Encoding and decoding problem in speex 1.0.4

I am using the speex 1.0.4 library from windows.
I have posted my problem before but didn't get a solution. I am doing an VoIP project
In which I am recording sound and streaming it to the peer. I wanted to encode and decode
Wav files that brought me to this site.

I am recording sound in the following format :-

M_waveformatex.wformattag = wave_format_pcm;
M_waveformatex.nchannels = 1;
M_waveformatex.wbitspersample = 8;
M_waveformatex.cbsize = 0;
M_waveformatex.nsamplespersec = 8000;
M_waveformatex.nblockalign = 1;
M_waveformatex.navgbytespersec = 8000;

The recording is as follows :-

When the buffer (size = 2000 bytes) gets filled with sound data
Function with the body shown
Below is called.

Lpwavehdr lphdr = (lpwavehdr) lparam;
If (lphdr-> dwbytesrecorded = 0 | lphdr = NULL)
Return error_success;
: Waveinunprepareheader (m_hrecord, lphdr, sizeof (wavehdr ));

Here lphdr-> lpdata contains the audio data in a character array.

Now here I want to use speex codec for encoding the data so the Encoding
Function is
Called (I am thankful to Tay yueweng for the function ).

Char * encode (char * buffer, Int & encodesize)
{
Char * encodedbuffer = new char [recbuffer/2];/* recbuffer = 2000 */
Short speexshort;
Float speexfloat [recbuffer/2];
Void * mencode = speex_encoder_init (& speex_nb_mode );

/* Initialization of the structure that holds the bits */
Speex_bits_init (& Mbits );

// Convert the audio to a short then to a float Buffer
Int halfbuffersize = recbuffer/2;

For (INT I = 0; I {
Memcpy (& speexshort, & buffer [I * 2], sizeof (short ));
Speexfloat [I] = speexshort;
}

// Encode the sound data using the float Buffer
Speex_bits_reset (& Mbits );
Speex_encode (mencode, speexfloat, & Mbits );
Encodesize = speex_bits_write (& Mbits, encodedbuffer, recbuffer/2 );

/* Destroy the encoder state */
Speex_encoder_destroy (mencode );
/* Destroy the bit-stream struct */
Speex_bits_destroy (& Mbits );

// Return the encoded Buffer
Return encodedbuffer;
}

Here I noticed that though my captured audio data is 2000 bytes
Compressed form is
Always 38 bytes. In the speexfloat array above I get values in the range
-32767 to + 32767.
Is it correct. Also after calling the 'speex _ encode' function the first
160 values in
Input float array I. e. speexfloat is changed (Why does it happen? Is
Anything abnormal ).

Further after calling the above function for testing I decode
Returned encoded data
Immediately by calling the decoding function shown bellow :-

Char * decode (char * buffer, int encodesize)
{
Char * decodedbuffer = new char [recbuffer];
Short speexshort;
Float speexfloat [recbuffer/2];
// Decode the sound data into a float Buffer
Void * mdecode = speex_decoder_init (& speex_nb_mode );

/* Initialization of the structure that holds the bits */
Speex_bits_init (& Mbits );

Int halfbuffersize = recbuffer/2;
Speex_bits_reset (& Mbits );
Speex_bits_read_from (& Mbits, buffer, encodesize );
Speex_decode (mdecode, & Mbits, speexfloat );
// Convert from float to short to Char

For (INT I = 0; I {
Speexshort = speexfloat [I];
Memcpy (& decodedbuffer [I * 2], & speexshort, sizeof (short ));
}

/* Destroy the decoder state */
Speex_encoder_destroy (mdecode );
/* Destroy the bit-stream truct */
Speex_bits_destroy (& Mbits );

// Return the buffer
Return decodedbuffer;
}

After decoding using the above function only the first 160 values in the decodedbuffer array is changed. i. e I encoded an 2000 byte audio data to get a 38 byte encoded audio data. on Decoding the 38 byte audio data I get an decompressed 160 byte data. I don't understand whats going wrong. I checked all the messages posted in this newsgroup and did' nt find an answer so I am posting this code hoping that it gets solved soon. thanks in advance.