SherbyNet - /page/wikibook/entry.mu

Micron Document

<!DOCTYPE html>

<title>Video decoder</title>

</head>

<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Video decoder</span></span>

</h1>

</header>

/* start https://en.wikipedia.org/ */

.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}

/* end https://en.wikipedia.org/ */

</style><div role="note" class="hatnote navigation-not-searchable">This article is about decoding analog video signals. For digital video compression decoders, see <a href="Video_codec" title="Video codec">video codec</a>.</div>

<p>A <b>video decoder</b> is an <a href="Electronic_circuit" title="Electronic circuit">electronic circuit</a>, often contained within a single <a href="Integrated_circuit" title="Integrated circuit">integrated circuit</a> chip, that converts base-band <a href="Analog_video" class="mw-redirect" title="Analog video">analog video</a> signals to digital video.<sup id="cite_ref-VideoDemystified_1-0" class="reference"><a href="#cite_note-VideoDemystified-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Video decoders commonly allow programmable control over video characteristics such as <a href="Hue" title="Hue">hue</a>, <a href="Contrast_(vision)" title="Contrast (vision)">contrast</a>, and <a href="Colorfulness" title="Colorfulness">saturation</a>. A video decoder performs the inverse function of a <b>video encoder</b>, which converts raw (uncompressed) digital video to analog video. Video decoders are commonly used in <a href="Video_capture_device" class="mw-redirect" title="Video capture device">video capture devices</a> and <a href="Frame_grabber" title="Frame grabber">frame grabbers</a>.

</p>

<div class="mw-heading mw-heading2"><h2 id="Signals">Signals</h2></div>

<p>The input signal to a video decoder is analog video that conforms to a standard format. For example, a standard definition (SD) decoder accepts (<a href="Composite_video" title="Composite video">composite</a> or <a href="S-Video" title="S-Video">S-Video</a>) that conforms to SD formats such as <a href="NTSC" title="NTSC">NTSC</a> or <a href="PAL" title="PAL">PAL</a>. High definition (HD) decoders accept analog HD formats such as AHD, HD-TVI, or HD-CVI.

</p><p>The output digital video may be formatted in various ways, such as 8-bit or 16-bit <a href="4%3A2%3A2" class="mw-redirect" title="4:2:2">4:2:2</a>, 12-bit <a href="4%3A1%3A1" class="mw-redirect" title="4:1:1">4:1:1</a>, <a href="ITU-R_BT.656" title="ITU-R BT.656">BT.656</a> (SD) or <a href="BT.1120" title="BT.1120">BT.1120</a> (HD). Usually, in addition to the digital video output bus, a video decoder will also generate a <a href="Clock_signal" title="Clock signal">clock signal</a> and other signals such as:

</p>

<ul><li><a href="Frame_synchronization_(video)" title="Frame synchronization (video)">Sync</a> — indicates the beginning of a video frame</li>

<li><a href="Blanking_(video)" title="Blanking (video)">Blanking</a> — indicates video blanking interval</li>

<li><a href="Field_(video)" title="Field (video)">Field</a> — indicates whether the current video field is even or odd (applies to interlaced formats)</li>

<li>Lock — indicates the decoder has detected and is locked (synchronized) to a valid analog input video signal</li></ul>

<div class="mw-heading mw-heading2"><h2 id="Functional_blocks">Functional blocks</h2></div>

<p>The main functional blocks of a video decoder typically include these:

</p>

<ul><li>Analog processors</li>

<li>Y/C (luminance/chrominance) separation</li>

<li>Chrominance processor</li>

<li>Luminance processor</li>

<li>Clock/timing processor</li>

<li>A/D converters for Y/C</li>

<li>Output formatter</li>

<li>Host communication interface</li></ul>

<div class="mw-heading mw-heading2"><h2 id="Process">Process</h2></div>

<p>Video decoding involves several processing steps. First the <a href="Analog_signal" title="Analog signal">analog signal</a> is digitized by an <a href="Analog-to-digital_converter" title="Analog-to-digital converter">analog-to-digital converter</a> to produce a raw, digital data stream. In the case of <a href="Composite_video" title="Composite video">composite video</a>, the <a href="Luminance" title="Luminance">luminance</a> and <a href="Chrominance" title="Chrominance">chrominance</a> are then separated; this is not necessary for <a href="S-Video" title="S-Video">S-Video</a> sources. Next, the chrominance is demodulated to produce color difference video data. At this point, the data may be modified so as to adjust brightness, contrast, saturation and hue. Finally, the data is transformed by a <a href="Color_space" title="Color space">color space</a> converter to generate data in conformance with any of several color space standards, such as <a href="RGB" class="mw-redirect" title="RGB">RGB</a> and <a href="YCbCr" title="YCbCr">YCbCr</a>. Together, these steps constitute <i>video decoding</i> because they "decode" an analog video format such as <a href="NTSC" title="NTSC">NTSC</a> or <a href="PAL" title="PAL">PAL</a>.

</p>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}

/* end https://en.wikipedia.org/ */

</style><div class="reflist">

/* start https://en.wikipedia.org/ */

.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("./mw/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("./mw/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("./mw/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("./mw/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}

/* end https://en.wikipedia.org/ */

</style><cite id="CITEREFJack1996" class="citation book cs1">Jack, Keith (1996). <i>Video demystified : a handbook for the digital engineer</i> (2nd ed.). San Diego, CA: HighText Interactive. p. 233. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>1-878707-23-X</bdi>.</cite></span>

</li>

</ol></div></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .asbox{position:relative;overflow:hidden}.mw-parser-output .asbox table{background:transparent}.mw-parser-output .asbox p{margin:0}.mw-parser-output .asbox p+p{margin-top:0.25em}.mw-parser-output .asbox-body{font-style:italic}.mw-parser-output .asbox-note{font-size:smaller}.mw-parser-output .asbox .navbar{position:absolute;top:-0.75em;right:1em;display:none}.mw-parser-output :not(p):not(.asbox)+style+.asbox,.mw-parser-output :not(p):not(.asbox)+link+.asbox{margin-top:3em}

/* end https://en.wikipedia.org/ */

</style></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2022-03-16" href="https://en.wikipedia.org/wiki/?title=Video_decoder&oldid=1077451060">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

</div>

</div></div>

</div>

</main>

</div>

</body></html>