[lwip-users] Error-"Incompatible Types"

[Teckinal Greek]

Hi all,

I am planning to implement RTP on lwIP in that means I am compressing the PCM data using a self written audio codec. 

For this I am using this piece of code to convert the data from Analog to Digital i.e to PCM[some functions are inbuilt functions on my Board]

int16_t pcm_buffer[1024] = {0};

void audio(void)

{

    int i, j;

    audio = audio_open(AUDIO_1);

    

    while (1)

    {

        get_audio(pcm_buf, 1024);

    }

}

int get_audio(short *buffer, int n)

{

    int s;

    do

    {

        s = audio_record(audio, buffer, n);

        n -= s;

        buffer += s;

    }while (n != 0);

    return s;

}

What I am assuming here is that the PCM data is stored in the buffer "pcm_buffer" and it is of int 16 bit.

My encoder code goes like this ....

unsigned char linear2alaw(int pcm_val) /*here we expect pcm_val to be 2's compliment which is of 16-bit-range */

{

    int sign, exponent, expMask, mantissa;

    unsigned char alaw;

    .......

    ........ 

   return (unsigned char)(alaw^0xD5);

}

In my RTP part of my code I need to put this compressed data on to a send buffer which is declared like  this......

#define RTP_PACKET_SIZE = 1500

static uint8_t rtp_send_packet[RTP_PACKET_SIZE];

Now I call the linear2alaw function pass the pcm value and again again the returned value to rtp_send_packet[] buffer like this.......

static uint8_t rtp_send_packet[RTP_PACKET_SIZE] = linear2alaw(stereo_buf);

When I compile my code it throws an error saying "incompatible types".

On the other hand if I assign this in another way like.......

static uint8_t rtp_send_packet[RTP_PACKET_SIZE] ;

rtp_send_packet[RTP_PACKET_SIZE] = linear2alaw(stereo_buf);

then it throws another error like ........"rtp_send_packet" redeclared with a different type"

Can anybody find out where am I making mistake. I am using lwIP TCP/IP stack for my implementation.

Regards,

Greek