What is present inside a Video ?

14 Nov 2021 in cs

Let’s revisit our understanding on Video. We have many Video format for diverse applications.  Understanding a video format helps in applying right way. Let’s check our understanding here.

1. Lab
   1. Container information
   2. Codec information
2. Concepts
   1. What is codec and how it works ?
3. Further reading

Video contains two main parts, Codec and Container.

Container: - we can find out easily by looking at video file extension. Codec: - Software to Compresses or De-Compresses the Video.

Lab

• Use any video or download a sample video file from this location - MP4-Sample video.
• Download the MediaInfo Software

Container information

• If you see below, it contains three parts.
• 

Codec information

• How video is compressed? Here, this sample video is using H264 codec to compress the video.
• In below, you see Codec Information about video file using Media Info.
• 

Concepts

What is codec and how it works ?

Codec is the reason we can play, store or stream the video, there are tons of codecs available today.

• Video is a series of images.
  • Main Idea: Most experts have a tough time agreeing on an exact number, but the conclusion is that most humans can see at a rate of 30 to 60 frames per second.
  • Video player plays these images one by one based on time.
    • So, we can optimize on how we are going to save the Video, right ? We don’t need to save 30-60 images per second.
• How to save these images as video file ? What Algorithm works ?
  • Humans invented the Codecs, which compresses/de-compresses the video file using many techniques in computer vision.
  • Simple example of one technique to compress series of images with visualization video is here

Further reading

1. H264 Overview
2. Understanding H264
3. Discrete cosine transform
4. How many frames per second

Let me know for comments.