void *melp_rec(void)
{
int length, frame,count, melp_file_count;
int eof_reached = 0;
//int num_frames = 0;
//short speech_in[11];
short speech_out[FRM];
unsigned char enc_speech[11];
FILE *fp_in, *fp_out;
melpe_i();
melp_file_count = 0;
printf("\n1.2 kb/s Proposed Federal Standard MELP speech coder by Jawad\n");
printf(" C simulation, version 1.0\n\n");
while (1)
{
sem_wait(&melp_start);
melp_file_count = melp_file_count + 1;
if(melp_file_count % 2 == 1)
{
fp_in = fopen("out1.bit" ,"rb");
fp_out = fopen("record0.raw","wb");
}
else
{
fp_in = fopen("out2.bit" ,"rb");
fp_out = fopen("record1.raw","wb");
}
eof_reached = 0;
while (eof_reached == 0)
{
length = fread(&enc_speech,sizeof(char),11,fp_in);
melpe_s(speech_out, enc_speech);
fwrite(speech_out,sizeof(short),FRM,fp_out);
///if (length < FRAME)
if (length < 11)
{
eof_reached = 1;
printf("eof reached \n");
}
}
fclose(fp_in);
fclose(fp_out);
eof_reached = 0;
sem_post(&play_start);
}
pthread_exit(NULL);
}
//*****************************************************************************
//receiving loop: grab 48KHz baseband samples from Line,
//demodulate, decrypt, decode, play 8KHz voice over Speaker
int rx(int typing)
{
//input: -1 for no typing chars, 1 - exist some chars in input buffer
//output: 0 - no any jobs doing, 1 - some jobs were doing
int i;
float f;
int job=0; //flag of any job were doing
char lag_flag=0; //block lag is locked (modems synchronization complete)
//char lock_flag=0; //phase of carrier (1333Hz, 6 samples per period) is locked
//char sync_flag=0; //the difference of frequency transmitter-to-receiver sampling rate is locked
//char current_lag=0; //block lag (0-90, aligned to last bit position, the 6 samples for bit)
char info[8]={0}; //call info
//regularly play Speaker's buffer
job=playjit(); //the first try to play a tail of samples in buffer
//check for we have enough samples for demodulation
if(cnt<180*6) //check we haven't enough of unprocessed samples
{
//move tail to start of receiving buffer
if(samples>speech) //check for tail
{
for(i=0; i<cnt; i++) speech[i]=samples[i]; //move tail to start of buffer
samples=speech; //set pointer to start of buffer
}
//record
i=_soundgrab((char*)(samples+cnt), 180*6); //try to grab new 48KHZ samples from Line
if((i>0)&&(i<=(180*6))) //some samples grabbed
{
cnt+=i; //add grabbed samples to account
job+=4; //set job
}
}
else //we have enough samples for processing
{
i=Demodulate(samples, buf); //process samples: 36*6 (35-37)*6 samples
samples+=i; //move pointer to next samples (with frequency adjusting)
cnt-=i; //decrease the number of unprocessed samples
if(0x80&buf[11]) //checks flag for output data block is ready
{
//check for synck and averages BER
lag_flag=!(!(buf[11]&0x40)); //block lag is locked (synchronization compleet)
//lock_flag=!(!(buf[11]&0x20)); //phaze of carrier (1333Hz, 6 samples per period) is locked
//sync_flag=!(!(buf[11]&0x10)); //the differency of frequency transmitter-to-receiver sampling rate is locked
//current_lag=buf[10]>>1; //block lag (0-90, aligned to last bit position, the 6 samples for bit)
if(lag_flag) //check modem sync
{
//averages BER
i=(0x0F&buf[11]); //count symbols errors (only 1 error per 9-bit symbol can be detected)
fber*=0.99; //fber in range 0-900
fber+=i; //in range 0-9 errored bits per 90 bits treceived
}
//output statistics
if(typing<0) //output call's info if no characters were typed by user
{
f=Mute(0); //get packets counter value
i=State(0); //get current connection step * vad flag
//notification of state and voice output
if(!i) strcpy(info, (char*)"IDLE");
else if(abs(i)<8) strcpy(info, (char*)"CALL");
else if(f<=0) strcpy(info, (char*)"MUTE");
else if(i<0) strcpy(info, (char*)"PAUS");
else strcpy(info, (char*)"TALK");
if(f<0) f=-f; //absolute value
i=f*0.0675; //computes total time of the call in sec: each packet 67,5 ms
f=fau/4-100; //computes authentification level in %
if(f<0) f=0; //only positive results have reason
//current state notification
if(lag_flag) printf("%s %dmin %dsec BER:%0.02f AU:%d%%\r", info, i/60, i%60, fber/90, (int)f);
else printf("%s %dmin %dsec BER:---- AU:%d%%\r", info, i/60, i%60, (int)f); //lost of sync in modem
}
//process received packet detects voice/silence type
buf[11]=0xFE; //set flag default as for silence descriptor
if(lag_flag) //check modem sync
{
i=ProcessPkt(buf); //decode received packet
if(i>=0) //received packet is a control type
{
fau*=0.99; //fau in range 0-800 (400 for random data)
fau+=i; //averages authentication level
}
else if(i==-3)
{
buf[11]=0xFF; //set flag for voice data received
}
} //end of sync ok, packets processing
} //end of data block received
} //end of a portion of sampless processing
//check we have received data and output buffer is empty for decoding
if((0x0E&buf[11])&&(l_jit_buf<=180))
{
//decode voice data or set silency
job+=16; //set job
if(1&buf[11]) //this is a voice frame, decode it
{
melpe_s(sp, buf); //decode 81 bits in 11 bytes to 540 8KHz samples
}
else memset(sp, 0, 1080); //or output 67.5 mS of silence
buf[11]=0; //clears flag: data buffer is processed
//computes average playing delay
i=getdelay()+l_jit_buf; //total number of unplayed samples in buffers
fdelay*=0.9; //averages
fdelay+=i;
//computes optimal resapling ratio for the optimum delay
f=fabs(fdelay/10-720)/10000000; //correction rate due inconsistency
if(i<360) qff-=f; //adjust current ratio
else if(i>1080) qff+=f;
if(qff<0.888) qff=0.888; //restrictions
else if(qff>1.142) qff=1.142;
//resample and play to Headset
if(l_jit_buf>180) l_jit_buf=0; //prevent overflow
l_jit_buf+=resample(sp, jit_buf+l_jit_buf, qff); //resample buffer for playing
playjit(); //immediately try to play buffer
}
return job;
}
