Video Transcoding: The Best Video Bitrates for Mobile Streaming [2022 Update]

By Max Wilbert

13 Min Read

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Max Wilbert

Max Wilbert is a passionate writer, live streaming practitioner, and has strong expertise in the video streaming industry.

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    Accessing online video content from mobile devices has evolved in recent years. When the first iPhone came out, mobile streaming was not possible due to incompatible video players. Even after this issue was resolved by the creation of HTML5 video players, mobile internet speeds continued to pose challenges.

    Transcoding is a technique that has helped broadcasters overcome these challenges by allowing them to stream multiple copies of their videos in sizes that are suitable for different internet connections. It can be tricky to figure out the best video resolution for mobile devices.

    When considering transcoding services, it’s important to get the settings just right. Incorrect settings can translate into a poor-quality or even unwatchable video. Because many people today use so many different devices, proper settings are even more essential than just ensuring the acceptable video quality. It takes a little effort to ensure you are providing your viewers with the best video format for mobile phones. 

    In this post, we’re going to talk about video transcoding and choosing the best bitrate settings for mobile phone viewers. We will start by digging deeper into the challenges posed by mobile devices before we get into the technical aspects of transcoding and video bitrate. From there, we will discuss some specific bitrate settings that broadcasters can use for reaching a mobile audience.

    You will know how to select and provide the best video resolution for mobile devices by the end of this article. 

    Table of Contents

    • Streaming to Mobile Viewers
    • What is Transcoding?
    • What is Video Bitrate?
    • Best Bitrate Settings for Mobile Phone Viewers
    • What is Multi-Bitrate Streaming?
    • Conclusion

    Streaming to Mobile Viewers

    mobile live streaming
    Streaming to mobile devices requires a special setup.

    In the past decade, smartphones and tablets have become insanely popular. Mobile devices have given people access to endless amounts of information and media at the tap of a screen. The size and efficiency of these devices have changed the ways of the world, and have provided unthinkable convenience.

    When smartphones first rose to popularity, the technology was not suitable for streaming video content. The standard video player, Adobe Flash player, was not compatible with mobile devices. Leaders in the online streaming community realized that by not serving mobile users, broadcasters would miss out on large potential audiences. This was great foresight, as more people access the internet now through mobile devices than traditional desktops.

    That’s where the HTML5 video player and HLS delivery came into play. These technological updates made it possible to stream on just about any internet-enabled device.

    However, challenges related to internet speed continued to prevail. Cellular data and WiFi connections were not nearly as strong or capable as Ethernet connections, but unfortunately, those are the only options for mobile devices. Without the support of a fast and reliable internet connection, viewers are subject to buffering and lagging, which detracts from the viewing experience.

    Today, WiFi and cellular data connections are stronger than ever. In most situations, they are capable of streaming online video content, but there are still situations where the connection is less than ideal. This is mostly the case when streaming with cellular data.

    Fortunately, there are techniques that broadcasters can use to bypass the current internet limitation of users to ensure the best quality streaming for all of their viewers.

    What is Transcoding?

    Video transcoding is the process of creating multiple renditions, or copies, of a video that is of different sizes. Video files are often bulky, so transcoding them makes it possible to stream them with different streaming setups.

    For example, you may wish to reduce file sizes further or change the resolution of the video. It may also be necessary to use an alternate format to reach users on a specific device or operating system. That is what video transcoding helps you with.

    Video Compression

    In order to better understand transcoding, it’s important to have a clear understanding of video compression.

    The natural format of a video is “uncompressed.” This means that each frame of the video is recorded as a standalone image. 30 frames per second is standard. However, uncompressed video results in huge file sizes that are impractical for streaming over the internet.

    As a result, most video cameras actually record compressed formats. This means that some data is thrown out to reduce file sizes. Compression is achieved through mathematical algorithms, but the basics are easy to understand.

    Let’s say the whole frame of your video is black for two seconds, for example, a subject could be entering a dark room. An uncompressed video would store all 60 frames as individual images.

    Compression enables you to save space by instead saying “render all pixels black for the next 60 frames.” In practice, this causes some loss of quality.

    Codecs

    There are a variety of different compression schemes used for reducing the file size of the video and then uncompressing it for playback. One example is a video codec.

    A video codec, which is a portmanteau for “coder/decoder,” is a technology that is used for encoding and decoding video files. Codecs are available in both hardware and software forms.

    Currently, the most common video codec is H.264. It is the most popular because it is efficient and supported on almost every mobile device.

    H.264 will likely eventually be replaced by H.265 and VVC. These two codecs are both more powerful than H.264 but are limited by the fact that they are not widely compatible.

    What is Video Bitrate?

    what is video bitrate
    There are some specific bitrate settings to keep in mind for accommodating mobile viewers.

    Video bitrate is the amount of data being transferred during a given time. Bitrate and streaming settings can be manipulated at the encoder level to produce different qualities of video, such as Standard Definition or High Definition.

