Redesign audio to support multiple audio tracks explicitly

src/Utils.cpp

@@ -22,6 +22,11 @@ namespace gsr {
         }
     }
 
+    bool starts_with(std::string_view str, const char *substr) {
+        size_t len = strlen(substr);
+        return str.size() >= len && memcmp(str.data(), substr, len) == 0;
+    }
+
     std::string get_home_dir() {
         const char *home_dir = getenv("HOME");
         if(!home_dir) {