This question seems poor but i really facing this problem (I am new to ubuntu). I install Ubuntu 12.04 on my HP laptop. I also upgraded all its packages using sudo apt-get update &amp;&amp; sudo apt-get upgrade. But when I play any video file through media player (default and smplayer), i can only hear audio but no video is seen, screen becomes blanks. All types of video file can be played but only audio can be heard, no video.
How to install all possible media codecs from console?  Is there a way to load and save them for some cases without Internet connection?  Thanks in Advance!
What would be the best approach to get the recordtype id Let $X_1$ and $X_2$ are independent $N(0, \sigma^2)$ random variables. What is the distribution of $X_1^2 + X_2^2$? Let $X_1$ and $X_2$ are independent $N(0, \sigma^2)$ which means (mean = 0, variance = $\sigma^2$) random variables. What is the distribution of $X_1^2 + X_2^2$?  My approach is that  $X_1\sim N(0, \sigma^2)$ and $X_2\sim N(0, \sigma^2)$  Then $X_1^2$ and $X_2^2$ have chi-squared distribution with 1 degree of freedom. (I am not sure the degree of freedom and not sure how to show it as well(please help on this))  Then I found the moment-generating function for $X_1^2$ and $X_2^2$;$$m_{X_1^2} = (1-2t)^{-1/2}$$ and $$m_{X_2^2} = (1-2t)^{-1/2}$$  So the moment generating function for $X_1^2 + X_2^2$ is $$m_{X_1^2}(t) m_{X_2^2}(t) = (1-2t)^{-2/2}$$  So $X_1^2 + X_2^2$ has a chi-squared distribution with 2 degrees of freedom. Is this correct? Help us test the alpha version of our Android app We are in the early stages of development of the official Stack Exchange Android app and we need your help with testing. To set a few expectations: there will be bugs, crashes, and missing features, all of which will be fixed in .    We are initially targeting Android devices running  (Android 4.1 or higher) starting with phones (up to ~5 inch) and eventually moving our way to tablets.    To register for alpha testing .  After you register we will send you an invite to a private Google community where you can find a link to download our app directly from the  store. The invitations will be sent out in waves, so if you don’t get an invite immediately, be patient.  Crash reports will be automatically reported back to us using . Bugs or feature requests should be reported here on meta and tagged . Please do not use the Google community to report bugs.  As always, we welcome your feedback and are committed to building the best mobile app possible for browsing the Stack Exchange sites. Downloading all my questions with the answerer names I am writing several papers in which I use answers which I received in various StackExchange websites. Naturally I would like to acknowlege and thank the SE members that gave the useful answers. But there are many such answers, and each answer is relevant to a different paper.   So, I would like to download all the questions that I asked in the various SE websites, including the answerer names, to an Excel worksheet in which I can organize the questions by subject.  Is this possible? Possible Duplicate:             According to , Win 7 only supports 4 GB of RAM. I, however have been reading some forums and some say they are using 8 GB RAM with good performance. I am wondering if I can use 8 GB before I purchase. Children’s books, one in space setting, the other in a jungle Are the complements of two homeomorphic compact, connected subsets of $\mathbb{R}^2$ homeomorphic? Convert .mov to .mp4 I want to convert .mov to .mp4! I saved the video from iMovie but it is in .mov format! How do I convert it to .mp4?  I'm using a MacBook and I want to share it to my phone, but my phone can't open .mov format video. It is very easy to put a tilde over the symbol in math mode. Simply type $\tilde{a}$. But how to put a tilde under the symbol in math mode? Integer partitions in all orderings I have the amulet of Mara but when I go to talk to maramal about a wedding nothing shows up. WHY is that. Meaning of different Orders of Derivative I have been trying to analyse the meaning of higher order derivatives and their geometrical significance.  Given a function $f(x)$ what are the unique geometric interpretation of its higher orders?   $f'(x)$ - slope (rate of change of x w.r.t y) $f''(x)$ - convexity / concavity of $f(x)$ based on $sign(f''(x))$ $f'''(x)$ - increasing / decreasing slope of $f'(x)$ $f''''(x)$ - ?? ... $f^n(x)$ - ??   I apologize if this question is rudimentary. I had an (extremely minor) identity crisis when I clicked on my username and saw a different identicon than I'd had previously. :)  According to , your identicon is based on a hash of your last known IP address.  