Encoding Ladders: The Key to Optimal Video Streaming

Video streaming has revolutionized media consumption, with video content projected to constitute 92% of all internet traffic by 2025. A key component behind smooth streaming experiences is the encoding ladder, which enables adaptive bitrate streaming by providing multiple video quality levels. Implementing optimized encoding ladders can lead to significant bandwidth savings—up to 50% in some instances—without compromising viewer experience. This optimization is essential for delivering content seamlessly across diverse devices and varying network conditions.

The difference between amateur and professional streaming services often comes down to how effectively they implement their encoding ladders. Top platforms like Netflix invest millions in perfecting their encoding workflow, resulting in superior viewer experience and reduced delivery costs. For content creators and streaming platforms, understanding and optimizing your encoding ladder isn’t just technical jargon—it’s a competitive necessity and a significant milestone in your streaming journey.

Let’s explore how encoding ladders work, why they matter, and how you can build one that delivers the best video quality for your audience without breaking your bandwidth bank.

What Is an Encoding Ladder?

An encoding ladder is a structured set of video renditions at varying resolutions and bitrates designed to deliver the optimal viewing experience across different network conditions and devices. Think of it as a menu of video quality options that your streaming system can select based on each viewer’s specific circumstances.

An encoding ladder provides multiple versions of a video, each with a different resolution and bitrate, referred to as video renditions. When someone starts watching your video, the streaming platform selects a rendition that matches their current connection. If their speed drops, it switches to a lower bitrate rendition to avoid buffering. If the connection improves, it shifts to a higher-quality version.

At its core, an encoding ladder is akin to a technical menu, with each level offering a distinct balance of resolution, bitrate, and codec parameters. These “rungs” of the ladder create versions of your video suitable for everything from high-speed internet on a 4K display all the way down to a basic mobile phone on a sluggish network.

The Evolution of Encoding Ladders

The journey of encoding ladders represents a fascinating evolution in video streaming technology:

1. The Original Fixed Ladder Approach

The original encoding ladder most professionals used came from Apple’s Tech Note TN2224, which has since been replaced by Apple’s HLS Authoring Specification. As the Streaming Learning Center points out, this H.264-only ladder had defined rungs, resolutions, and bitrates, and served as the starting point for a wide array of encoding ladders used on the web.

This fixed approach provided a one-size-fits-all solution that worked reasonably well but wasn’t optimized for different types of content.

2. Frame-by-Frame Optimization

The next evolution involved technologies that optimized individual rungs in the ladder by adjusting the data rate up or down according to the complexity of the content. These techniques, such as Capped CRF, don’t change the number of rungs or their resolution—only the data rate of each rung.

3. Per-Title Encoding

In December 2015, Netflix introduced a groundbreaking approach known as “per-title encoding.” This technique analyzes each video and creates a unique ladder optimized for that specific content. Unlike earlier methods, per-title encoding can vary both the number of rungs in the ladder and their resolutions.

For example, an easy-to-encode animation that looks great at 1080p at 3 Mbps doesn’t need the same number of rungs as an action movie that requires 8 Mbps for acceptable 1080p quality. Some content actually retains higher quality at lower bitrates when encoded at larger resolutions.

4. Shot-Based Encoding

Netflix further innovated with shot-based encoding, which divides videos into separate shots using scene detection rather than arbitrary chunks. This technique produces bitrate savings of around 30%, depending on the codec and metric used for analysis.

5. Context-Aware Encoding

The latest advancement is context-aware encoding, which considers not only content complexity but also network and device playback statistics to create a unique encoding ladder that optimizes quality based on how viewers actually watch videos.

How to Build Your Own Encoding Ladder

Creating an effective encoding ladder involves several critical steps. Here’s how to approach it:

1. Understand Your Audience and Their Devices

First, analyze your audience demographics and their viewing habits. Are they primarily mobile users on fluctuating networks? Or desktop viewers with stable internet speeds? Mobile viewers may need lower resolutions, while those on desktops or TVs usually expect higher-quality streams.

2. Set Your Floor and Ceiling Bitrates

• The floor is the lowest bitrate you intend to support. Some producers set a higher floor, concluding that if they can’t deliver at least a reasonable quality experience, they won’t bother.
• The ceiling is the top rate you want to support. This is often determined by economics—whatever your monetization plan, you need to ensure you can afford to distribute at this rate.

3. Choose Intermediate Bitrates

For the rungs between your floor and ceiling, the general rule is to ensure each “jump” between rungs is no more than 1.5 to 2x. For example, if your floor is 500 kbps and your ceiling is 5 Mbps, your second rung should be anywhere from 2.5 Mbps to 3.333 Mbps.

The smaller the jump (say 1.5x), the more rungs you produce, which increases encoding and storage costs but may slightly improve the quality of experience. The larger the jump (say 2.0x), the lower the costs; however, the quality of the experience may drop slightly.

4. Select Appropriate Resolutions

Match each bitrate with an appropriate resolution. Your top rung should deliver the best video quality. If your top bitrate is over 4 Mbps, you should be able to deliver very good quality at 1080p. Below that, consider 900p (1600×900) or 720p.

