In a late 2017 study, 63 percent of streaming video viewers cited buffering issues as the most serious problem they encounter. That number represented an increase from the 2016 figures, and the same findings are true today. Overall, they point to a very serious challenge with online video. How can you provide a good quality video streaming experience to all of your users? And one of the best ways to mitigate this potential problem is through video transcoding.
Simply put, video transcoding refers to the process of creating multiple versions of the same video. Each discrete version has an optimization that’s ideal for different users. In other words, video transcoding allows you to deliver high-quality videos to users with fast internet speeds. At the same time, you can deliver lower-resolution videos to viewers with slower internet connections. The end result, ideally, is decreased buffering and latency for all your viewers.
In this article, we’ll review several topics related to video transcoding. First, we’ll discuss how video transcoding works. Next, we’ll review how to maximize QoE (Quality of Experience) for viewers. Later, we’ll cover the differences between video transcoding locally versus in the cloud. Finally, we cover streaming solutions for multi-bitrate video, to ensure the best-quality video for all of your viewers.
What is video transcoding?
Video files are very large. That’s because they contain a lot of data. In other words, video files consumer a lot of bandwidth and device memory during transmission over the internet.
To address the large file sizes of video, we can use a technology called “codecs” to compress them. The most common video codec today is called H.264, though there are many other codecs as well. Overall, all codecs work in a similar way. Namely, they remove extraneous data from the video feed to reduce file size while maintaining a high-quality video as possible.
In order to shrink video files, codecs use complex algorithms. As computers and digital processing devices have become more powerful, more effective codecs have allowed users to further shrink down video files. Today, “next-generation” video codecs like AV1 and H.265 are now used on a limited scale.
Technically speaking, video transcoding refers to the process of taking an existing video file (or ongoing stream) and re-encoding it with a different codec or different settings. Generally, when someone makes a video recording, we call the resulting file a “master” file.
This master file is the best quality recording that exists. Any subsequent versions usually encode down the quality—that is, video transcoding renders a lower resolution and/or lower bitrate copy. Note that so-called up-encoding (video transcoding to a higher bitrate) is impossible. (However, limited up-rezzing (increasing resolution) is possible—but also with a loss of quality.)
Codecs, bitrate, resolution, and file size
As we’ve stated above, video transcoding can help to provide smaller versions of the original file. As an example, let’s imagine that you encoder your master file using the following settings:
- Codec: H.264
- Resolution: 1920 x 1080 (full HD)
- Bitrate: 6 Mbps
- Audio: AAC, 44.1 KHz, 164 kbps
From this original file/stream, we would usually recommend that broadcasters create a few different lower-bitrate, lower-resolution versions. These alternatives can provide a better viewing experience by allowing viewers with slower internet speeds to watch your stream. For example, these alternative versions might include:
- 720p version at 4 Mbps
- 480p version at 1.5 Mbps
- 360p version at 1000 kbps
Maximizing QoE (Quality of Experience) for viewers
When they watch a poor-quality stream, viewers become upset before they even realize that they’re upset. In short, their happiness levels fall fairly dramatically. After a negative streaming experience, a viewer is much more likely to leave the stream and to view your brand negatively. One survey, for example, found that 62 percent of viewers view a brand negatively if they publish a poor-quality video.
And all of this points to the importance of quality for video streaming. And video transcoding, once again, allows us to address this issue. Remember, video transcoding is key for broadcasters because the internet speed of a given viewer must be able to accommodate the bitrate of your video stream.
For example, my current internet speed is roughly 16 Mbps* (*that’s megabits, not the more common megabytes. Divide by 8 for a more common measure; 16 Mbps is equal to roughly 2 Megabytes per second). With a connection speed like that, I can watch 1080p HD streams. However, if I leave the house and want to keep watching on my cell phone, I may need to receive a smaller video file—especially if reception is poor.
If smaller, transcoded versions of the stream are not available, I may experience buffering, lagging, slow startup, or even failure to play. Taken together, these problems all relate to QoE (Quality of Experience). The takeaway? Maximizing QoE is essential for any video broadcaster. And video transcoding can help!
Video transcoding locally vs. in the cloud
Generally speaking, there are two ways to transcode your video: locally, or in the cloud. There are benefits and drawbacks to each approach. In most cases, local video transcoding is slower. It also results in multiple files that you must upload and manage separately. However, it’s also a free approach to video transcoding. Cloud transcoding, on the other hand, may entail specific pricing plans. In some cases, limited transcoding may come with an online video platform.
Local transcoding usually involves using a video editing or compression software (like Avid, Final Cut X, Compressor, or Adobe Premier). This software allows you to transcode a video file on your computer.
If you’re using a cloud video hosting solution, such as the Dacast platform, you first upload your “master file” to the Dacast platform. Then, you can click through to the “multi-bitrate” options for that file. Once there, you can select various resolutions and transcode your file into those versions.
With a pro OVP like Dacast, you can also select “auto-encoding” when uploading a video. This option automatically transcodes your VOD into several different renditions and makes them available to your viewers.
Which file formats does Dacast support for video transcoding?
Dacast uses the most common file formats for video transcoding. These standard settings include the following:
- Video codec: H.264
- Audio codec: AAC
- Video file format: MP4
- Resolutions supported: 1080p, 720p, 576p, 480p, 240p
Any video files that you transcode manually over Dacast, or that auto-encoding automatically transcodes, will use those settings.
Using an adaptive video player to deliver multi-bitrate streams
Of course, after you’ve done video transcoding into a multi-bitrate stream, you need a way to deliver it to your viewers. This delivery requires via a technology called “adaptive video players.”
First, an adaptive video player automatically detects the internet speed of a given viewer. Then, the player attempts to deliver the appropriate-quality video from the available options to each viewer. Adaptive video players also allow viewers to manually select the video quality from a menu within the player window. (Today, most of these video players are native html5 players.)
Research has found that online videos with a start-up time exceeding even two seconds have significantly higher streaming video abandonment rates. In fact, each incremental second of start-up time propels another 6% of viewers to tune out. Given these findings, an adaptive video player with transcoded videos is essential for today’s broadcasters.
Live streaming vs. video-on-demand in multiple bitrates
To do so, you need to set up multiple different outputs in your live stream encoding software or hardware. Each output should correspond to a given bitrate/resolution that you wish to stream live. The encoder will create versions of the stream that correspond to each setting. Then, it will send all of these versions to your online video platform simultaneously.
The only drawback to this method is that it requires more processing power and more upload bandwidth. That said, we do highly recommend that everyone do multi-bitrate live streaming to reach as many viewers on their own devices as possible.
We hope this article has clearly introduced you to key concepts around video transcoding for both online video and live streaming. As these topics determine QoE, we think it’s an important subject for any broadcaster to understand.
Do you already have a video streaming solution? If not, we hope you’ll consider the Dacast platform. It’s a powerful, versatile live streaming and video-on-demand hosting platform with analytics, video monetization, security, and privacy settings, and much more!
In fact, why not take advantage of our free 30-day trial (no credit card required)? You can try all the Dacast features yourself to see if our platform is a good fit for you before committing.
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