private static VBRData getFhGInfo(BufferedBinaryReader source)
{
VBRData result = new VBRData();
byte[] data = new byte[9];
// Extract FhG VBR info at given position
result.Found = true;
result.ID = VBR_ID_FHG.ToCharArray();
source.Seek(5, SeekOrigin.Current);
source.Read(data, 0, 9);
result.Scale = data[0];
result.Bytes =
data[1] * 0x1000000 +
data[2] * 0x10000 +
data[3] * 0x100 +
data[4];
result.Frames =
data[5] * 0x1000000 +
data[6] * 0x10000 +
data[7] * 0x100 +
data[8];
result.VendorID = "";
return(result);
}
private static VBRData findVBR(BufferedBinaryReader source, long position)
{
VBRData result;
byte[] data = new byte[4];
// Check for VBR header at given position
source.Seek(position, SeekOrigin.Begin);
source.Read(data, 0, 4);
string vbrId = Utils.Latin1Encoding.GetString(data);
if (VBR_ID_XING.Equals(vbrId))
{
result = getXingInfo(source);
}
else if (VBR_ID_FHG.Equals(vbrId))
{
result = getFhGInfo(source);
}
else
{
result = new VBRData();
result.Reset();
}
return(result);
}
// ---------------------------------------------------------------------------
private VBRData FindVBR(ushort Index, byte[] Data)
{
VBRData result = new VBRData();
// Check for VBR header at given position
result.Found = false;
Array.Clear(result.ID, 0, result.ID.Length);
result.Frames = 0;
result.Bytes = 0;
result.Scale = 0;
result.VendorID = "";
char[] tempArray = new char[4] {
(char)Data[Index], (char)Data[Index + 1], (char)Data[Index + 2], (char)Data[Index + 3]
};
if (Utils.StringEqualsArr(VBR_ID_XING, tempArray))
{
result = GetXingInfo(Index, Data);
}
if (Utils.StringEqualsArr(VBR_ID_FHG, tempArray))
{
result = GetFhGInfo(Index, Data);
}
return(result);
}
private static VBRData getXingInfo(BufferedBinaryReader source)
{
VBRData result = new VBRData();
byte[] data = new byte[8];
result.Found = true;
result.ID = VBR_ID_XING.ToCharArray();
source.Seek(4, SeekOrigin.Current);
source.Read(data, 0, 8);
result.Frames =
data[0] * 0x1000000 +
data[1] * 0x10000 +
data[2] * 0x100 +
data[3];
result.Bytes =
data[4] * 0x1000000 +
data[5] * 0x10000 +
data[6] * 0x100 +
data[7];
source.Seek(103, SeekOrigin.Current);
result.Scale = source.ReadByte();
source.Read(data, 0, 8);
result.VendorID = Utils.Latin1Encoding.GetString(data, 0, 8);
return(result);
}
// ---------------------------------------------------------------------------
private VBRData GetFhGInfo(ushort Index, byte[] Data)
{
VBRData result = new VBRData();
// Extract FhG VBR info at given position
result.Found = false;
Array.Clear(result.ID, 0, result.ID.Length);
result.Frames = 0;
result.Bytes = 0;
result.Scale = 0;
result.VendorID = "";
result.Found = true;
result.ID = VBR_ID_FHG.ToCharArray();
result.Scale = Data[Index + 9];
result.Bytes =
Data[Index + 10] * 0x1000000 +
Data[Index + 11] * 0x10000 +
Data[Index + 12] * 0x100 +
Data[Index + 13];
result.Frames =
Data[Index + 14] * 0x1000000 +
Data[Index + 15] * 0x10000 +
Data[Index + 16] * 0x100 +
Data[Index + 17];
return(result);
}
// ---------------------------------------------------------------------------
private FrameData FindFrame(byte[] Data, ref VBRData oVBR)
{
byte[] HeaderData = new byte[4];
FrameData result = new FrameData();
// Search for valid frame
//FillChar(result, sizeof(result), 0);
result.Found = false;
result.Position = 0;
result.Size = 0;
result.Xing = false;
Array.Clear(result.Data, 0, result.Data.Length);
result.VersionID = 0;
result.LayerID = 0;
result.ProtectionBit = false;
result.BitRateID = 0;
result.SampleRateID = 0;
result.PaddingBit = false;
result.PrivateBit = false;
result.ModeID = 0;
result.ModeExtensionID = 0;
result.CopyrightBit = false;
result.OriginalBit = false;
result.EmphasisID = 0;
Array.Copy(Data, HeaderData, 4);
for (uint iterator = 0; iterator <= Data.Length - MAX_MPEG_FRAME_LENGTH; iterator++)
{
// Decode data if frame header found
if (IsFrameHeader(HeaderData))
{
DecodeHeader(HeaderData, ref result);
// Check for next frame and try to find VBR header
if (ValidFrameAt((ushort)(iterator + GetFrameLength(result)), Data))
{
result.Found = true;
result.Position = (int)iterator;
