Android 视频 YUV i420格式转换为位图Bitmap

Android 视频 YUV i420格式转换为位图Bitmap

YUV基础描述

YUV(YCbCr，图像除了RGB，还有YUV)

定义：是电视系统所采用的一种颜色编码方法

• Y 标识明亮度，也就是灰阶值
• U和V标识的色度，描述影像色彩和饱和度

YUV常见格式：

YUV 4:2:0
YUV 4:2:2
YUV 4:4:4

YUV存储格式

YUV格式有两大类：planar和packed。

对于planar的YUV格式，先连续存储所有像素点的Y，随后存储U、V。存储类型表示为采样方式后缀加P。

对于packed的YUV格式，每个像素点的Y,U,V是连续交错存储的。存储类型表示为采样方式后缀加SP

YUV i420格式转换为位图Bitmap

import android.renderscript.Allocation;
import android.renderscript.Element;
import android.renderscript.RenderScript;
import android.renderscript.ScriptIntrinsicYuvToRGB;
import android.renderscript.Type.Builder;

public static byte[] I420ToNV21(byte[] input, int width, int height) {
        byte[] output = new byte[4147200];
        int frameSize = width * height;
        int qFrameSize = frameSize / 4;
        int tempFrameSize = frameSize * 5 / 4;
        System.arraycopy(input, 0, output, 0, frameSize);

        for(int i = 0; i < qFrameSize; ++i) {
            output[frameSize + i * 2] = input[tempFrameSize + i];
            output[frameSize + i * 2 + 1] = input[frameSize + i];
        }

        return output;
}

public byte[] nv21ToI420(byte[] data, int width, int height) {
		byte[] ret = globalBuffer;
		int total = width * height;
		
		ByteBuffer bufferY = ByteBuffer.wrap(ret, 0, total);
		ByteBuffer bufferU = ByteBuffer.wrap(ret, total, total / 4);
		ByteBuffer bufferV = ByteBuffer.wrap(ret, total + total / 4, total / 4);
		
		bufferY.put(data, 0, total);
		for (int i=total; i<data.length; i+=2) {
			bufferV.put(data[i]);
			bufferU.put(data[i+1]);
		}
		return ret;
}

public static Bitmap NV21ToBitmap(Context context, byte[] nv21, int width, int height) {
        RenderScript rs = RenderScript.create(context);
        ScriptIntrinsicYuvToRGB yuvToRgbIntrinsic = ScriptIntrinsicYuvToRGB.create(rs, Element.U8_4(rs));
        Builder yuvType = null;
        yuvType = (new Builder(rs, Element.U8(rs))).setX(nv21.length);
        Allocation in = Allocation.createTyped(rs, yuvType.create(), 1);
        Builder rgbaType = (new Builder(rs, Element.RGBA_8888(rs))).setX(width).setY(height);
        Allocation out = Allocation.createTyped(rs, rgbaType.create(), 1);
        in.copyFrom(nv21);
        yuvToRgbIntrinsic.setInput(in);
        yuvToRgbIntrinsic.forEach(out);
        Bitmap bmpout = Bitmap.createBitmap(width, height, Config.ARGB_8888);
        out.copyTo(bmpout);
        return bmpout;
}

参考：

1. http://www.zeroplace.cn/article.asp?id=984
2. YUV数据格式
3. Android——Nv21高效率转Bitmap