CBR vs. VBR: Differentiating Constant Bitrate from Variable Bitrate

Bitrate refers to the amount of data sent per second during video playback. It directly affects video quality, buffering, and performance, especially for live and mobile streaming. Whether you’re broadcasting a concert, webinar, or sports match, the right bitrate ensures a smooth, high-quality experience.

One key decision for broadcasters is choosing between Constant Bitrate (CBR) and Variable Bitrate (VBR) encoding. These two methods handle data differently and can impact how your video performs across platforms like OBS Studio, Twitch, and YouTube. There’s also a third option—Constrained VBR—which offers a hybrid approach.

In this guide, we’ll compare CBR vs. VBR, explain how to choose based on your goals (live streaming, VOD, mobile), and explore 2025-ready trends like AV1, H.266/VVC, AI-powered encoding, and 5G. We’ll also show how tools like Dacast help businesses make smart bitrate decisions for efficient, high-quality streaming.

Let’s dive into the differences between constant bitrate vs variable bitrate, and how to choose the best option in today’s streaming landscape.

Table of Contents

• What is Bitrate?
• What is Constant Bitrate (CBR)?
• What is Variable Bitrate (VBR)?
• How AI, New Codecs and 5G are Revolutionizing Bitrates
• CBR vs. VBR: Feature-by-Feature Comparison
• CBR vs. VBR for Multi-Bitrate Streaming
• CBR vs. VBR in Tools (OBS, Wirecast, vMix, FFmpeg)
• Bitrate Optimization by Device (Mobile vs Desktop)
• When to Use CBR vs. VBR
• Practical Implementation and Encoder Comparisons
• Use Cases by Industry
• Sustainability Considerations
• Sustainability and Bandwidth Efficiency
• Recommended Encoder Settings for Live Streaming with Dacast
• Which Bitrate Should You Choose?
• FAQs
• Conclusion

What is Bitrate?

Bitrate measures the amount of data that is transferred over a period of time. In online video streaming, video bitrate is measured in kilobits per second or kbps. Bitrate affects the quality of a video stream. Streaming with a higher bitrate helps you produce higher-quality streams.

When it comes to online video streaming, broadcasters often make their content available in multiple bitrates. This is referred to as adaptive bitrate streaming. This allows viewers to access the bitrate that is appropriate for their internet speed, which allows them to access the highest quality content with the least amount of lagging, skipping, and buffering.

Adaptive bitrate video players have been game-changing since they automatically deliver the rendition of the video with the appropriate bitrate in response to a real-time analysis of each viewer’s internet speed.

Bitrate is also something that is important in the the encoding process or transcoding stage of the streaming process since this too deals with the transfer of data. As we mentioned, constant bitrate streaming (CBR) and variable bitrate streaming (VBR) are the two most popular types of encoding, which is why you often see VBR vs CBR comparisons.

What is Constant Bitrate (CBR)?

Constant Bitrate (CBR) is a method of video and audio encoding where the bitrate remains fixed throughout the entire file or live stream, regardless of the complexity of the content. This means each second of video transmits the same amount of data, whether the scene is simple or highly detailed.

Definition

In simple terms, CBR sends data at a steady rate from start to finish. It doesn’t adjust to what’s happening on screen. This approach is especially useful for live streaming, where consistency and stability matter most.

Pros

• Stable stream quality: Ideal for live events where buffering is a risk.
• Predictable file size and bandwidth usage: Helps broadcasters budget for delivery costs.
• Easy to configure across platforms: Supported by most encoding tools, including OBS, FFmpeg, and vMix.

Cons

• Not efficient with complex scenes: May compromise quality when the content has fast motion or high detail.
• Wastes bandwidth on simple scenes: Since it always uses the same bitrate, even for static or low-complexity content.
• Less adaptive for modern codecs: Doesn’t take full advantage of newer compression algorithms like AV1 or H.266/VVC.

Common Use Cases

• Live streaming on Twitch, YouTube, or Facebook: CBR helps prevent buffering on unreliable networks.
• Streaming to mobile viewers: On 4G/5G networks, CBR ensures steady delivery.
• When using bitrate-constrained CDNs or streaming plans: Helps avoid overages.
• Recommended for OBS settings when streaming with Dacast: A fixed bitrate reduces variability and keeps streams smooth, especially when paired with adaptive bitrate ladders.

