android 将Bitmap转YUV420sp(实例)

/**     * 将bitmap里得到的argb数据转成yuv420sp格式     * 这个yuv420sp数据就可以直接传给MediaCodec,通过AvcEncoder间接进行编码     * @param yuv420sp 用来存放yuv429sp数据     * @param argb 传入argb数据     * @param width   图片width     * @param height 图片height     */    public static void encodeYUV420SP(byte[] yuv420sp, int[] argb, int width, int height) {        final int frameSize = width * height;        int yIndex = 0;        int uvIndex = frameSize;        int a, R, G, B, Y, U, V;        int index = 0;        for (int j = 0; j < height; j++) {            for (int i = 0; i < width; i++) {                a = (argb[index] & 0xff000000) >> 24; // a is not used obviously                R = (argb[index] & 0xff0000) >> 16;                G = (argb[index] & 0xff00) >> 8;                B = (argb[index] & 0xff) >> 0;                // well known RGB to YUV algorithm                Y = ( (  66 * R + 129 * G +  25 * B + 128) >> 8) +  16;                U = ( ( -38 * R -  74 * G + 112 * B + 128) >> 8) + 128;                V = ( ( 112 * R -  94 * G -  18 * B + 128) >> 8) + 128;                // NV21 has a plane of Y and interleaved planes of VU each sampled by a factor of 2                //    meaning for every 4 Y pixels there are 1 V and 1 U.  Note the sampling is every other                //    pixel AND every other scanline.                yuv420sp[yIndex++] = (byte) ((Y < 0) ? 0 : ((Y > 255) ? 255 : Y));                if (j % 2 == 0 && index % 2 == 0) {                    yuv420sp[uvIndex++] = (byte)((V<0) ? 0 : ((V > 255) ? 255 : V));                    yuv420sp[uvIndex++] = (byte)((U<0) ? 0 : ((U > 255) ? 255 : U));                }                index ++;            }        }    }
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