science

Video codec

Video codec is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Video codec rather than just read about it. In short: A video codec is software or hardware that compresses and decompresses digital video. In the context of video compression, codec is a portmanteau of encoder and decoder, while a device that only compresses is typically called an encoder, and one that only decompresses is a decoder.

Key takeaways

Video codec belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Video codec to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Video codec from memory before moving on to harder problems.

Reference excerpt

A video codec is software or hardware that compresses and decompresses digital video. In the context of video compression, codec is a portmanteau of encoder and decoder, while a device that only compresses is typically called an encoder, and one that only decompresses is a decoder. The compressed data format usually conforms to a standard video coding format. The compression is typically lossy, meaning that the compressed video lacks some information present in the original video. A consequence of this is that decompressed video has lower quality than the original, uncompressed video because there is insufficient information to accurately reconstruct the original video. There are complex relationships between the video quality, the amount of data used to represent the video (determined by the bit rate), the complexity of the encoding and decoding algorithms, sensitivity to data losses and errors, ease of editing, random access, and end-to-end delay (latency).

History

Historically, video was stored as an analog signal on magnetic tape. Around the time when the compact disc entered the market as a digital-format replacement for analog audio, it became feasible to also store and convey video in digital form. Because of the large amount of storage and bandwidth needed to record and convey raw video, a method was needed to reduce the amount of data used to represent the raw video. Since then, engineers and mathematicians have developed a number of solutions for achieving this goal that involve compressing the digital video data. In 1974, discrete cosine transform (DCT) compression was introduced by Nasir Ahmed, T. Natarajan and K. R. Rao. During the late 1980s, a number of companies began experimenting with DCT lossy compression for video coding, leading to the development of the H.261 standard. H.261 was the first practical video coding standard, and was developed by a number of companies, including Hitachi, PictureTel, NTT, BT, and Toshiba, among others. Since H.261, DCT compression has been adopted by all the major video coding standards that followed. The most popular video coding standards used for codecs have been the MPEG standards. MPEG-1 was developed by the Motion Picture Experts Group (MPEG) in 1991, and it was designed to compress VHS-quality video. It was succeeded in 1994 by MPEG-2/H.262, which was developed by a number of companies, primarily Sony, Thomson and Mitsubishi Electric. MPEG-2 became the standard video format for DVD and SD digital television. In 1999, it was followed by MPEG-4/H.263, which was a major leap forward for video compression technology. It was developed by a number of companies, primarily Mitsubishi Electric, Hitachi and Panasonic. The most widely used video coding format, as of 2016, is H.264/MPEG-4 AVC. It was developed in 2003 by a number of organizations, primarily Panasonic, Godo Kaisha IP Bridge and LG Electronics. H.264 is the main video encoding standard for Blu-ray Discs, and is widely used by streaming internet services such as YouTube, Netflix, Vimeo, and iTunes Store, web software such as Adobe Flash Player and Microsoft Silverlight, and various HDTV broadcasts over terrestrial and satellite television. AVC has been succeeded by HEVC (H.265), developed in 2013. It is heavily patented, with the majority of patents belonging to Samsung Electronics, GE, NTT and JVC Kenwood. The adoption of HEVC has been hampered by its complex licensing structure. HEVC is, in turn, succeeded by Versatile Video Coding (VVC). There are also the open and free VP8, VP9 and AV1 video coding formats, used by YouTube, all of which were developed with involvement from Google.

Applications Video codecs are used in DVD players, Internet video, video on demand, digital cable, digital terrestrial television, videotelephony and a variety of other applications. In particular, they are widely used in applications that record or transmit video, which may not be feasible with the high data volumes and bandwidths of uncompressed video. For example, they are used in operating theaters to record surgical operations, in IP cameras in security systems, and in remotely operated underwater vehicles and unmanned aerial vehicles. Any video stream or file can be encoded using a wide variety of live video format options.

Video codec design

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Video codec

Start with the simplest possible case. Write down what Video codec claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Video codec before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Video codec ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Video codec

In research: Video codec appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Video codec in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Video codec is common in secondary-school and first-year university syllabi. It links to neighbouring topics Data compression, Video codecs, Videotelephony, so understanding it makes those chapters shorter.
In everyday life: Look for Video codec outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Video codec in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Video codec means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Video codec out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Video codec in simple terms?

Why does Video codec matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Video codec?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Video codec.