ARTICLE: DEMYSTIFYING CODECS AND FILE COMPRESSION

An important part of the video file format process is the codec. The codec is the software used to compress video so it can be easily stored and played back. Codecs digitise and tightly compress an audio or video signal for transmission, online streaming and storage requirements. 
 
Encoders and Decoders 
There are two main components within a Codec: an encoder and a decoder. These both work in parallel to create a video file size which is easier to manage and work with. The encoder is responsible for handling file compression whilst the decoder prepares the file for viewing once it has been compressed, decompressing the file in to the specific video container.  
 
Compression 
Compression plays a pivotal role within video formats and codecs. Uncompressed files can crash, and take a long time to load and playback - which is far from ideal, particularly in the world of fast scrolling and digital media consumption!  In order to stream video content, you need a combination of both audio and video codecs working in harmony together.  
 
Codecs compress files through an algorithm which determines the best way to shrink the size of the video without affecting and compromising quality and playback.  
 
Lossy and Lossless compression 
Lossless compression (as the very nature of the word itself means), reduces file size without losing any visual quality. All file information is retained so you can tweak as need be and even reverse the file back to it’s original state if so desired. As a result, lossless files can still prove to be generally large in file size despite compression which can affect uploading to certain platforms and streaming on some devices and platforms.  
 
Lossy compression discards unnecessary data at the source which enables large amounts of data to be handled economically.  This can affect picture quality to a certain degree (for example detailed colour tonal ranges) but it does mean the file size is a lot smaller and more workable. This makes lossy files an ideal contender for sharing content online. It’s also worth noting that it is not possible to reverse lossy files back to their original file format like you can with lossless.  
 
Video Bitrate 
When using a codec for video compression, you can select the bitrate. This refers to the amount of data transferred at any given time, often referred to as the number of bits per second. The bitrate affects how the codec compresses the video file, a high bitrate means data can be processed faster improving quality but also means it won’t be as compressed leading to a larger file size. High bitrates require fast internet connection and playback, which means you need to be careful choosing the platform for transmitting your video file. 
 
It can seem like the world of video file formats is tricky to understand and navigate your way through. However, taking a little time out to understand each element, being clear on how your video will be transmitted, whether it is for online use or broadcast purposes or just future storage or archive will help decide the best file format for your needs.  

 
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Originally published: 23/08/2022