what is a video file format? and is it any different then a video container format?

Question

hello, i’m trying to understand what a video file format is and if it’s any different then a video container format, for example

mp4

mv4

mkv

.webm

.flv

.ogg

.gif

.avi
.mov

are these all “video file formats” or video container formats? if these are container formats then what is the video file format of each of them and the difference between the video file format and the container format?

thank you

In: 3

Answer 1

A “file format” is an agreement about how to represent some sort of information as a file so that someone else can know how to get the information back out of the file later. A “video file format” is a file format where the information stored represents a video.

A “container format” is a file format that arranges information in “chunks” of information with some additional description of the chunk. If you know what a zip file is, it’s a container where the “chunks” represent other files. A container has a way of describing chunks of different types. A “video container format” is a container format where the chunks contain video information, and stuff that goes along with it (sound, subtitles, a list of cast and crew, release date, copyright, an icon for the file, etc.).

In the case of video, the information has to be compressed otherwise it’s too big to be useful. There’s all sorts os ways of doing that – simplifying the number of colors, saving only the bits that change from frame to frame, etc. In a simple file format, you’d expect the video to be represented a certain way every time. In a container, you expect to find a chunk of “video” that has a description of how the video was compressed. The creator of the video has a lot of flexibility using a container on how they shrink their video down, and they can use any of the methods that the container can describe. A video player will use the description to decide which method it will use to playback the video.

So, a .gif, which is not a container, always stores video using the same approach. It doesn’t include sound, subtitles, and you can’t add those things.

An .mp4 file is a container; it can store many chunks of audio and video using a whole bunch of different methods. It can have multiple audio chunks so the same file can multiple languages, or commentary. It can have subtitles, text, a preview icon, etc. The container not only contains the information (in chunks) but also a description of it all (“audio track 1 is English stereo, track 2 is Spanish stereo”, etc.).