diff --git a/src/audio/audio.h b/src/audio/audio.h
index 1bcb3512..bb15aaff 100644
--- a/src/audio/audio.h
+++ b/src/audio/audio.h
@@ -10,12 +10,19 @@
 namespace fs = std::filesystem;
 
 namespace audio {
+    /// @brief playing speaker uid
     using speakerid_t = int64_t;
-    /// @brief duration unit is second
+
+    /// @brief duration unit is a second
     using duration_t = double;
 
+    /// @brief not important sounds (steps, random noises)
     constexpr inline int PRIORITY_LOW = 0;
+
+    /// @brief default sounds priority
     constexpr inline int PRIORITY_NORMAL = 5;
+
+    /// @brief streams and important sounds
     constexpr inline int PRIORITY_HIGH = 10;
 
     class Speaker;
@@ -31,10 +38,16 @@ namespace audio {
     struct PCM {
         /// @brief May contain 8 bit and 16 bit PCM data
         std::vector<char> data;
+        /// @brief Total number of mono samples (sampleRate per second)
         size_t totalSamples;
+        /// @brief Track channels number (1 - mono, 2 - stereo)
         uint8_t channels;
+        /// @brief Sample bit depth (8 and 16 supported)
+        /// does not depend on the channels number
         uint8_t bitsPerSample;
+        /// @brief Number of mono samples per second (example: 44100)
         uint sampleRate;
+        /// @brief Audio source is seekable
         bool seekable;
 
         PCM(  
@@ -51,12 +64,8 @@ namespace audio {
             sampleRate(sampleRate),
             seekable(seekable) {}
 
-        inline size_t countSamplesMono() const {
-            return totalSamples / channels;
-        }
-
         inline duration_t getDuration() const {
-            return static_cast<duration_t>(countSamplesMono()) / 
+            return static_cast<duration_t>(totalSamples) / 
                    static_cast<duration_t>(sampleRate);
         }
     };
@@ -142,7 +151,7 @@ namespace audio {
     };
 
     /// @brief Sound is an audio asset that supposed to support many 
-    /// simultaneously playing instances with different sources.
+    /// simultaneously playing instances (speakers).
     /// So it's audio data is stored in memory.
     class Sound {
     public:
diff --git a/src/coders/ogg.cpp b/src/coders/ogg.cpp
index 2be7fe95..38e401b0 100644
--- a/src/coders/ogg.cpp
+++ b/src/coders/ogg.cpp
@@ -53,7 +53,7 @@ audio::PCM* ogg::load_pcm(const std::filesystem::path& file, bool headerOnly) {
                 data.insert(data.end(), std::begin(buffer), std::begin(buffer)+ret);
             }
         }
-        totalSamples = data.size();
+        totalSamples = data.size() / channels / 2;
     }
     ov_clear(&vf);
     return new PCM(std::move(data), totalSamples, channels, 16, sampleRate, seekable);
diff --git a/src/constants.h b/src/constants.h
index fffa9c22..bf7771f0 100644
--- a/src/constants.h
+++ b/src/constants.h
@@ -5,33 +5,33 @@
 #include <string>
 #include "typedefs.h"
 
-const int ENGINE_VERSION_MAJOR = 0;
-const int ENGINE_VERSION_MINOR = 20;
-const bool ENGINE_VERSION_INDEV = true;
+inline constexpr int ENGINE_VERSION_MAJOR = 0;
+inline constexpr int ENGINE_VERSION_MINOR = 20;
+inline constexpr bool ENGINE_VERSION_INDEV = true;
 #define ENGINE_VERSION_STRING "0.20"
 
-const int BLOCK_AIR = 0;
-const int ITEM_EMPTY = 0;
+inline constexpr int BLOCK_AIR = 0;
+inline constexpr int ITEM_EMPTY = 0;
 
-const int CHUNK_W = 16;
-const int CHUNK_H = 256;
-const int CHUNK_D = 16;
+inline constexpr int CHUNK_W = 16;
+inline constexpr int CHUNK_H = 256;
+inline constexpr int CHUNK_D = 16;
 
-const uint VOXEL_USER_BITS = 8;
-constexpr uint VOXEL_USER_BITS_OFFSET = sizeof(blockstate_t)*8-VOXEL_USER_BITS;
+inline constexpr uint VOXEL_USER_BITS = 8;
+inline constexpr uint VOXEL_USER_BITS_OFFSET = sizeof(blockstate_t)*8-VOXEL_USER_BITS;
 
-const int ITEM_ICON_SIZE = 48;
+inline constexpr int ITEM_ICON_SIZE = 48;
 
 /* Chunk volume (count of voxels per Chunk) */
-constexpr int CHUNK_VOL = (CHUNK_W * CHUNK_H * CHUNK_D);
+inline constexpr int CHUNK_VOL = (CHUNK_W * CHUNK_H * CHUNK_D);
 
 /* BLOCK_VOID is block id used to mark non-existing voxel (voxel of missing chunk) */
-const blockid_t BLOCK_VOID = std::numeric_limits<blockid_t>::max();
-const itemid_t ITEM_VOID = std::numeric_limits<itemid_t>::max();
+inline constexpr blockid_t BLOCK_VOID = std::numeric_limits<blockid_t>::max();
+inline constexpr itemid_t ITEM_VOID = std::numeric_limits<itemid_t>::max();
 
-const blockid_t MAX_BLOCKS = BLOCK_VOID;
+inline constexpr blockid_t MAX_BLOCKS = BLOCK_VOID;
 
-constexpr uint vox_index(uint x, uint y, uint z, uint w=CHUNK_W, uint d=CHUNK_D) {
+inline constexpr uint vox_index(uint x, uint y, uint z, uint w=CHUNK_W, uint d=CHUNK_D) {
 	return (y * d + z) * w + x;
 }