWithFallback(1, 0)) { // inter_ref_pic_set_prediction_flag
reader.skipBits(1); // delta_rps_sign
skipUE(&reader); // abs_delta_rps_minus1
uint32_t nextNumPics = 0;
for (uint32_t j = 0; j <= numPics; ++j) {
if (reader.getBitsWithFallback(1, 0) // used_by_curr_pic_flag[j]
|| reader.getBitsWithFallback(1, 0)) { // use_delta_flag[j]
++nextNumPics;
}
}
numPics = nextNumPics;
} else {
uint32_t numNegativePics = parseUEWithFallback(&reader, 0);
uint32_t numPositivePics = parseUEWithFallback(&reader, 0);
if (numNegativePics > UINT32_MAX - numPositivePics) {
return ERROR_MALFORMED;
}
numPics = numNegativePics + numPositivePics;
for (uint32_t j = 0; j < numPics; ++j) {
skipUE(&reader); // delta_poc_s0|1_minus1[i]
reader.skipBits(1); // used_by_curr_pic_s0|1_flag[i]
}
}
}
if (reader.getBitsWithFallback(1, 0)) { // long_term_ref_pics_present_flag
uint32_t numLongTermRefPicSps = parseUEWithFallback(&reader, 0);
for (uint32_t i = 0; i < numLongTermRefPicSps; ++i) {
reader.skipBits(log2MaxPicOrderCntLsb); // lt_ref_pic_poc_lsb_sps[i]
reader.skipBits(1); // used_by_curr_pic_lt_sps_flag[i]
}
}
reader.skipBits(1); // sps_temporal_mvp_enabled_flag
reader.skipBits(1); // strong_intra_smoothing_enabled_flag
if (reader.getBitsWithFallback(1, 0)) { // vui_parameters_present_flag
if (reader.getBitsWithFallback(1, 0)) { // aspect_ratio_info_present_flag
uint32_t aspectRatioIdc = reader.getBitsWithFallback(8, 0);
if (aspectRatioIdc == 0xFF /* EXTENDED_SAR */) {
reader.skipBits(16); // sar_width
reader.skipBits(16); // sar_height
}
}
if (reader.getBitsWithFallback(1, 0)) { // overscan_info_present_flag
reader.skipBits(1); // overscan_appropriate_flag
}
if (reader.getBitsWithFallback(1, 0)) { // video_signal_type_present_flag
reader.skipBits(3); // video_format
uint32_t videoFullRangeFlag;
if (reader.getBitsGraceful(1, &videoFullRangeFlag)) {
mParams.add(kVideoFullRangeFlag, videoFullRangeFlag);
}
if (reader.getBitsWithFallback(1, 0)) { // colour_description_present_flag
mInfo = (Info)(mInfo | kInfoHasColorDescription);
uint32_t colourPrimaries, transferCharacteristics, matrixCoeffs;
if (reader.getBitsGraceful(8, &colourPrimaries)) {
mParams.add(kColourPrimaries, colourPrimaries);
}
if (reader.getBitsGraceful(8, &transferCharacteristics)) {
mParams.add(kTransferCharacteristics, transferCharacteristics);
if (transferCharacteristics == 16 /* ST 2084 */
|| transferCharacteristics == 18 /* ARIB STD-B67 HLG */) {
mInfo = (Info)(mInfo | kInfoIsHdr);
}
}
if (reader.getBitsGraceful(8, &matrixCoeffs)) {
mParams.add(kMatrixCoeffs, matrixCoeffs);
}
}
// skip rest of VUI
}
}
return reader.overRead() ? ERROR_MALFORMED : OK;
}