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Don't update sps if they are only repeated
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This is an attempt to improve the mitigations from strukturag#365 and strukturag#366 and picks up an idea I described at strukturag#345:

> One way would be just to look at the pointers of the SPS (fast and easy, but
> may reject more than required), or investigate if the SPS used for the image
> generations are "compatible".

This changes do exactly this: It (very conservativly) checks if the old and new sps have
identical information -- except the reference picture set, which I believe is supposed
to be updated by new sps'). If they are basically identical, the old sps will be
used instead of the new one, (of course, reference image set is updated from the new one)

I'm using standalone operator== and helper functions to avoid changing ABI of the library;
if an ABI bump would be done, of course this should go to the respective classes.

I've tested the patch with several videos, they still play fine.

@farindk I'd really appreciate to receive your feedback; the reason is that I want
to fix the many open CVE's for the package as it is currently in Debian and other distributions…

--
Cheers,
tobi
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Tobias Frost committed Jan 13, 2023
1 parent c96962c commit c71d6d9
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273 changes: 273 additions & 0 deletions libde265/decctx.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -545,6 +545,263 @@ de265_error decoder_context::read_vps_NAL(bitreader& reader)
return DE265_OK;
}

// implemented as freestanding functions to avoid changing API

bool operator==(const profile_data &lhs, const profile_data &rhs) {
if(&lhs == &rhs) return true;
if(lhs.profile_present_flag != rhs.profile_present_flag ) return false;
if(lhs.profile_present_flag) {
if(lhs.profile_space != rhs.profile_space ) return false;
if(lhs.tier_flag != rhs.tier_flag ) return false;
if(lhs.profile_idc != rhs.profile_idc ) return false;

if(memcmp(lhs.profile_compatibility_flag, rhs.profile_compatibility_flag, sizeof(rhs.profile_compatibility_flag)) ) return false;

if(lhs.progressive_source_flag != rhs.progressive_source_flag ) return false;
if(lhs.interlaced_source_flag != rhs.interlaced_source_flag ) return false;
if(lhs.non_packed_constraint_flag != rhs.non_packed_constraint_flag ) return false;
if(lhs.frame_only_constraint_flag != rhs.frame_only_constraint_flag ) return false;
}

if(lhs.level_present_flag != rhs.level_present_flag) return false;
if(lhs.level_present_flag && lhs.level_idc != rhs.level_idc ) return false;

return true;
}

bool operator!=(const profile_data &lhs, const profile_data &rhs) {
if(&lhs == &rhs) return false;
return (!(lhs==rhs));
}

// class does not store max_sub_layers, so operator == cannot be done.
bool isEqual(const profile_tier_level &lhs , const profile_tier_level &rhs, int sps_max_sub_layers ) {
if(&lhs == &rhs) return true;

if(lhs.general != rhs.general ) return false;
for(int i = 0 ; i < sps_max_sub_layers; i++ ) {
if(lhs.sub_layer[i] != rhs.sub_layer[i]) return false;
}
return true;
}

bool isEqual(const video_usability_information &lhs, const video_usability_information &rhs, const seq_parameter_set &sps) {
if(&lhs == &rhs) return true;

// not seen yet if(lhs.nal_hrd_parameters_present_flag != rhs.nal_hrd_parameters_present_flag ) return false;

// populated by video_usability_information::read()
if(lhs.aspect_ratio_info_present_flag != rhs.aspect_ratio_info_present_flag ) return false;
if(lhs.aspect_ratio_info_present_flag) {
if(lhs.sar_width != rhs.sar_width ) return false;
if(lhs.sar_height != rhs.sar_height ) return false;
}

if(lhs.overscan_info_present_flag != rhs.overscan_info_present_flag ) return false;
if(lhs.overscan_info_present_flag) {
if(lhs.overscan_appropriate_flag != rhs.overscan_appropriate_flag ) return false;
}

