ABR vs MBR: Adaptive vs multi-bitrate streaming

With the rise of online video consumption, streaming technology has rapidly evolved to meet the demand for smooth, uninterrupted viewing. Two key technologies, Adaptive bitrate streaming (ABR) and Multi-bitrate streaming (MBR), play a crucial role in this.

ABR automatically adjusts video quality in real-time based on the user's network speed, ensuring smooth playback even on fluctuating connections. MBR, on the other hand, offers multiple fixed-quality streams, and the viewer needs to switch between them depending on their network, without real-time adaptation. Both aim to provide clear video, but ABR offers more flexibility in varying network conditions, while MBR relies on switching between pre-encoded streams (with different resolution outputs).

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In this article, we'll compare Adaptive bitrate streaming (ABR) and Multi-bitrate streaming (MBR). We'll cover how each technology works, their advantages, and real-world use cases. This will help developers understand which technology is best for their video platforms.

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Why bitrate in streaming?

Bitrate plays a pivotal role in online video streaming, defining the amount of data transmitted per unit of time. Essentially, it determines the bandwidth a video requires for continuous playback. Here’s an overview of bitrate and its impact:

• Measurement: Bitrate is typically quantified in kilobits per second (kbps). ‍
• Effect on streaming quality: To achieve smooth video playback, users must have an internet connection speed that surpasses the video's bitrate. ‍
• Variability in network conditions: Internet speeds can vary greatly by location. For example, streaming in densely populated areas such as mainland China can be challenging due to high network congestion and generally lower average internet speeds.

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How bitrate impacts user experience in streaming

Bitrate plays a critical role in determining the quality and performance of a video stream. Here's how it affects user experience:
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Video quality
Higher bitrates result in better video quality. A high bitrate means more data is being processed, leading to clearer images, sharper details, and smoother motion. A low bitrate, on the other hand, can cause pixelation and blurriness.

Higher bitrate equals sharper, clearer images.
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Buffering and playback
If a video’s bitrate exceeds the user’s internet speed, the stream will buffer frequently. An optimal bitrate ensures smooth playback without interruptions. Poorly managed bitrates lead to frustrating pauses or loading screens.

High bitrates on slow connections can cause buffering.
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Data usage
Higher bitrates consume more data, which can impact users with limited data plans. Low bitrates are more data-friendly, but they sacrifice visual quality. Striking the right balance is key for a good experience.

Higher bitrates lead to higher data consumption.
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In essence, the bitrate determines whether users enjoy high-quality visuals, smooth streaming, or end up with constant buffering and excessive data use.

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What is multi-bitrate streaming (MBR)?

MBR is the simpler of the two (when compared with ABR). It involves creating multiple versions of the same video at different bitrates (e.g., 240p, 480p, 720p, 1080p). These pre-encoded versions are stored on a server, and when a user plays the video, the server selects the most appropriate bitrate based on their initial network speed and device capabilities. However, once the bitrate is selected, it remains fixed throughout the session.

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How MBR works:

• The user’s device requests the video, and the server delivers a fixed bitrate version based on the initial bandwidth check.
• The bitrate doesn’t adjust dynamically during the playback, so if network conditions change, users might experience buffering or a drop in quality.
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Pros of MBR:

• Simple implementation: MBR is easy to implement as it involves basic logic for selecting a bit rate at the start of streaming. ‍
• Predictable performance: If the user's connection is stable, the selected bitrate delivers consistent quality throughout the session.
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Cons of MBR:

• No adaptation to network changes: If a user’s connection fluctuates, MBR won’t adapt, resulting in potential buffering or degraded quality. ‍
• Increased storage requirements: Multiple versions of the same video must be stored, taking up significant server space.

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What is adaptive bitrate streaming (ABR)?

ABR takes things to the next level by dynamically adjusting the video bitrate in real time, based on current network conditions. Instead of selecting a fixed bitrate at the start, ABR continuously monitors bandwidth and switches between different bitrates as needed. Videos are broken into small segments (usually a few seconds long), with each segment available in multiple bitrates.

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How ABR works:

• The video is segmented, and each segment is encoded at several different bitrates.
• As the video plays, the player continuously checks the user's bandwidth. If the network slows down, it switches to a lower bitrate segment to avoid buffering. If the network improves, it increases the bitrate for better quality.
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Pros of ABR:

• Seamless user experience: ABR adjusts to bandwidth fluctuations, delivering the best possible quality without interruptions, making it ideal for users on mobile or unstable networks. ‍
• Bandwidth optimization: ABR intelligently uses the available bandwidth, ensuring smooth playback and minimizing excessive data usage.
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Cons of ABR:

• Complex setup: ABR requires more sophisticated infrastructure, including encoding videos into multiple segments and implementing real-time bandwidth detection algorithms. ‍
• Slight latency in switching: While ABR generally adjusts quickly, there can be slight delays when switching between bitrates, especially on slower networks.