Since a user's profile picture part of their identity, I would prefer if my profile picture only changed through deliberate action on my part.  Since the user's IP hash is already saved (the identicon has to be displayed to people even during the unthinkable periods when we're not actively browsing), I propose preserving the first one assigned to a user, and not updating it even if the user's IP address changes.  Are there any upsides to the current behavior that I haven't thought of? Show that $a(-1) = (-1)a = -a $. Auxhook warning cannot patch document using AtBeginDocument instead I'm using subfiles within my report (written on sharelatex), when I compile a subfile it produces a warning. Am I doing something wrong or is this normal?  Example  \documentclass[report.tex]{subfiles} % \usepackage{acronym} \begin{document}  some text  \end{document}   Error     /usr/local/texlive/2015/texmf-dist/tex/latex/oberdiek/auxhook.sty   Package auxhook Warning: Cannot patch \document, using \AtBeginDocument instead.   When I compile the main document it does not produce this warning.  The raw log file produces this warning     ......   Package: auxhook 2011/03/04 v1.3 Hooks for auxiliary files (HO)   Package auxhook Warning: Cannot patch \document,   (auxhook)                using \AtBeginDocument instead.   ) (/usr/local/texlive/2015/texmf-dist/tex/latex/oberdiek/kvoptions.sty   Package: kvoptions 2011/06/30 v3.11 Key value format for package options (HO)   ....    Packages  I'm using the following packages:    \documentclass[whitelogo]{tudelft-report}   % Used for referencing   \usepackage{natbib}   % For writing remarks in the text (is this going to be used?)   \usepackage{changes}   % used to write and render different subfiles   \usepackage{subfiles}   % used to draw boxed problems   \usepackage{mdframed}   % for subcaptions in combined figures   \usepackage{subcaption}    % used for Epigraphs of course   \usepackage{epigraph}   % Makes weblinks clickable   \usepackage{hyperref}   % used to display pictures   \usepackage{graphicx}   % used to add urls with strange symbols   \usepackage{grffile}   % used for H command in figures   \usepackage{float}   % used for tickz pictures (Causes a warning)   %\usepackage{pgfplots}   %used for the acronym page [printonlyused,withpage] are options   \usepackage{acronym}    % ######################### open section for code appendix #######################   \usepackage[utf8]{inputenc}   \usepackage{listings}   \usepackage{color}   \definecolor{codegreen}{rgb}{0,0.6,0}   \definecolor{codegray}{rgb}{0.5,0.5,0.5}   \definecolor{codepurple}{rgb}{0.58,0,0.82}   \definecolor{backcolour}{rgb}{0.95,0.95,0.92} When electric dipole placed in non uniform electric field, what is the approach to calculate torque acting on it? Can it be zero? The usage of singular and plural has always been confusing for me.   I often see sentences like these         People are using cell phones.   People are using a cell phone.      Does the first sentence mean everyone has a phone and they are all using their own?  Does the second sentence mean they are sharing one cell phone?   If I see a group of people holding a cell phone in their hand(s), &lt;- even this is confusing for me, should I use the first sentence then?   Another example: you see two men, and both of them are carrying a bag. Which sentence should I say/use?        They are carrying backpacks          They are carrying a backpack      Could you please make it clear for me? I deleted the "/etc/passwd" file and cannot log in Refreshing a question doesn't update the answer count properly In the Stack Exchange Android App v1.0.7 1.0.33 (with a HTC One running Android 4.4.2), the answer count for a question you're viewing is displayed in two places:   In the label of the answer tab:   At the bottom of the question tab:    I've noticed that these counts don't reliably update when new answers arrive.   If you refresh the question tab, neither count updates. If you refresh the answer tab, the second count will be updated, but the answer tab's count will not, leaving the two out of sync.   Refreshing either tab should probably update both counts!    Screenshots of the bug in action:    I waited for it to be answered. A while later, the question now has an answer.    The tab still says 0 answers though. Switching back to the question tab, , but the tab count still doesn't. Application always show in the third position in Ubuntu 16.04 After I update my ubutu to 16.04, I got a problem with Unity launcher. Whenever I open an application which is not listed in launcher, it will take the third position instead of last position. Has anyone the same problem?