android-Renderscript將NV12 yuv轉換為RGB

Question

我寫下面的代碼將NV12 yuv轉換為RGB，但顏色不正確。 yuv2rgb.rs

#pragma version(1)
#pragma rs java_package_name(com.example.myexam)
#pragma rs_fp_relaxed

rs_allocation gYUV;
uint32_t gW;
uint32_t gH;

uchar4 __attribute__((kernel)) YUV2RGB(uint32_t x,uint32_t y)
{
    uchar yps = rsGetElementAt_uchar(gYUV, x, y);
    uchar u = rsGetElementAt_uchar(gYUV,(x & ~1),gH + (y>>1));
    uchar v = rsGetElementAt_uchar(gYUV,(x & ~1)+1,gH + (y>>1));
    uchar4 rgb = rsYuvToRGBA_uchar4(yps, u, v);
    return rgb;
}

Java代碼：

public Bitmap NV12_toRGB(byte[] yuv,int W,int H) {
    RenderScript rs = RenderScript.create(this);
    Type.Builder yuvBlder = new Type.Builder(rs, Element.U8(rs))
            .setX(W).setY(H*3/2);
    Allocation allocIn = Allocation.createTyped(rs,yuvBlder.create(),Allocation.USAGE_SCRIPT);
    Type rgbType = Type.createXY(rs, Element.RGBA_8888(rs), W, H);
    Allocation allocOut = Allocation.createTyped(rs,rgbType,Allocation.USAGE_SCRIPT);

    ScriptC_yuv2rgb scriptC_yuv2rgb = new ScriptC_yuv2rgb(rs);
    scriptC_yuv2rgb.set_gW(W);
    scriptC_yuv2rgb.set_gH(H);
    allocIn.copyFrom(yuv);
    scriptC_yuv2rgb.set_gYUV(allocIn);
    scriptC_yuv2rgb.forEach_YUV2RGB(allocOut);

    Bitmap bmp = Bitmap.createBitmap(W, H, Bitmap.Config.ARGB_8888);
    allocOut.copyTo(bmp);

    allocIn.destroy();
    scriptC_yuv2rgb.destroy();
    return bmp;
}

我猜想（x，y）是矩陣坐標，所以y應該在（x，y）處，u應該在（（x / 2）* 2，H + y / 2），v應該在u旁邊，（（x / 2）* 2 + 1，H + y / 2）。 聽起來這種邏輯是錯誤的！

Answer 1

需要修復兩個錯誤：

1. -1應該為〜1，因為x＆-1剛好等於x，但是x＆〜1將掩蓋最后一位，因此請保持值均勻。
2. yuv矩陣大小不正確。 由於uv向量存儲在y數據的末尾，因此總矩陣大小應為W * H * 3/2。

應用這兩個更改后，它可以正常工作。 Java的：

public Bitmap YUV_toRGB(byte[] yuv,int W,int H) {
        RenderScript rs = RenderScript.create(this);
        Type.Builder yuvBlder = new Type.Builder(rs, Element.U8(rs))
                .setX(W).setY(H*3/2);
        Allocation allocIn = Allocation.createTyped(rs,yuvBlder.create(),Allocation.USAGE_SCRIPT);
        Type rgbType = Type.createXY(rs, Element.RGBA_8888(rs), W, H);
        Allocation allocOut = Allocation.createTyped(rs,rgbType,Allocation.USAGE_SCRIPT);

        ScriptC_yuv2rgb scriptC_yuv2rgb = new ScriptC_yuv2rgb(rs);
        allocIn.copyFrom(yuv);
        scriptC_yuv2rgb.set_gW(W);
        scriptC_yuv2rgb.set_gH(H);
        scriptC_yuv2rgb.set_gYUV(allocIn);
        scriptC_yuv2rgb.forEach_YUV2RGB(allocOut);

        Bitmap bmp = Bitmap.createBitmap(W, H, Bitmap.Config.ARGB_8888);
        allocOut.copyTo(bmp);

        allocIn.destroy();
        scriptC_yuv2rgb.destroy();
        return bmp;
    }

yuv2rgb.rs

#pragma version(1)
#pragma rs java_package_name(com.example.myexam)
#pragma rs_fp_relaxed

rs_allocation gYUV;
uint32_t gW;
uint32_t gH;

uchar4 __attribute__((kernel)) YUV2RGB(uint32_t x,uint32_t y)
{
    uchar yps = rsGetElementAt_uchar(gYUV, x, y);
    uchar u = rsGetElementAt_uchar(gYUV,(x & ~1),gH + (y>>1));
    uchar v = rsGetElementAt_uchar(gYUV,(x & ~1)+1,gH + (y>>1));
    uchar4 rgb = rsYuvToRGBA_uchar4(yps, u, v);
    return rgb;
}