if(lhs.video_signal_type_present_flag != rhs.video_signal_type_present_flag ) return false;
if(lhs.video_signal_type_present_flag) {
if(lhs.video_format != rhs.video_format ) return false;
if(lhs.video_full_range_flag != rhs.video_full_range_flag) return false;
if(lhs.colour_description_present_flag != rhs.colour_description_present_flag) return false;
if(lhs.colour_primaries != rhs.colour_primaries ) return false;
if(lhs.transfer_characteristics != rhs.transfer_characteristics ) return false;
if(lhs.matrix_coeffs != rhs.matrix_coeffs ) return false;
}

if(lhs.chroma_loc_info_present_flag != rhs.chroma_loc_info_present_flag ) return false;
if(lhs.chroma_loc_info_present_flag) {
if(lhs.chroma_sample_loc_type_top_field != rhs.chroma_sample_loc_type_top_field ) return false;
if(lhs.chroma_sample_loc_type_bottom_field != rhs.chroma_sample_loc_type_bottom_field ) return false;
}
if(lhs.neutral_chroma_indication_flag != rhs.neutral_chroma_indication_flag ) return false;
if(lhs.field_seq_flag != rhs.field_seq_flag ) return false;
if(lhs.frame_field_info_present_flag != rhs.frame_field_info_present_flag ) return false;

if(lhs.default_display_window_flag != rhs.default_display_window_flag ) return false;
if(lhs.default_display_window_flag) {
if(lhs.def_disp_win_left_offset != rhs.def_disp_win_left_offset ) return false;
if(lhs.def_disp_win_right_offset != rhs.def_disp_win_right_offset ) return false;
if(lhs.def_disp_win_top_offset != rhs.def_disp_win_top_offset ) return false;
if(lhs.def_disp_win_bottom_offset != rhs.def_disp_win_bottom_offset ) return false;
}

if(lhs.vui_timing_info_present_flag != rhs.vui_timing_info_present_flag ) return false;
if(lhs.vui_timing_info_present_flag) {
if(lhs.vui_num_units_in_tick != rhs.vui_num_units_in_tick ) return false;
if(lhs.vui_time_scale != rhs.vui_time_scale ) return false;
if(lhs.vui_timing_info_present_flag != rhs.vui_timing_info_present_flag ) return false;
if(lhs.vui_timing_info_present_flag) {
if(lhs.vui_num_ticks_poc_diff_one != rhs.vui_num_ticks_poc_diff_one ) return false;
}
}

if(lhs.vui_hrd_parameters_present_flag != rhs.vui_hrd_parameters_present_flag ) return false;


if(lhs.vui_hrd_parameters_present_flag) {
// check things made by hrd_parametes

if(lhs.vui_hrd_parameters_present_flag != rhs.vui_hrd_parameters_present_flag ) return false;
if(lhs.vcl_hrd_parameters_present_flag != rhs.vcl_hrd_parameters_present_flag ) return false;

if(lhs.nal_hrd_parameters_present_flag || lhs.vcl_hrd_parameters_present_flag) {
if(lhs.sub_pic_hrd_params_present_flag != rhs.sub_pic_hrd_params_present_flag ) return false;
if(lhs.sub_pic_hrd_params_present_flag) {
if(lhs.tick_divisor_minus2 != rhs.tick_divisor_minus2 ) return false;
if(lhs.du_cpb_removal_delay_increment_length_minus1 != rhs.du_cpb_removal_delay_increment_length_minus1 ) return false;
if(lhs.sub_pic_cpb_params_in_pic_timing_sei_flag != rhs.sub_pic_cpb_params_in_pic_timing_sei_flag ) return false;
if(lhs.dpb_output_delay_du_length_minus1 != rhs.dpb_output_delay_du_length_minus1 ) return false;
}
if(lhs.bit_rate_scale != rhs.bit_rate_scale ) return false;
if(lhs.cpb_size_scale != rhs.cpb_size_scale ) return false;
if(lhs.sub_pic_hrd_params_present_flag) {
if(lhs.cpb_size_du_scale != rhs.cpb_size_du_scale ) return false;
}
if(lhs.initial_cpb_removal_delay_length_minus1 != rhs.initial_cpb_removal_delay_length_minus1 ) return false;
if(lhs.au_cpb_removal_delay_length_minus1 != rhs.au_cpb_removal_delay_length_minus1 ) return false;
if(lhs.dpb_output_delay_length_minus1 != rhs.dpb_output_delay_length_minus1 ) return false;
}

