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翻译中 by Linux-pdz
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CISCO Announce New Open Source H.264 Codec
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================================================================================
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*YouTube Is One of Many Sites Using H.264*
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**American networking company Cisco [has announced plans to offer an open-source H.264 codec][1] - a move it says will “remove barriers” to its use in WebRTC.**
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H.264 is widely used in HTML5 video streaming, though not all browsers and operating systems are able to make use of it.
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This is because use of the codec for encoding or decoding requires royalty payments to be made to the MPEG LA, an organisation who license the tangle of patents related to it (which, perhaps not so coincidentally, [includes some patents owned by Cisco][2]).
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Furthermore, the codec is prohibited from being distributed with open-source products like web browsers.
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This is why some of YouTube’s HTML5 videos don’t play in Firefox but do in Google Chrome. The latter is able to pay licensing costs on behalf of its users.
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But Cisco are aiming to reset this inequality by offering an open-source implementation of the H.264 codec – called OpenH264, developed by them – that **can be used by any project**, including open-source ones, **for free**. No license fees and no restrictions will apply to the use of its binary modules.
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The company say that by open-sourcing their H.264 codec, and offering a pre-compiled binary file for free download, it can be used to power newer technologies like WebRTC – a HTML5 API that allows for ‘real time communication’ between browsers.
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> ‘Cisco aren’t the first to create an open-source implementation of H.264…’
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Indeed, Mozilla [has already announced][3] that it plans to support Cisco’s H.264 binary modules in Firefox.
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Cisco aren’t the first to create an open-source implementation of this code. The GNU libavcodec library includes both a decoder and an encoder, the latter based on [x264][4]. But what Cisco are offering is a legal foothold – something other open-source efforts have lacked. This makes the decoder far more useful to companies like Mozilla, who can use it without fear or legal redress.
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The nitty-gritty of how this this new offering from Cisco will be offered is a little less straightforward, however.
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Cisco will open-source their H.264 stack. This, along with pre-compiled binary modules, will be available to download, for free, from their website. Applications such as Firefox will be able to ‘load’ the binary (even auto-download it where needed) to make use of it.
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While Cisco will pay patent license costs to the MPEG LA they won’t pass this on to users of their module. It’s less clear what protection those compiling directly from its source will have, though with the code due to hit Github in the coming weeks more information will be available.
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### Summary ###
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The tl;dr is that Cisco are helping to move the web forward. High-quality video streaming based on a widely used standard will, with OpenH264, be available to more people on more platforms thanks to some goodwill and open-source effort on behalf of Cisco.
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Whether you’re a fan of H.264, or favour the adoption of truly free codecs like VP8, the ‘levelling of the playing field’ this move offers can only be seen as a good move.
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--------------------------------------------------------------------------------
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via: http://www.omgubuntu.co.uk/2013/10/cisco-announce-open-source-h-264-codec
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译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
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[1]:http://blogs.cisco.com/collaboration/open-source-h-264-removes-barriers-webrtc/
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[2]:http://en.wikipedia.org/wiki/MPEG_LA#H.264.2FMPEG-4_AVC_Licensors
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[3]:https://blog.mozilla.org/blog/2013/10/30/video-interoperability-on-the-web-gets-a-boost-from-ciscos-h-264-codec/
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[4]:http://en.wikipedia.org/wiki/X264
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occupied by rogetfan
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Daily Ubuntu Tips – Webcam Support In Ubuntu Via Cheese
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================================================================================
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For new users who are just starting with Ubuntu, here’s some information that may help you if you want to use webcam in Ubuntu. You see, Ubuntu aims to support the vast majority of webcam right out of the box. Most webcam manufacturers don’t provide drivers for for Linux systems, including Ubuntu. So Linux developers must do the hard work by enabling support for most webcam devices in the Linux Kernel.
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Webcam support for Linux is provided by the Linux UVC Project’s [UVC][1] driver. The aim of this project is to provide a universal USB support for webcam in the same way a general USB driver handles USB devices like thumb drives, external USB devices and others.
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The vast majority of USB webcam out there should work with Linux systems, including Ubuntu with the support of the Linux UVC project driver. If you want to purchase a webcam for your Ubuntu computer, but want to make sure it’s supported, [check out the UVC supported webcam list][2].
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Webcam on the list above support Linux machines easily. So, before purchasing webcam for your machine check out the list and find the model you like and purchase it.
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After purchasing a model that supports Linux systems, you’ll need an application in to display or view your videos. Currently the most popular webcam application for Ubuntu is Cheese. Cheese allows you to access your webcam and display the video easily.
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To install Cheese, run the commands below.
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sudo apt-get install cheese
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After installing it, open it via Unity Dash and launch it. If the webcam device is already attached, Cheese should begin showing the video from the webcam.
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If you have a laptop equipped with webcam, chances are it should work because support for generic USB webcam is common with Ubuntu. All you have to do is install Cheese and enjoy!
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If you can’t get your current webcam to work in Ubuntu, you may have to purchase a model that works.
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Enjoy!