Key characteristics of CBR:

• Consistent data rate: CBR encoders output data at a constant rate, irrespective of the size or complexity of the files they process. This means that simple scenes and complex scenes are allocated the same amount of data.
• Predictable file size: Since the bitrate remains constant, the final file size of CBR-encoded content is easily predictable, which can be beneficial for storage planning.
• Real-time processing: The consistency of CBR makes it well-suited for situations where video content must be encoded in real-time, such as live streaming.
• Compatibility: CBR format has been the standard in online video streaming for some time, making it the most compatible option across various platforms and players.
• Bitrate setting: When using CBR, it’s recommended to set the bitrate relatively high to ensure the encoder can handle more complex segments of data as it processes your video. This helps maintain quality across varying scene complexities.

Use cases and considerations:

• Live streaming: CBR is often preferred in many streaming situations due to its reliability and compatibility. For real-time live streaming, CBR is a great solution as it ensures consistent bandwidth usage.
• Storage: While CBR is excellent for streaming, it’s not always the most efficient choice for storing data, especially for content with varying complexity.
• Quality variation: One drawback of CBR is that it may lead to quality fluctuations. Simple scenes might be allocated more data than necessary, while complex scenes might not receive enough data to maintain optimal quality.

Understanding CBR is crucial for content creators and streamers, as it directly impacts the quality, file size, and compatibility of their media. When set up correctly, CBR video encoding can provide a stable and reliable output, particularly beneficial for live streaming scenarios where consistent bandwidth usage is crucial.

What is Variable Bitrate (VBR)?

Variable Bitrate (VBR) is an encoding method that adjusts how much data is used depending on what’s happening in the video. Instead of sending a constant amount of data, VBR allocates more bitrate to complex scenes and less to simpler ones. This approach is designed to balance quality and file size efficiently.

Types of VBR

There are several VBR modes used today, especially in modern encoding tools and bitrate optimization platforms:

• Average VBR (ABR): Targets a set average bitrate over time but adjusts moment by moment.
• Quality VBR (QVBR): Focuses on visual quality, regardless of bitrate, using intelligent encoding logic.
• Constrained VBR (CVBR): Uses a max bitrate cap to avoid bandwidth spikes while still varying the bitrate.
• Unconstrained VBR: Offers full flexibility, but may be less predictable for streaming.

Constrained VBR is particularly popular in 2025, as it combines the benefits of efficiency with better control over peak bitrate—especially useful in live streaming and mobile delivery environments.

Pros

• Better visual quality: Optimizes bitrate where it’s needed most.
• Smaller file sizes: Great for video-on-demand (VOD) and storage.
• More efficient use of network bandwidth: Especially when using AV1 or H.266 codecs in cloud-based workflows.
• Ideal for adaptive bitrate (ABR) ladders: Works well in multi-bitrate setups delivered by platforms like Dacast.

Cons

• Inconsistent bandwidth usage: Not ideal for networks with strict limits.
• More processing power required: Especially in multi-pass or AI-optimized VBR workflows.
• Can cause buffering during bitrate spikes: Unless constrained by buffer or peak rate controls.

Common Use Cases

• Video-on-demand platforms: Efficient for storage and playback on Dacast’s cloud video hosting system.
• Long-form video content: Where maintaining visual quality is more important than real-time delivery.
• When using bitrate optimization tools or AI encoding engines: Such as those adjusting for H.266/VVC or AV1.
• Pre-recorded content delivery on mobile: Especially when paired with adaptive streaming formats like HLS or MPEG-DASH.

Key characteristics of VBR:

• Adaptive data rate: VBR encoders output data at varying rates, allocating more bits to complex scenes and fewer bits to simpler ones.
• Efficient file size: VBR typically results in smaller file sizes compared to CBR for the same average quality, as it doesn’t waste bits on simple scenes.
• Quality-focused: VBR encoding prioritizes maintaining consistent quality throughout the content, rather than maintaining a constant bitrate.
• Measurement: VBR quality is measured by taking the average bitrate of complex segments over the entire file.
• Processing time: VBR can take longer to process data, making it better suited for on-demand video transcoding rather than live streaming.

Use cases and considerations:

• On-demand video: VBR streaming works well with on-demand video, where processing time is less critical.
• Quality optimization: There’s better quality retention in complex scenes with the VBR format, making it ideal for content with varying visual complexity.
• Storage efficiency: VBR is excellent for storing video files, as it can achieve better quality-to-file-size ratios compared to CBR.
• Compatibility: It’s important to note that VBR is not as widely supported as CBR, which may limit its use in some scenarios.

