private bool int_FindFirstHeader(Stream i_Stream)
{
try
{
// Go to start of file
i_Stream.Seek(0, SeekOrigin.Begin);
if (m_FirstHeader == null)
m_FirstHeader = new MP3Header();
BinaryReader Reader = new BinaryReader(i_Stream);
if (Reader == null)
{
Debugger.Trace("There was an error opening the BinaryReader to initialize the MP3File");
return false;
}
BufferedReader MyReader = new BufferedReader(Reader, 1024);
MP3Header NextHeader = new MP3Header();
byte[] HeaderBuffer = new byte[4];
HeaderBuffer[0] = MyReader.ReadByte();
HeaderBuffer[1] = MyReader.ReadByte();
HeaderBuffer[2] = MyReader.ReadByte();
HeaderBuffer[3] = MyReader.ReadByte();
// Find the first valid header
while (!m_FirstHeader.IsValid || !NextHeader.IsValid)
{
// Find the next header tag
while ((HeaderBuffer[0] != 0xFF) || (HeaderBuffer[1] & 0xE0) != 0xE0)
{
// Get the Next Byte
HeaderBuffer[0] = HeaderBuffer[1];
HeaderBuffer[1] = HeaderBuffer[2];
HeaderBuffer[2] = HeaderBuffer[3];
HeaderBuffer[3] = MyReader.ReadByte();
}
if (m_FirstHeader.Initialize(HeaderBuffer, MyReader.Position - 4))
{
// Move to the next header to check if it is the same format
// make sure the reader can move that far forward
if (MyReader.MoveForward(m_FirstHeader.FrameSize - 4))
{
byte[] NextHeaderBuffer = new byte[4];
NextHeaderBuffer[0] = MyReader.ReadByte();
NextHeaderBuffer[1] = MyReader.ReadByte();
NextHeaderBuffer[2] = MyReader.ReadByte();
NextHeaderBuffer[3] = MyReader.ReadByte();
if ((NextHeaderBuffer[0] == 0xFF) && (NextHeaderBuffer[1] & 0xE0) == 0xE0)
{
if (NextHeader.Initialize(NextHeaderBuffer, MyReader.Position - 4))
{
// If it is not the same header as the previous one then reset it
if (NextHeader != m_FirstHeader)
NextHeader = new MP3Header();
}
}
MyReader.MoveBackward(m_FirstHeader.FrameSize);
}
}
// Get the Next Byte
HeaderBuffer[0] = HeaderBuffer[1];
HeaderBuffer[1] = HeaderBuffer[2];
HeaderBuffer[2] = HeaderBuffer[3];
HeaderBuffer[3] = MyReader.ReadByte();
}
return true;
}
catch (Exception ex)
{
Debugger.Trace(ex);
return false;
}
}
public override bool Trim(TimeSpan i_Start, TimeSpan i_End, String i_FileDestination)
{
try
{
if (!m_Initialized)
{
Debugger.Trace("MP3File.Trim() not initialized");
return false;
}
if (i_Start > i_End)
{
Debugger.Trace("MP3File.Trim() The End time is before the Start time");
return false;
}
if (i_End > m_SongLength)
{
Debugger.Trace("MP3File.Trim() The End time after the End of the song");
return false;
}
Debugger.Trace("Trimming the MP3 File");
if (m_FirstHeader == null)
m_FirstHeader = new MP3Header();
IsolatedStorageFile Store = IsolatedStorageFile.GetUserStoreForApplication();
if (!Store.FileExists(m_FileName))
{
Debugger.Trace("The mp3 file does not exist");
return false;
}
Debugger.Trace("Opening File streams");
using (IsolatedStorageFileStream OriginalStream = Store.OpenFile(m_FileName, FileMode.Open))
{
using (IsolatedStorageFileStream DestinationStream = Store.OpenFile(i_FileDestination, FileMode.Create))
{
OriginalStream.Seek(0, 0);
DestinationStream.Seek(0, 0);
BinaryReader Reader = new BinaryReader(OriginalStream);
if (Reader == null)
{
Debugger.Trace("There was an error opening the BinaryReader to trim the MP3File");
return false;
}
BinaryWriter Writer = new BinaryWriter(DestinationStream);
if (Writer == null)
{
Debugger.Trace("There was an error opening the BinaryWriter to trim the MP3File");
return false;
}
BufferedReader MyReader = new BufferedReader(Reader, 1024);
// Copy the Header information
Debugger.Trace("Copying meta data");
MyReader.MoveForward(m_FirstHeader.StartLocation);
//MyReader.Copy(Writer, m_FirstHeader.StartLocation);
// Skip over headers until we get to the start time
double CurTime = 0.0;
MP3Header NextHeader = new MP3Header();
byte[] HeaderBuffer = new byte[4];
HeaderBuffer[0] = MyReader.ReadByte();
HeaderBuffer[1] = MyReader.ReadByte();
HeaderBuffer[2] = MyReader.ReadByte();
HeaderBuffer[3] = MyReader.ReadByte();
while (CurTime < i_Start.TotalSeconds && NextHeader.Initialize(HeaderBuffer, MyReader.Position - 4))
{
// Update the time
CurTime += NextHeader.SamplesPerFrame / (double)NextHeader.SampleRate;
if (!MyReader.MoveForward(NextHeader.FrameSize - 4))
{
Debugger.Trace("Reached the end of the mp3 file");
return false;
}
HeaderBuffer[0] = MyReader.ReadByte();
HeaderBuffer[1] = MyReader.ReadByte();
HeaderBuffer[2] = MyReader.ReadByte();
HeaderBuffer[3] = MyReader.ReadByte();
}
// Copy Frames until we get to the end position
while (CurTime < i_End.TotalSeconds && NextHeader.Initialize(HeaderBuffer, MyReader.Position - 4))
{
// Update the time
CurTime += NextHeader.SamplesPerFrame / (double)NextHeader.SampleRate;
MyReader.MoveBackward(4);
MyReader.Copy(Writer, NextHeader.FrameSize);
HeaderBuffer[0] = MyReader.ReadByte();
HeaderBuffer[1] = MyReader.ReadByte();
HeaderBuffer[2] = MyReader.ReadByte();
HeaderBuffer[3] = MyReader.ReadByte();
}
Writer.Flush();
return true;
}
}
}
catch(Exception ex)
{
Debugger.Trace(ex);
return false;
}
}