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--------------------------------------------------------------------------------
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via: http://www.liberiangeek.net/2013/09/daily-ubuntu-tips-webcam-support-ubuntu-via-cheese/
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
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译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID)
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[1]:https://help.ubuntu.com/community/UVC
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[2]:http://www.ideasonboard.org/uvc/
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flsf
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Linux Pmap Command – Find How Much Memory Process Use
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================================================================================
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Pmap provide memory map of a process, The pmap command display the memory usage map of a process or multiple processes. Pmap reports information about the address space or memory usage map of a process. Pmap is actually a Sun OS command and Linux supports only very limited number of features. But it is very helpful for finding the complete address space of a process. To check [memory usage of process][1] we need PID or unique process ID of running process, we can get PID from /proc or regular commands like top or ps.
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### Syntax or usage ###
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#pmap PID
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or
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#pmap [options] PID
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In outout it display total address, kbytes, mode and mapping.
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### Options ###
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-x extended Show the extended format.
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-d device Show the device format.
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-q quiet Do not display some header/footer lines.
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-V show version Displays version of program.
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### Memory usage map of single process ###
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[root@info ~]# pmap 1013
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1013: /usr/sbin/sshd
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00110000 1480K r-x– /usr/lib/libcrypto.so.1.0.0
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00282000 80K rw— /usr/lib/libcrypto.so.1.0.0
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00296000 12K rw— [ anon ]
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00299000 36K r-x– /lib/libkrb5support.so.0.1
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002a2000 4K rw— /lib/libkrb5support.so.0.1
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002a3000 16K r-x– /lib/libplc4.so
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002a7000 4K rw— /lib/libplc4.so
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002ab000 88K r-x– /lib/libaudit.so.1.0.0
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002c1000 4K r—- /lib/libaudit.so.1.0.0
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002c2000 4K rw— /lib/libaudit.so.1.0.0
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002c3000 216K r-x– /lib/libgssapi_krb5.so.2.2
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002f9000 4K rw— /lib/libgssapi_krb5.so.2.2
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002fa000 808K r-x– /lib/libkrb5.so.3.3
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003c4000 24K rw— /lib/libkrb5.so.3.3
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003ca000 152K r-x– /lib/libk5crypto.so.3.1
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003f0000 4K rw— /lib/libk5crypto.so.3.1
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003f1000 92K r-x– /usr/lib/libnssutil3.so
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00738000 4K r—- /lib/libresolv-2.12.so
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00739000 4K rw— /lib/libresolv-2.12.so
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0073a000 8K rw— [ anon ]
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00825000 120K r-x– /lib/ld-2.12.so
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00843000 4K r—- /lib/ld-2.12.so
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00844000 4K rw— /lib/ld-2.12.so
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0090d000 32K r-x– /lib/libwrap.so.0.7.6
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00915000 4K rw— /lib/libwrap.so.0.7.6
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00948000 484K r-x– /usr/sbin/sshd
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009c1000 8K rw— /usr/sbin/sshd
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009c3000 20K rw— [ anon ]
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009e0000 92K r-x– /lib/libpthread-2.12.so
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009f7000 4K r—- /lib/libpthread-2.12.so
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total 8232K
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### Memory usage map of multiple processes ###
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We can check memory map of multiple processes by inserting multiple PIDs. Add multiple PIDs with adding space.
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pmap 1013 1217 1118
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### Extended memory map about a process ###
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[root@info ~]# pmap -x 1013
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1013: /usr/sbin/sshd
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Address Kbytes RSS Dirty Mode Mapping
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00110000 1480 92 0 r-x– libcrypto.so.1.0.0
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00282000 80 80 80 rw— libcrypto.so.1.0.0
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00296000 12 8 4 rw— [ anon ]
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00299000 36 0 0 r-x– libkrb5support.so.0.1
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002a2000 4 4 4 rw— libkrb5support.so.0.1
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002a3000 16 0 0 r-x– libplc4.so
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002a7000 4 4 4 rw— libplc4.so
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002ab000 88 4 0 r-x– libaudit.so.1.0.0
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002c1000 4 4 4 r—- libaudit.so.1.0.0
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002c2000 4 4 4 rw— libaudit.so.1.0.0
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002c3000 216 4 0 r-x– libgssapi_krb5.so.2.2
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002f9000 4 4 4 rw— libgssapi_krb5.so.2.2
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002fa000 808 4 0 r-x– libkrb5.so.3.3
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003c4000 24 24 24 rw— libkrb5.so.3.3
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003ca000 152 4 0 r-x– libk5crypto.so.3.1
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003f0000 4 4 4 rw— libk5crypto.so.3.1
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003f1000 92 0 0 r-x– libnssutil3.so
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00408000 12 12 12 rw— libnssutil3.so
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0040b000 12 0 0 r-x– libplds4.so
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0040e000 4 4 4 rw— libplds4.so
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——– ——- ——- ——- ——-
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total kB 8232 – – -
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Here Address, Kbyte, Dirty, RSS, mode and mapping containd information as below
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### Extended and Device Format Fields ###
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Address: start address of map
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Kbytes: size of map in kilobytes
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RSS: resident set size in kilobytes
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Dirty: dirty pages (both shared and private) in kilobytes
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Mode: permissions on map: read, write, execute, shared, private (copy on write)
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Mapping: file backing the map, or ‘[ anon ]‘ for allocated memory, or ‘[ stack ]‘ for the program stack
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Offset: offset into the file
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Device: device name (major:minor)
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--------------------------------------------------------------------------------
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via: http://linoxide.com/linux-command/pmap-command/
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译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
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[1]:http://www.linoxide.com/linux-shell-script/linux-memory-usage-program/
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