This task aims to give an introductory look at what makes up a video file. To do this we will download a video file and take a look at what is inside.

Download a video file from a video sharing site that make it easy to do this. If you are not sure then you can visit engagemedia.org and follow these instructions.

Choose a video and go to the page of the video. When you have a player

Click on one of the videos options under download. Let's click on webm low res to download this and for comparison let's also download the mp4 high res to compare it.

We can play these file on our desktop using an video playing applications like movie player, or VLC or iTunes. To support open video we recomend that you use VLC player, a great open source solution.

However, just playing the file doesn't help us to really understand what is inside it. To find out more we will use another Free Software programme called Media Info. You can download it from here.

Using MediaInfo to investigate the anatomy of video files

When you have installed MediaInfo launch it and you should get an interface like the one shown below.

Let's open one of our video files by clicking on the Open File icon or selecting File > Open > Open File(s) from the menu.

When we open the video file MediaInfo reads the file but instead of playing the video it displays information about it.

The General section here gives us the following information

WebM: 4.64MiB, 2mn 38s
1 Video Stream: VP8
1 Audio Stream: Ogg Theora

This information will be useful to us later in this course when we start to work with video files. It is also useful right at the start to understand the parts video files are made up of.

WebM here describes the video container. Popular video containers include .mp4, .mov, .avi. Containers themselves don't contain any video or audio content, they are the vehicle in which that content travels.

We can see that the WebM container here has one video stream and one audio stream. Sometimes we can have files that contain many different video and audio streams, this can be particularly useful if we have a film with different audio streams in different languages. We can see this in the video file listed below.

The information of the video above shows us a video file using the Matroska container (.mkv). This container allows you to add more than one audio stream.

Codecs

Each stream that we see here has audio or video information that is compressed using codecs. We we learn more about Codec and containers in the following chapters. Right now we just need to understand that they are used to compress media data so that it takes up less space.

Popular video codecs include h264, vp8, mpeg2.
Popular audio codecs include ac-2, ogg theora and mp3.

Task -

Download and Install MediaInfo
Open a video file and examine the different parts of it, streams, metadata,