安卓 - 利用Renderscript将NV12 yuv转换为RGB

Question

安卓 - 利用Renderscript将NV12 yuv转换为RGB

3

我写了下面的代码来将NV12 YUV转换为RGB，但颜色不正确。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 代码：

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(x,y)是矩阵坐标，所以y应该在(x,y)，u应该在((x/2)*2,H + y/2)，v应该在u旁边，即((x/2)*2+1,H + y/2)。听起来这个逻辑是错误的！

- lucky1928

我能否使用renderscript将RGB转换为NV12格式？ - NeoWang

1个回答

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- beetlej · Accepted Answer

需要修正两个错误：

应该将-1改为~1，因为x & -1等于x，但是x & ~1会掩盖最后一位，以保持值偶数。
yuv矩阵大小不正确。由于uv向量存储在y数据的末尾，因此总矩阵大小应为W * H * 3/2。

应用这两个更改后，它可以正常工作。 java:

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;
}