/// <summary>
/// Quickly checks an array of bytes to see if it represents a valid AAC frame header.
/// </summary>
/// <param name="frameHeader">Bytes representing an AAC frame header.</param>
/// <returns>true if the supplied bytes are a valid frame header, otherwise, false.</returns>
public static bool IsValidFrame(byte[] frameHeader)
{
if (frameHeader == null)
{
throw new ArgumentNullException("frameHeader");
}
int value = BitTools.MaskBits(frameHeader, 0, 12);
if (value != AacpFrame.syncValue)
{
return(false);
}
int sampleRate = AacpFrame.ParseSampleRate(frameHeader);
if (sampleRate == -1)
{
return(false);
}
int numberOfChannels = AacpFrame.ParseChannel(frameHeader);
if (numberOfChannels == -1)
{
return(false);
}
return(true);
}
/// <summary>
/// Initializes a new instance of the AacpFrame class.
/// </summary>
/// <remarks>
/// <para>
/// This class is a partial implementation of an AAC audio frame. The primary purpose of this class is to represent an AAC
/// file. Many of the features not explicitly needed for audio rendering are omitted from the implementation.
/// </para>
/// <para>
/// Data on this format is readily discoverable in many books as well as by
/// searching for "AAC Frame" in your favorite search engine. As always,
/// Wikipedia is well stocked in all of these areas as well.
/// </para>
/// </remarks>
/// <param name="frameHeader">Byte array containing 4 bytes representing an AAC header.</param>
public AacpFrame(byte[] frameHeader)
: base()
{
if (frameHeader == null)
{
throw new ArgumentNullException("frameHeader");
}
// Sync
int value = BitTools.MaskBits(frameHeader, 0, 12);
if (value != syncValue)
{
throw new ArgumentException("Invalid sync value.");
}
this.NumberOfChannels = AacpFrame.ParseChannel(frameHeader);
this.SamplingRate = AacpFrame.ParseSampleRate(frameHeader);
this.BitRate = AacpFrame.CalculateBitRate(this.SamplingRate, this.NumberOfChannels);
this.FrameSize = AacpFrame.ParseFrameSize(frameHeader);
int objectTypeId = BitTools.MaskBits(frameHeader, 16, 2);
}