result.Size = GetFrameLength(result);
result.Xing = IsXing((ushort)(iterator + 4), Data);
oVBR = FindVBR((ushort)(iterator + GetVBRDeviation(result)), Data);
break;
}
}
// Prepare next data block
HeaderData[0] = HeaderData[1];
HeaderData[1] = HeaderData[2];
HeaderData[2] = HeaderData[3];
HeaderData[3] = Data[iterator + 4];
}
return(result);
}
// ---------------------------------------------------------------------------
private VBRData GetXingInfo(ushort Index, byte[] Data)
{
VBRData result = new VBRData();
// Extract Xing VBR info at given position
result.Found = false;
Array.Clear(result.ID, 0, result.ID.Length);
result.Frames = 0;
result.Bytes = 0;
result.Scale = 0;
result.VendorID = "";
result.Found = true;
result.ID = VBR_ID_XING.ToCharArray();
result.Frames =
Data[Index + 8] * 0x1000000 +
Data[Index + 9] * 0x10000 +
Data[Index + 10] * 0x100 +
Data[Index + 11];
result.Bytes =
Data[Index + 12] * 0x1000000 +
Data[Index + 13] * 0x10000 +
Data[Index + 14] * 0x100 +
Data[Index + 15];
result.Scale = Data[Index + 119];
// Vendor ID can be not present
char[] tempArray = new char[8] {
(char)(Data[Index + 120]),
(char)(Data[Index + 121]),
(char)(Data[Index + 122]),
(char)(Data[Index + 123]),
(char)(Data[Index + 124]),
(char)(Data[Index + 125]),
(char)(Data[Index + 126]),
(char)(Data[Index + 127])
};
result.VendorID = new String(tempArray);
return(result);
}
private static FrameHeader findFrame(BufferedBinaryReader source, ref VBRData oVBR, SizeInfo sizeInfo)
{
byte[] headerData = new byte[4];
FrameHeader result = new FrameHeader();
source.Read(headerData, 0, 4);
result.Found = isValidFrameHeader(headerData);
/*
* Many things can actually be found before a proper MP3 header :
* - Padding with 0x55, 0xAA and even 0xFF bytes
* - RIFF header declaring either MP3 or WAVE data
* - Xing encoder-specific frame
* - One of the above with a few "parasite" bytes before their own header
*
* The most solid way to deal with all of them is to "scan" the file until proper MP3 header is found.
* This method may not the be fastest, but ensures audio data is actually detected, whatever garbage lies before
*/
if (!result.Found)
{
// "Quick win" for files starting with padding bytes
// 4 identical bytes => MP3 starts with padding bytes => Skip padding
if ((headerData[0] == headerData[1]) && (headerData[1] == headerData[2]) && (headerData[2] == headerData[3]))
{
// Scan the whole padding until it stops
while (headerData[0] == source.ReadByte())
{
;
}
source.Seek(-1, SeekOrigin.Current);
// If padding uses 0xFF bytes, take one step back in case MP3 header lies there
if (0xFF == headerData[0])
{
source.Seek(-1, SeekOrigin.Current);
}
source.Read(headerData, 0, 4);
result.Found = isValidFrameHeader(headerData);
}
// Blindly look for the MP3 header
if (!result.Found)
{
source.Seek(-4, SeekOrigin.Current);
long limit = sizeInfo.ID3v2Size + (long)Math.Round((source.Length - sizeInfo.ID3v2Size) * 0.3);
// Look for the beginning of the MP3 header (2nd byte is variable, so it cannot be searched that way)
while (!result.Found && source.Position < limit)
{
while (0xFF != source.ReadByte() && source.Position < limit)
{
;
}
source.Seek(-1, SeekOrigin.Current);
source.Read(headerData, 0, 4);
result.Found = isValidFrameHeader(headerData);
// Valid header candidate found
// => let's see if it is a legit MP3 header by using its Size descriptor to find the next header
if (result.Found)
{
result.LoadFromByteArray(headerData);
result.Position = source.Position - 4;
result.Size = getFrameSize(result);
byte[] nextHeaderData = new byte[4];
source.Seek(result.Position + result.Size, SeekOrigin.Begin);
source.Read(nextHeaderData, 0, 4);
result.Found = isValidFrameHeader(nextHeaderData);
if (result.Found)
{
source.Seek(result.Position + 4, SeekOrigin.Begin); // Go back to header candidate position
break;
}
else
{
// Restart looking for a candidate
source.Seek(result.Position + 1, SeekOrigin.Begin);
}
}
else
{
source.Seek(-3, SeekOrigin.Current);
}
}
}
}
if (result.Found)
{
result.LoadFromByteArray(headerData);
result.Position = source.Position - 4;