Understanding VBR encoding is crucial for content creators looking to optimize their video quality while managing file sizes effectively. While it may not be ideal for live streaming due to its variable nature, VBR offers significant advantages for on-demand content, particularly when consistent visual quality is a priority.

Understanding the Full Form of Bitrates

When discussing bitrate encoding, it’s important to understand what the terms “CBR” and “VBR” actually stand for. CBR stands for Constant Bitrate, and VBR stands for Variable Bitrate. These full forms highlight how data is managed during encoding. A CBR file format maintains the same bitrate throughout the entire file, providing a consistent data stream, while VBR full form adjusts the bitrate based on the complexity of the content, leading to more efficient compression.

Choosing the right rate control, like CBR or VBR, is crucial for achieving optimal performance in streaming and recording. For platforms like OBS, understanding bitrate settings—such as CBR mode or VBR rate control—helps deliver the best results based on your needs, whether it’s for smooth streaming or recording. When working with OBS, for example, users often ask “what is a CBR file format” or “what is the best rate control for streaming?” The answer depends on the situation.

How AI, New Codecs and 5G are Revolutionizing Bitrates

AI-Powered Bitrate Optimization

• AI tools now choose between CBR and VBR in real time, based on video complexity and network performance.
• Content-aware encoding powered by AI ensures efficient delivery while maintaining high visual quality.

AI is transforming the way bitrate encoding is handled. With AI-driven encoding advancements, systems can now optimize the choice between CBR and VBR in real time. AI-based content-aware encoding adjusts bitrate based on the complexity of a video, ensuring both quality and efficiency.

Solutions like adaptive bitrate encoding powered by AI automatically switch between CBR and VBR based on network conditions. This helps deliver smooth CBR streaming and high-quality VBR encoding even when bandwidth fluctuates. The result: reduced data use with no drop in clarity.

AI-Driven Quality Metrics for Bitrate Selection

• Metrics like VMAF and SSIM analyze video quality from a viewer’s perspective to guide bitrate decisions.
• Real-time adjustments to CBR or VBR settings improve encoding efficiency for live and on-demand video.

AI is also changing how we choose between constant bitrate vs variable bitrate settings. Tools such as VMAF (Video Multi-Method Assessment Fusion) and SSIM (Structural Similarity Index) help optimize bitrate using perceptual quality, not just technical metrics.

Using AI-assisted scoring, platforms can decide when to use CBR for live streaming (for stability) or VBR for video-on-demand (for flexibility). This makes decisions like CBR vs VBR for OBS, or VBR vs CBR for mobile live streaming, more data-driven.

Codec Advancements: H.266/VVC and AV1

• Newer codecs like H.266 and AV1 allow for lower bitrates with better quality.
• These codecs work with both CBR and VBR, improving efficiency across streaming workflows.

Emerging codecs such as H.266/VVC and AV1 are reshaping bitrate standards. Compared to H.264 CBR and H.264 VBR, these next-gen codecs deliver higher quality at much lower bitrates.

For example, H.266 bitrate recommendations show up to 50% better compression than H.265. Both AV1 and H.266 support flexible encoding, helping with VBR vs CBR for live streaming, mobile delivery, and video-on-demand workflows.

5G and Edge Computing for Bitrate Control

• 5G enables smoother high-bitrate streaming, even for 4K and mobile.
• Edge computing reduces latency, allowing more responsive bitrate switching.

With the continued rollout of 5G, CBR and VBR streaming have become more reliable at higher bitrates. Lower latency and faster data transfer mean fewer interruptions, even with demanding video quality.

Edge computing supports this by processing data closer to the user. That means quicker bitrate adjustments, smoother CBR streaming, and more flexible VBR encoding, especially in mobile and global content delivery.

Adaptive Bitrate (ABR) Innovations with AI

• Machine learning now powers adaptive streaming, choosing the best bitrate for each viewer and device.
• Per-title encoding and content-aware bitrate allocation improve streaming efficiency.

Adaptive streaming with AI in 2025 means more personalized bitrate decisions. ML-powered ABR engines dynamically select the best rate for each viewer, depending on their device, bandwidth, and location.

