diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index e586818..7eb9bdf 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -24,7 +24,7 @@ target_sources(xsystem35 PRIVATE
   ags.c
   ald_manager.c
   alpha_plane.c
-  bgi.c
+  audio_meta.c
   bmp.c
   cache.c
   cali.c
diff --git a/src/bgi.c b/src/audio_meta.c
similarity index 57%
rename from src/bgi.c
rename to src/audio_meta.c
index f9a9f9d..95c8670 100644
--- a/src/bgi.c
+++ b/src/audio_meta.c
@@ -1,5 +1,5 @@
 /*
- * bgi.c: BGI (BGM information) parser
+ * audio_meta.c: BGI (BGM information) / WAI (wave information) parser
  *
  * Copyright (C) 1997-1998 Masaki Chikama (Wren) <chikama@kasumi.ipl.mech.nagoya-u.ac.jp>
  *               1998-                           <masaki-c@is.aist-nara.ac.jp>
@@ -23,10 +23,12 @@
 #include "config.h"
 
 #include <stdio.h>
+#include <stdlib.h>
 
 #include "portab.h"
 #include "system.h"
-#include "bgi.h"
+#include "audio_meta.h"
+#include "LittleEndian.h"
 
 #define BGI_MAX 100
 
@@ -82,3 +84,77 @@ bgi_t *bgi_find(int no) {
 	}
 	return NULL;
 }
+
+static int *wai_channels;
+static int wai_count;
+
+static void wai_unload(void) {
+	free(wai_channels);
+	wai_channels = NULL;
+	wai_count = 0;
+}
+
+bool wai_load(const char *path) {
+	wai_unload();
+	if (!path)
+		return false;
+
+	FILE *fp = fopen(path, "rb");
+	if (!fp)
+		return false;
+
+	uint8_t header[24];
+	if (fread(header, 1, sizeof(header), fp) != sizeof(header) ||
+		header[0] != 'X' || header[1] != 'I' || header[2] != '2' || header[3] != '\0')
+	{
+		WARNING("not WAI file");
+		fclose(fp);
+		return false;
+	}
+
+	int count = LittleEndian_getDW(header, 8);
+	if (count <= 0) {
+		WARNING("invalid WAI record count: %d", count);
+		fclose(fp);
+		return false;
+	}
+
+	int version = LittleEndian_getDW(header, 12);
+	if (version != 3) {
+		WARNING("unsupported WAI version: %d", version);
+		fclose(fp);
+		return false;
+	}
+
+	int *channels = calloc(count, sizeof(*channels));
+	if (!channels) {
+		fclose(fp);
+		return false;
+	}
+
+	uint8_t record[12];
+	for (int i = 0; i < count; i++) {
+		if (fread(record, 1, sizeof(record), fp) != sizeof(record)) {
+			WARNING("truncated WAI file");
+			free(channels);
+			fclose(fp);
+			return false;
+		}
+		channels[i] = LittleEndian_getDW(record, 8);
+	}
+
+	fclose(fp);
+	wai_channels = channels;
+	wai_count = count;
+	return true;
+}
+
+bool wai_loaded(void) {
+	return wai_channels != NULL;
+}
+
+int wai_mixch(int no) {
+	if (!wai_channels || no < 0 || no >= wai_count)
+		return -1;
+	return wai_channels[no];
+}
diff --git a/src/bgi.h b/src/audio_meta.h
similarity index 89%
rename from src/bgi.h
rename to src/audio_meta.h
index 0ede362..cefce41 100644
--- a/src/bgi.h
+++ b/src/audio_meta.h
@@ -1,5 +1,5 @@
 /*
- * bgi.c: BGI (BGM information) parser
+ * audio_meta.h: BGI (BGM information) / WAI (wave information) parser
  *
  * Copyright (C) 1997-1998 Masaki Chikama (Wren) <chikama@kasumi.ipl.mech.nagoya-u.ac.jp>
  *               1998-                           <masaki-c@is.aist-nara.ac.jp>
@@ -35,4 +35,8 @@ typedef struct {
 extern bool bgi_read(const char *path);
 extern bgi_t *bgi_find(int no);
 
