Quality of Experience is top of mind for today’s brands, and video streaming technologies have been rapidly improving to keep up with demand. In fact, studies show that buffering issues have fallen 41% and picture quality has risen 25% year-over-year.
Even so, companies still need to make a tradeoff between video quality and performance often, and bitrates are a key aspect of this. That’s why many broadcasters are turning to adaptive bitrate and multi-bitrate streaming to automatically optimize bitrates to end-users.
First, we’ll cover why bitrates matter for broadcasters. Then we’ll take a closer look at the differences between multi-bitrate and adaptive bitrate streaming. Finally, we’ll see how Dacast supports both ways for streaming quality video to viewers.
Let’s get started!
Table of Contents
- Why Streaming Bitrates Matter
- Multi-Bitrate Streaming Explained
- What Is Adaptive Bitrate Streaming?
- Adaptive & Multi-Bitrate Streaming With Dacast
Why Streaming Bitrates Matter
Streaming bitrates—a measure of how much bandwidth videos will consume—are crucial for understanding the tradeoff between quality and performance for end-users.
Bitrate impacts performance because users need to have an Internet connection or mobile data speed with the bandwidth that exceeds the video’s bitrate. That way, the user’s video player can download the video fast enough to ensure smooth playback.
The problem is that these network conditions often fluctuate throughout the day, and different geographical regions have varying connection speeds. For example, video delivery to mainland China—with over 1.4 billion people—can be challenging due to low internet speeds on average.
While broadcasters could offer lower bitrates that are accessible for nearly any device or bandwidth capacity, today’s viewers often expect much more. Over the top (OTT) platforms need to deliver high definition video that’s on par with normal TV viewing experiences as well.
Viewers that do have the capability to watch high-quality streams won’t bother watching poor-quality videos for long. In fact, video quality is the most important factor for 67% of viewers watching live streams.
With this in mind, let’s look at how bitrates affect video quality and what a good bitrate is for video streaming.
Does Bitrate Affect Video Quality?
In general, videos with higher bitrates often have a higher quality than videos encoded at lower bitrates. That’s because higher bitrates are a result of higher resolutions or more frames per second (fps), but bitrates are also affected by the efficiency of compression codecs.
The resolution of a video is the number of pixels within each video frame, which determines how sharp the video appears. On larger screens or when viewing videos up close, the resolution becomes especially important.
Most videos have a framerate that’s 24 fps, which is fast enough for humans to perceive as fluid motion. While this framerate is fine for most videos, broadcasters may choose 30 to 60 fps for sporting events or fast-paced clips.
Compression is another factor that determines a video’s file size, and in turn, its bitrate. While newer codecs like H.264 and H.265 can intelligently reduce enormous amounts of unnecessary data without impacting quality, legacy codecs aren’t as efficient.
While higher bitrates can equate to greater picture quality, it’s important to remember that there are other factors that contribute to the viewing experience. For example, issues like buffering, lagging, or slow start times can greatly diminish the Quality of Experience for viewers as well.
What’s a Good Bitrate for Streaming?
Choosing bitrates for streaming comes down to the type of videos a broadcaster wants to stream, and the streaming quality expected by their target audience. That means bitrates aren’t one-size-fits-all, so broadcasters should create a video streaming profile that’s tailored to their audience.
A streaming profile or bitrate ladder should offer varying qualities and bitrates to maximize compatibility. At Dacast, we recommend providing a stream below 1000 Kbps so viewers can watch with nearly any device.
Providing higher bitrates as well can improve the experience for viewers that have the necessary capabilities. We’ll cover streaming profiles more later on.
Once broadcasters set up a streaming profile, they’ll be able to use multi-bitrate and adaptive bitrate streaming to deliver a higher-quality experience for their target audience.
Multi-Bitrate Streaming Explained
Most broadcasters have global audiences with different internet speeds and devices for streaming videos. That means streaming at a single bitrate could limit compatibility for some viewers or lead to a less than optimal viewing experience for others.
Multi-bitrate streaming allows broadcasters to offer a wide range of stream qualities to improve the overall Quality of Experience. With multiple bitrate options, viewers can choose the highest quality stream their connection and device can handle without interruptions.
Using a video streaming platform, broadcasters can easily transcode their streams into multiple bitrates and formats from a single source file. In fact, transcoding videos in the cloud is a great way to ensure compatibility, enable adaptive playback, and reduce the costs for doing so.
What Is Adaptive Bitrate Streaming?
Adaptive bitrate streaming (ABR) is a method for delivering the highest quality video possible for users based on their network conditions and device capabilities in real-time.
Similar to multi-bitrate streaming, broadcasters that want to use ABR must have multiple streams available at different bitrates. That way, the user’s video player can adjust the streaming quality in real-time to ensure playback doesn’t lag or buffer.
How Does Adaptive Bitrate Streaming Work?
More specifically, viewers need to use a video player with adaptive playback capabilities to make ABR streaming work. For example, HTML5 and Video.js video players can detect network or processing capacity fluctuations to adjust the stream quality automatically.
For ABR streaming, each of the encoded video files is segmented into 2 to 10-second chunks. These separate parts and their bitrates are described in a manifest file, which makes up the streaming profile. We’ll cover streaming profiles and bitrate ladders later on.
ABR streaming is currently supported by HLS and MPEG-DASH protocols. With these protocols, the video player will download the manifest file to understand the video assets that are available for a particular stream. These protocols are both HTTP-based, so they’re an efficient way to stream progressively downloaded video content as individual parts.
