Product Updates

Bitmovin’s Smart Chunking: the evolution of the split and stitch algorithm

Markus Hafellner
. 3 min read
smart chunking

Speed, quality and scale are always top of mind when it comes to providing the highest quality of viewing experiences. In this blog, we are joined by Markus Hafellner (Senior Product Manager, VOD Encoding), who takes us through a key update to the Bitmovin Next-Generation VOD Encoder and advancements made to the split and stitch algorithm allowing users to enjoy content at the highest possible quality.

Q:  Markus, thanks for joining us today. To start with, can you go into detail what our Smart Chunking functionality enables?

A:  To start with, we have made changes and key updates to our VOD Encoder with Smart Chunking to further increase the quality and turnaround times with split and stitch. We have decoupled the chunk duration which allows for variable chunk size depending on the type of codec and the complexity of encoding allowing many immediate improvements and future optimizations.

Q:  What were the reasons for creating this?

A:  A key driver for us was to deliver improvements to our customers without the need to change their workflow. A lot of really beneficial changes require workflow changes, which are costly and need dedicated efforts..We looked to answer the question “how do we improve quality and ideally speed and have as few tradeoffs as possible?” And this is something we’re very happy with. 

For context, if you process an entire file on a single machine you will encode in the best possible quality but the downside is, it will be incredibly slow. Especially for codecs like HEVC or AV1. By using split and stitch you see the benefit of splitting the job into multiple parallel encodings but you also face the general challenge that segmented encoding faces when it comes to fixed GOP and segment sizes. Smart Chunking addresses this issue by making optimizations to chunk lengths and bitrate distribution which has an overall positive impact on the visual quality throughout the whole asset and achieving this at an even faster pace than before. 

Q:  As of today, how do Bitmovin customers get access to the Smart Chunking functionality?

A:  The great news is that everyone benefits from this immediately if you are using the most up to date encoder version (which is automatically the case for all encodings created in our dashboard). It is also worth mentioning that there are no additional costs to this. You can regard this as Bitmovin setting a new standard. Whether you’re working at a big broadcaster or a smaller sized company, the benefits of our Smart Chunking is going to be felt by all who are making use of our VOD Encoding product. 

Q:  Can you give us a more detailed example of this in action?

A:  Sure. This is where it gets a bit technical. Video quality is nowadays often measured with VMAF. An objective quality metric created by Netflix and widely used in the video industry to compare quality. We created a comparison of a highly complex asset processed with the standard split and stitch approach vs the new Smart Chunking. The key numbers you can see are the lowest 1% frames are increased by 6 VMAF points (6 VMAF is exactly the noticeable difference for the human eye). The lowest 0.1% frames are increased by an impressive 22 VMAF points and the worst frame sees an increase of a ridiculous 60 VMAF points.

smart chunking - Bitmovin

Now this is to say that what you see on the left is already what has won bake offs against any competition and has beaten several benchmarks. This goes to show just how much our customers gain from using the Bitmovin Encoder over in-house developments or competing encoders.

Not all assets will see exactly results as above, but it showcases the capabilities of Smart Chunking.

Q:  What is the next evolution of this? And what can Bitmovin users/customers think about after feeling the impact of our Smart Chunking?

A:  This announcement can very much be seen as a key step towards making Per-Shot Encoding available to all. This is something we are very excited about working towards. The upcoming launch of our Per-Shot Encoding capability will enable you to divide the video file into shots with variable duration. Each shot can then be further optimized which is another major step to driving highly optimized bitrates and flawless quality. 

Give it a try today by clicking here!

Markus Hafellner

Markus Hafellner

Sr. Product Manager | VOD Encoding

Markus has multiple years of experience in product management as well as software engineering. As such he is well versed in defining a product strategy as well as breaking it down to weekly work increments. He works closely with customers to identify gaps in existing workflows and bring new innovative solutions to market. His focus is on working on the next generation of encoding technologies like per-title, shot-based encoding and AV1/VVC in the real world.

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