Per-title encoding further refines this process by tailoring bitrate strategies for each video. This ensures the most efficient encoding for both live and on-demand streaming, reducing bandwidth usage while keeping quality high.

2025 Trends – AI, 5G, Codecs (AV1, H.266/VVC), Energy Efficiency

In 2025, streaming technology continues evolving with AI-powered encoding, 5G networks, and advanced codecs like AV1 and H.266/VVC. These innovations improve video quality while optimizing bandwidth use. AI enables adaptive streaming with AI in 2025 by dynamically adjusting bitrate based on network conditions and content complexity. 

5G’s low latency and high speeds boost live streaming performance, allowing better use of VBR encoding, which adapts bitrate on the fly. New codecs like H.266 provide higher compression efficiency, reducing energy consumption during transmission and decoding. As sustainability grows in importance, broadcasters consider both bandwidth and energy efficiency when choosing between CBR vs VBR to balance quality and environmental impact.

CBR vs. VBR: Feature-by-Feature Comparison

Here is a quick overview of constant bitrate vs variable bitrate, so you can see the top features and differences between these two encoding methods.

In terms of constant bitrate vs variable bitrate use scenarios, CBR is best for live streaming encoding, while VBR is best for on-demand videos.

CBR vs. VBR for Multi-Bitrate Streaming

How CBR and VBR Work Together in an ABR Workflow

The difference between CBR and VBR comes down to Constant Bitrate (CBR) and Variable Bitrate (VBR) each having unique strengths when it comes to streaming. Is CBR better than VBR? It comes down to circumstances and needs.

In an Adaptive Bitrate (ABR) workflow, these two methods can work together to create a smoother viewing experience. CBR, where the bitrate remains constant, is ideal for maintaining stability, especially in low-bandwidth environments. On the other hand, VBR adjusts the bitrate based on the complexity of the content, offering better quality when bandwidth allows. By combining CBR and VBR in ABR streaming, platforms can switch between stable, lower-quality streams and high-quality streams as network conditions change. This hybrid approach helps ensure consistent playback without buffering, catering to diverse audience needs.

Real-Time Switching with Cloud Transcoding

Advancements in cloud transcoding technology now allow real-time switching between CBR and VBR, enhancing performance for live streams. This flexibility is particularly valuable for platforms using OBS (Open Broadcaster Software) or similar tools, where choosing the best rate control for recording or streaming is crucial.

OBS rate control for streaming often favors CBR for stability, but OBS variable bitrate with target quality can improve visual performance when bandwidth is sufficient. Real-time switching optimizes performance by adapting to network conditions, reducing bandwidth usage, and maintaining quality. As new codecs like AV1 and H.266/VVC emerge alongside 5G and edge computing, this dynamic approach will continue to improve streaming efficiency across industries such as OTT, gaming, and corporate events.

CBR vs. VBR in Tools (OBS, Wirecast, vMix, FFmpeg)

Popular streaming tools like OBS, Wirecast, vMix, and FFmpeg offer both CBR streaming and VBR encoding options. OBS bitrate rate control 2025 supports CBR or VBR, letting creators choose based on their streaming goals. 

CBR is often preferred for live streaming on platforms like Twitch or YouTube where stable bandwidth matters, while VBR vs CBR for live streaming suits VOD or pre-recorded content to maximize quality. FFmpeg provides flexible bitrate control settings for streaming and file encoding, supporting advanced codecs such as AV1 and H.266. Understanding the best rate control for OBS 2025 or Wirecast can help broadcasters optimize their streams across devices, ensuring smooth playback and efficient bandwidth use.

Rate Controls to Use in OBS

Choosing the right OBS rate​ control is essential for achieving the best video and audio performance during streaming or recording. By understanding the differences between CBR and VBR, you can optimize your OBS target quality stream based on your needs.

In OBS, CBR bit rate (Constant Bitrate) mode ensures a consistent bitrate throughout the stream, providing reliable quality with minimal fluctuations. This is ideal for live streaming, where stable data rates are crucial. However, it might not be the most efficient for recordings, especially when storage space is a concern.

On the other hand, VBR (Variable Bitrate) adapts the bitrate depending on the complexity of the video, delivering higher quality for scenes with more detail while reducing the bitrate for simpler scenes. For recording, this can help balance file size and quality.

When using OBS, research bitrates for optimal performance. A target bitrate that matches your internet speed and recording preferences ensures the best results. For streaming, finding the best rate control and understanding whether OBS CBR vs VBR, CBR file format, or VBR file format works better for your needs is crucial for an efficient workflow.

