Basics-基础知识

An encoded video contains two major parts: 1-codecs( compression decompression algorithms ), which compress the video; 2-containers(or formats), the file type that is output after the compression. 

Encoder + Decoder = CODEC

Video CODEC are everywhere, for example, your smart phone encodes video from its camera before saving it on the phone's memory, it will decode video from memory or from a YouTube Stream before display it. You will find video codecs inside phones, cameras, laptops, TVs and so on. 

The format is like the shipping box and codecs are goods inside. 

Examples of popular video codecs are h.265/HEVC h.264/AVC, VP6, VC1, MP2.

Examples of containers or formats include MOV, AVI, WMV(Window Meida), MP4.

The majority of video on the web is the Adobe Flash format. 

Adobe Flash contain three different codecs: spark, VP6, H.264. There are pros and cons to each codec. 

Before encoding your video for the web, one more thing you need to understand is Delivery  Method . 

There two methods in which to deliver your online video: Progressive Download and Streaming. 

With the progressive download, video begins playing on the a flasher player load, the entire video needs to be downloaded before you can finish the video. This is the most pervasive(最普遍的) method and is typically used for videos under 10 minutes in length. 

Stream video is easier to navigate through because you can easily click play and seek to any point in the video. The file begins downloading from that point. This method is typically used for long-form video.