int i;
unsigned int j, nalOrVcl;

for (i = 0; i < sps.sps_max_sub_layers; i++) {
if(lhs.fixed_pic_rate_general_flag[i] != rhs.fixed_pic_rate_general_flag[i] ) return false;
if(lhs.fixed_pic_rate_general_flag[i]) {
if(lhs.elemental_duration_in_tc_minus1[i] != rhs.elemental_duration_in_tc_minus1[i] ) return false;
}
if(lhs.low_delay_hrd_flag[i] != rhs.low_delay_hrd_flag[i] ) return false;
if(lhs.cpb_cnt_minus1[i] != rhs.cpb_cnt_minus1[i] ) return false;

for (nalOrVcl = 0; nalOrVcl < 2; nalOrVcl++) {
if (((nalOrVcl == 0) && lhs.nal_hrd_parameters_present_flag) || ((nalOrVcl == 1) && lhs.vcl_hrd_parameters_present_flag)) {
for (j = 0; j <= lhs.cpb_cnt_minus1[i]; j++) {
if(lhs.bit_rate_value_minus1[i][j][nalOrVcl] != rhs.bit_rate_value_minus1[i][j][nalOrVcl]) return false;
if(lhs.cpb_size_value_minus1[i][j][nalOrVcl] != rhs.cpb_size_value_minus1[i][j][nalOrVcl]) return false;

if (lhs.sub_pic_hrd_params_present_flag) {
if(lhs.cpb_size_du_value_minus1[i][j][nalOrVcl] != rhs.cpb_size_du_value_minus1[i][j][nalOrVcl]) return false;
if(lhs.bit_rate_du_value_minus1[i][j][nalOrVcl] != rhs.bit_rate_du_value_minus1[i][j][nalOrVcl]) return false;
}
if( lhs.cbr_flag[i][j][nalOrVcl] != rhs.cbr_flag[i][j][nalOrVcl]) return false;
}
}
}
}
}
return true;
}

bool operator==(const sps_range_extension &lhs, const sps_range_extension &rhs) {
if(&lhs == &rhs) return true;
if(lhs.transform_skip_rotation_enabled_flag != rhs.transform_skip_rotation_enabled_flag ) return false;
if(lhs.transform_skip_context_enabled_flag != rhs.transform_skip_context_enabled_flag ) return false;
if(lhs.implicit_rdpcm_enabled_flag != rhs.implicit_rdpcm_enabled_flag ) return false;
if(lhs.explicit_rdpcm_enabled_flag != rhs.explicit_rdpcm_enabled_flag ) return false;
if(lhs.extended_precision_processing_flag != rhs.extended_precision_processing_flag ) return false;
if(lhs.intra_smoothing_disabled_flag != rhs.intra_smoothing_disabled_flag ) return false;
if(lhs.high_precision_offsets_enabled_flag != rhs.high_precision_offsets_enabled_flag ) return false;
if(lhs.persistent_rice_adaptation_enabled_flag != rhs.persistent_rice_adaptation_enabled_flag ) return false;
if(lhs.cabac_bypass_alignment_enabled_flag != rhs.cabac_bypass_alignment_enabled_flag ) return false;
return true;
}

bool operator!=(const sps_range_extension &lhs, const sps_range_extension &rhs) {
if(&lhs == &rhs) return false;
return !(lhs==rhs);
}


bool operator==(const seq_parameter_set &lhs, const seq_parameter_set &rhs) {

if(&lhs== &rhs) return true;

if(lhs.sps_read != rhs.sps_read) return false;

if(lhs.video_parameter_set_id != rhs.video_parameter_set_id) return false;
if(lhs.sps_max_sub_layers != rhs.sps_max_sub_layers) return false;
if(lhs.sps_temporal_id_nesting_flag != rhs.sps_temporal_id_nesting_flag) return false;

