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Audio and video interfaces and connectors
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<p>Audio connectors and video connectors are <a href="/facts/Electrical_connector/rJh0cHs6">electrical</a> or <a href="/facts/Optical_fiber_connector/uIC3170n">optical connectors</a> for carrying <a href="/facts/Audio_signal/rFSTI9IF">audio</a> or <a href="/facts/Video_signal/F1AV8ben">video signals</a>. Audio interfaces or video interfaces define physical parameters and interpretation of signals. Some connectors and interfaces carry either audio only or video only, whereas others carry both, <a href="/facts/Audiovisual/7BPs5I28">audio and video</a>. </p><p>For <a href="/facts/Digital_audio/PgugcLAI">digital audio</a> and <a href="/facts/Digital_video/xsn9omqG">digital video</a>, this can be thought of as defining the <a href="/facts/Physical_layer/WuATCrVw">physical layer</a>, <a href="/facts/Data_link_layer/K9yPufbt">data link layer</a>, and most or all of the <a href="/facts/Application_layer/FAFhLruA">application layer</a>. For <a href="/facts/Analog_audio/1Ggd37l0">analog audio</a> and <a href="/facts/Analog_video/F1AV8ben">analog video</a> these functions are all represented in a single signal specification like <a href="/facts/NTSC/HYWIvxCR">NTSC</a> or the direct <a href="/facts/Loudspeaker/tqEjnJ2z">speaker</a>-driving signal of analog audio. </p><p>Physical characteristics of the electrical or optical equipment include the types and numbers of wires required, voltages, frequencies, optical intensity, and the physical design of the connectors. Any data link layer details define how application data is encapsulated (for example for <a href="/facts/Synchronization/L39sYwbr">synchronization</a> or <a href="/facts/Error-correction/o2rH8e3n">error-correction</a>). Application layer details define the actual audio or video format being transmitted, often incorporating <a href="/facts/Codec/C7b7Am8t">codecs</a> not specific to the interface, such as <a href="/facts/PCM/5gdfjtH3">PCM</a>, <a href="/facts/MPEG-2/SpuH5FJu">MPEG-2</a>, or the <a href="/facts/DTS_Coherent_Acoustics_codec/wbQwqtdQ">DTS Coherent Acoustics codec</a>. In some cases, the application layer is left open; for example, <a href="/facts/HDMI/HuNwzm04">HDMI</a> contains an <a href="/facts/Ethernet/nMfhU8tU">Ethernet</a> channel for general data transmission. </p><p>Some types of connectors are used by multiple hardware interfaces; for example, <a href="/facts/RCA_connector/A9etkIUn">RCA connectors</a> are used both by the <a href="/facts/Composite_video/FIsE6mBz">composite video</a> and <a href="/facts/Component_video/UEXxJ2gy">component video</a> interfaces, but <a href="/facts/Digital_Visual_Interface/Dpnu9JmB">DVI</a> is the only interface that uses the DVI connector. This means that in some cases not all components with physically compatible connectors will actually work together. </p><p>Analog A/V connectors often use <a href="/facts/Shielded_cable/BqyI4KSu">shielded cables</a> to inhibit <a href="/facts/RF_interference/gv3DlKNr">radio frequency interference</a> (RFI) and <a href="/facts/Noise/aUstHDqU">noise</a>. </p>