Android NDK and RenderScript

Android NDK is a set of tools that lets us use C and C++ code in our Android app, whereas RenderScript is a framework for running heavy computations at high performance. Both share the goal of improving the performance of apps.

In this blog, we will be comparing Android NDK and RenderScript. Both NDK and RenderScript share the common goal of improving the performance of applications. Each has its own advantages and drawbacks.

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What’s NDK?

As per official documentation, The Native Development Kit (NDK) is a set of tools that allow you to leverage C and C++ code in your Android app. You can use it to build from your own source code or to take advantage of existing prebuilt libraries.

I must say that the NDK is not that easy for those who have just started with Android Development as when it comes to implementation, NDK brings complexity to the development process.

But it can be useful in cases in which you need to:

Get the extra performance out of a device for computationally intensive applications like games or physics simulations.
Reuse your C or C++ libraries.

What’s RenderScript?

RenderScript is a framework for running computationally intensive tasks at high performance on Android.

RenderScript mainly uses for the data-parallel computation, however, the serial computationally intensive workloads can benefit as well.

The RenderScript runtime will parallelize work across all processors available on a device such as multi-core CPUs and GPUs allowing you to focus on expressing algorithms rather than scheduling work or load balancing.

RenderScript is especially useful for applications performing image processing, computational photography, or computer vision.

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Now, let's get back to the topic.

To begin with RenderScript, there are two main concepts you should understand:

High-performance compute kernels are written in a C99-derived language.
A Java API is used for managing the lifetime of RenderScript resources and controlling kernel execution.

How NDK and RenderScript differ

As we know both NDK and RenderScript share the common goal of improving the performance of applications. However, each has its own advantages and drawbacks.

Advantages of NDK over RenderScript:

C++ code can be shared between Android and IOS, whereas RenderScript code can be used only in Android.
Easy integration with other C++ libraries.
No API limitations, while Android provides only a few API for RenderScript.
Debugging is easier.

Advantages of RenderScript over NDK:

RenderScript can use CPU, GPU, or other processing units, which leads to a huge performance benefit.
Android architecture independence across x86, mips, and intel, whereas NDK code, needs to be compiled for each different architecture.
Easier parallel execution.
Best for image processing, computational photography, 3D rendering, or computer vision.

Frequently Asked Questions

Is the NDK easy to use for beginners in Android?

No. The NDK is not that easy for those who have just started with Android development, because it brings complexity to the development process. It is useful when we need extra performance for computationally intensive apps like games or physics simulations, or when we want to reuse our C or C++ libraries.

We can share NDK code, but not RenderScript code. C++ code written with the NDK can be shared between Android and iOS. RenderScript code can be used only in Android.

Which one should we pick for image processing?

RenderScript is the better fit. It is especially useful for image processing, computational photography, 3D rendering, and computer vision. Its runtime parallelizes work across all processors on a device, such as multi-core CPUs and GPUs.

Do we need to compile the code for each CPU architecture?

With the NDK, yes. NDK code needs to be compiled for each different architecture. RenderScript gives architecture independence across x86, mips, and intel, so we do not have to do this.

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That's it for now.

Thanks

Amit Shekhar
Founder @ Outcome School

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