問題描述

我已經(jīng)實(shí)現(xiàn)了一個(gè)在屏幕上顯示相機(jī)圖片的簡單應(yīng)用程序.我現(xiàn)在喜歡做的是抓取一個(gè)幀并將其作為位圖處理.據(jù)我所知，這并不是一件容易的事.

I've implemented a simple application which shows the camera picture on the screen. What I like to do now is grab a single frame and process it as bitmap. From what I could find out to this point it is not an easy thing to do.

我嘗試使用 onPreviewFrame 方法將當(dāng)前幀作為字節(jié)數(shù)組獲取，并嘗試使用 BitmapFactory 類對(duì)其進(jìn)行解碼，但它返回 null.幀的格式是無標(biāo)題的 YUV，可以轉(zhuǎn)換為位圖，但在手機(jī)上花費(fèi)的時(shí)間太長.此外，我還了解到 onPreviewFrame 方法對(duì)運(yùn)行時(shí)有限制，如果耗時(shí)過長，應(yīng)用程序可能會(huì)崩潰.

I've tried using the onPreviewFrame method with which you get the current frame as a byte array and tried to decode it with the BitmapFactory class but it returns null. The format of the frame is a headerless YUV which could be translated to bitmap but it takes too long on a phone. Also I've read that the onPreviewFrame method has contraints on the runtime, if it takes too long the application could crash.

那么正確的方法是什么?

So what is the right way to do this?

推薦答案

在 API 17+ 中，您可以使用 'ScriptIntrinsicYuvToRGB' RenderScript 從 NV21 轉(zhuǎn)換為 RGBA888.這使您無需手動(dòng)編碼/解碼幀即可輕松處理預(yù)覽幀:

In API 17+, you can do conversion to RGBA888 from NV21 with the 'ScriptIntrinsicYuvToRGB' RenderScript. This allows you to easily process preview frames without manually encoding/decoding frames:

@Override 
public void onPreviewFrame(byte[] data, Camera camera) { 
   Bitmap bitmap = Bitmap.createBitmap(r.width(), r.height(), Bitmap.Config.ARGB_8888);
    Allocation bmData = renderScriptNV21ToRGBA888(
        mContext,
        r.width(),
        r.height(),
        data);
    bmData.copyTo(bitmap);
}

public Allocation renderScriptNV21ToRGBA888(Context context, int width, int height, byte[] nv21) {
  RenderScript rs = RenderScript.create(context);
  ScriptIntrinsicYuvToRGB yuvToRgbIntrinsic = ScriptIntrinsicYuvToRGB.create(rs, Element.U8_4(rs));

  Type.Builder yuvType = new Type.Builder(rs, Element.U8(rs)).setX(nv21.length);
  Allocation in = Allocation.createTyped(rs, yuvType.create(), Allocation.USAGE_SCRIPT);

  Type.Builder rgbaType = new Type.Builder(rs, Element.RGBA_8888(rs)).setX(width).setY(height);
  Allocation out = Allocation.createTyped(rs, rgbaType.create(), Allocation.USAGE_SCRIPT);

  in.copyFrom(nv21);

  yuvToRgbIntrinsic.setInput(in);
  yuvToRgbIntrinsic.forEach(out);
  return out;
}

這篇關(guān)于從 Android 中的視頻圖像中獲取幀的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！