{"id":267,"date":"2015-08-27T15:05:00","date_gmt":"2015-08-27T15:05:00","guid":{"rendered":"http:\/\/machineryequipmentonline.com\/video-equipment\/uncategorized\/digital-televisionthe-bit-rate\/"},"modified":"2015-08-27T15:05:00","modified_gmt":"2015-08-27T15:05:00","slug":"digital-televisionthe-bit-rate","status":"publish","type":"post","link":"http:\/\/machineryequipmentonline.com\/video-equipment\/digital-televisionthe-bit-rate\/","title":{"rendered":"Digital television:The bit rate"},"content":{"rendered":"<div class=\"lbdrn6a0dae068115f\" ><script type=\"text\/javascript\">\n\tatOptions = {\n\t\t'key' : '61e5902552e2353963d8d2f1bd1f4a8f',\n\t\t'format' : 'iframe',\n\t\t'height' : 250,\n\t\t'width' : 300,\n\t\t'params' : {}\n\t};\n<\/script>\n<script type=\"text\/javascript\" src=\"\/\/www.highperformanceformat.com\/61e5902552e2353963d8d2f1bd1f4a8f\/invoke.js\"><\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.lbdrn6a0dae068115f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.lbdrn6a0dae068115f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.lbdrn6a0dae068115f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.lbdrn6a0dae068115f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.lbdrn6a0dae068115f {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<p align=\"justify\"><strong>The bit rate<\/strong><\/p>\n<p align=\"justify\">Sampling is followed by quantisation where sample values are rounded up or down to quantum values before they are converted into a multi-bit code. The precise number of quantums or levels is determined by the bit depth, the number of bits in the code. For studio applications, 10-bit cod- ing is used. For domestic applications such as TV broadcasting and DVD, 8-bit coding is regarded as adequate. Given a bit depth of 8, the number of discrete signal levels or quantums available is 28 = 256.  <\/p>\n<p align=\"justify\">The bit rate may then be calculated as follows:  <\/p>\n<p align=\"justify\">\u25cf Bit rate = number of samples per second X number of bits per sample  <\/p>\n<p align=\"justify\">\u25cf But, the number of samples per second = number of samples per pic-  <\/p>\n<p align=\"justify\">ture X number of pictures per second  <\/p>\n<p align=\"justify\">\u25cf And the number of samples per PAL picture = 720 X 576 = 414,720  <\/p>\n<p align=\"justify\">\u25cf Then, given a picture rate of 25,  <\/p>\n<p align=\"justify\">Number of samples per second = 720X 576X 25 = 1,036,800  <\/p>\n<p align=\"justify\">For NTSC, the number of samples is the same, namely  <\/p><div class=\"rcyfc6a0dae068130d\" ><script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-0778475562755157\"\n     crossorigin=\"anonymous\"><\/script>\n<!-- 300x600 television-and-video -->\n<ins class=\"adsbygoogle\"\n     style=\"display:inline-block;width:300px;height:600px\"\n     data-ad-client=\"ca-pub-0778475562755157\"\n     data-ad-slot=\"6549443290\"><\/ins>\n<script>\n     (adsbygoogle = window.adsbygoogle || []).push({});\n<\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.rcyfc6a0dae068130d {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.rcyfc6a0dae068130d {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.rcyfc6a0dae068130d {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.rcyfc6a0dae068130d {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.rcyfc6a0dae068130d {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<div class=\"rtrgy6a0dae0681241\" ><script type=\"text\/javascript\">\n\tatOptions = {\n\t\t'key' : '0c1eb4c533eaedb7b996f49a5a4983a9',\n\t\t'format' : 'iframe',\n\t\t'height' : 300,\n\t\t'width' : 160,\n\t\t'params' : {}\n\t};\n<\/script>\n<script type=\"text\/javascript\" src=\"\/\/www.highperformanceformat.com\/0c1eb4c533eaedb7b996f49a5a4983a9\/invoke.js\"><\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.rtrgy6a0dae0681241 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.rtrgy6a0dae0681241 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.rtrgy6a0dae0681241 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.rtrgy6a0dae0681241 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.rtrgy6a0dae0681241 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n\n<p align=\"justify\">720X 480X 30 = 1, 036, 800  <\/p>\n<p align=\"justify\">The bit rate generated by the luminance component using an 8-bit code is therefore  <\/p>\n<p align=\"justify\">= 720X 576X 25X8  <\/p>\n<p align=\"justify\">= 82, 944, 000  <\/p>\n<p align=\"justify\">= 82.944 Mbps  <\/p>\n<p align=\"justify\">The bit rate for the chrominance components depends on the sampling structure used. For a 4:2:2 sampling structure with horizontal subsam- pling only, the number of samples = 360 X 576 = 207,360 per picture.  <\/p>\n<p align=\"justify\"><a href=\"http:\/\/lh3.googleusercontent.com\/-SM6goTo6HRY\/Vd8m-GgRH4I\/AAAAAAAB3ck\/WM1-m3hRDh4\/s1600-h\/Digital-television-05122.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-right-width: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px; padding-top: 0px\" title=\"Digital television-0512\" border=\"0\" alt=\"Digital television-0512\" src=\"http:\/\/lh3.googleusercontent.com\/-nyVEC6NPUo4\/Vd8nMd2Yw_I\/AAAAAAAB3c8\/-xXqTrFVvh8\/Digital-television-0512_thumb.jpg?imgmax=800\" width=\"384\" height=\"359\" \/><\/a>  <\/p>\n<p align=\"justify\">The actual bandwidth requirements depend on the type of modulation used. However, for pure pulse code modulation (PCM), the bandwidth is half the bit rate, which in this case is in the region of 60 MHz. This is impractically high and clearly illustrates the need for data compression which is the subject of the next chapter.  <\/p>\n<p align=\"justify\">\n","protected":false},"excerpt":{"rendered":"<p>The bit rate Sampling is followed by quantisation where sample values are rounded up or down to quantum values before they are converted into a multi-bit code. The precise number of quantums or levels is determined by the bit depth, the number of bits in the code. For studio applications, 10-bit cod- ing is used. 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