I forgot to add the new file

crates/voicevox_core/src/engine/audio_file.rs

@@ -0,0 +1,34 @@
+use std::io::{Cursor, Write as _};
+
+/// 16bit PCMにヘッダを付加しWAVフォーマットのバイナリを生成する。
+pub fn wav_from_s16le(pcm: &[u8], output_sampling_rate: u32, output_stereo: bool) -> Vec<u8> {
+    // TODO: 44.1kHzなどの対応
+
+    let num_channels: u16 = if output_stereo { 2 } else { 1 };
+    let bit_depth: u16 = 16;
+    let block_size: u16 = bit_depth * num_channels / 8;
+
+    let bytes_size = pcm.len() as u32;
+    let wave_size = bytes_size + 44;
+
+    let buf: Vec<u8> = Vec::with_capacity(wave_size as usize);
+    let mut cur = Cursor::new(buf);
+
+    cur.write_all("RIFF".as_bytes()).unwrap();
+    cur.write_all(&(wave_size - 8).to_le_bytes()).unwrap();
+    cur.write_all("WAVEfmt ".as_bytes()).unwrap();
+    cur.write_all(&16_u32.to_le_bytes()).unwrap(); // fmt header length
+    cur.write_all(&1_u16.to_le_bytes()).unwrap(); //linear PCM
+    cur.write_all(&num_channels.to_le_bytes()).unwrap();
+    cur.write_all(&output_sampling_rate.to_le_bytes()).unwrap();
+
+    let block_rate = output_sampling_rate * block_size as u32;
+
+    cur.write_all(&block_rate.to_le_bytes()).unwrap();
+    cur.write_all(&block_size.to_le_bytes()).unwrap();
+    cur.write_all(&bit_depth.to_le_bytes()).unwrap();
+    cur.write_all("data".as_bytes()).unwrap();
+    cur.write_all(&bytes_size.to_le_bytes()).unwrap();
+    cur.write_all(&pcm).unwrap();
+    cur.into_inner()
+}