Consider the content type when setting resolutions:

• Sports content might look better at slightly smaller resolutions
• Animations will definitely look better at larger resolutions
• Action sequences need higher bitrates to maintain quality

Different Codecs, Different Ladders

A crucial consideration when building your encoding ladder is that different video codecs necessitate distinct approaches. Whether you opt for per-title or static encoding, your ladder should change based on the codec you’re using.

If you check Apple’s Authoring specification, you’ll see they recommend different ladders for H.264 and HEVC (Versatile Video Coding). The same principle applies to VP9, AV1, and other emerging codecs.

Why? More advanced codecs are typically more efficient, meaning:

• You can use lower bitrates at higher resolutions
• They work more efficiently at higher resolutions, allowing you to eliminate some lower-resolution rungs
• Your ladder structure should be optimized for each codec’s strengths

Practical Examples of Encoding Ladders

Let’s look at some real-world examples of encoding ladders used by leading platforms:

Apple’s H.264 Ladder

From the HLS Authoring Specification, Apple recommends the following for H.264:

Apple notes these are “initial encoding targets for typical content delivered via HLS” and recommends evaluating them against your specific content and encoding workflow.

Netflix’s Per-Title Example

For Netflix’s animated show “BoJack Horseman,” per title encoding produced this ladder (compared to their default):

Notice how the animated content actually performed better at higher resolutions with lower bitrates compared to the default ladder.

Advanced Considerations for Encoding Ladders

Adaptive Bitrate Streaming

Adaptive bitrate streaming (ABR) is the technology that leverages your encoding ladder to deliver the appropriate quality to each viewer. When internet speed fluctuates, ABR selects the best video quality to match the connection. The encoding ladder makes this possible by providing all the video versions ABR can choose from.

Content-Specific Optimization

Different types of content require different approaches:

• Fast-paced sports need higher bitrates to avoid blurring
• Talking-head videos can work with lower bitrates
• Animation often maintains better quality at lower bitrates

Digital Rights Management

Content licensing agreements may require digital rights management (DRM) protection. Some DRM considerations impact your encoding choices:

• Software-based DRM may add overhead
• Hardware decoder compatibility must be considered
• Some DRM solutions work better with certain codecs and container formats

Live vs. VOD Considerations

Live events introduce additional challenges compared to video on demand:

• Live encoding typically uses a slow preset to balance encoding time with quality
• Live streams often have different quality metrics priorities
• Consistent performance is crucial for live events

Measuring the Success of Your Encoding Ladder

How do you know if your encoding ladder is effective? Consider these metrics:

1. Rebuffering rate: How often viewers experience buffering
2. Average bitrate delivered: The typical bandwidth consumed
3. Quality switches: How frequently the player changes quality levels
4. Startup time: How quickly videos begin playing
5. Viewer engagement: How long viewers watch your content

Tools like video analytics platforms can help you track these metrics and refine your ladder based on real-world performance.

Future Trends in Encoding Ladder Optimization

The field continues to evolve with several emerging trends:

AI-Driven Encoding

Artificial intelligence is playing an increasingly important role in encoding strategies. Instead of using fixed ladders, AI can analyze video content and viewer data to create dynamic ladders that adjust renditions based on specific needs.

Sustainability Considerations

Streaming platforms are seeking ways to reduce their carbon footprint. Optimizing encoding ladders to use fewer resources without compromising quality is one approach. Newer codecs and smarter bitrate choices help reduce energy consumption and data usage.

8K and Beyond

As 8K streaming and larger screens become more prevalent, encoding ladders must support higher resolutions and bitrates while also accommodating viewers with slower connections. This requires balancing the need for future-proofing with new technologies while maintaining content accessibility for all viewers.

Try Castr for Seamless Streaming Experiences

An optimal encoding ladder is essential for delivering high-quality, buffer-free video streaming experiences across all devices and network conditions. From the fixed ladders of the past to today’s AI-driven, content-aware approaches, the technology continues to evolve rapidly.

Whether you’re building a simple ladder for a small audience or implementing sophisticated per-title encoding for millions of viewers, understanding these principles will help you deliver the best video quality possible while optimizing bandwidth and storage costs.

Remember that there’s no one-size-fits-all solution—the perfect ladder depends on your content, audience, and business requirements. Regular testing and refinement based on real-world performance data will help you develop an encoding ladder that truly meets your needs.

Ready to implement optimized encoding ladders for your streaming content? Castr offers a comprehensive streaming platform with advanced adaptive bitrate streaming capabilities, multiple codec support, and intelligent delivery optimization.

With Castr, you can:

• Create customized encoding ladders for different content types
• Deliver smooth playback across all devices and connection speeds
• Monitor performance with detailed analytics
• Scale your streaming infrastructure effortlessly

Experience the difference professional streaming technology makes with our 7-day free trial—no credit card required. Visit Castr today to start delivering exceptional streaming experiences to your audience.