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什麼是視訊編碼 (Video Encoding),以及運作原理為何?
What is Video Encoding and How Does it Work

What is Video Encoding and How Does it Work

2022-06-08

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Video encoding is a very complicated process that converts a video file to another digital format for streaming or downloading. Without video encoding, you wouldn’t be able to watch your favorite television shows, movies, YouTube videos, or Facebook clips. But how does it work? And what do terms like transcoding and multi-bitrate encoding mean?

This article will explain everything you need to know about video encoding, including what it is, the difference between encoding, transcoding, and decoding, plus much more. So, let’s get right into it.


What is Video Encoding?

Video encoding is the process of converting raw video data into a format that can be stored, transmitted, and played back. It’s a complex process that involves taking the raw video data, encoding it, and then sending it to the right device for storage transmission in order to be played back. live streaming and VOD as two of the ubiquitous applications in modern days also requires video encoding to convert the video into a suitable format to stream over the internet.

It’s important to note that there are two major types of video encoding: lossy and lossless. Lossless video encodings result in better picture quality but take up more space than their lossy counterparts.


Encoding, Transcoding, Decoding, What’s the Difference?

Encoding is simply compressing a file into another format. Encoding is what makes videos play on your phone or tablet; if you’ve ever downloaded a video from YouTube and watched it on your phone or tablet, that’s because the content was encoded specifically for mobile devices.

Decoding is the process of converting a video file back to its original format; for example, decoding an H264/AVC video file will give you an M4V file that’s playable on iTunes or QuickTime Player. This is one of the most important video streaming processes before you can watch videos on your devices.

Transcoding is different than encoding because instead of compressing a video file from one form into another (as in encoding), transcoding converts one type of media into another while keeping its quality largely intact. So if you have an AVC-encoded video but want to play it on Apple TV via AirPlay™ streaming protocol, transcoding would convert that AVC-encoded file into HLS format so it can be streamed over Wi-Fi via AirPlay™ technology without losing too much visual quality.


How Does Video Encoding Work?

Video encoding involves breaking a video into frames, then encoding each frame into a bitstream. In the process of video streaming, encoding is integral to compressing the video size to make the video transmission more efficient.  There are many different techniques that can be used to encode the frames, including intra-frame and inter-frame techniques. Intra-frame techniques encode each frame separately, while inter-frame techniques encode the difference between successive frames.


What are the Most Popular Video Encoding Formats?

There are several popular video encoding formats, but there are two that stand out as the most widely used. The first is H.264, which was developed in 2003 and has been adopted by every major streaming service except YouTube. It’s similar to MPEG-2, which was released in 1993 and is still used for DVDs today.

The second format is VP8, which Google released in 2008 as one of its open-source projects. In 2010 it became known as WebM when it was incorporated into HTML5 videos on YouTube and Vimeo accounts (it isn’t currently supported by Netflix). VP8 offers high quality at low bitrates compared to other formats such as MPEG-4 or AVC/H264

Video Encoding Technology to Make Video Encoding Better and Easier

There are a number of different best-in-class video encoding techniques that are widely used in the industry, including multi-bitrate encoding, per-title-encoding, and video super resolution (VSR). Let’s briefly go over each of these popular video encoding techniques and examine what each technique involves and why you might choose to use a specific encoding technique versus another.

Multi-Bitrate encoding

Multi-bitrate encoding means that when encoding one specific video file, the technique encodes the video into multiple video streams at different bitrates. This allows you to create different versions of your video program without having to re-encode it every time you want to adjust its quality settings. It is for the purpose of making sure that your videos look as good as possible in all streaming environments. For example, if you watch a video on a phone, in a room with a bad internet connection, the highest quality video might not be the most suitable video to watch, therefore the player can pick other streams at different bitrates that is more suitable for the current situation.

Per-title-encoding

Before we dive into per-title encoding, we need to understand that not all types of video content require the same resolution and bitrate. It depends on the complexity of the video. Per-title encoding is a video encoding technique that optimizes the encoding process by analyzing and categorizing the source file into different bitrate intervals before encoding. Instead of encoding the video with the highest bitrate, the encoder process the source file at the most suitable bitrate. The audience can enjoy optimal video quality while consuming less bandwidth. It not only can increase the efficiency of video encoding but also save the cost by saving the bandwidth.

Video Super Resolution

Video Super Resolution (VSR) is a technique that allows you to upscale low-resolution video content. It uses a complex algorithm, which analyzes the average values of all pixels in each frame to create a sharpened image that has more detail than it originally had.

The process works by taking advantage of our eyes’ ability to perceive motion better than still images, so VSR only analyzes moving parts of an image and duplicates these movements in high resolution, allowing for better quality even at lower resolutions.

For example, if you took footage from an old camcorder and upscaled it using VSR, you would see your friend’s face come alive with details like freckles and wrinkles that were not visible before.


Conclusion

In this article, we defined encoding as the process of converting a video from one format to another. Encoding allows you to compress the original file size without losing quality, so it can be streamed on any device over the internet.

There are several benefits of having your videos encoded, but the main advantages of encoding are that you’ll have fewer buffering issues and a more engaging experience for your viewers.

BlendVision provides AI video encoding services for businesses that have a huge amount of video to encode and leverage online. Our proprietary per-title encoding analyzes video and audio content and encodes it into the most efficient streams to deliver, providing high-quality images under the most compact bandwidth. It effectively optimizes the video transmission process and saves up to 40% cost for enterprises. Reach out to our agent today to learn more.

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