We are using a 3rd party API that processes video stream files to update a
data structure in the file.  I am writting a C# facade for this API but I am
having a hard time getting it to pass data correctly.  Can someone please
check out the approach I am using and give me some advice?

The API is structured where I initialize it by passing in two callback
methods.  These methods in my C# code are called by the API to read and write
buffers from the input or output files.  When I populate the "get" buffer in
the GetStreamBuf method I should see that same buffer in the subsequent
PutStreamBuf callback, but the PutStreamCallback appears to recieve an empty
buffer, as though the GetStreamBuf didn't really popultate the buffer.

//API Initialization
public delegate Int32 GetStreamBufCallback([In, Out] Byte[] Buf, Int32
buf_len);
public delegate Int32 PutStreamBufCallback([In, Out] Byte[] Buf, Int32
buf_len);

[DllImport("tableprocessor.dll", CharSet = CharSet.Ansi, EntryPoint = "#33",
CallingConvention=CallingConvention.StdCall)]
private static extern int InitProcessor(
GetStreamBufCallback GsCb,
PutStreamBufCallback PsCb,
Boolean enableLogging,
Int32 logLevel,
String logFile
);

//Callback methods
      System.IO.FileStream fsInput;
       Byte[] sharedGetBuf = new Byte[PACKET_SIZE];  //Allocate buffer
       Byte[] sharedPutBuf = new Byte[PACKET_SIZE];  //Allocate buffer

       public Int32 GetStreamBuf(Byte[] buf, Int32 bufSize)
       {
           if (fsInput != null)
           {
               if (fsInput.Read(sharedGetBuf, 0, bufSize) ==
TpFacade.PACKET_SIZE)
                   {
                   buf = sharedGetBuf;
                   return SUCCESS;                 //return callback status
to API
                   }
            }
         }

public Int32 PutStreamBuf(Byte[] buf, Int32 bufSize)
{
    sharedPutBuf = buf;
  //...
    return SUCCESS; //Success == 0

 }