// result.Xing = isXing(i + 4, Data); // Will look into it when encoder ID is needed by upper interfaces
// Look for VBR signature
oVBR = findVBR(source, result.Position + getVBRDeviation(result));
}
return(result);
}
// ---------------------------------------------------------------------------
private FrameData FindFrame(byte[] Data, ref VBRData oVBR)
{
byte[] HeaderData = new byte[4];
FrameData result = new FrameData();
// Search for valid frame
//FillChar(result, sizeof(result), 0);
result.Found = false;
result.Position = 0;
result.Size = 0;
result.Xing = false;
Array.Clear(result.Data,0,result.Data.Length);
result.VersionID = 0;
result.LayerID = 0;
result.ProtectionBit = false;
result.BitRateID = 0;
result.SampleRateID = 0;
result.PaddingBit = false;
result.PrivateBit = false;
result.ModeID = 0;
result.ModeExtensionID = 0;
result.CopyrightBit = false;
result.OriginalBit = false;
result.EmphasisID = 0;
Array.Copy(Data, HeaderData, 4);
for (uint iterator=0; iterator <= Data.Length - MAX_MPEG_FRAME_LENGTH; iterator++)
{
// Decode data if frame header found
if ( IsFrameHeader(HeaderData) )
{
DecodeHeader(HeaderData, ref result);
// Check for next frame and try to find VBR header
if ( ValidFrameAt((ushort)(iterator + GetFrameLength(result)), Data) )
{
result.Found = true;
result.Position = (int)iterator;
result.Size = GetFrameLength(result);
result.Xing = IsXing((ushort)(iterator + 4), Data);
oVBR = FindVBR((ushort)(iterator + GetVBRDeviation(result)), Data);
break;
}
}
// Prepare next data block
HeaderData[0] = HeaderData[1];
HeaderData[1] = HeaderData[2];
HeaderData[2] = HeaderData[3];
HeaderData[3] = Data[iterator + 4];
}
return result;
}
// ---------------------------------------------------------------------------
private VBRData FindVBR(ushort Index, byte[] Data)
{
VBRData result = new VBRData();
// Check for VBR header at given position
result.Found = false;
Array.Clear(result.ID,0,result.ID.Length);
result.Frames = 0;
result.Bytes = 0;
result.Scale = 0;
result.VendorID = "";
char[] tempArray = new char[4] { (char)Data[Index], (char)Data[Index+1], (char)Data[Index+2], (char)Data[Index+3] };
if ( Utils.StringEqualsArr(VBR_ID_XING,tempArray) ) result = GetXingInfo(Index, Data);
if ( Utils.StringEqualsArr(VBR_ID_FHG,tempArray) ) result = GetFhGInfo(Index, Data);
return result;
}
// ---------------------------------------------------------------------------
private VBRData GetFhGInfo(ushort Index, byte[] Data)
{
VBRData result = new VBRData();
// Extract FhG VBR info at given position
result.Found = false;
Array.Clear(result.ID,0,result.ID.Length);
result.Frames = 0;
result.Bytes = 0;
result.Scale = 0;
result.VendorID = "";
result.Found = true;
result.ID = VBR_ID_FHG.ToCharArray();
result.Scale = Data[Index + 9];
result.Bytes =
Data[Index + 10] * 0x1000000 +
Data[Index + 11] * 0x10000 +
Data[Index + 12] * 0x100 +
Data[Index + 13];
result.Frames =
Data[Index + 14] * 0x1000000 +
Data[Index + 15] * 0x10000 +
Data[Index + 16] * 0x100 +
Data[Index + 17];
return result;
}
// ---------------------------------------------------------------------------
private VBRData GetXingInfo(ushort Index, byte[] Data)
{
VBRData result = new VBRData();
// Extract Xing VBR info at given position
result.Found = false;
Array.Clear(result.ID,0,result.ID.Length);
result.Frames = 0;
result.Bytes = 0;
result.Scale = 0;
result.VendorID = "";
result.Found = true;
result.ID = VBR_ID_XING.ToCharArray();
result.Frames =
Data[Index + 8] * 0x1000000 +
Data[Index + 9] * 0x10000 +
Data[Index + 10] * 0x100 +
Data[Index + 11];
result.Bytes =
Data[Index + 12] * 0x1000000 +
Data[Index + 13] * 0x10000 +
Data[Index + 14] * 0x100 +
Data[Index + 15];
result.Scale = Data[Index + 119];
// Vendor ID can be not present
char[] tempArray = new char[8] {
(char)(Data[Index + 120]),
(char)(Data[Index + 121]),
(char)(Data[Index + 122]),
(char)(Data[Index + 123]),
(char)(Data[Index + 124]),
(char)(Data[Index + 125]),
(char)(Data[Index + 126]),
(char)(Data[Index + 127]) };
result.VendorID = new String(tempArray);
return result;
}
