feat: added audio type detector

um_audio/src/lib.rs

@@ -0,0 +1,131 @@
+mod metadata;
+
+use std::fmt::Display;
+use thiserror::Error;
+
+#[derive(Error, Debug, Clone)]
+pub enum AudioError {
+    #[error("Require at least {0} bytes of header.")]
+    NeedMoreHeader(usize),
+}
+
+pub const MASK_LOSSLESS: u32 = 0x80000000;
+
+#[repr(u32)]
+#[derive(Debug, PartialEq, Eq)]
+pub enum AudioType {
+    Unknown = 0,
+
+    // Lossy
+    OGG = 1,
+    AAC = 2,
+    MP3 = 3,
+    M4A = 4,
+    M4B = 5,
+    MP4 = 6,
+    WMA = 7, // While possible, it is rare to find a lossless WMA file.
+
+    // Lossless
+    FLAC = MASK_LOSSLESS | 1,
+    DFF = MASK_LOSSLESS | 2,
+    WAV = MASK_LOSSLESS | 3,
+    APE = MASK_LOSSLESS | 5,
+}
+
+impl AudioType {
+    pub fn as_str(&self) -> &str {
+        match self {
+            AudioType::OGG => "ogg",
+            AudioType::AAC => "aac",
+            AudioType::MP3 => "mp3",
+            AudioType::M4A => "m4a",
+            AudioType::M4B => "m4b",
+            AudioType::MP4 => "mp4",
+            AudioType::WMA => "wma",
+            AudioType::FLAC => "flac",
+            AudioType::DFF => "dff",
+            AudioType::WAV => "wav",
+            AudioType::APE => "ape",
+
+            _ => "bin",
+        }
+    }
+}
+
+impl Display for AudioType {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.as_str())
+    }
+}
+
+fn is_mp3(magic: u32) -> bool {
+    // Frame sync should have the first 11 bits set to 1.
+    const MP3_AND_MASK: u32 = 0b1111_1111_1110_0000u32 << 16;
+    const MP3_EXPECTED: u32 = 0b1111_1111_1110_0000u32 << 16;
+
+    (magic & MP3_AND_MASK) == MP3_EXPECTED
+}
+
+fn is_aac(magic: u32) -> bool {
+    // Frame sync should have the first 12 bits set to 1.
+    const AAC_AND_MASK: u32 = 0b1111_1111_1111_0110u32 << 16;
+    const AAC_EXPECTED: u32 = 0b1111_1111_1111_0000u32 << 16;
+
+    (magic & AAC_AND_MASK) == AAC_EXPECTED
+}
+
+const MAGIC_FLAC: [u8; 4] = *b"fLaC";
+const MAGIC_OGG: [u8; 4] = *b"OggS";
+const MAGIC_DFF: [u8; 4] = *b"FRM8";
+const MAGIC_WMA: [u8; 4] = *b"\x30\x26\xB2\x75";
+const MAGIC_WAV: [u8; 4] = *b"RIFF";
+const MAGIC_APE: [u8; 4] = *b"MAC ";
+
+pub fn detect_audio_type(buffer: &[u8]) -> Result<AudioType, AudioError> {
+    let offset = metadata::get_header_metadata_size(buffer, 0)?;
+    if buffer.len() < offset + 0x10 {
+        Err(AudioError::NeedMoreHeader(offset + 0x10))?;
+    }
+    let buffer = &buffer[offset..];
+    let mut magic = [0u8; 4];
+    magic.copy_from_slice(&buffer[..4]);
+    match magic {
+        MAGIC_FLAC => return Ok(AudioType::FLAC),
+        MAGIC_OGG => return Ok(AudioType::OGG),
+        MAGIC_DFF => return Ok(AudioType::DFF),
+        MAGIC_WMA => return Ok(AudioType::WMA),
+        MAGIC_WAV => return Ok(AudioType::WAV),
+        MAGIC_APE => return Ok(AudioType::APE),
+        _ => {}
+    }
+    let magic = u32::from_be_bytes(magic);
+    if is_aac(magic) {
+        return Ok(AudioType::AAC);
+    } else if is_mp3(magic) {
+        return Ok(AudioType::MP3);
+    }
+
+    // MP4 Containers
+    if &buffer[0x04..0x08] == b"ftyp" {
+        let mut magic = [0u8; 4];
+        magic.copy_from_slice(&buffer[0x08..0x0c]);
+        match &magic {
+            // MSNV: SonyPSP
+            // isom / iso2: MP4 (Generic?)
+            b"isom" | b"iso2" | b"MSNV" => return Ok(AudioType::MP4),
+            b"NDAS" => return Ok(AudioType::M4A), // Nero Digital AAC Audio
+            _ => {}
+        };
+
+        let mut magic = [0u8; 3];
+        magic.copy_from_slice(&buffer[0x08..0x0b]);
+        match &magic {
+            b"M4A" => return Ok(AudioType::M4A), // iTunes AAC-LC Audio
+            b"M4B" => return Ok(AudioType::M4B), // iTunes AAC-LC Audio
+            b"mp4" => return Ok(AudioType::MP4), // QQMusic
+            _ => {}
+        };
+    }
+
+    Ok(AudioType::Unknown)
+}