YUV格式、RGB格式、JPEG格式、MJPEG格式之间的转换（C程序）之一

1. Convert YUV420p to YUV422sp

2. Convert YUV422sp to YUV420sp

3. Convert YUV420sp to YUV420p

4. Convert YUV422sp to YUV420p

/* Convert YUV420p to YUV422sp */

void convert_yuv420p_to_yuv422sp(char *inbuf, char *outbuf, int width, int height){

        long int i, k, j;

        long YSize = width * height;

        for (i = 0, j = 1; i < height; i += 2, j += 2)

        {

                long int line1 = i * width;

                long int line2 = j * width;

                long int UOffset1 = YSize + line1 / 4;

                long int VOffset1 = YSize * 5 / 4 + line1 / 4;

                long int m = line1 * 2;

                long int n = line2 * 2;

                for(k = 0; k < width / 4; k++){

                        unsigned char Y1, Y2, Y3, Y4, Y5, Y6, Y7, Y8;

                        unsigned char U1, U2, V1, V2;

                        U1 = inbuf[UOffset1++];U2 = inbuf[UOffset1++];

                        V1 = inbuf[VOffset1++];V2 = inbuf[VOffset1++];

                        Y1 = inbuf[line1++];Y2 = inbuf[line1++];

                        Y3 = inbuf[line1++];Y4 = inbuf[line1++];

                        Y5 = inbuf[line2++];Y6 = inbuf[line2++];

                        Y7 = inbuf[line2++];Y8 = inbuf[line2++];

                        outbuf[m++] = Y1;outbuf[m++] = U1;

                        outbuf[m++] = Y2;outbuf[m++] = V1;

                        outbuf[m++] = Y3;outbuf[m++] = U2;

                        outbuf[m++] = Y4;outbuf[m++] = V2;

                        outbuf[n++] = Y5;outbuf[n++] = U1;

                        outbuf[n++] = Y6;outbuf[n++] = V1;

                        outbuf[n++] = Y7;outbuf[n++] = U2;

                        outbuf[n++] = Y8;outbuf[n++] = V2;

                }

        }
}

/* Convert YUV422sp to YUV420sp */ 

void convert_yuv422sp_to_yuv420sp(unsigned char *InBuff, unsigned char *OutBuff, int width, int height)

{

        //LOGI("convert_yuv422sp_to_yuv420sp:width=%d, height=%d\n", width, height);

        int line1 = 0, line2 = 0;

        int m = 0, n = 0;

        int y = 0, u = width * height;

        for (int i = 0, j = 1; i < height; i += 2, j += 2)

        {

                /* Input Buffer Pointer Indexes */

                line1 = i * width * 2;

                line2 = j * width * 2;

                /* Output Buffer Pointer Indexes */

                m = width * y;

                y = y + 1;

                n = width * y;

                y = y + 1;

                /* Scan two lines at a time */

                for (int k = 0; k < (width * 2); k += 4)

                {

                        unsigned char Y1, Y2, U, V;

                        unsigned char Y3, Y4, U2, V2;

                        /* Read Input Buffer */

                        Y1 = InBuff[line1++];

                        U  = InBuff[line1++];

                        Y2 = InBuff[line1++];

                        V  = InBuff[line1++];

                        Y3 = InBuff[line2++];

                        U2 = InBuff[line2++];

                        Y4 = InBuff[line2++];

                        V2 = InBuff[line2++];

                        /* Write Output Buffer */

                        OutBuff[m++] = Y1;

                        OutBuff[m++] = Y2;

                        OutBuff[n++] = Y3;

                        OutBuff[n++] = Y4;

                        OutBuff[u++] = (V + V2)/2;

                        OutBuff[u++] = (U + U2)/2;

                }

        }

}

/* Convert YUV420sp to YUV420p */ 

void convert_yuv420sp_to_yuv420p(unsigned char *InBuff, unsigned char *OutBuff, int width, int height)

{

        LOGI("convert_yuv422sp_to_yuv420p:width=%d, height=%d\n", width, height);

        int i = 0;

        // Copy Y first

        for (i = 0; i < width * height; i++)

        {

                OutBuff[i] = InBuff[i];

        }

        int p = width * height;

        int q = (width * height) * 5/4;

        // Copy U and V

        for (; i < (width * height * 3/2);)

        {

                // V

                OutBuff[q++] = InBuff[i++];

                // U

                OutBuff[p++] = InBuff[i++];

        }

}

/* Convert YUV422sp to YUV420p */

void convert_yuv422sp_to_yuv420p(unsigned char *InBuff, unsigned char *OutBuff, int width, int height)

{

        int UOffset = width * height;

        int VOffset = (width * height) * 5/4;

        int UVSize = (width * height) / 4;

        int line1 = 0, line2 = 0;

        int m = 0, n = 0;

        int y = 0, u = 0, v = 0;

        u = UOffset;

        v = VOffset;

        LOGI("convert_yuv422sp_to_yuv420p:width=%d, height=%d\n", width, height);

#if BLACK_AND_WHITE

        memset (OutBuff, 127, (width * height * 2));

        for (int i = 0, j = 0; i < (width * height * 2); i+=4)

        {

                OutBuff[j++] = InBuff[i];

                OutBuff[j++] = InBuff[i + 2];

        }

#else

        for (int i = 0, j = 1; i < height; i += 2, j += 2)

        {

                /* Input Buffer Pointer Indexes */

                line1 = i * width * 2;

                line2 = j * width * 2;

                /* Output Buffer Pointer Indexes */

                m = width * y;

                y = y + 1;

                n = width * y;

                y = y + 1;

                /* Scan two lines at a time */

                for (int k = 0; k < (width * 2); k += 4)

                {

                        unsigned char Y1, Y2, U, V;

                        unsigned char Y3, Y4, U2, V2;

                        /* Read Input Buffer */

                        Y1 = InBuff[line1++];

                        U  = InBuff[line1++];

                        Y2 = InBuff[line1++];

                        V  = InBuff[line1++];

                        Y3 = InBuff[line2++];

                        U2 = InBuff[line2++];

                        Y4 = InBuff[line2++];

                        V2 = InBuff[line2++];

                        /* Write Output Buffer */

                        OutBuff[m++] = Y1;

                        OutBuff[m++] = Y2;

                        OutBuff[n++] = Y3;

                        OutBuff[n++] = Y4;

                        OutBuff[u++] = (U + U2)/2;

                        OutBuff[u++] = (V + V2)/2;

                }

        }

#endif

}