{"id":145,"date":"2012-02-25T23:44:56","date_gmt":"2012-02-25T22:44:56","guid":{"rendered":"http:\/\/www.deven.cz\/?p=145"},"modified":"2014-06-15T00:02:34","modified_gmt":"2014-06-14T23:02:34","slug":"vse-o-kodeku-xvid-a-jeho-nastavenich","status":"publish","type":"post","link":"https:\/\/www.deven.cz\/?p=145","title":{"rendered":"V\u0161e o kodeku Xvid, a jeho nastaven\u00edch"},"content":{"rendered":"<p><strong><span style=\"font-size: x-large;\">Co je to Xvid?<\/span><\/strong><\/p>\n<p>Xvid je video kodek, kter\u00fd umo\u017e\u0148uje\u00a0u\u017eivateli\u00a0p\u0159ehr\u00e1vat video. Kodek je vlastn\u011b program kter\u00fd k\u00f3duje \/ dek\u00f3duje digit\u00e1ln\u00ed video obraz.\u00a0K\u00f3dov\u00e1n\u00edm\u00a0(komprimac\u00ed) videa m\u016f\u017eeme sn\u00ed\u017eit datov\u00fd tok (nap\u0159. Mb\/s) videa a t\u00edm se tedy sn\u00ed\u017e\u00ed i celkov\u00e1 velikost souboru. P\u0159i\u00a0p\u0159\u00edli\u0161\u00a0vysok\u00e9\u00a0komprimaci\u00a0videa m\u016f\u017ee doj\u00edt k projeven\u00ed negativn\u00edch vad v obraze -&gt; pixalizaci (rozkosti\u010dkovan\u00ed\u00a0obrazu).<\/p>\n<p>Kodeky \u00a0m\u016f\u017eeme br\u00e1t jako n\u011bco jako form\u00e1t zip s t\u00edm rozd\u00edlem, \u017ee xvid\u00a0pou\u017e\u00edv\u00e1\u00a0ztr\u00e1tovou kompresi. \u00a0P\u0159i\u00a0ztr\u00e1tov\u00e9 kompresi se nen\u00e1vratn\u011b ztrat\u00ed p\u016fvodn\u00ed data a nelze video obnovit. V praxi to znamen\u00e1 \u017ee p\u0159i ka\u017ed\u00e9\u00a0uprav\u011b\u00a0videa n\u00e1m kles\u00e1 kvalita obrazu kterou nelze obnovit do p\u016fvodn\u00edho stavu.<\/p>\n<p><span style=\"font-style: italic; color: #999999;\">\n<div class=\"adsense-shortcode alignnone\"><div class=\"adsense-wrapper\"><script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"><\/script><ins class=\"adsbygoogle adsense format-display responsive sm-rectangle md-banner lg-leaderboard\"\n data-ad-client=\"ca-\" \n data-ad-format=\"auto\" \n data-full-width-responsive=\"true\" ><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/div>\n<\/div>\n<\/span><\/p>\n<p>Tento kodek\u00a0nevy\u017eaduje\u00a0nejnov\u011bj\u0161\u00ed\u00a0hardware\u00a0v\u00a0za\u0159\u00edzen\u00edch, ve kter\u00fdch\u00a0m\u00e1 b\u00fdt video p\u0159ehr\u00e1v\u00e1no. Pr\u00e1v\u011b jeho mal\u00e1 z\u00e1t\u011b\u017e na hardware za\u0159\u00edzen\u00ed a vysok\u00e1 komprese videa, p\u0159i\u00a0kter\u00e9\u00a0je obraz st\u00e1le kvalitn\u00ed, mu pomohla roz\u0161\u00ed\u0159it\u00a0se po sv\u011bt\u011b.<\/p>\n<p><span style=\"font-size: small;\"><span style=\"font-size: large;\"><strong>Funce kodeku Xvid<\/strong><\/span><\/span><\/p>\n<p>Xvid vych\u00e1z\u00ed z MPEG-4 a aplikoval z n\u011bj \u0159adu\u00a0funkc\u00ed, kter\u00e9 jsou pops\u00e1ny n\u00ed\u017ee v tabulce. MPEG-4 je standart metoda definuj\u00edc\u00edch kompresi a zp\u016fsob ulo\u017een\u00ed zvukov\u00fdch a obrazov\u00fdch dat.<\/p>\n<p>&nbsp;<\/p>\n<hr \/>\n<p>&nbsp;<\/p>\n<p><span style=\"font-size: medium;\"><strong>Obecn\u00e1 nastaven\u00ed<\/strong><\/span><\/p>\n<table lang=\"cz, cs\" style=\"border: 3px solid #000000;\" border=\"3\" align=\"left\">\n<tbody>\n<tr>\n<td>\n<h4>Profil<\/h4>\n<\/td>\n<td>Pokud nechcete zdlouhav\u011b\u00a0nastavovat parametry enk\u00f3dov\u00e1n\u00ed (konverze), m\u016f\u017eete pou\u017e\u00edt z jeden z p\u0159ednastaven\u00fdch profil\u016f.