镜像之后，果然要旋转。于是从网上搜索了几个算法，并进行了验证、优化。分享给大家。
需要提醒的是，如果进行编码，注意90、270时，宽高要进行对换。
public static byte[] NV21_rotate_to_270(byte[] nv21_data, byte[] nv21_rotated, int width, int height) { int y_size = width * height; int i = 0; // Rotate the Y luma for (int x = width - 1; x >= 0; x--) { int offset = 0; for (int y = 0; y < height; y++) { nv21_rotated[i] = nv21_data[offset + x]; i++; offset += width; } } // Rotate the U and V color components i = y_size; for (int x = width - 1; x > 0; x = x - 2) { int offset = y_size; for (int y = 0; y < height / 2; y++) { nv21_rotated[i] = nv21_data[offset + (x - 1)]; i++; nv21_rotated[i] = nv21_data[offset + x]; i++; offset += width; } } return nv21_rotated; } public static byte[] NV21_rotate_to_180(byte[] nv21_data, byte[] nv21_rotated, int width, int height) { int y_size = width * height; int buffser_size = y_size * 3 / 2; int i = 0; int count = 0; for (i = y_size - 1; i >= 0; i--) { nv21_rotated[count] = nv21_data[i]; count++; } for (i = buffser_size - 1; i >= y_size; i -= 2) { nv21_rotated[count++] = nv21_data[i - 1]; nv21_rotated[count++] = nv21_data[i]; } return nv21_rotated; } public static byte[] NV21_rotate_to_90(byte[] nv21_data, byte[] nv21_rotated, int width, int height) { int y_size = width * height; int buffser_size = y_size * 3 / 2; // Rotate the Y luma int i = 0; int startPos = (height - 1)*width; for (int x = 0; x < width; x++) { int offset = startPos; for (int y = height - 1; y >= 0; y--) { nv21_rotated[i] = nv21_data[offset + x]; i++; offset -= width; } } // Rotate the U and V color components i = buffser_size - 1; for (int x = width - 1; x > 0; x = x - 2) { int offset = y_size; for (int y = 0; y < height / 2; y++) { nv21_rotated[i] = nv21_data[offset + x]; i--; nv21_rotated[i] = nv21_data[offset + (x - 1)]; i--; offset += width; } } return nv21_rotated; }