When configuring OBS (Open Broadcaster Software) for live streaming, choosing the right rate control is crucial for optimal performance. The best rate control in OBS depends on your streaming needs. For most live streaming scenarios, however, the recommended OBS rate control is CBR.

Here’s a guide on what rate control to use in OBS:

• CBR (Constant Bitrate): Best for live streaming due to its consistency and compatibility with most platforms
• VBR (Variable Bitrate): Suitable for local recordings but not recommended for live streaming.
• CRF (Constant Rate Factor): Ideal for local recordings when file size isn’t a concern. CRF sets a target quality level, allowing the encoder to adjust the bitrate as needed to achieve that quality.
• CQP (Constant Quantization Parameter): Similar to CRF, but with less sophisticated rate control. CQP maintains a constant level of compression across the entire video, which can result in larger file sizes but consistent quality.
• ICQ (Intelligent Constant Quality): A more advanced form of quality-based encoding. ICQ aims to maintain consistent perceived quality while optimizing bitrate efficiency.

Bitrate Optimization by Device (Mobile vs Desktop)

Bitrate optimization is crucial because mobile and desktop devices differ in screen size, processing power, and network reliability. Variable bitrate vs constant bitrate for mobile devices often favors VBR to adapt to fluctuating mobile networks and save data, improving viewer experience. 

On desktops with stable connections, CBR streaming can ensure consistent quality and reduce buffering. Best bitrate settings for live streaming in 2025 consider these differences, using adaptive streaming with AI in 2025 to deliver the right bitrate automatically. Platforms like Dacast support device-based bitrate optimization, helping broadcasters tailor streams for mobile live streaming or desktop viewers efficiently.

When to Use CBR vs. VBR

CBR encoding and VBR encoding are both important in video and audio encoding. Neither is better than the other since they both serve unique purposes due to their individual strengths and weaknesses.

Let’s break down the use cases for these two encoding processes.

Live Stream Encoding

CBR is the best setting for live stream encoding. The consistency of CBR makes it more reliable for time-sensitive data transport. This is ideal for live streaming since most live videos are broadcast at a single bitrate.

Since constant bitrate processes data at a consistent rate, there is no concern about the bitrate exceeding internet speeds. However, the reliability of output data from this encoding method leads to sacrificing quality in some situations.

It is possible to use VBR for live stream encoding, however, it is rarely recommended unless it is used with a one-pass setup.

VOD Transcoding

Constrained VBR is the optimal setting for on-demand  because it is capable of handling larger files while still maintaining some sense of consistency with audio formats. Overall, VBR produces better sound quality than streams, and on-demand video transcoding provides the flexibility to use VBR, so it’s a no-brainer.

Variable video bitrate produces higher-quality streams. Since there is less time sensitivity in transcoding on-demand video files, you don’t have to worry about the bitrate exceeding internet speed which gives you the flexibility to lean into the benefits of VBR.

Audio-Only Streaming

Just like video content, audio-only streaming should use CBR for live audio broadcasts and VBR for on-demand audio streaming.

However, some audio-specific encoders will not give you the option to choose. In that case, you must go with whatever option is available to you. Audio files are much less bulky than video files, so either option should be fine. If possible, though, go with CBR audio for live broadcasts. VBR sound quality is great for on-demand audio streaming.

Encoding vs. Transcoding

Before we dive into the use cases of VBR and CBR, it is important to acknowledge the similarities and differences between encoding and transcoding.

Encoding refers to converting a still video file or audio file from one format to another. In the live streaming context, encoding refers to converting the RAW video files that are captured by the camera into a digital format that is able to be streamed over the internet. This is important because RAW video files are too bulky to be streamed.

Encoding is made possible with dedicated encoding hardware or software.

Transcoding refers to compressing video files to create copies of media files in different sizes. These copies by file size are called “renditions.” Transcoding is generally used for on-demand video streaming. Many online video platforms, including Dacast, are equipped with cloud transcoding tools that transcode video files as they are uploaded to the platform.

Practical Implementation and Encoder Comparisons

When choosing between Constant Bitrate (CBR) and Variable Bitrate (VBR) encoding, it’s important to understand how each method functions across different encoders and how they impact video quality at various resolutions and frame rates.

