/// <summary>
/// Finds the <see cref="VbriHeader"/> header within the <paramref name="firstFrame"/>.
/// </summary>
/// <param name="firstFrame">The first frame.</param>
/// <returns>The VBRI header if found; otherwise, null.</returns>
/// <remarks>
/// The VBRI header is located exactly 32 bytes after the end of the first MPEG audio header in the file.
/// It will compare the first 4 bytes against the <see cref="HeaderIndicator"/>
/// to see if the header contains a <see cref="VbriHeader"/> or not.
/// </remarks>
public static new VbriHeader FindHeader(MpaFrame firstFrame)
{
if (firstFrame == null)
throw new ArgumentNullException("firstFrame");
using (StreamBuffer buffer = new StreamBuffer())
{
byte[] data = firstFrame.ToByteArray();
buffer.Write(data);
// 32 bytes = data indicating silence
const long Offset = MpaFrame.FrameHeaderSize + SilenceDataSize;
buffer.Seek(Offset, SeekOrigin.Begin);
string tagName = buffer.ReadString(4, false, false);
return String.Compare(tagName, HeaderIndicator, StringComparison.OrdinalIgnoreCase) == 0
? new VbriHeader(firstFrame, buffer, Offset)
: null;
}
}
/// <summary>
/// Finds the <see cref="VbriHeader"/> header within the <paramref name="firstFrame"/>.
/// </summary>
/// <param name="firstFrame">The first frame.</param>
/// <returns>The VBRI header if found; otherwise, null.</returns>
/// <remarks>
/// The XING header is located after the side information in Layer III in the first MPEG audio header in the file.
/// It will compare the first 4 bytes against the <see cref="VbrHeaderIndicator"/>
/// to see if the header contains a <see cref="XingHeader"/> or not.
/// </remarks>
public static new XingHeader FindHeader(MpaFrame firstFrame)
{
if (firstFrame == null)
throw new ArgumentNullException("firstFrame");
long offset = MpaFrame.FrameHeaderSize + firstFrame.SideInfoSize;
using (StreamBuffer buffer = new StreamBuffer())
{
byte[] data = firstFrame.ToByteArray();
buffer.Write(data);
buffer.Seek(offset, SeekOrigin.Begin);
string tagName = buffer.ReadString(4, false, false);
if ((String.Compare(tagName, VbrHeaderIndicator, StringComparison.OrdinalIgnoreCase) == 0)
|| (String.Compare(tagName, CbrHeaderIndicator, StringComparison.OrdinalIgnoreCase) == 0))
return new XingHeader(firstFrame, buffer, offset);
}
return null;
}
