How to convert YUV422 to YUV420
I want to get data using H.264 form camera preview, normal camera isYv12, so I can use:
public byte[] YV12toYUV420PackedSemiPlanar(final byte[] input, final byte[] output, final int width, final int height)
{
this.halfWidth = width / 2;
this.halfHeight = height / 2;
this.frameRate = framerate;
this.yStride = (int) Math.ceil(width/16.0f) * 16;
this.cStride = (int) Math.ceil(width/32.0f) * 16;
this.ySize = yStride * height;
this.cSize = cStride * height / 2;
for (int i=0; i<height; i++)
System.arraycopy(input, yStride*i, output, yStride*i, yStride); // Y
for (int i=0; i<halfHeight; i++)
{
for (int j=0; j<halfWidth; j++)
{
output[ySize + (i*halfWidth + j)*2] = input[ySize + cSize + i*cStride + j]; // Cb (U)
output[ySize + (i*halfWidth + j)*2 + 1] = input[ySize + i*cStride + j]; // Cr (V)
}
}
return output;
}
but now my camera preview is yuv422, so how to convert YUV422 to YUV420 using java, i am looking for some c methods and theory but i cant convert it successfully.
I used this: am I right?
static void yuyv_to_yuv420PackedSemiPlanar( byte[] yuyv, byte[] yuv, int w, int h ) {
int expected_length;
int actual_length;
actual_length = yuyv.length;
expected_length = PixelFormat.V4L2_PIX_FMT_YUYV.frameSize( w, h );
if ( actual_length < expected_length ) {
throw new IllegalArgumentException( "invalid input buffer length " + actual_length + " for yuyv image of size ( " + w + ", " + h + " ). Should be " + expected_length );
}
actual_length = yuv.length;
expected_length = PixelFormat.V4L2_PIX_FMT_RGB24.frameSize( w, h );
if ( actual_length < expected_length ) {
throw new IllegalArgumentException( "invalid output buffer length " + actual_length + " for yuv image of size ( " + w + ", " + h + " ). Should be " + expected_length );
}
for( int i = 0, j = 0; i < w * h * 3; i += 6, j += 4 ) {
yuv[ i + 0 ] = yuyv[ j + 0 ];
yuv[ i + 1 ] = yuyv[ j + 1 ];
yuv[ i + 2 ] = yuyv[ j + 3 ];
yuv[ i + 3 ] = yuyv[ j + 2 ];
yuv[ i + 4 ] = yuyv[ j + 1 ];
yuv[ i + 5 ] = yuyv[ j + 3 ];
}
}
+3
source to share
2 answers
Here is a sample code that converts from YUV422 (yuyv, V4L2_PIX_FMT_YUYV, interleaved format) to YUV420SP (NV21, V4L2_PIX_FMT_NV21, semi-flat format).
struct pixel_yvuv {
uint8_t Y0;
uint8_t V;
uint8_t Y1;
uint8_t U;
};
struct pixel_NV21_y_plane{
uint8_t Y0;
uint8_t Y1;
uint8_t Y2;
uint8_t Y3;
};
struct pixel_NV21_uv_plane{
uint8_t U;
uint8_t V;
};
/*
SRC
-------
Y0V0Y1U1
Y2V1Y3U1
....
....
....
....
DST
-------
Y0Y1Y2Y3
...
...
U0V0
...
*/
void
yuyv422_to_yuv420sp(unsigned char *bufsrc, unsigned char *bufdest, int width, int height, bool flipuv)
{
int i,j;
volatile struct pixel_yvuv* src;
volatile struct pixel_NV21_y_plane* dst_p1;
volatile struct pixel_NV21_uv_plane* dst_p2;
src = (struct pixel_yvuv*)bufsrc;
/* plane 1 */
dst_p1 = (struct pixel_NV21_y_plane*) bufdest;
/* plane 2 */
dst_p2 = (struct pixel_NV21_uv_plane*) (bufdest + (height*width)); /* offset to UV plane */
for(i=1; i<=height; i++)
{
for(j=1; j<=width/2; j++)
{
if(j%2) {
dst_p1->Y0 = src->Y0;
dst_p1->Y1 = src->Y1;
} else {
dst_p1->Y2 = src->Y0;
dst_p1->Y3 = src->Y1;
dst_p1++;
}
/* vertical subsampling for U and V plane */
if(i%2) {
/* U and V Plane */
if(flipuv) {
dst_p2->U = src->U;
dst_p2->V = src->V;
} else {
dst_p2->U = src->V;
dst_p2->V = src->U;
}
dst_p2++;
}
src++;
}
}
}
0
source to share