Comparing CBR and VBR Settings Across Different Encoders

OBS Studio: In OBS Studio, CBR stream is commonly used for live streaming to maintain a steady bitrate, which helps prevent buffering issues. To set OBS CBR::

1. Go to Settings > Output.
2. Set the Output Mode to Advanced.
3. Under the Streaming tab, choose CBR as the Rate Control method.
4. Specify your desired bitrate (e.g., 4500 Kbps for 1080p at 60fps).

VBR can be set similarly by selecting VBR as the Rate Control method and defining target and maximum bitrates. VBR may offer better quality for complex scenes but requires careful configuration to avoid bitrate spikes that could affect stream stability.

Wirecast: Wirecast allows users to select between CBR and VBR in the encoding settings. For live streaming, CBR is typically recommended to ensure consistent delivery. To configure:

1. Open Output Settings.
2. Choose your encoding preset or create a new one.
3. Select CBR or VBR and set the appropriate bitrate values.

vMix: In vMix, you can set the bitrate control method in the Streaming Settings:

1. Click on the gear icon next to the Stream button.
2. In Quality settings, select CBR for consistent bitrate or VBR for adaptive bitrate.
3. Adjust the bitrate according to your resolution and frame rate needs.

FFmpeg: FFmpeg offers detailed control over encoding parameters. To use CBR:

ffmpeg -i input.mp4 -b:v 5000k -maxrate 5000k -bufsize 5000k output.mp4

This command sets a constant bitrate of 5000 Kbps. For VBR:

ffmpeg -i input.mp4 -b:v 5000k -maxrate 10000k -bufsize 10000k output.mp4

This allows the bitrate to vary, peaking at 10000 Kbps for complex scenes.

Real-World Bitrate Settings for Different Resolutions, Codecs, and Frame Rates in 2025

Selecting the right bitrate is crucial for balancing video quality and bandwidth usage. Below are recommended bitrate ranges for various resolutions and frame rates using the H.264 codec, which remains widely supported:

• 4K (2160p) at 60fps: 20,000–51,000 Kbps
• 4K (2160p) at 30fps: 13,000–34,000 Kbps
• 1440p at 60fps: 9,000–18,000 Kbps
• 1440p at 30fps: 6,000–13,000 Kbps
• 1080p at 60fps: 4,500–9,000 Kbps
• 1080p at 30fps: 3,000–6,000 Kbps
• 720p at 60fps: 2,250–6,000 Kbps
• 720p at 30fps: 1,500–4,000 Kbps
• 480p: 500–2,000 Kbps
• 360p: 400–1,000 Kbps
• 240p: 300–700 Kbps

These recommendations are based on current standards and may evolve with advancements in codecs and network infrastructure. For instance, newer codecs like AV1 or H.266/VVC offer improved compression efficiency, potentially reducing the required bitrate for comparable quality. Additionally, the widespread adoption of 5G technology enhances bandwidth availability, allowing for higher bitrates and better quality in live streaming scenarios.

When configuring your encoder, consider your audience’s internet capabilities and the platforms you’re streaming to, as they may have specific bitrate recommendations or limitations.

Use Cases by Industry

Choosing between constant bitrate and variable bitrate depends on your content type, audience size, and delivery platform. For example, streamers using OBS for Twitch or YouTube should use CBR to avoid lag during fast-paced gameplay, while VBR may be better for uploading on-demand content to reduce file size.

Tools like OBS, vMix, and FFmpeg all offer bitrate control settings to help you fine-tune your stream. If you’re broadcasting to mobile audiences, especially over 5G, choosing the right bitrate mode is even more important for optimizing quality while managing bandwidth. For those hosting videos long-term, Dacast’s cloud video hosting platform supports both CBR and VBR workflows, making it easier to adapt to your specific encoding goals.

Sustainability Considerations

Sustainability is an increasing concern in video streaming. Choosing between constant vs variable bitrate impacts not only viewer experience but also bandwidth consumption and energy use. VBR encoding typically reduces bandwidth by adjusting bitrate to content complexity, leading to lower energy use across networks and devices. CBR streaming, while stable, can waste bandwidth during low-motion scenes, increasing energy costs. 

New codecs like H.266 bitrate recommendations also focus on energy-efficient compression. For businesses using platforms like Dacast, balancing high-quality streams with sustainability means selecting video bitrate control methods that minimize environmental impact without sacrificing performance.

