Sur d’autres sites (9404)

• Progress with rtc.io

  12 août 2014, par silvia

  At the end of July, I gave a presentation about WebRTC and rtc.io at the WDCNZ Web Dev Conference in beautiful Wellington, NZ.

  

  Putting that talk together reminded me about how far we have come in the last year both with the progress of WebRTC, its standards and browser implementations, as well as with our own small team at NICTA and our rtc.io WebRTC toolbox.

  

  One of the most exciting opportunities is still under-exploited : the data channel. When I talked about the above slide and pointed out Bananabread, PeerCDN, Copay, PubNub and also later WebTorrent, that’s where I really started to get Web Developers excited about WebRTC. They can totally see the shift in paradigm to peer-to-peer applications away from the Server-based architecture of the current Web.

  Many were also excited to learn more about rtc.io, our own npm nodules based approach to a JavaScript API for WebRTC.

  

  We believe that the World of JavaScript has reached a critical stage where we can no longer code by copy-and-paste of JavaScript snippets from all over the Web universe. We need a more structured module reuse approach to JavaScript. Node with JavaScript on the back end really only motivated this development. However, we’ve needed it for a long time on the front end, too. One big library (jquery anyone ?) that does everything that anyone could ever need on the front-end isn’t going to work any longer with the amount of functionality that we now expect Web applications to support. Just look at the insane growth of npm compared to other module collections :

  

  For those that – like myself – found it difficult to understand how to tap into the sheer power of npm modules as a font end developer, simply use browserify. npm modules are prepared following the CommonJS module definition spec. Browserify works natively with that and “compiles” all the dependencies of a npm modules into a single bundle.js file that you can use on the front end through a script tag as you would in plain HTML. You can learn more about browserify and module definitions and how to use browserify.

  For those of you not quite ready to dive in with browserify we have prepared prepared the rtc module, which exposes the most commonly used packages of rtc.io through an “RTC” object from a browserified JavaScript file. You can also directly download the JavaScript file from GitHub.

  

  So, I hope you enjoy rtc.io and I hope you enjoy my slides and large collection of interesting links inside the deck, and of course : enjoy WebRTC ! Thanks to Damon, JEeff, Cathy, Pete and Nathan – you’re an awesome team !

  On a side note, I was really excited to meet the author of browserify, James Halliday (@substack) at WDCNZ, whose talk on “building your own tools” seemed to take me back to the times where everything was done on the command-line. I think James is using Node and the Web in a way that would appeal to a Linux Kernel developer. Fascinating !!

• What Every Programmer Should Know

  24 décembre 2012, par Multimedia Mike — General

  During my recent effort to force myself to understand Unicode and modern text encoding/processing, I was reminded that this is something that “every programmer should just know”, an idea that comes up every so often, usually in relation to a subject in which the speaker is already an expert. One of the most absurd examples I ever witnessed was a blog post along the lines of “What every working programmer ought to know about [some very specific niche of enterprise-level Java programming]“. I remember reading through the article and recognizing that I had almost no knowledge of the material. Disturbing, since I am demonstrably a “working programmer”.

  For fun, I queried the googles on the matter of what ever programmer ought to know.

  Specific Topics
  Here is what every programmer should know about : Unicode, time, memory (simple), memory (extremely in-depth), regular expressions, search engine optimization, floating point, security, basic number theory, race conditions, managed C++, VIM commands, distributed systems, object-oriented design, latency numbers, rate monotonic algorithm, merging branches in Mercurial, classes of algorithms, and human names.

  Broader Topics
  20 subjects every programmer should know, 97 things every programmer should know, 12 things every programmer should know, things every programmer should know (27 items), 10 papers every programmer should read at least twice, 10 things every programmer should know for their first job.

  Meanwhile, I remain fond of this xkcd comic whose mouseover text describes all that a person genuinely needs to know. Still, the new year is upon us, a time when people often make commitments to bettering themselves, and it couldn’t hurt (much) to at least skim some of the lists and find out what you never knew that you never knew.

  What About Multimedia ?
  Reading the foregoing (or the titles of the foregoing pieces), I naturally wonder if I should write something about what every programmer should know about multimedia. I think it would look something like a multimedia programming FAQ. These are some items that I can think of :

  1. YUV : The other colorspace (since most programmers are only familiar with RGB and have no idea what to make of the YUV that comes out of most video decoding APIs)
  2. Why you can’t easily seek randomly to any specific frame in a video file (keyframe/interframe discussion and their implications)
  3. Understand your platform before endeavoring to implement multimedia software (modern platforms, particularly mobile platforms, probably provide everything you need in the native APIs and there is likely little reason to compile libavcodec for the platform)
  4. Difference between containers and codecs (longstanding item, but I would argue it’s less relevant these days due to standardization on the MPEG — MP4/H.264/AAC — stack)
  5. What counts as a multimedia standard in this day and age (comparing the foregoing MPEG stack with the WebM/VP8/Vorbis stack)
  6. Trade-offs to consider when engineering a multimedia solution
  7. Optimization doesn’t always work the way you think it does (not everything touted as a massive speed-up in the world of computing — whether it be multithreaded CPUs, GPGPUs, new SIMD instruction sets — will necessarily be applicable to multimedia processing)
  8. A practical guide to legal issues would not be amiss
  9.  ???

  What other items count as “something multimedia-related that every programmer should know” ?

