安卓MediaCodec解码YUV420结果转换位图比较高性能的方法

private static ScriptIntrinsicYuvToRGB yuvToRgbIntrinsic;
private static ScriptC_yuv420888 yuv420888;
private static Type.Builder typeUcharY;
private static Type.Builder typeUcharUV;

private static RenderScript renderScript;
public Bitmap YUV_420_888_toRGB(Image image, int width, int height){
    // Get the three image planes
    Image.Plane[] planes = image.getPlanes();
    ByteBuffer buffer = planes[0].getBuffer();
    byte[] y = new byte[buffer.remaining()];
    buffer.get(y);

    buffer = planes[1].getBuffer();
    byte[] u = new byte[buffer.remaining()];
    buffer.get(u);

    buffer = planes[2].getBuffer();
    byte[] v = new byte[buffer.remaining()];
    buffer.get(v);

    // get the relevant RowStrides and PixelStrides
    // (we know from documentation that PixelStride is 1 for y)
    int yRowStride= planes[0].getRowStride();
    int uvRowStride= planes[1].getRowStride();  // we know from   documentation that RowStride is the same for u and v.
    int uvPixelStride= planes[1].getPixelStride();  // we know from   documentation that PixelStride is the same for u and v.

    if (yuv420888 == null) {
        yuv420888 = new ScriptC_yuv420888 (renderScript);
        typeUcharY = new Type.Builder(renderScript, Element.U8(renderScript));
        typeUcharUV= new Type.Builder(renderScript, Element.U8(renderScript));
    }

    // Y,U,V are defined as global allocations, the out-Allocation is the Bitmap.
    // Note also that uAlloc and vAlloc are 1-dimensional while yAlloc is 2-dimensional.
    typeUcharY.setX(yRowStride).setY(height);
    Allocation yAlloc = Allocation.createTyped(renderScript, typeUcharY.create());
    yAlloc.copyFrom(y);
    yuv420888.set_ypsIn(yAlloc);

    // note that the size of the u's and v's are as follows:
    //      (  (width/2)*PixelStride + padding  ) * (height/2)
    // =    (RowStride                          ) * (height/2)
    // but I noted that on the S7 it is 1 less...
    typeUcharUV.setX(u.length);
    Allocation uAlloc = Allocation.createTyped(renderScript, typeUcharUV.create());
    uAlloc.copyFrom(u);
    yuv420888.set_uIn(uAlloc);

    Allocation vAlloc = Allocation.createTyped(renderScript, typeUcharUV.create());
    vAlloc.copyFrom(v);
    yuv420888.set_vIn(vAlloc);

    // handover parameters
    yuv420888.set_picWidth(width);
    yuv420888.set_uvRowStride (uvRowStride);
    yuv420888.set_uvPixelStride (uvPixelStride);

    Bitmap outBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
    Allocation outAlloc = Allocation.createFromBitmap(renderScript, outBitmap, Allocation.MipmapControl.MIPMAP_NONE, Allocation.USAGE_SCRIPT);

    Script.LaunchOptions lo = new Script.LaunchOptions();
    lo.setX(0, width);  // by this we ignore the y’s padding zone, i.e. the right side of x between width and yRowStride
    lo.setY(0, height);

    yuv420888.forEach_doConvert(outAlloc,lo);
    outAlloc.copyTo(outBitmap);

    return outBitmap;
}

yuv420888.rs Renderscript脚本：

  #pragma version(1)
  #pragma rs java_package_name(hikvision.zhanyun.com.hikvision);
  #pragma rs_fp_relaxed

  int32_t width;
  int32_t height;

  uint picWidth, uvPixelStride, uvRowStride ;
  rs_allocation ypsIn,uIn,vIn;

 // The LaunchOptions ensure that the Kernel does not enter the padding  zone of Y, so yRowStride can be ignored WITHIN the Kernel.
 uchar4 __attribute__((kernel)) doConvert(uint32_t x, uint32_t y) {

 // index for accessing the uIn's and vIn's
uint uvIndex=  uvPixelStride * (x/2) + uvRowStride*(y/2);

// get the y,u,v values
uchar yps= rsGetElementAt_uchar(ypsIn, x, y);
uchar u= rsGetElementAt_uchar(uIn, uvIndex);
uchar v= rsGetElementAt_uchar(vIn, uvIndex);

// calc argb
int4 argb;
    argb.r = yps + v * 1436 / 1024 - 179;
    argb.g =  yps -u * 46549 / 131072 + 44 -v * 93604 / 131072 + 91;
    argb.b = yps +u * 1814 / 1024 - 227;
    argb.a = 255;

uchar4 out = convert_uchar4(clamp(argb, 0, 255));
return out;
}
使用方法：
MediaCode使用略：
mediaDecode = MediaCodec.createDecoderByType("video/avc");
MediaFormat mediaFormat = MediaFormat.createVideoFormat("video/avc", 640, 480);
mediaFormat.setInteger(MediaFormat.KEY_BITRATE_MODE, MediaCodecInfo.EncoderCapabilities.BITRATE_MODE_CQ);
mediaFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, ImageFormat.YUV_420_888);
mediaDecode.configure(mediaFormat, null, null, 0);
mediaDecode.start();
// 中间开始解码视频流
int inputBufferIndex = mediaDecode.dequeueInputBuffer(0);
            if (inputBufferIndex >= 0) {   //当输入缓冲区有效时,就是>=0
                ByteBuffer inputBuffer = mediaDecode.getInputBuffer(inputBufferIndex);
                inputBuffer.put(frame, 0, frame.length);
                mediaDecode.queueInputBuffer(inputBufferIndex, 0, frame.length, System.nanoTime() / 1000, 0);
            } else {
                Log.w(Log.TAG, "解码缓冲区不足");
            }
            MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
            int outputBufferIndex = mediaDecode.dequeueOutputBuffer(bufferInfo, 0);//拿到输出缓冲区的索引
            if (outputBufferIndex >= 0) {
                Image img = mediaDecode.getOutputImage(outputBufferIndex);
                long t = System.currentTimeMillis();
                Bitmap bitmap = YUV_420_888_toRGB(img, 1920, 1080);
                Log.e(Log.TAG, "转换YUV到位图: " + (System.currentTimeMillis() - t) + " " + bitmap.getHeight());
//                saveBitmapAsJPEG(bitmap, "/sdcard/zhjinrui/spgp/demo.bmp");
                mediaDecode.releaseOutputBuffer(outputBufferIndex, true);
            }
以上转换