<\/td>\n<\/tr>\n<tr>\n<td>\n<h4>Motion search algorithm \/\u00a0Algoritmus vyhled\u00e1v\u00e1n\u00ed pohybu<\/h4>\n<\/td>\n<td>the motion search algorithm neboli \u010desky algoritmus pro\u00a0vyhodnocov\u00e1n\u00ed pohybu\u00a0se pokou\u0161\u00ed nal\u00e9zt pohybov\u00fd rozd\u00edl v obvykl\u00e9 barevn\u00e9 oblasti a minimalizovat tak rozd\u00edl mezi referen\u010dn\u00edm (kl\u00ed\u010dov\u00fd sn\u00edmek) &#8211; k\u00f3dovan\u00fdm sn\u00edmkem. Jestli\u017ee je\u00a0algoritmus pro\u00a0vyhodnocov\u00e1n\u00ed pohybu (VHQ)\u00a0aktivn\u00ed,\u00a0\u00a0Xvid\u00a0pou\u017eije frekven\u010dn\u00ed oblast (DCT), \u00a0kter\u00e1\u00a0minimalizuje\u00a0nejen prostorov\u00fd rozd\u00edl, ale tak\u00e9 zak\u00f3dovanou d\u00e9lku bloku.<\/td>\n<\/tr>\n<tr>\n<td>\n<h4>motion estimation quality \/ kvalita\u00a0odhadu pohybu<\/h4>\n<\/td>\n<td>\u00a0Touto volbou m\u016f\u017eeme nastavit kvalitu odhadu vyhodnocov\u00e1n\u00ed pohybu.\u00a0Obecn\u011b plat\u00ed \u017ee \u010d\u00edm\u00a0vy\u0161\u0161\u00ed hodnota, t\u00edm bude kvalitn\u011bji vyhodnocen pohyb a zv\u00fd\u0161\u00ed se komprese videa. Vysok\u00e1 komprese negativn\u011b zat\u011b\u017euje procesor, ale sni\u017euje n\u00e1m bitrate (datov\u00fd tok\/s) a t\u00edm zvy\u0161uje kvalitu obrazu p\u0159i n\u00edzk\u00e9m datov\u00e9m toku (hlavn\u011b v\u00a0rychl\u00fdch\u00a0sc\u00e9n\u00e1ch). Dopo\u0159u\u010duji pou\u017e\u00edvat vysokou p\u0159esnost\u00a0vyhodnocov\u00e1n\u00ed pohybu (volba 5 a 6)\u00a0pro\u00a0n\u00edzk\u00fd datov\u00fd tok nap\u0159\u00edklad: cca\u00a01280 x 800 bitrate pod 1800 kbps. Pro realtime kodov\u00e1n\u00ed\u00a0doporu\u010duji\u00a0volby (1-2). \u00a0Celkov\u011b pak m\u00e1te\u00a0na v\u00fdb\u011br\u00a0ze 6 voleb (1-6). V media coderu je\u00a0standardn\u011b nastavena volba &#8211; 6.<\/td>\n<\/tr>\n<tr>\n<td>\n<h4>\u00a0quantitizer type \/ typ kvantiz\u00e9ru<\/h4>\n<\/td>\n<td>\u00a0Velmi jednodu\u0161e \u0159e\u010deno\u00a0kvantizace\u00a0ur\u010duje\u00a0zp\u016fsob jak o\u0159ezat detaily. \u00a0P\u0159i vy\u0161\u0161\u00edch datov\u00fdch toc\u00edch\u00a0zjist\u00edte (bitrate), \u017ee MPEG\u00a0ponech\u00e1v\u00e1 v obrazu v\u00edce detail\u016f oproti H.263. Naopak p\u0159i ni\u017e\u0161\u00edm datov\u00e9m toku je vhodn\u011bj\u0161\u00ed H.263. ten obraz vyhlad\u00ed a d\u00edky tomu bude v\u00fdsledn\u00e9 video vypadat\u00a0st\u00e1le\u00a0dob\u0159e.<\/td>\n<\/tr>\n<tr>\n<td>\n<h4>greyscale \/\u00a0odst\u00edny \u0161ed\u00e9<\/h4>\n<\/td>\n<td>\u00a0Jak u\u017e n\u00e1zev napov\u00edd\u00e1 xvid bude konvertovat video v odst\u00edn\u016f\u00a0\u0161ed\u00e9\u00a0a to\u00a0bohu\u017eel\u00a0nijak neurychl\u00ed konvertov\u00e1n\u00ed videa a ani nikterak\u00a0nezmen\u0161\u00ed\u00a0v\u00fdstupn\u00ed velikost videa.<\/td>\n<\/tr>\n<tr>\n<td>\n<h4>quarter pixel precision \/ P\u0159esnost na\u00a0\u010dtvrt\u00a0pixelu<\/h4>\n<\/td>\n<td>\u00a0MPEG-4 (xvid, divx a atd.) m\u00e1\u00a0standardn\u011b\u00a0nastavenou p\u0159esnost\u00a0vyhled\u00e1van\u00ed\u00a0pohybu na p\u016fl pixelu. Funkce\u00a0quarter pixel precision n\u00e1m dovol\u00ed nastavit vyhled\u00e1van\u00ed na \u010dvrt pixelu a to tedy vede &#8222;v\u011bt\u0161inou&#8220; k ost\u0159ej\u0161\u00edmu obrazu na\u00a0\u00fakor\u00a0vysok\u00e9ho datov\u00e9ho toku. N\u00e9 v\u017edy je tato volba v\u00fdhodn\u00e1 proto je lep\u0161\u00ed vyzkou\u0161et zda-li jej\u00ed aktivace stoj\u00ed zato.