private void WriteVbrHeader(bool isPlaceholder)
        {
            var buffer = new byte[GetFrameLength(_mpegVersion, 64000, _sampleRate, 0)];

            if (!isPlaceholder)
            {
                uint header     = _firstFrameHeader;
                int  dataOffset = GetFrameDataOffset(_mpegVersion, _channelMode);
                header &= 0xFFFE0DFF;                                                                                   // Clear CRC, bitrate, and padding fields
                header |= (uint)(_mpegVersion == 3 ? 5 : 8) << 12;                                                      // 64 kbit/sec
                BitHelper.CopyBytes(buffer, 0, BigEndianBitConverter.GetBytes(header));
                BitHelper.CopyBytes(buffer, dataOffset, BigEndianBitConverter.GetBytes(0x58696E67));                    // "Xing"
                BitHelper.CopyBytes(buffer, dataOffset + 4, BigEndianBitConverter.GetBytes((uint)0x7));                 // Flags
                BitHelper.CopyBytes(buffer, dataOffset + 8, BigEndianBitConverter.GetBytes((uint)_frameOffsets.Count)); // Frame count
                BitHelper.CopyBytes(buffer, dataOffset + 12, BigEndianBitConverter.GetBytes(_totalFrameLength));        // File length

                for (int i = 0; i < 100; i++)
                {
                    int frameIndex = (int)((i / 100.0) * _frameOffsets.Count);

                    buffer[dataOffset + 16 + i] = (byte)(_frameOffsets[frameIndex] / (double)_totalFrameLength * 256.0);
                }
            }

            _fileStream.Write(buffer, 0, buffer.Length);
        }