Sustainability and Bandwidth Efficiency

Energy-Efficient Encoding as a Business Priority

As streaming demand grows, energy efficiency is becoming essential for businesses. Encoding methods like Constant Bitrate (CBR) and Variable Bitrate (VBR) directly impact bandwidth usage and power consumption. With growing concerns about sustainability, companies are exploring how encoding choices affect their environmental footprint. Efficient encoding not only cuts costs but also helps organizations meet their sustainability goals.

AI-Powered VBR for Reduced Server Energy Use

AI-powered VBR encoding is emerging as a smarter alternative to traditional CBR methods. Unlike CBR, which maintains a constant vs variable bitrate regardless of content complexity, VBR adjusts bitrate dynamically. This flexibility reduces server load and minimizes energy use. By optimizing bitrate in real time, VBR lowers power consumption and cooling needs, making it a greener choice. As businesses seek ways to reduce operational costs, VBR offers an eco-friendly solution that outperforms CBR in bandwidth efficiency.

Recommended Encoder Settings for Live Streaming with Dacast

Dacast recommends using CBR for live broadcasting on our streaming platform. That’s because the constant bitrate is more reliable for encoding video content in real-time.

There are some other encoder settings that we require for our live streaming software. Straying from this configuration may cause issues in your stream.

Here are our required settings:

Please note that these settings are specifically for live streaming. Please check out our transcoding walkthrough for more relevant information on configuring your transcoding settings on Dacast.

Resolution & Bitrate Settings

In addition to the live streaming encoder settings we mentioned above, broadcasters must choose resolution and bitrate settings to achieve their desired stream quality.

There are different bitrates and resolution combinations required to create streams in ultra-low definition, low definition, standard definition, high definition, and full high definition.

Here is a breakdown of the resolution and bitrate settings for achieving each video quality:

Which Bitrate Should You Choose?

Choosing between Constant Bitrate vs Variable Bitrate depends on your streaming needs. Use this simple checklist to decide:

• Need steady upload speed or streaming on mobile? Choose CBR.
• Want better video quality with flexible file size? Go for VBR.
• Streaming live on Twitch or YouTube using OBS? Pick the rate control that matches your platform’s guidelines.
• Encoding video-on-demand content? VBR is usually more efficient.
• Using newer codecs like AV1 or H.266? Consider bitrate optimization tools for best results.

This checklist helps simplify how to choose between CBR and VBR for streaming in 2025.

FAQs

1. Is CBR better than VBR?

The suitability of either constant bitrate or variable bitrate depends on the desired application. CBR is generally better for live streaming due to its consistency and compatibility. VBR is often preferred for on-demand content as it can offer better quality-to-file-size ratios.

2. What is the difference between CBR and VBR encoding?

The main difference lies in how they allocate bits. CBR maintains a constant bitrate throughout, while VBR adjusts the bitrate based on content complexity. CBR format ensures predictable file sizes and bandwidth usage, while VBR format optimizes quality across varying scene complexities.

3. What happens if the bitrate is too high?

If the bitrate is too high, it can lead to buffering issues for viewers with slower internet connections. For a CBR stream, this could result in consistent playback problems. In VBR streaming, extremely high bitrates might cause unnecessary file bloat without significant quality improvements.

4. Which bitrate mode is best?

The best bitrate mode depends on the use case. For live streaming, constant bitrate vs variable bitrate comparisons often favor CBR due to its consistency. For recorded content or video on demand, VBR is usually the better option due to its efficiency and potential for higher quality.

5. What is a good bitrate for H.264?

A good bitrate for H.264 varies based on resolution and frame rate. For 1080p at 30fps, Dacast recommends a bitrate of 1,900-4,500 kbps. For 720p at 30fps, 1,200-1,900 kbps is typically suitable. You may need to adjust the H.264 CBR or VBR based on your specific requirements and network conditions.