<\/td>\n<\/tr>\n<tr>\n<td>\n<h4>\u00a0\u00a0<strong>G<\/strong>lobal\u00a0<strong>M<\/strong>otion\u00a0<strong>C<\/strong>ompensation \/ GMC<\/h4>\n<\/td>\n<td>\u00a0Xvid vygeneruje pomocn\u00e9 sn\u00edmky takzvan\u00e9\u00a0(GMC-sn\u00edmky), kter\u00e9 se hod\u00ed k ot\u00e1\u010den\u00ed a p\u0159iblizov\u00e1n\u00ed obrazu. GMC (Global Motion Compensation) rozd\u011bluje sn\u00edmek na makrobloky\u00a0\u00a0( \u010dtverce). \u010c\u00e1sti\u00a0pohybu\u00a0v makrobloku se\u00a0naz\u00fdvaj\u00ed vektory pohybu, ty jsou ur\u010dov\u00e1ny podle klasick\u00e9 sou\u0159adnice X Y \u00a0(dvou-dimenzion\u00e1ln\u00ed hodnoty). V\u011bt\u0161inou \u00a0m\u00e1 ka\u017ed\u00fd\u00a0makroblok\u00a0sv\u016fj vlastn\u00ed vektor pohybu u GMC jak u\u017e n\u00e1zev napov\u00edd\u00e1 <span style=\"text-decoration: underline;\"><strong>GLOBAL<\/strong><\/span>\u00a0maj\u00ed v\u0161echny makrobloky spole\u010dn\u00e9 vektory pohybu.<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><span style=\"color: #ff9900;\">\u00a0Postupn\u011b budu p\u0159in\u00e1\u0161et dal\u0161\u00ed informace. Posledn\u00ed zm\u011bna 21.7.2012<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"<p>Co je to Xvid? Xvid je video kodek, kter\u00fd umo\u017e\u0148uje\u00a0u\u017eivateli\u00a0p\u0159ehr\u00e1vat video. Kodek je vlastn\u011b program kter\u00fd k\u00f3duje \/ dek\u00f3duje digit\u00e1ln\u00ed video obraz.\u00a0K\u00f3dov\u00e1n\u00edm\u00a0(komprimac\u00ed) videa m\u016f\u017eeme sn\u00ed\u017eit datov\u00fd tok (nap\u0159. Mb\/s) videa a t\u00edm se tedy sn\u00ed\u017e\u00ed i celkov\u00e1 velikost souboru. P\u0159i\u00a0p\u0159\u00edli\u0161\u00a0vysok\u00e9\u00a0komprimaci\u00a0videa m\u016f\u017ee doj\u00edt k projeven\u00ed negativn\u00edch vad v obraze -&gt; pixalizaci &#8230;<\/p>\n","protected":false},"author":1,"featured_media":329,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0},"categories":[1,4,3],"tags":[50,45,39,49,57,63,51,54,61,53,52,55,60,62,20,56,48],"_links":{"self":[{"href":"https:\/\/www.deven.cz\/index.php?rest_route=\/wp\/v2\/posts\/145"}],"collection":[{"href":"https:\/\/www.deven.cz\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.deven.cz\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.deven.cz\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.deven.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=145"}],"version-history":[{"count":48,"href":"https:\/\/www.deven.cz\/index.php?rest_route=\/wp\/v2\/posts\/145\/revisions"}],"predecessor-version":[{"id":358,"href":"https:\/\/www.deven.cz\/index.php?rest_route=\/wp\/v2\/posts\/145\/revisions\/358"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.deven.cz\/index.php?rest_route=\/wp\/v2\/media\/329"}],"wp:attachment":[{"href":"https:\/\/www.deven.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=145"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.deven.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=145"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.deven.cz\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=145"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}