What are Codecs?


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What are Codecs

CODECS

Whether you make your own video and audio files available on the Internet or want to use existing resources, there are a host of different player programs, codecs, and file formats available. Here we guide you through the jungle of MPEG, AVI, MKV & Co. On the one hand, the relationships between the different components of the system are explained. This will solve puzzles for example why only certain AVI videos are displayed on your computer and how you can solve such problems. On the other hand, the advantages and disadvantages of the different formats and methods are explained. In this way, you can evaluate what quality you can expect from an audio or video file and which files are particularly suitable for your purposes.

Codecs

As an end user, you are particularly familiar with one type of program: playback programs (or “players”). They play audio or video files and are therefore the software equivalent to CD or DVD playback devices. The program interface contains elements of a remote control: there are buttons for play, forward, backward, pause, etc. B. Windows Media Player, VLC Player, or Apple iTunes. Instead of inserting a data carrier, the files must be opened on the software players. Audio and video files can only be opened by a player if it can do something with the file format used.

File formats

The digital data with which analog video or audio signals are represented can be organized in various formats. This can best be explained for a single image – there are multiple ways to store individual pixels in a file. For example, if the image points are stored one after the other from left to right or first from top to bottom in the file it is of course a convention that must be specified. The way a color value is stored must also be clearly defined. These and many other specifications are determined by the respective file format. To store the data, a predefined encoding rule is always followed, which is ultimately decisive for the data to be interpreted correctly. Perhaps the difference between individual formats is better understood if you think of them as different data carriers: CDs, large and small discs, tapes, etc. they may contain audio data, but you still cannot put a disc in the CD player! The MPEG, Quicktime or Matroska formats are equally different. These formats are also known as container formats. The container can easily be imagined as a box that in turn contains various audio and video codecs. These codecs can encode and decode files, that is, compress a signal for transport, and then decompress it again during playback. if you think of them as different data carriers: CDs, large and small discs, tapes, etc. can contain audio data; however, you cannot put a disc in the CD player. The MPEG, Quicktime or Matroska formats are equally different. These formats are also known as container formats. The container can easily be imagined as a box that in turn contains various audio and video codecs. These codecs can encode and decode files, that is, compress a signal for transport, and then decompress it again during playback. if you think of them as different data carriers: CDs, large and small discs, tapes, etc. can contain audio data; however, you cannot put a disc in the CD player. The MPEG, Quicktime or Matroska formats are equally different. These formats are also known as container formats. The container can easily be imagined as a box that in turn contains various audio and video codecs. These codecs can encode and decode files, that is, compress a signal to transport it and then decompress it again during playback. The MPEG, Quicktime or Matroska formats are equally different. These formats are also known as container formats. The container can easily be imagined as a box that in turn contains various audio and video codecs. These codecs can encode and decode files, that is, compress a signal to transport it and then decompress it again during playback. The MPEG, Quicktime or Matroska formats are equally different. These formats are also known as container formats. The container can easily be imagined as a box that in turn contains various audio and video codecs. These codecs can encode and decode files, that is, compress a signal to transport it and then decompress it again during playback.

Many different codecs for playing video and audio data
In the living room, the various playback devices are often combined into one system, so multiple devices are not necessary. Different playback programs work the same way: they can read and play different formats. A separate codec is used for each format. These are snippets that only do one job: encode and decode audio or video information. Each codec can be used to write and read exactly one format. Different codecs are used for different formats; correspond roughly to the individual technical components of your stereo system. But instead of a K device for playing discs and a C device for playing DVDs, there is an M codec for playing audio in MP3 files and a W codec for playing video according to the MPEG-4 standard in MP4 files. Most of the players already have multiple codecs built in and therefore can play multiple file formats. There is also the possibility for a player to learn to understand other file formats by adapting additional codecs. Just as you can connect additional devices to your stereo system, such as an old record player or a high-end CD player, the players can be upgraded with plug-ins. A codec plugin is independent of a specific player and can be used by different players. Additional codecs are required, eg. Eg B. if you want to play newer or rarely used file formats with your playback software.


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What is a Codec? Clarifying concepts

What is a Codec? Clarifying concepts

Speaking of multimedia terminology, there is a fairly widespread confusion between the concept of image and / or sound format and that of audio and / or video container format (also called multimedia container format) To finish bundling it, it is very common to refer to both with the term codec that does not express any of the two previous concepts.

The image, video, audio format… is the way in which this type of information is encoded so that it can be treated by computer, which includes both being able to store it and transmit it. That format, therefore, would be a series of rules to describe images and sound in a computer way; a mathematical model, if you want to see it that way.

A codec (or codec, with tilde, in its Spanish version) is a program that encodes or decodes multimedia information according to a certain format. Once the data is encoded, it can be processed, for example stored or transmitted. As you may have guessed, the word codec is an acronym formed by the English words coder and decoder: encoder and decoder in Spanish.

An audio / video container format (or multimedia container format) is a computer file structure according to which audio and / or video is stored or transmitted as well as information associated with them (such as subtitles or bookmarks) The same container You can include together (multiplexed) the different components (tracks) in a single document. It is very common to add an extension to the name of the documents (those few letters that are at the end of the name separated by a period) that usually refer to the type of document. If you are rigorous in establishing that extension, it can serve as a clue to know which container is the document.

Considering the above, we could say that the document «feature film.avi» is a container in AVI format that includes video in MPEG4 format encoded using the Xvid codec. As the orthodox version is a very long phrase, it is common, for example, to say colloquially that the document “short.avi” is an MPEG4: it is obvious that it is an AVI container and everyone will know what codec has installed in their system for what formats

Most of the time, when packaging the information according to a certain format, it is compressed, that is, it is transformed so that the resulting information requires less memory to be stored or less bandwidth when transmitted than the original information.

There are two ways to compress information, with or without losses. Lossless (or lossless) formats allow you to reconstruct the information as it was originally, before compressing, without any difference from the original. In most cases the lossless coding usually allows (much) less compression (takes up much more) and is reserved for the documents that are going to be edited, that is, that they are not final documents.

The most frequent image and sound coding is with losses (lossy) Of course, the coding system seeks to make these losses as less noticeable as possible, considering for this, for example, the movement (What changes the image between a frame and another) The level of quality-compression is usually configurable so you can choose the degree you want between occupying more and having more quality. In line with what has been said about lossless formats, it is not a good idea to code according to a material loss format that is going to be edited since the successive recompressions cause more and more quality information to be lost to images and sound. Do not compress again and again using a lossy format!

One moment, you said that it is better to encode the original material using a lossless format but also that it will take up more. Then I must give the button on my camera that records video without compression? For starters, unfortunately, it is quite rare for your camcorder to have that button (in those of taking pictures and in audio systems it is something that is usually possible) Only in some cameras you can do something like that, they will usually be professionals and of the highest range. On the other hand, be prepared to spend a lot of memory and quickly, since you will need to store a lot and at full speed. So, what should I do? Our advice is that you choose, if you can, the best possible quality, even with losses, for the images you are going to edit and suitable for those that do not require more editing than the “cut” assembly since, properly processed , does not have to be compressed again.