6. How do CBR and VBR impact viewer experience in fluctuating network conditions?

CBR maintains a consistent bitrate throughout the stream, which can be advantageous for viewers with stable internet connections, ensuring smooth playback. However, in fluctuating network conditions, this consistency might lead to buffering or reduced quality, as the stream doesn’t adapt to available bandwidth. Conversely, VBR adjusts the bitrate based on content complexity, which can optimize quality and reduce buffering in variable network environments. Yet, sudden increases in bitrate during complex scenes might challenge networks with limited bandwidth, potentially causing playback issues. ​

7. What are the considerations for storage and bandwidth when choosing between CBR and VBR?

CBR streams, due to their constant bitrate, often result in larger file sizes, especially when encoding content with varying complexity, leading to potentially inefficient storage and higher bandwidth usage. This predictability, however, simplifies bandwidth planning. VBR, by allocating bitrate dynamically, typically produces smaller files and uses bandwidth more efficiently, especially for content with fluctuating complexity. This efficiency can lead to cost savings in storage and distribution but requires more sophisticated encoding and may result in variable streaming performance depending on network conditions.

8. How do CBR and VBR affect compatibility with different streaming platforms and devices?

CBR is widely supported across various streaming platforms and devices due to its simplicity and predictability, making it a safe choice for broad compatibility. It’s particularly favored for live streaming scenarios. VBR, while offering quality and efficiency benefits, may face compatibility issues with certain platforms or devices that expect a constant bitrate, potentially leading to playback problems. Therefore, when targeting a diverse audience with varying devices and platforms, CBR might offer more consistent performance, whereas VBR is better suited for controlled environments where compatibility is assured.

9. Is CBR better than VBR for streaming?

It depends on your streaming goals. CBR (Constant Bitrate) provides a steady stream, making it ideal for live broadcasts where consistency is key, especially on platforms like Twitch or YouTube. VBR (Variable Bitrate), however, can improve video quality at the same file size, making it a better fit for video-on-demand. When deciding between Constant Bitrate vs Variable Bitrate, consider your audience, stream type, and bandwidth.

10. What is the best bitrate for 1080p or 4K in 2025?

For 1080p streaming in 2025, a CBR of 6,000 to 8,000 Kbps is common for platforms like OBS and Dacast. For 4K live streams, VBR is often preferred with a target bitrate of 13,000–20,000 Kbps or more, depending on codec efficiency (e.g., AV1 or H.266/VVC). Your final choice should reflect codec support, available bandwidth, and device compatibility.

11. Can you switch between CBR and VBR in OBS or Dacast?

Yes, OBS supports both CBR and VBR under its rate control settings. You can adjust this based on the platform you’re streaming to, such as Twitch or Dacast. Dacast also supports multiple encoder setups and bitrate modes through cloud transcoding, making it easy to fine-tune your stream quality or switch modes for live vs. on-demand content.

12. What are the environmental benefits of VBR encoding?

VBR encoding is more bandwidth-efficient, only using high bitrate when needed—like during motion-heavy scenes. This reduces the total data transferred, which in turn lowers energy use across CDNs and servers. In 2025, more streaming platforms like Dacast are adopting sustainable encoding practices, including energy-aware transcoding powered by AI.

13. Which bitrate mode is best for mobile viewers?

For mobile live streaming, VBR is often the better choice. It adapts to fluctuating mobile network conditions, like 4G or 5G, without overloading the connection. VBR also works well with adaptive bitrate streaming (ABR), delivering smoother playback across devices. When choosing between CBR vs VBR for mobile live streaming, prioritize flexibility and data efficiency.

14. How do AI and machine learning help optimize bitrate today?

In 2025, AI is a key player in bitrate optimization tools. Machine learning models now analyze real-time network conditions, viewer behavior, and content complexity to automatically select the best bitrate mode and codec—whether H.264, AV1, or H.266. Platforms like Dacast increasingly use AI to deliver higher quality with fewer resources, especially for hybrid events and global live streams.

Conclusion

Understanding the difference between constant bitrate (CBR) and variable bitrate (VBR) is essential for delivering smooth, high-quality video. In simple terms, CBR offers reliability and consistency, which makes it ideal for live stream encoding, especially over unpredictable internet connections. VBR, on the other hand, can deliver better visual quality by adjusting bitrate based on scene complexity, which is why it’s often preferred for video-on-demand encoding.

In 2025, broadcasters and content creators also need to consider factors like adaptive bitrate streaming, energy usage, and new codec support (such as AV1 and H.266/VVC). Tools like OBS Studio, which supports both CBR and VBR, make it easier to experiment with settings and find what works best for your platform—whether you’re streaming to Twitch, YouTube, or mobile viewers.

If you’re just getting started or want to test different bitrate control strategies, try Dacast’s 14-day free trial. It’s a full-featured live and VOD streaming platform with support for OBS, bitrate optimization tools, and cloud transcoding.

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