Audio codec
Software codec
A software level audio codec is a specialized computer program, a codec that compresses (compresses) or decompresses (decompresses) digital audio data according to an audio file format or streaming audio format. The task of an audio codec as a compressor is to provide an audio signal with a certain quality / precision and the smallest possible size. Compression reduces the amount of space required to store audio data, and it is also possible to reduce the bandwidth of the channel through which the audio data is transmitted. Most audio codecs are implemented as software libraries that interact with one or more audio players such as QuickTime Player, XMMS, Winamp, VLC Media Player, MPlayer, or Windows Media Player.
Popular software audio codecs by application:
MPEG-1 Layer III (MP3): a proprietary audio codec (music, audiobooks, etc.) for computers and digital players
Advanced Audio Codec (AAC) – The second most common proprietary codec, positioned as an alternative to MP3. Most popular along with H.264 (AVC) video codec received in online video (eg flash video on YouTube)
Ogg Vorbis (OGG) is a free codec widely used in computer games and file-sharing networks to transfer music.
Free Lossless Audio Codec (FLAC) is a free codec that uses lossless compression. Alternative and less common lossless codecs: WavPack (WV), Monkey’s Audio (APE), etc.
GSM-FR is the first digital voice coding standard used in GSM phones
Adaptive multi rate (AMR): human voice recording on mobile phones and other mobile devices
G.723.1: one of the basic codecs for IP telephony applications
G.729 is a proprietary narrowband codec used to digitally represent speech
Internet Low Bit Rate Codec (iLBC) – A popular free codec for IP telephony (in particular for Skype and Google Talk)
Hardware codec
Realtek ALC 882 HD audio codec chip on motherboard
Realtek ALC 882 HD audio codec chip on motherboard
A hardware audio codec refers to a separate chip that encodes and decodes an analog audio signal into a digital signal and vice versa using analog-to-digital and digital-to-analog converters. Digital-to-analog conversion occurs when the computer sends sound to external speakers, and analog-to-digital conversion occurs when sound enters the computer from outside.
The audio codec is the main, but not always the only, component of a sound card. It is an intermediate link, an interface between analog ports to receive and transmit sound and digital sound processing units
In massive onboard sound cards on motherboards, the audio codec actually represents the entire sound card: it converts the analog signal received from the connectors into digital and transmits it to the south bridge of the motherboard, from where the sound digital goes to the central processor. This technology for processing digital audio in a central processor is called host signal processing.
In discrete sound cards connected to the motherboard, the audio codec performs the same function as in the integrated ones, but after digitization it transmits the audio signal not to the central processor, but to an audio processing and control chip special, also located on the sound card.
An audio codec chip is typically about 7mm², and in the case of an integrated sound card, it is typically located near the back of the motherboard. The main manufacturers of hardware audio codecs are Realtek, VIA Technologies, C-Media, Intel, and Analog Devices.