After the video player begins playback, it uses a selection algorithm to analyze streaming conditions and choose which video chunks to download. For example, THEOplayer evaluates download speed and adjusts the bitrate to ensure the buffer has enough content available to continue playback.
Other algorithms, however, rely solely on download bandwidth or throughput to determine which chunks to download next. In the future, adaptive playback algorithms will likely evolve to better leverage machine learning to optimize playback for viewers.
Adaptive & Multi-Bitrate Streaming With Dacast
Dacast is an online video platform (OVP) that supports both adaptive and multi-bitrate streaming. That’s because broadcasters can easily set up multiple streams within the online platform and use Dacasts’s HTML5 video player for adaptive playback.
Here are the top factors broadcasters will need to assess to implement multi-bitrate video streaming with Dacast.
1. Create a Bitrate Ladder
The streaming profile or encoding ladder is the set of bitrates and resolutions that broadcasters plan to stream to end-users. Many broadcasters choose a universal ladder that’s meant to optimize every video file for any device or connection.
In fact, Apple proposed a fixed bitrate encoding ladder for HLS streaming that’s optimized for Apple devices. Since then, Netflix introduced per-title encoding to optimize the bitrate ladder to the content rather than viewing conditions. Either way, there’s no one-size-fits-all approach for broadcasters.
Within Dacast, users can choose multi-streaming settings for every video file, whether it’s a video on demand (VOD) or live streaming. You’ll want to choose set from a set of renditions that include the bitrates and resolutions that suit your intended audience.
In general, however, Dacast suggests this set of live encoder resolution & bitrate settings for most broadcasters:
|Name||Ultra-Low Definition||Low Definition||Standard Definition||High Definition||Full High Definition|
|Video Bitrate (kbps)||350||350 – 800||800 – 1200||1200 – 1900||1900 – 4500|
|Resolution Width (px)||426||640||854||1280||1920|
|Resolution Height (px)||240||360||480||720||1080|
2. Select an Encoding Method
When encoding bitrates there are two techniques broadcasters can use: constant bitrate encoding or variable bitrate encoding.
Constant bitrate (CBR) encoding uses a consistent bitrate for an entire video file. While this is faster and more efficient during the encoding process, the result is often much larger file sizes for high-quality videos. That’s why encoding has evolved to using variable bitrates.
Variable bitrate (VBR) encoding takes into account the contents of a video file and dynamically changes the bitrate throughout the encoding process. VBR reduces the bitrate during less complex segments and increases the bitrate if there’s a lot of motion or complexity.
In general, we recommend VBR encoding for most broadcasters because it can reduce bitrates while retaining a similar perceivable video quality.
3. Choose Your Streaming Protocol
We mentioned before that both HLS and DASH support ABR streaming, but each video streaming protocol has its advantages and drawbacks.
Dynamic Adaptive Streaming of HTTP (DASH) is a newer protocol that’s codec-agnostic and supports both 4K video and HDR (High Dynamic Range). That means DASH can deliver video content in a wide variety of high-quality formats. While the protocol is ABR ready, DASH still lacks native compatibility with HTML5 video players.
HTTP Live Streaming (HLS) is a streaming protocol that supports the H.264 and HEVC/H.265 codecs, which are highly efficient video compression codecs. Along with these codecs, HLS can deliver video in 4K and HDR as well. DASH may have similar support for codecs, resolutions, and other features, but HLS still has the advantage of universal compatibility for delivery to desktop browsers, mobile devices, Smart TVs, and more.
By leveraging HTTP for delivery, HLS can work with nearly any web server or CDN. This is an enormous advantage over legacy protocols like for Real-Time Messaging Protocol (RTMP), which required specialized streaming servers to host and deliver video content.
Moreover, many top-tier CDNs are launching low-latency HLS streaming to further improve streaming performance. That’s because CDNs use a network of streaming servers around the world to reduce the distance video content needs to travel to reach end-users.
At Dacast, the default streaming protocol is HLS because it’s compatible with HTML5 video players. Since HLS is currently the most widely used, broadcasters can maximize its reach while dynamically delivering the best video quality possible from moment to moment.
4. Choose a Codec
The codecs that broadcasters can choose from will largely depend on which protocol they will use for streaming. As mentioned earlier, DASH is compatible with any codec, but HLS is more limited.
Since Dacast uses HLS by default, most broadcasters will need to choose between H.264 or HEVC/H.265. We currently recommend H.264 because it continues to be the de-facto codec for video streaming. While H.265 is more efficient, it’s still in development and not widely supported yet, so it’s best to focus on the codec that can maximize your audience today.
Companies shouldn’t sacrifice on Quality of Experience or viewer compatibility. Choosing a video streaming software that has multi-bitrate and ABR streaming capabilities ensures brands can reach their target audience and give them the best quality video streaming experience possible.
Dacast is a VOD and live streaming platform for efficiently delivering video content. Along with robust encoding and delivery capabilities, Dacast comes with an HTML5 video player that’s ready for adaptive playback. That’s why Dacast has been recognized in Streaming Media Magazine’s Readers’ Choice Awards as the best video platform for SMB (Small & Medium Business).
Are you looking for a video streaming platform that adapts to your audience? Try our 30-day trial to see if Dacast fits your needs.
Any questions, comments, or feedback on your own experience with bitrates and streaming in general? Let us know what you think about this article by leaving a comment below. We love to hear from our readers and look forward to responding to your comments. Thanks for reading!
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