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ABR vs. MBR: Key differences

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Learning from use cases and examples

When it comes to choosing between Adaptive bitrate streaming (ABR) and Multi-bitrate streaming (MBR), real-world applications offer invaluable insights. Let’s explore some examples where these technologies have made a significant impact, helping companies achieve their goals and deliver exceptional streaming experiences.

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Netflix with ABR

• Use case: Netflix utilizes Adaptive Bitrate Streaming (ABR) to deliver a seamless viewing experience across different devices and network conditions. ‍
• Success story: By employing ABR, Netflix ensures high video quality and minimal buffering, even in regions with fluctuating internet speeds. This approach has contributed to its global success and user satisfaction.
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YouTube with MBR

• Use case: YouTube historically used Multi-Bitrate Streaming (MBR) for its early video delivery. Users selected the video quality manually based on their network speed. ‍
• Success story: As internet speeds improved, YouTube transitioned to ABR to enhance user experience by automatically adjusting video quality, leading to smoother playback and reduced buffering.

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When to Use MBR vs. ABR

• MBR is best when:
  • You’re dealing with controlled environments where network speeds are stable (e.g., corporate intranets or local networks).
  • Server space is not a concern, and you need a simple, cost-effective solution.

• ABR is best when:
  • You’re targeting a broad, diverse audience with varying network conditions.
  • The user experience is a priority, especially on mobile networks where connectivity can fluctuate.

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What’s the suitable bitrate for streaming?

Choosing the suitable bitrate for streaming is essential to ensure optimal quality and a smooth experience. Bitrate directly impacts video resolution, data consumption, and the chances of buffering. Based on Apple’s HLS Authoring Specification, it is crucial to strike a balance between performance and quality depending on several factors:

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1. Resolution: Higher resolutions like 1080p or 4K require more bandwidth to maintain sharpness and clarity, while lower resolutions like 480p use less but sacrifice quality.
   
   1. ‍480p: 1,000 - 2,500 kbps ‍
   2. 720p: 2,500 - 5,000 kbps ‍
   3. 1080p: 5,000 - 10,000 kbps ‍
   4. 4K: 15,000 - 25,000 kbps  

2. Frame rate: Fast-paced content, like gaming or sports, demands a higher bitrate to avoid stuttering or motion blur.
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   1. ‍30fps: Standard streaming ‍
   2. 60fps: Ideal for action-heavy content  

3. Internet connection: A user’s internet bandwidth plays a critical role. A higher bitrate than the available bandwidth causes buffering. Adaptive bitrate streaming (ABR) helps by adjusting the quality in real-time.
   
   1. ‍Stable networks can handle higher bitrates for better quality. ‍
   2. Unstable networks may need lower bitrates to avoid interruptions.
      

4. Device type: Streaming on mobile devices often requires a lower bitrate for efficiency, while desktops and TVs can handle higher bitrates for better image quality.  

5. Content type: Different types of content, such as fast-moving sports or slow-paced presentations, may require different bitrates to ensure optimal quality without artifacts like pixelation.

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Recommended bitrates:

• Mobile (Low-medium quality):
  • 480p at 1,000 – 2,000 kbps
  • 720p at 2,000 – 3,500 kbps

• Desktop/TV (High quality):
  • 1080p at 5,000 – 10,000 kbps
  • 4K at 15,000 – 25,000 kbps

• Streaming games:
  • 720p at 3,500 – 6,000 kbps (30-60fps)
  • 1080p at 6,000 – 12,000 kbps (60fps)

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The ideal bitrate depends on various factors such as the resolution, frame rate, and internet speed. Apple’s HLS authoring specification emphasizes the need to use adaptive technologies like ABR to maintain the best possible quality across devices and networks.

For more detailed specifications, refer to the official HLS authoring specification.

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Streaming with FastPix: Using ABR and HLS

Delivering a smooth and high-quality viewing experience is necessary and when you’re building a video-centric product or application, this is what really matters more than anything else. FastPix, with developer-friendly APIs for modern video products, stands out by offering Adaptive bitrate streaming (ABR) and HLS (HTTP live streaming) for video delivery.

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Using adaptive bitrate streaming (ABR)

FastPix’s ABR technology ensures that your video content is delivered with the best possible quality, no matter the viewer’s internet connection. ABR dynamically adjusts the video quality in real-time based on the user’s available bandwidth. This means viewers can enjoy a seamless experience without interruptions or buffering, whether they’re on a high-speed connection or a more modest one.
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Using HLS (HTTP live streaming)

FastPix’s adherence to Apple’s HLS specification guarantees compatibility with a wide range of devices and platforms. HLS is a widely accepted streaming protocol that breaks video content into small chunks, which are then delivered over HTTP. This approach not only enhances compatibility but also improves streaming performance across different network conditions.

By integrating ABR and following HLS standards, FastPix ensures that your video content is optimized for performance and quality, providing an exceptional viewing experience for audiences everywhere.

At FastPix, we provide the infrastructure and technologies to build video better. This reduces the technical complexity in video so developers and product builders can focus on what really matters – that is offering viewers with great viewing experiences.