NScumm.Scumm.Audio.IMuse.IMuseInternal.FindStartOfSound C# (CSharp) Method

        internal protected byte[] FindStartOfSound(int sound, ChunkType ct = ChunkType.MThd | ChunkType.FORM)
        {
            int size, pos;

            var ptr = ScummEngine.Instance.ResourceManager.GetSound(ScummEngine.Instance.Sound.MusicType, sound);

            if (ptr == null)
            {
                Debug.WriteLine("IMuseInternal::findStartOfSound(): Sound {0} doesn't exist", sound);
                return null;
            }

            // Check for old-style headers first, like 'RO'
            const ChunkType trFlag = ChunkType.MThd | ChunkType.FORM;
            if (System.Text.Encoding.UTF8.GetString(ptr, 0, 3) == "ROL")
                return ct == trFlag ? ptr : null;
            if (System.Text.Encoding.UTF8.GetString(ptr, 4, 2) == "SO")
            {
                if (ct == trFlag)
                {
                    var tmp = new byte[ptr.Length - 4];
                    Array.Copy(ptr, 4, tmp, 0, tmp.Length);
                    return tmp;
                }
                return null;
            }

            var ids = new string[]
            {
                "MThd",
                "FORM",
                "MDhd",
                "MDpg"
            };

            using (var ms = new MemoryStream(ptr))
            {
                var br = new BinaryReader(ms);
                ms.Seek(4, SeekOrigin.Current);
                size = (int)br.ReadUInt32BigEndian();

                // Okay, we're looking for one of those things: either
                // an 'MThd' tag (for SMF), or a 'FORM' tag (for XMIDI).
                size = 48; // Arbitrary; we should find our tag within the first 48 bytes of the resource
                pos = 0;
                while (pos < size)
                {
                    for (int i = 0; i < ids.Length; ++i)
                    {
                        var sig = System.Text.Encoding.UTF8.GetString(br.ReadBytes(4));
                        ms.Seek(-4, SeekOrigin.Current);
                        if ((((int)ct) & (1 << i)) != 0 && (sig == ids[i]))
                        {
                            var tmp = new byte[ptr.Length - ms.Position];
                            Array.Copy(ptr, (int)ms.Position, tmp, 0, tmp.Length);
                            return tmp;
                        }
                    }
                    ++pos; // We could probably iterate more intelligently
                    ms.Seek(1, SeekOrigin.Current);
                }

                if (ct == (ChunkType.MThd | ChunkType.FORM))
                    Debug.WriteLine("IMuseInternal.FindStartOfSound(): Failed to align on sound {0}", sound);
            }

            return null;
        }