if(!isEqual(lhs.profile_tier_level_, rhs.profile_tier_level_, lhs.sps_max_sub_layers)) return false;

if(lhs.seq_parameter_set_id != rhs.seq_parameter_set_id) return false;
if(lhs.chroma_format_idc != rhs.chroma_format_idc) return false;

if(lhs.separate_colour_plane_flag != rhs.separate_colour_plane_flag) return false;
if(lhs.pic_width_in_luma_samples != rhs.pic_width_in_luma_samples) return false;
if(lhs.pic_height_in_luma_samples != rhs.pic_height_in_luma_samples) return false;
if(lhs.conformance_window_flag != rhs.conformance_window_flag) return false;

if(lhs.conformance_window_flag) {
if(lhs.conf_win_left_offset != rhs.conf_win_left_offset) return false;
if(lhs.conf_win_right_offset != rhs.conf_win_right_offset) return false;
if(lhs.conf_win_top_offset != rhs.conf_win_top_offset) return false;
if(lhs.conf_win_bottom_offset != rhs.conf_win_bottom_offset) return false;
}

if(lhs.bit_depth_luma != rhs.bit_depth_luma) return false;
if(lhs.bit_depth_chroma != rhs.bit_depth_chroma) return false;

if(lhs.log2_max_pic_order_cnt_lsb != rhs.log2_max_pic_order_cnt_lsb) return false;
if(lhs.sps_sub_layer_ordering_info_present_flag != rhs.sps_sub_layer_ordering_info_present_flag) return false;

if(memcmp(lhs.sps_max_dec_pic_buffering, rhs.sps_max_dec_pic_buffering, sizeof(rhs.sps_max_dec_pic_buffering))) return false;
if(memcmp(lhs.sps_max_num_reorder_pics, rhs.sps_max_num_reorder_pics, sizeof(rhs.sps_max_num_reorder_pics))) return false;
if(memcmp(lhs.sps_max_latency_increase_plus1, rhs.sps_max_latency_increase_plus1, sizeof(rhs.sps_max_latency_increase_plus1))) return false;

if(lhs.log2_min_luma_coding_block_size != rhs.log2_min_luma_coding_block_size) return false;
if(lhs.log2_diff_max_min_luma_coding_block_size != rhs.log2_diff_max_min_luma_coding_block_size) return false;
if(lhs.log2_min_transform_block_size != rhs.log2_min_transform_block_size) return false;
if(lhs.log2_diff_max_min_transform_block_size != rhs.log2_diff_max_min_transform_block_size) return false;
if(lhs.max_transform_hierarchy_depth_inter != rhs.max_transform_hierarchy_depth_inter) return false;
if(lhs.max_transform_hierarchy_depth_intra != rhs.max_transform_hierarchy_depth_intra) return false;

if(lhs.scaling_list_enable_flag != rhs.scaling_list_enable_flag) return false;
if(lhs.scaling_list_enable_flag) {
if(lhs.sps_scaling_list_data_present_flag != rhs.sps_scaling_list_data_present_flag) return false;
if(lhs.sps_scaling_list_data_present_flag) {
// compare only needed if present, otherwise it is the default scaling list.
if(memcmp(&lhs.scaling_list, &rhs.scaling_list, sizeof(rhs.scaling_list))) return false;
}
}

if(lhs.amp_enabled_flag != rhs.amp_enabled_flag) return false;
if(lhs.sample_adaptive_offset_enabled_flag != rhs.sample_adaptive_offset_enabled_flag) return false;
if(lhs.pcm_enabled_flag != rhs.pcm_enabled_flag) return false;

if(lhs.pcm_enabled_flag) {
if(lhs.pcm_sample_bit_depth_luma != rhs.pcm_sample_bit_depth_luma) return false;
if(lhs.pcm_sample_bit_depth_chroma != rhs.pcm_sample_bit_depth_chroma) return false;
if(lhs.log2_min_pcm_luma_coding_block_size != rhs.log2_min_pcm_luma_coding_block_size) return false;
if(lhs.log2_diff_max_min_pcm_luma_coding_block_size != rhs.log2_diff_max_min_pcm_luma_coding_block_size) return false;
if(lhs.pcm_loop_filter_disable_flag != rhs.pcm_loop_filter_disable_flag) return false;
}