+bool wai_load(const char *path);
+bool wai_loaded(void);
+int wai_mixch(int no);
+
 #endif /* _BGI_H__ */
diff --git a/src/bgm.emscripten.c b/src/bgm.emscripten.c
index fa37d16..44580d0 100644
--- a/src/bgm.emscripten.c
+++ b/src/bgm.emscripten.c
@@ -23,7 +23,7 @@
 #include "portab.h"
 #include "nact.h"
 #include "bgm.h"
-#include "bgi.h"
+#include "audio_meta.h"
 #include "system.h"
 
 bool musbgm_init(DRIFILETYPE type, int base_no) {
diff --git a/src/bgm.sdlmixer.c b/src/bgm.sdlmixer.c
index 99c7a54..35b39aa 100644
--- a/src/bgm.sdlmixer.c
+++ b/src/bgm.sdlmixer.c
@@ -32,7 +32,7 @@
 #include "system.h"
 #include "nact.h"
 #include "bgm.h"
-#include "bgi.h"
+#include "audio_meta.h"
 #include "music_private.h"
 #include "ald_manager.h"
 
diff --git a/src/pcm.sdlmixer.c b/src/pcm.sdlmixer.c
index 2349005..3f2cc14 100644
--- a/src/pcm.sdlmixer.c
+++ b/src/pcm.sdlmixer.c
@@ -35,8 +35,7 @@
 #include "music_pcm.h"
 #include "music_private.h"
 #include "nact.h"
-#include "LittleEndian.h"
-#include "mmap.h"
+#include "audio_meta.h"
 
 #define SAMPLE_RATE 44100
 #define BYTES_PER_SAMPLE 4
@@ -51,12 +50,6 @@ static struct {
 	uint32_t start_time;
 } slots[PCM_SLOTS];
 
-static bool load_wai();
-static mmap_t *wai_map;
-
-// Volume mixer channel
-#define WAIMIXCH(no) LittleEndian_getDW(wai_map->addr, 36 + (no -1) * 4 * 3 + 8)
-
 // Apply the slot's volume valancer level via its chunk volume.
 static void apply_valance(int slot) {
 	if (!slots[slot].chunk)
@@ -152,7 +145,7 @@ bool muspcm_init(int audio_buffer_size) {
 	if (Mix_OpenAudio(SAMPLE_RATE, AUDIO_S16LSB, 2, audio_buffer_size) < 0)
 		return false;
 	Mix_AllocateChannels(PCM_SLOTS);
-	load_wai();
+	wai_load(nact->files.wai);
 	return true;
 }
 
@@ -177,8 +170,8 @@ bool muspcm_load_no(int slot, int no) {
 	}
 	
 	// if has .wai file
-	if (wai_map) {
-		int ch = WAIMIXCH(no);
+	if (wai_loaded()) {
+		int ch = wai_mixch(no);
 		prv.vol_pcm_sub[slot] = ch < 0 ? 0: ch;
 	} else {
 		prv.vol_pcm_sub[slot] = SE_VOLVAL_CH;
@@ -333,24 +326,3 @@ void muspcm_reapply_valance(void) {
 	for (int slot = 0; slot < PCM_SLOTS; slot++)
 		apply_valance(slot);
 }
-
-static bool load_wai() {
-	if (wai_map) {
-		unmap_file(wai_map);
-		wai_map = NULL;
-	}
-	if (nact->files.wai == NULL)
-		return false;
-	wai_map = map_file(nact->files.wai);
-	if (!wai_map)
-		return false;
-
-	char *adr = wai_map->addr;
-	if (*adr != 'X' || *(adr+1) != 'I' || *(adr+2) != '2') {
-		WARNING("not WAI file");
-		unmap_file(wai_map);
-		wai_map = NULL;
-		return false;
-	}
-	return true;
-}