Add a function to compute the log-spectral distance between two sets …

…of audio samples

The function also checks that the resulting distance is below a given threshold.

PiperOrigin-RevId: 678820628

iamf/cli/tests/BUILD

@@ -43,8 +43,11 @@ cc_library(
         "//iamf/obu/decoder_config:lpcm_decoder_config",
         "//iamf/obu/decoder_config:opus_decoder_config",
         "@com_google_absl//absl/container:flat_hash_map",
+        "@com_google_absl//absl/log",
         "@com_google_absl//absl/status:status_matchers",
+        "@com_google_absl//absl/status:statusor",
         "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/types:span",
         "@com_google_googletest//:gtest",
     ],
 )
@@ -96,6 +99,7 @@ cc_test(
         "@com_google_absl//absl/container:flat_hash_set",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:status_matchers",
+        "@com_google_absl//absl/types:span",
         "@com_google_googletest//:gtest_main",
         "@com_google_protobuf//:protobuf",
     ],

iamf/cli/tests/cli_test_utils.cc

@@ -12,6 +12,7 @@
 #include "iamf/cli/tests/cli_test_utils.h"
 
 #include <algorithm>
+#include <cmath>
 #include <cstdint>
 #include <filesystem>
 #include <list>
@@ -23,9 +24,12 @@
 #include <vector>
 
 #include "absl/container/flat_hash_map.h"
+#include "absl/log/log.h"
 #include "absl/status/status_matchers.h"
+#include "absl/status/statusor.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
+#include "absl/types/span.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "iamf/cli/audio_element_with_data.h"
@@ -343,4 +347,21 @@ std::string GetAndCreateOutputDirectory(absl::string_view suffix) {
   return output_directory;
 }
 
+bool IsLogSpectralDistanceBelowThreshold(
+    const absl::Span<const InternalSampleType>& first_log_spectrum,
+    const absl::Span<const InternalSampleType>& second_log_spectrum,
+    double threshold_db) {
+  const int num_samples = first_log_spectrum.size();
+  if (num_samples != second_log_spectrum.size()) {
+    LOG(ERROR) << "Spectrum sizes are not equal.";
+    return false;
+  }
+  double log_spectral_distance = 0.0;
+  for (int i = 0; i < num_samples; ++i) {
+    log_spectral_distance += (first_log_spectrum[i] - second_log_spectrum[i]) *
+                             (first_log_spectrum[i] - second_log_spectrum[i]);
+  }
+  return (10 * std::sqrt(log_spectral_distance / num_samples)) <= threshold_db;
+}
+
 }  // namespace iamf_tools

iamf/cli/tests/cli_test_utils.h

@@ -19,7 +19,9 @@
 #include <vector>
 
 #include "absl/container/flat_hash_map.h"
+#include "absl/status/statusor.h"
 #include "absl/strings/string_view.h"
+#include "absl/types/span.h"
 #include "iamf/cli/audio_element_with_data.h"
 #include "iamf/cli/demixing_module.h"
 #include "iamf/cli/renderer/audio_element_renderer_base.h"
@@ -190,6 +192,22 @@ std::string GetAndCleanupOutputFileName(absl::string_view suffix);
  */
 std::string GetAndCreateOutputDirectory(absl::string_view suffix);
 
+/*!\brief Computes the log-spectral distance (LSD) between two spectra.
+ *
+ * The log-spectral distance (LSD) is a distance measure (expressed in dB)
+ * between two spectra.
+ *
+ * \param first_log_spectrum First log-spectrum to compare.
+ * \param second_log_spectrum Second log-spectrum to compare.
+ * \param threshold_db LSD threshold to compare against, in db.
+ * \return true if the log-spectral distance
+ *    between the two spectra is below the specified threshold, false otherwise.
+ */
+bool IsLogSpectralDistanceBelowThreshold(
+    const absl::Span<const InternalSampleType>& first_log_spectrum,
+    const absl::Span<const InternalSampleType>& second_log_spectrum,
+    double threshold_db);
+
 }  // namespace iamf_tools
 
 #endif  // CLI_TESTS_CLI_TEST_UTILS_H_

iamf/cli/tests/cli_util_test.cc

@@ -15,13 +15,15 @@
 #include <cstdint>
 #include <list>
 #include <memory>
+#include <numeric>
 #include <utility>
 #include <vector>
 
 #include "absl/container/flat_hash_map.h"
 #include "absl/container/flat_hash_set.h"
 #include "absl/status/status.h"
 #include "absl/status/status_matchers.h"
+#include "absl/types/span.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "iamf/cli/audio_element_with_data.h"
@@ -738,5 +740,35 @@ TEST(GenerateParamIdToMetadataMapTest,
   EXPECT_FALSE(param_id_to_metadata_map.ok());
 }
 
+TEST(IsLogSpectralDistanceBelowThreshold, BelowThresholdSucceeds) {
+  std::vector<double> first_log_spectrum(10);
+  std::iota(first_log_spectrum.begin(), first_log_spectrum.end(), 0);
+  std::vector<double> second_log_spectrum(10);
+  std::iota(second_log_spectrum.begin(), second_log_spectrum.end(), 1);
+  EXPECT_TRUE(IsLogSpectralDistanceBelowThreshold(
+      absl::MakeConstSpan(first_log_spectrum),
+      absl::MakeConstSpan(second_log_spectrum), 11.0));
+}
+
+TEST(IsLogSpectralDistanceBelowThreshold, AtThresholdSucceeds) {
+  std::vector<double> first_log_spectrum(10);
+  std::iota(first_log_spectrum.begin(), first_log_spectrum.end(), 0);
+  std::vector<double> second_log_spectrum(10);
+  std::iota(second_log_spectrum.begin(), second_log_spectrum.end(), 1);
+  EXPECT_TRUE(IsLogSpectralDistanceBelowThreshold(
+      absl::MakeConstSpan(first_log_spectrum),
+      absl::MakeConstSpan(second_log_spectrum), 10.0));
+}
+
+TEST(ExpectLogSpectralDistanceBelowThreshold, AboveThresholdFails) {
+  std::vector<double> first_log_spectrum(10);
+  std::iota(first_log_spectrum.begin(), first_log_spectrum.end(), 0);
+  std::vector<double> second_log_spectrum(10);
+  std::iota(second_log_spectrum.begin(), second_log_spectrum.end(), 1);
+  EXPECT_FALSE(IsLogSpectralDistanceBelowThreshold(
+      absl::MakeConstSpan(first_log_spectrum),
+      absl::MakeConstSpan(second_log_spectrum), 9.0));
+}
+
 }  // namespace
 }  // namespace iamf_tools