Avoid implicit converstion of filesystem::path to string

Use explicit conversion because the implicit does not work on Windows builds.

PiperOrigin-RevId: 668154026

iamf/cli/encoder_main.cc

@@ -152,8 +152,9 @@ int main(int argc, char** argv) {
           ? std::filesystem::temp_directory_path()
           : std::filesystem::path(absl::GetFlag(FLAGS_output_iamf_directory));
 
-  absl::Status status = iamf_tools::TestMain(
-      *user_metadata, input_wav_directory, output_iamf_directory);
+  absl::Status status =
+      iamf_tools::TestMain(*user_metadata, input_wav_directory.string(),
+                           output_iamf_directory.string());
 
   // Log success or failure. Success is defined as a valid test vector returning
   // `absl::OkStatus()` or an invalid test vector returning a different status.

iamf/cli/encoder_main_lib.cc

@@ -280,8 +280,9 @@ absl::Status GenerateObus(
   // Write the output audio streams which were used to measure loudness to the
   // same directory as the IAMF file.
   const std::string output_wav_file_prefix =
-      std::filesystem::path(output_iamf_directory) /
-      user_metadata.test_vector_metadata().file_name_prefix();
+      (std::filesystem::path(output_iamf_directory) /
+       user_metadata.test_vector_metadata().file_name_prefix())
+          .string();
   LOG(INFO) << "output_wav_file_prefix = " << output_wav_file_prefix;
   auto mix_presentation_finalizer = CreateMixPresentationFinalizer(
       output_wav_file_prefix, output_wav_file_bit_depth_override,

iamf/cli/iamf_components.cc

@@ -54,8 +54,9 @@ std::vector<std::unique_ptr<ObuSequencerBase>> CreateObuSequencers(
   // TODO(b/314895932): Find a more portable alternative to `/dev/null/`.
   const std::string iamf_filename =
       prefix.empty() ? "/dev/null"
-                     : std::filesystem::path(output_iamf_directory) /
-                           std::filesystem::path(absl::StrCat(prefix, ".iamf"));
+                     : (std::filesystem::path(output_iamf_directory) /
+                        std::filesystem::path(absl::StrCat(prefix, ".iamf")))
+                           .string();
   obu_sequencers.emplace_back(std::make_unique<ObuSequencerIamf>(
       iamf_filename, include_temporal_delimiters, *leb_generator));
 

iamf/cli/wav_sample_provider.cc

@@ -60,7 +60,7 @@ absl::Status WavSampleProvider::Initialize(
                                audio_frame_metadata.wav_filename();
 
     auto wav_reader = WavReader::CreateFromFile(
-        wav_filename,
+        wav_filename.string(),
         static_cast<size_t>(codec_config.GetNumSamplesPerFrame()));
     if (!wav_reader.ok()) {
       return wav_reader.status();