    Bitrate is measured in bits per second or bps. Video bitrate, in particular, is measured in megabits per second (Mbps).

    Best Bitrate Settings for Mobile Phone Viewers

    Mobile device users have a few unique requirements. For one, data is precious. Although most people have unlimited data plans, fast internet is restricted to an allotted amount of data. For example, users on an unlimited plan may see a decrease in speed for every 30 GB that they use.

    Furthermore, web connections in mobile environments can vary dramatically over short periods of time, so the streaming video has to be properly transcoded for the mobile environment. Due to this, minimizing file sizes for mobile video is essential. This involves reducing the bitrate, or the amount of data per second in a streaming file.

    At the same time, processing power and screen quality on mobile are advancing. Retina and Ultra-HD (4K) screens are becoming common on smartphones. Poor video quality is especially apparent on screens of this quality. Screen size is increasing too. The norm for smartphone screen sizes these days is around five inches. In this larger environment, a video that is too compressed or too small delivers a subpar viewing experience.

    Fortunately for viewers (but unfortunate for broadcasters), there is a wide range of mobile devices on the market. It’s great for choice, but it also means that older devices don’t support the newer formats and file sizes that work best on more modern phones and tablets. With that said, here are our recommendations for a few different categories of users.

    To reach every device, regardless of age:

    • Video bitrate: 400 kbps or less
    • Frame size: 320 x 240
    • Frame rate: 30 fps
    • Audio bitrate: 64 kbps or less

    These settings will reach just about every mobile device around, including old iPods, Blackberries, and more.

    To reach almost every device, but deliver better quality:

    • Video bitrate: 1100 kbps or less
    • Frame size: 480 x 270 pixels (very low-end devices) or 640 x 360 pixels (plays better on iPhone 4G and Droid phones)
    • Frame rate: 30 fps
    • Audio bitrate: 128 kbps or less

    This should reach nearly every smartphone and tablet, but is too small for more modern phones.

    To reach higher-end smartphones:

    • Video bitrate: 3500 kbps (WiFi), 2000 kbps (cellular) or less
    • Frame size: 1280 x 720 or 960 x 640
    • Frame rate: 30 fps
    • Audio bitrate: 160 kbps or less

    These settings will work best for most modern smartphones and tablets.

    H.264 Profile Settings

    Of course, choosing the right video bitrate for mobile isn’t the only thing to consider. That’s why we included frame size, frame rate, and audio bitrate information here. However, another important consideration is the H.264 profile you use.

    In general, we recommend the “baseline” profile for all mobile devices. It ensures backward compatibility and delivers good quality.

    What is Multi-Bitrate Streaming?

    Multi-bitrate streaming allows broadcasters to stream multiple renditions of a video at the same time do gives viewers access to a video with a bitrate that makes sense with their internet speed. An adaptive bitrate video player determines the best bitrate for each individual viewer and automatically pushes the optimal rendition. It is the best way to achieve the best video resolution for mobile devices for all of your viewers.

    These techniques allow broadcasters to simultaneously stream to users with fast and slow internet connections without sacrificing the quality of experience for either. Users with faster internet can watch crystal clear high-resolution content, while users with slower internet can watch lower-resolution content without lagging or buffering. This helps ensure the best video format for mobile phones and tablets. 

    Bitrate Settings for Different Resolutions

    As we discussed earlier, different bitrate settings yield different resolutions. Here are the bitrate combinations for the most common video resolutions.

    ULDLDSDHDFHD
    NameUltra-Low DefinitionLow DefinitionStandard DefinitionHigh DefinitionFull High Definition
    Video Bitrate (kbps)350350 – 800800 – 12001200 – 19001900 – 4500
    Resolution Width (px)42664085412801920
    Resolution Height (px)2403604807201080
    H.264 ProfileMainMainHighHighHigh

    There are the most common video bitrates for each type of viewing resolution.

    Conclusion

    mobile bitrate streaming
    Understanding bitrate settings, especially for mobile streaming, will improve your viewers’ experience.

    Delivering video to mobile devices is essential, but it requires high quality coupled with manageable file sizes. The settings we’ve discussed here should help you make the best of this situation, delivering excellent video to your viewers.

    As you choose an online video platform (OVP) for hosting your streams, you should look out for transcoding support. Luckily, most well-rounded OVPs should include video transcoding tools in their offerings. These tools are essential to make multiple versions of each video file you host.

    You should also look out for adaptive bitrate streaming support. That way, viewers can automatically be sent the version of the video that works best for them.

    Dacast offers support for these and other professional broadcasting tools. Try our live streaming platform risk-free for 14 days and test all of our features for yourself. Sign up today to start streaming for free.

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    Max Wilbert

    Max Wilbert is a passionate writer, live streaming practitioner, and has strong expertise in the video streaming industry.

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