Sure, I can help you with that. Here's some sample code that you can use as a starting point:
```c
#include <stdio.h>
#include <stdint.h>
#include <emmintrin.h>

void rgba_to_yuv420_sse2(uint8_t *rgba, uint8_t *y, uint8_t *u, uint8_t *v, int width, int height) {
    __m128i rfac = _mm_set1_epi16(19595);
    __m128i gfac = _mm_set1_epi16(38470);
    __m128i bfac = _mm_set1_epi16(7471);
    __m128i off = _mm_set1_epi16(1 << 13);
    int i, j;
    
    for (i = 0; i < height; i += 2) {
        for (j = 0; j < width; j += 8) {
            __m128i r0 = _mm_loadu_si128((__m128i *)(rgba + (i * width + j) * 4));
            __m128i r1 = _mm_loadu_si128((__m128i *)(rgba + ((i + 1) * width + j) * 4));
            __m128i r01lo = _mm_unpacklo_epi8(r0, r1);
            __m128i r01hi = _mm_unpackhi_epi8(r0, r1);
            __m128i r01l = _mm_unpacklo_epi16(r01lo, r01hi);
            __m128i r01h = _mm_unpackhi_epi16(r01lo, r01hi);
            __m128i r01 = _mm_add_epi32(_mm_mullo_epi16(r01l, rfac), _mm_mullo_epi16(r01h, rfac));
            
            __m128i g0 = _mm_loadu_si128((__m128i *)(rgba + (i * width + j) * 4 + 2));
            __m128i g1 = _mm_loadu_si128((__m128i *)(rgba + ((i + 1) * width + j) * 4 + 2));
            __m128i g01lo = _mm_unpacklo_epi8(g0, g1);
            __m128i g01hi = _mm_unpackhi_epi8(g0, g1);
            __m128i g01l = _mm_unpacklo_epi16(g01lo, g01hi);
            __m128i g01h = _mm_unpackhi_epi16(g01lo, g01hi);
            __m128i g01 = _mm_add_epi32(_mm_mullo_epi16(g01l, gfac), _mm_mullo_epi16(g01h, gfac));
            
            __m128i b0 = _mm_loadu_si128((__m128i *)(rgba + (i * width + j) * 4 + 1));
            __m128i b1 = _mm_loadu_si128((__m128i *)(rgba + ((i + 1) * width + j) * 4 + 1));
            __m128i b01lo = _mm_unpacklo_epi8(b0, b1);
            __m128i b01hi = _mm_unpackhi_epi8(b0, b1);
            __m128i b01l = _mm_unpacklo_epi16(b01lo, b01hi);
            __m128i b01h = _mm_unpackhi_epi16(b01lo, b01hi);
            __m128i b01
```
물론 도와드릴 수 있습니다. 다음은 시작점으로 사용할 수 있는 몇 가지 샘플 코드입니다:
```c
#include <stdio.h>
#include <stdint.h>
#include <emmintrin.h>

void rgba_to_yuv420_sse2(uint8_t *rgba, uint8_t *y, uint8_t *u, uint8_t *v, int width, int height) {
    __M128I RFAC = _MM_SET1_EPI16(19595);
    __m128i gfac = _mm_set1_epi16(38470);
    __M128I BFAC = _MM_SET1_EPI16(7471);
    __M128I OFF = _MM_SET1_EPI16(1 << 13);
    int i, j;
    
    for (i = 0; i < height; i += 2) {
        for (j = 0; j < width; j += 8) {
            __m128i r0 = _mm_loadu_si128((__m128i *)(rgba + (i * width + j) * 4));
            __m128i r1 = _mm_loadu_si128((__m128i *)(rgba + ((i + 1) * width + j) * 4));
            __M128I R01LO = _MM_UNPACKLO_EPI8(R0, R1);
            __M128I R01HI = _MM_UNPACKHI_EPI8(R0, R1);
            M128I R01L = _MM_UNPACKLO_EPI16(R01LO, R01HI);
            M128I R01H = _MM_UNPACKHI_EPI16(R01LO, R01HI);
            M128I R01 = _MM_ADD_EPI32(_MM_MULLO_EPI16(R01L, RFAC), _MM_MULLO_EPI16(R01H, RFAC));
            
            __M128I G0 = _MM_LOAD_SI128((__M128I *)(RGBA + (I * WIDTH + J) * 4 + 2));
            __m128i g1 = _mm_loadu_si128((__m128i *)(rgba + ((i + 1) * width + j) * 4 + 2));
            __M128I G01LO = _MM_UNPACKLO_EPI8(G0, G1);
            __M128I G01HI = _MM_UNPACKHI_EPI8(G0, G1);
            __M128I G01L = _MM_UNPACKLO_EPI16(G01LO, G01HI);
            __M128I G01H = _MM_UNPACKHI_EPI16(G01LO, G01HI);
            M128I G01 = _MM_ADD_EPI32(_MM_MULLO_EPI16(G01L, GFAC), _MM_MULLO_EPI16(G01H, GFAC));
            
            __M128I B0 = _MM_LOAD_SI128((__M128I *)(RGBA + (I * WIDTH + J) * 4 + 1));
            __m128i b1 = _mm_loadu_si128((__m128i *)(rgba + ((i + 1) * width + j) * 4 + 1));
            __M128I B01LO = _MM_UNPACKLO_EPI8(B0, B1);
            __M128I B01HI = _MM_UNPACKHI_EPI8(B0, B1);
            __M128I B01L = _MM_UNPACKLO_EPI16(B01LO, B01HI);
            __M128I B01H = _MM_UNPACKHI_EPI16(B01LO, B01HI);
            __M128I B01
```