fn read_tenc()

in mp4parse/src/lib.rs [5893:5931]

• 34 lines of code
• 1 McCabe index (conditional complexity)

fn read_tenc<T: Read>(src: &mut BMFFBox<T>) -> Result<TrackEncryptionBox> {
    let (version, _) = read_fullbox_extra(src)?;

    // reserved byte
    skip(src, 1)?;
    // the next byte is used to signal the default pattern in version >= 1
    let (default_crypt_byte_block, default_skip_byte_block) = match version {
        0 => {
            skip(src, 1)?;
            (None, None)
        }
        _ => {
            let pattern_byte = src.read_u8()?;
            let crypt_bytes = pattern_byte >> 4;
            let skip_bytes = pattern_byte & 0x0f;
            (Some(crypt_bytes), Some(skip_bytes))
        }
    };
    let default_is_encrypted = src.read_u8()?;
    let default_iv_size = src.read_u8()?;
    let default_kid = read_buf(src, 16)?;
    // If default_is_encrypted == 1 && default_iv_size == 0 we expect a default_constant_iv
    let default_constant_iv = match (default_is_encrypted, default_iv_size) {
        (1, 0) => {
            let default_constant_iv_size = src.read_u8()?;
            Some(read_buf(src, default_constant_iv_size.into())?)
        }
        _ => None,
    };

    Ok(TrackEncryptionBox {
        is_encrypted: default_is_encrypted,
        iv_size: default_iv_size,
        kid: default_kid,
        crypt_byte_block_count: default_crypt_byte_block,
        skip_byte_block_count: default_skip_byte_block,
        constant_iv: default_constant_iv,
    })
}