// (longterm) reference pics likely to change with a new sps, so ignored here.

if(lhs.sps_temporal_mvp_enabled_flag != rhs.sps_temporal_mvp_enabled_flag) return false;
if(lhs.strong_intra_smoothing_enable_flag != rhs.strong_intra_smoothing_enable_flag) return false;

if(lhs.vui_parameters_present_flag != rhs.vui_parameters_present_flag) return false;
if(lhs.vui_parameters_present_flag) {
if(!isEqual(lhs.vui, rhs.vui, lhs )) return false;
}

if(lhs.sps_extension_present_flag != rhs.sps_extension_present_flag ) return false;
if(lhs.sps_extension_present_flag) {
if(lhs.sps_range_extension_flag != rhs.sps_range_extension_flag ) return false;
if(lhs.sps_multilayer_extension_flag != rhs.sps_multilayer_extension_flag ) return false;
if(lhs.sps_extension_6bits != rhs.sps_extension_6bits ) return false;
if(lhs.range_extension != rhs.range_extension) return false;
}

return true;
}

de265_error decoder_context::read_sps_NAL(bitreader& reader)
{
logdebug(LogHeaders,"----> read SPS\n");
Expand All @@ -560,6 +817,22 @@ de265_error decoder_context::read_sps_NAL(bitreader& reader)
new_sps->dump(param_sps_headers_fd);
}

if ( sps[ new_sps->seq_parameter_set_id ] ) {
auto old_sps = sps[ new_sps->seq_parameter_set_id ].get();
if ( *old_sps == *new_sps ) {
printf(" **** keeping sps *****\n");
// the new sps is identical to the old one, so no replacing needed.
// however, reference pics and long-term reference pics might need updating.
old_sps->ref_pic_sets = new_sps->ref_pic_sets;
old_sps->long_term_ref_pics_present_flag = new_sps->long_term_ref_pics_present_flag;
memcpy(old_sps->lt_ref_pic_poc_lsb_sps, new_sps->lt_ref_pic_poc_lsb_sps, sizeof(old_sps->lt_ref_pic_poc_lsb_sps));
memcpy(old_sps->used_by_curr_pic_lt_sps_flag, new_sps->used_by_curr_pic_lt_sps_flag, sizeof(old_sps->used_by_curr_pic_lt_sps_flag));
return DE265_OK;
}
printf(" **** replacing sps *****\n");

}

sps[ new_sps->seq_parameter_set_id ] = new_sps;

// Remove the all PPS that referenced the old SPS because parameters may have changed and we do not want to
Expand Down
6 changes: 6 additions & 0 deletions libde265/sps.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -287,6 +287,11 @@ de265_error seq_parameter_set::read(error_queue* errqueue, bitreader* br)
int firstLayer = (sps_sub_layer_ordering_info_present_flag ?
0 : sps_max_sub_layers-1 );

// zero out so that comparing is easier.
memset(sps_max_dec_pic_buffering, 0 , sizeof(sps_max_dec_pic_buffering));
memset(sps_max_num_reorder_pics, 0 , sizeof(sps_max_num_reorder_pics));
memset(sps_max_latency_increase_plus1, 0 , sizeof(sps_max_latency_increase_plus1));

for (int i=firstLayer ; i <= sps_max_sub_layers-1; i++ ) {

// sps_max_dec_pic_buffering[i]
Expand Down Expand Up @@ -347,6 +352,7 @@ de265_error seq_parameter_set::read(error_queue* errqueue, bitreader* br)
if (sps_scaling_list_data_present_flag) {

de265_error err;
memset(&scaling_list, 0 , sizeof(scaling_list)); // zero out, so that memcmp will do it to check for equality.
if ((err=read_scaling_list(br,this, &scaling_list, false)) != DE265_OK) {
return err;
}
Expand Down

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