Some of the more technical aspects of video making deal with file formats, conversion, compression and codecs.
Read on for a simple, common sense explanation of these subjects.
File Formats
Have you ever tried to play a video and it simply would not play? Chances are high you were experiencing problems with digital video file format incompatibilities. In other words, the file format, indicated by the last three or four letters in a digital file name after the dot – Video.mov, or video.mpg – are incompatible. To make it work, the file formats will have to be converted to a compatible format, or you’d need to switch players to one that matches your file.
There are dozens of digital video file formats, and they can be drastically different on a technical level. This is where the incompatibilities arise.
Each format has its specific uses. You have everything from the huge, raw files straight out of the camera to the tiny, highly-compressed files that are meant to be uploaded to the web. It’s important to know what type of format you are working with so you know how to use it properly.
For instance, large files directly out of the camera are meant to be used as source material in an editing program. The large file size means the file contains lots of digital information and should therefore have the highest quality. If you uploaded that same huge file to the internet, it probably would not play well because the tremendous size and amount of digital info clogs up the system, so to speak. If you compress the file to a different format, and perhaps change a few other parameters as well, you can make it small enough to play well online, and the average viewer won’t see a discernable difference between the two files, especially when viewing on a small screen as one normally does online.
Video Conversion
Video conversion is the process of running a video through some conversion software to change it from one format to the other. Other parameters besides file format can be changed at the same time.
There are dozens of video conversion choices on the market. Read the specs carefully before you get one because each program is designed to work with specific formats and codecs. The best programs have a lot of versatility. I’ve used free programs for years and they were enough.
When you do a deep dive on this subject, it can get tremendously complex. The people who work converting high budget Hollywood movies to run on Netflix, for example, have to study for years to become proficient, but the average video hobbyist only needs to know the basics. Often, the default setting will work for you. Since conversion can get so complex, most programs do their best to make it simple. So if you don’t know exactly what you are doing, stick with default setting and chances are high that will work for you.
Here is an article on two free video conversion software choices that are quite versatile. I’ve used them for years with fabulous results. (I make no money from that recommendation and have no personal relationship with those products other than longtime user.)
What is Digital Video Compression and Why Bother?
The word compression basically means to make something smaller. You can compress a foam ball by squeezing it. You can compress air using temperature or pressure. With video, you use software to compress your video files and make them smaller. Compression often happens when you convert files, but not always. Sometimes a conversion will make your file size bigger. Compression is usually done so a video will shrink in file size and therefore play more easily on a crowded internet.
Without video compression, Internet video would simply not be possible. It’s that important.
Compared to text or audio files, video files are HUGE. Download times for raw, uncompressed video would be so high that no one would bother, even at broadband speeds.
Compression is the process of taking the huge raw file and knocking the file size down while preserving a decent picture.
Compression works by first analyzing the complex and detailed video signal. Portions of the signal not noticeable to the human eye are dropped. Some detail and resolution can be lost, but hopefully not too much.
Different compression methods select differing data to lose, and this causes variable results. It is also a cause of incompatibility.
On the flip side of video compression is video decompression. Decompression happens automatically when the compressed file is opened and played. Some of the lost information is restored by the player software you use. This means your player software needs to work with the file format you are trying to play.
What is a Video Codec?
Codec is a term that combines the root words compression and decompression.
What is compressed must then be decompressed.
To do so properly, requires the machine reading the file be able to reverse the process used for compression. This means the software playing the video needs to be compatible with the software that compressed the video.
Hence, the two go together like a lock and key and form the word codec.
Compatibility issues come up with editing software or playing devices if the compression and decompression methods are incompatible.
This happens frequently and produces the joy known as the video maker’s headache. I don’t know any serious video maker who hasn’t struggled at one point with compression and file format incompatibility.
Different software platforms and the file formats they produce differ, in part, by their codecs. So if incompatibility arises, it almost always can be traced back to codecs.
Rarely do you need to concern yourself with the specifics of which codec is being used when, but being aware of compatibility issues can help you slog through whenever the inevitable problems arise.
For most of my digital video compression and conversion, I use the free software Handbrake and convert my finished video to MPEG4 before uploading it to the web. I usually bring it out of my editing program as a QuickTime (.mov). My edit software is Final Cut, so dot mov is its native format.
Handbrake is easy to use, and MPEG4 is the most universally accepted format for the web today.
I hope this information helps you make better videos to share online.
Lorraine Grula
FOOD FOR THOUGHT
- True or False: Video file formats are all very similar to each other, so they become irrelevant.
- True or False? Without video compression and decompression, internet video would not work!
- In your own words, explain what the term “CODEC” means and how it was derived.
- Explain how the analogy with a lock and key pertains to video compression.
