Last updated on November 10th, 2023 at 03:48 am
According to the book Emerging Research on Networked Multimedia Communication Systems by Dimitris Kanellopoulos, “A video codec is a hardware device or software, which enables compression or decompression of digital video.”
Basically, it takes a big video file and squeezes it into a smaller file size while keeping the original quality as much as possible. It also ‘expands’ a small video file and makes its file size larger while improving video quality.
Let’s say you have an HD-quality video captured in your video camera and want to share it online but don’t want to contend with a huge file size. You just want normal clarity and a smaller file size for easy uploading, and you want the video to be streamed to those with slower internet connections.
What you would do is you would want to squeeze it down to a much smaller file size while still maintaining its quality as far as possible.
This is when a codec comes into play.
Why is a Video Codec Necessary?
A codec efficiently compresses and decompresses video data without significant quality loss.
This compression and decompression makes it possible to store, transmit and process video files.
Codecs work by mapping complex visual data into more manageable, compressed forms. This is done without sacrificing important details.
Practically speaking, codecs make using video in various applications and devices possible. Especially those with limited processing power and storage capacity.
For example, if you want to create a video to be viewed over a smartphone, you would have to use a codec to compress it and reduce file size to be easily played without quality loss.
Real-World Codec Usage
Wheever video is produced and transmitted, there’s almost always a codec involved.
Let’s take a look at platforms with video content like YouTube, Tik Tok, Facebook, and WhatsApp.
When you upload a video to these platforms, they’ll compress your video to lower file size before your video is published.
This compression is necessary to make them playable over mobile devices with slow Internet connections.
Each of these platforms uses different codecs. Some may even require you to use a certain codec to compress your video before uploading.
For example, YouTube recommends that use the H.264 codec to process your video before uploading.
Where to Find a Codec?
Let’s say you’ve shot a video. Where do you find a codec to compress the video according to your needs?
You can find it through a video converter or a video editor. When do you use a video converter, and when do you use a video editor?
You could use a video converter if you don’t need to add or remove anything from the original video file. With a video converter, you input a file and then convert it with the codec you want in the output settings.
If you would like to trim your video and add titles or effects, you would want to put it through a video editing program.
After you’ve edited the video, you can choose one of the many export settings provided in the video editor.
The settings come with different codecs tailored to the use the video will be put to.
Video Capture Device
There is another method which is not very popular where codecs come into play.
This happens when you transfer video from your camcorder to your computer via a video capture card. Here you could choose the compression you need via one of the many preset codecs with the software that controls the video capture device.
Without a codec, a second of uncompressed would typically require a space of 20MB to store it. One minute of uncompressed digital video requires over 1GB of storage space.
Also, hard disk drives can’t handle a data transfer speed of 20MB per second.
So, a DV codec is employed. In most camcorders, it compresses the raw video to 3.6MB per second, which most computers can handle.
Most capture cards encode in DV, but you could choose MPEG-1 if you want to burn your video to VCD or MPEG-2 if you want to create a DVD.
Two Types of Codecs
There are two types of codecs you need to be aware of. Lossless codecs and lossy codecs.
A lossless codec takes a video source file and compresses it without any quality loss. The only thing that changes in the compression process is the file size which is reduced.
For example, you may have a video file size of 100MB and by using a lossless codec you can get the size reduced to say 50MB or 40MB depending on the codec you use.
How is this done? A lossless codec ignores redundant information and retains only data which contributes to the video quality.
Information that is repeated is combined into a whole unit instead of leaving them as separate units which would take up more space.
Lossy codecs are used when video quality is not paramount, but the file size is. For example, if you need to attach a video file to an email or stream video, you would want the smallest size possible to save on upload time and download time.
An example of a video where you want to use a lossy codec is a talking head video. For example, a lecture, where what’s being said is more important than the image quality.
With lossless compression, you could decompress it to the original file before it was compressed.
With lossy compression, with much information removed, you can use it to recover the original uncompressed file. So, you should make it a point to retain the original video file if you foresee using it for a different purpose.
Here are some codecs popularly used :
MPEG ( Moving Picture Experts Group)
MPEG-1 is typically used for VCDs.
MPEG-2 is a higher-quality compression associated with DVDs.
MP3 (MPEG-1 Layer 3) is a popular standard for audio compression at 128kbits per second, approximately 1/11th the size of a similar audio CD file.
MPEG-4 has superior compression ability. A popular codec associated with it is the H.264 codec which could be used for Blu-ray.
H.264’s compression flexibility must be noted. It allows for compression at higher and lower bit rates and resolutions from mobile phone video right up to videos with broadcast quality.
Windows Media Video by Microsoft emerged as an answer to RealVideo when it was the top choice for Internet video streaming.
In the WMV family, you should take note of WMV9. The Microsoft camp claims that the WMV9 has better compression ability than MPEG-2 or even MPEG-4.
This codec is popularly used when capturing video from a mini-DV camcorder into your computer.
DV25 captures video at 25Mbps (Megabits per second). On a PC it will be captured into an AVI and on a Mac into a MOV file, both of which are container formats.
Which Codec(s) to Choose?
There is no one right answer. You choose a codec based on your video production needs. There are two considerations here. First is the video quality you need. If you are going to share video over the Internet or social media networks, you wouldn’t need a lossless codec. You would go for the smallest file size to help speed up uploading and streaming time.
Try a few codecs that come with your video editing program or video converter and check their file sizes and quality.
You’ll soon get a hang of which codec to use for which video project.