Av9 Codec
Cortney Ruic
In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or data stream,[5] and hence is a type of codec. Endec is a portmanteau of encoder/decoder.
A coder or encoder encodes a data stream or a signal for transmission or storage, possibly in encrypted form, and the decoder function reverses the encoding for playback or editing. Codecs are used in videoconferencing, streaming media, and video editing applications.
In the mid-20th century, a codec was a device that coded analog signals into digital form using pulse-code modulation (PCM). Later, the name was also applied to software for converting between digital signal formats, including companding functions.
An audio codec converts analog audio signals into digital signals for transmission or encodes them for storage. A receiving device converts the digital signals back to analog form using an audio decoder for playback. An example of this is the codecs used in the sound cards of personal computers. A video codec accomplishes the same task for video signals.
In addition to encoding a signal, a codec may also compress the data to reduce transmission bandwidth or storage space. Compression codecs are classified primarily into lossy codecs and lossless codecs.
Lossless codecs are often used for archiving data in compressed form while retaining all information present in the original stream. If preserving the original quality of the stream is more important than eliminating the correspondingly larger data sizes, lossless codecs are preferred. This is especially true if the data is to undergo further processing (for example, editing) in which case the repeated application of processing (encoding and decoding) on lossy codecs will degrade the quality of the resulting data such that it is no longer identifiable (visually, audibly, or both). Using more than one codec or encoding scheme successively can also degrade quality significantly. The decreasing cost of storage capacity and network bandwidth has a tendency to reduce the need for lossy codecs for some media.
Many popular codecs are lossy. They reduce quality in order to maximize compression. Often, this type of compression is virtually indistinguishable from the original uncompressed sound or images, depending on the codec and the settings used.[7] The most widely used lossy data compression technique in digital media is based on the discrete cosine transform (DCT), used in compression standards such as JPEG images, H.26x and MPEG video, and MP3 and AAC audio. Smaller data sets ease the strain on relatively expensive storage sub-systems such as non-volatile memory and hard disk, as well as write-once-read-many formats such as CD-ROM, DVD, and Blu-ray Disc. Lower data rates also reduce cost and improve performance when the data is transmitted, e.g., over the internet.
Two principal techniques are used in codecs, pulse-code modulation and delta modulation. Codecs are often designed to emphasize certain aspects of the media to be encoded. For example, a digital video (using a DV codec) of a sports event needs to encode motion well but not necessarily exact colors, while a video of an art exhibit needs to encode color and surface texture well.
Audio codecs for cell phones need to have very low latency between source encoding and playback. In contrast, audio codecs for recording or broadcasting can use high-latency audio compression techniques to achieve higher fidelity at a lower bit rate.
There are thousands of audio and video codecs, ranging in cost from free to hundreds of dollars or more. This variety of codecs can create compatibility and obsolescence issues. The impact is lessened for older formats, for which free or nearly-free codecs have existed for a long time. The older formats are often ill-suited to modern applications, however, such as playback on small portable devices. For example, raw uncompressed PCM audio (44.1 kHz, 16-bit stereo, as represented on an audio CD or in a .wav or .aiff file) has long been a standard across multiple platforms, but its transmission over networks is slow and expensive compared with more modern compressed formats, such as Opus and MP3.
Many multimedia data streams contain both audio and video, and often some metadata that permits synchronization of audio and video. Each of these three streams may be handled by different programs, processes, or hardware; but for the multimedia data streams to be useful in stored or transmitted form, they must be encapsulated together in a container format.
Lower bitrate codecs allow more users, but they also have more distortion. Beyond the initial increase in distortion, lower bit rate codecs also achieve their lower bit rates by using more complex algorithms that make certain assumptions, such as those about the media and the packet loss rate. Other codecs may not make those same assumptions. When a user with a low bitrate codec talks to a user with another codec, additional distortion is introduced by each transcoding.
Audio Video Interleave (AVI) is sometimes erroneously described as a codec, but AVI is actually a container format, while a codec is a software or hardware tool that encodes or decodes audio or video into or from some audio or video format. Audio and video encoded with many codecs might be put into an AVI container, although AVI is not an ISO standard. There are also other well-known container formats, such as Ogg, ASF, QuickTime, RealMedia, Matroska, and DivX Media Format. MPEG transport stream, MPEG program stream, MP4, and ISO base media file format are examples of container formats that are ISO standardized.
The product results from a partnership with the Fraunhofer Institute, the body that was significant in creating the mp3 and AAC formats that most listen to today. Audition codecs in real time before committing to encode, ensuring your music sounds as good online as it does in the studio.
A codec is a hardware- or software-based process that compresses and decompresses large amounts of data. Codecs are used in applications to play and create media files for users, as well as to send media files over a network. The term is a blend of the words coder and decoder, as well as compression and decompression.
A codec takes data in one form, encodes it into another form and decodes it at the Egress point in the communication session. Codecs are made up of an encoder and decoder. The encoder compresses a media file, and the decoder decompresses the file. There are hundreds of different codecs designed to encode different mediums such as video and audio.
Codecs are invisible to the end user and come built into the software or hardware of a device. For example, Windows Media Player, which comes pre-installed with every edition of Windows, provides a limited set of codecs that play media files. Users can also download codecs to their computers if they need to open a specific file, but in those cases, it might be easier to download a codec pack or a player program. However, before adding codecs, users should first check which codecs are already installed on their system by using a software program.
Codecs serve a major purpose as, without them, media files would take up much more storage space, online downloads would take significantly longer and services like voice over IP would not be possible.
In communications, codecs can be hardware- or software-based. Hardware-based codecs perform analog-to-digital and digital-to-analog conversions. A common example is a modem used to send data traffic over analog voice circuits. In this case, the term codec is a blend of coder/decoder.
Software-based codecs describe the process of encoding source audio and video captured by a microphone or video camera in digital form for transmission to other participants in calls, video conferences, and streams or broadcasts, as well as shrinking media files for users to store or send over the internet. In this example, the term codec is a blend of compression/decompression.
A codec's main job is data transformation and encapsulation for transmission across a network. Voice and video codecs both use a software algorithm that runs either on a common processor or in hardware optimized for data encapsulation and decapsulation. Most smartphones also provide optimized hardware to support video codecs.
Predictive codecs use an algorithm to convert data into a byte sequence for easy transmission across a data network and then convert the byte sequence back into voice or video for reception at the endpoint.
The higher the bit rate, the less compression there is. And less compression generally means higher -- or closer to the original -- quality overall. Some codecs create smaller files with reasonably acceptable quality, but they are more difficult to edit. Other codecs create efficient files that are higher quality but take up more space. Still other codecs create small and efficient files but lack overall quality. Multimedia files that have different data streams are encapsulated together. So, for example, a multimedia file that has both audio and video is encapsulated together.
Codecs exist for audio-, video- and image-based media files. These codecs are categorized by whether they are lossy or lossless and compressed or uncompressed. Lossy codecs reduce the file's quality in order to maximize compression. This minimizes bandwidth requirements for media transmission. Lossy codecs capture only a portion of the data needed by a predictive algorithm to produce a near-identical copy of the original voice or video data. Lossy codecs produce manageable file sizes, which are good for transmitting data over the internet.
Lossless codecs have a data compression algorithm that enables the compression and decompression of files without loss of quality. This is good for preserving the original quality of the file. Lossless codecs capture, transmit and decode all audio and video information at the expense of higher bandwidth requirements. Lossless codecs are a good fit for film, video and photo editing.
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