• Error finding watermark path using ffmpeg in asp.net application

  27 août 2013, par irfanmcsd

  I am using .net ffmpeg wrapper to post watermark on videos. Posting watermark works fine if i execute ffmpeg command directly but failed to find suitable watermark png file location if command executed via asp.net application.

  here is sample ffmpeg command

  string RootPath = HttpContext.Current.Server.MapPath(HttpContext.Current.Request.ApplicationPath);
  
  _mhandler.FFMPEGPath = RootPath + "/ffmpeg_aug_2013/bin/ffmpeg.exe";
  
  _mhandler.InputPath = RootPath + "/contents/original";
  
  _mhandler.OutputPath = RootPath + "/contents/mp4";
  
  _mhandler.BackgroundProcessing = false;
  
  _mhandler.FileName = "wildlife.wmv";
  
  _mhandler.OutputFileName = "wildlife_ddd";
  
  string presetpath = RootPath + "/ffmpeg_aug_2013/presets/libx264-ipod640.ffpreset";
  
  _mhandler.OutputExtension = ".mp4";
  
  _mhandler.Parameters = "-s 640x380 -b:v 500k -bufsize 500k -b:a 128k -ar 44100 -c:v libx264 -vf \"movie = watermark.png [watermark]; [in][watermark] overlay=main_w-overlay_w-10:main_h-overlay_h-10 [out]\"";
  
  _mhandler.Parameters = _mhandler.Parameters + " -fpre \"" + presetpath + "\"";
  
  VideoInfo info =  _mhandler.Process();

  i tried direct code too

  string _out = "";
  
  Process _process = new Process();
  
  _process.StartInfo.UseShellExecute = false;
  
  _process.StartInfo.RedirectStandardInput = true;
  
  //_process.StartInfo.RedirectStandardOutput = true;
  
  _process.StartInfo.RedirectStandardError = true;
  
  _process.StartInfo.CreateNoWindow = true;
  
  _process.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
  
  _process.StartInfo.FileName = _ffmpegpath;
  
  _process.StartInfo.Arguments = cmd;
  
  if (_process.Start())
  
  {             
  
      _process.WaitForExit(ExitProcess);
  
      _out = _process.StandardError.ReadToEnd();
  
      if (!_process.HasExited)
  
        _process.Kill();
  
  
  
      return _out;
  
   }

  ffmpeg error output as

  FFMPEG Output:ffmpeg version N-55753-g88909be Copyright (c) 2000-2013
  the FFmpeg developers built on Aug 24 2013 21:40:51 with gcc 4.7.3
  (GCC) configuration : —enable-gpl —enable-version3
  —disable-w32threads —enable-avisynth —enable-bzlib —enable-fontconfig —enable-frei0r —enable-gnutls —enable-iconv —enable-libass —enable-libbluray —enable-libcaca —enable-libfreetype —enable-libgsm —enable-libilbc —enable-libmodplug —enable-libmp3lame —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-libopenjpeg —enable-libopus —enable-librtmp —enable-libschroedinger —enable-libsoxr —enable-libspeex —enable-libtheora —enable-libtwolame —enable-libvo-aacenc —enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx —enable-libx264 —enable-libxavs —enable-libxvid —enable-zlib libavutil 52. 42.100 / 52. 42.100 libavcodec 55. 29.100 / 55. 29.100 libavformat 55. 14.102 / 55. 14.102 libavdevice 55. 3.100
  / 55. 3.100 libavfilter 3. 82.102 / 3. 82.102 libswscale 2. 5.100 / 2.
  5.100 libswresample 0. 17.103 / 0. 17.103 libpostproc 52. 3.100 / 52. 3.100 [asf @ 024c9960] Stream #0 : not enough frames to estimate rate ; consider increasing probesize Guessed Channel Layout for Input Stream

  0.0 : stereo Input #0, asf, from 'F :\own\mhp_new/contents/original\wildlife.wmv' : Metadata :

  SfOriginalFPS : 299700 WMFSDKVersion : 11.0.6001.7000 WMFSDKNeeded :
  0.0.0.0000 comment : Footage : Small World Productions, Inc ; Tourism New Zealand | Producer : Gary F. Spradling | Music : Steve Ball title :
  Wildlife in HD copyright : © 2008 Microsoft Corporation IsVBR : 0
  DeviceConformanceTemplate : AP@L3 Duration : 00:00:30.09, start :
  0.000000, bitrate : 6977 kb/s Stream #0:0(eng) : Audio : wmav2 (a1[0][0] / 0x0161), 44100 Hz, stereo, fltp, 192 kb/s Stream

  0:1(eng) : Video : vc1 (Advanced) (WVC1 / 0x31435657), yuv420p, 1280x720, 5942 kb/s, 29.97 tbr, 1k tbn, 1k tbc [image2 @ 024c76e0]

  Could find no file with path 'watermark.png' and index in the range
  0-4 [Parsed_movie_0 @ 024c0540] Failed to avformat_open_input
  'watermark.png' [AVFilterGraph @ 024ca100] Error initializing filter
  'movie' with args 'watermark.png' Error opening filters ! Error Code= 0

  Error on point ( Could find no file with path 'watermark.png' ) shows watermark.png file not found.
  I place watermark.png file in the following locations but still can't found

  i : application root

  ii : root where actual aspx page located

  iii : ffmpeg root

  iv : ffmpeg/bin/

  I also used complete path but still can't detected.

  Note : if i use same ffmpeg command in php and place watermark.png on location where actual php page exist watermark properly detected and command executed properly, but same approach not working in asp.net

  Can any one help me where should i place watermark.png file so that script can access it.