bad working mcu with _delay_ms()

hi guys

i use timer1 for send NTSC Signal To Composite TV.

but my problem is this :
i want after 1 secound delay change frame buffer inormation but when i call _delay_ms(1000) , i see big noise on tv.

even i replace _delay_ms() with a long while() loop, but i see big noise again;

my code is :


/*
*
* ATmega32a NTSC Video Signal Generator
* CPU Frequency : 20 MHz
*
* ------------------------------------------------------------
* Pin Used : PORTB0 --> Sync Signal
* PORTB5 (MOSI) --> Video Signal
* ------------------------------------------------------------
*
* Written by : Majid Soltani
*
* Date : 1394/01/06
* Firmware Version : 1.1
*
* Tested on : JVC 15" CRT TV
* Sony 32" LCD
* EasyCAP USB Video Capture
*/


#define F_CPU 20000000UL
#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include "header/Pattern.h"
#include "header/Main_Config.h"
#include "header/delay.h"

uint16_t rasterline=0; // Counting lines drawn on TV
unsigned char line_row asm("line_r") = 0;
unsigned int screen_row asm("scr_r") = 0;
//Main Screen buffer for Drawn
unsigned int Screen[19*28] asm("sc_b")={
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x080,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x080,0x000,0x000,0x000,0x000,0x000,0x080,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x080,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x080,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x040,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,
0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000,0x000};

/* Video buffer */
/* Timers and SPI initialization */
void timer_init(void){
line_row = 0;
screen_row = 0;

init_sync_port;

TCCR1B = (1<<WGM12);
TIMSK |= (1<<OCIE1A);
TCNT1 = 0;
OCR1A = 1270;
TCCR1B |= (1<<CS10);
}

/* Timer interrupt */
ISR (TIMER1_COMPA_vect) {

if((rasterline > 31 && rasterline <= 255))
{ // ____________
_delay_us(1.5); // Front porch ( FP ) ___| |_
blank_sync; // ___/ |
_delay_us(4.7); // Horizontal Black interval ( HSync ) __ __/\/\/\/\/\/\/\/\/\_| Draw Color |__
sync; // FP| HS |BP Color Burst FP
_delay_us(4.7); // Back porch ( BP ) ----


//------------- Patter Draw Start -----------
// R16 -> for read cell color for each row from PROGMEM array
// R30 & R31 -> for set address of POGMEM array
// R19 -> for get line_row variable value
// R26 & R28 -> for set address of screen array
// R17 -> value of each cell screen_row
// R21 -> Column Counter 0-9
asm volatile(" PUSH R16 \
\n PUSH R18 \
\n PUSH R17 \
\n PUSH R30 \
\n PUSH R31 \
\n PUSH R19 \
\n PUSH R20 \
\n PUSH R26 \
\n PUSH R27 \
\n PUSH R21 \
\n LDI R21,0 \
\n LDS R19,line_r \
\n LDI R30,lo8(scr_r) \
\n LDI R31,hi8(scr_r) \
\n LD R16,Z+ \
\n LD R20,Z+ \
\n LDI R26,lo8(sc_b) \
\n LDI R27,hi8(sc_b) \
\n ADD R26,R16 \
\n ADC R27,R20 \
\n;-------------------------------------\
\n LD R17,X+ \
\n LD R18,X+ \
\n LDI R30,lo8(sc_p) \
\n LDI R31,hi8(sc_p) \
\n ADD R30,R19 \
\n ADC R31,0 \
\n ADD R30,R17 \
\n ADC R31,R18 \
\n;-------------------------------------\
\n LOOP: \
\n;-------------------------------------\
\n LPM R16 , Z+ \
\n OUT 0x12 , R16 \
\n LD R17,X+ \
\n;-------------------------------------\
\n LPM R16 , Z+ \
\n OUT 0x12 , R16 \
\n LD R18,X+ \
\n;-------------------------------------\
\n LPM R16 , Z+ \
\n OUT 0x12 , R16 \
\n LDI R28,lo8(sc_p) \
\n LDI R29,hi8(sc_p) \
\n;-------------------------------------\
\n LPM R16 , Z+ \
\n OUT 0x12 , R16 \
\n ADD R28,R19 \
\n ADC R29,0 \
\n;-------------------------------------\
\n LPM R16 , Z+ \
\n OUT 0x12 , R16 \
\n ADD R28,R17 \
\n;-------------------------------------\
\n LPM R16 , Z+ \
\n OUT 0x12 , R16 \
\n ADC R29,R18 \
\n;-------------------------------------\
\n LPM R16 , Z+ \
\n OUT 0x12 , R16 \
\n INC R21 \
\n;-------------------------------------\
\n LPM R16 , Z \
\n OUT 0x12 , R16 \
\n MOVW R30,R28 \
\n;-------------------------------------\
\n CPI R21,0x13 \
\n BRNE LOOP \
\n OUT 0x12 , 0x0 \
\n End: POP R21 \
\n POP R27 \
\n POP R26 \
\n POP R20 \
\n POP R19 \
\n POP R31 \
\n POP R30 \
\n POP R17 \
\n POP R18 \
\n POP R16 ");

/* \n ADD R19,8 \
\n CPI R19,64 \
\n BRNE END \
\n LDI R19,0 \
\n END: STS line_r,R19 \
*/
line_row+=8;
if (line_row>=64){
line_row=0;
screen_row+=(unsigned int)0x26;
}

//------------- Pattern Draw ------------
} else if( rasterline >= 0 && rasterline < 3 ) { // Duration First of Sequence Vertical Sync
blank_sync;
_delay_us(2);
sync;
_delay_us(30);
blank_sync;
_delay_us(2);
sync;
} else if(rasterline >= 3 && rasterline <= 5) { // Duration Second of Sequence Vertical Sync
blank_sync;
_delay_us(29);
sync;
_delay_us(2);
blank_sync;
_delay_us(29);
sync;
} else if( rasterline >= 6 && rasterline < 9) { // Duration third of Sequence Vertical Sync
blank_sync;
_delay_us(2);
sync;
_delay_us(30);
blank_sync;
_delay_us(2);
sync;
}/* else if( rasterline > 9 && rasterline <= 31) {
} */else {
blank_sync;
_delay_us(4.5);
sync;
}

rasterline++;

if( rasterline > 262 ){
screen_row=rasterline = 0;
frame++;
}

}

/* Main */

int main() {
DDRD=0b11111111;

DDRB=0b11111011;
PORTB=0xFF;

DDRA |= 0xFF;
PORTA |=0xFF;

PORTC |=0xFF;
PORTC =0xFF;

timer_init();

sei();
while(1){
if ((PINB & (1 <<PINB2))==0){
Screen[270]=0x40;
// here i want set delay
Screen[270]=0x80;
// here i want set delay
}
else
Screen[270]=0x80;
}
for( ;; );
}

please help me...

Using delay should not create noise on your I/O pins. You should probably look at the circuit layout, PSU and ensure you have suitable decoupling capacitors, or maybe even a filter on the signal output.