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• Use deck.js as a remote presentation tool

  8 janvier 2014, par silvia

  deck.js is one of the new HTML5-based presentation tools. It’s simple to use, in particular for your basic, every-day presentation needs. You can also create more complex slides with animations etc. if you know your HTML and CSS.

  Yesterday at linux.conf.au (LCA), I gave a presentation using deck.js. But I didn’t give it from the lectern in the room in Perth where LCA is being held – instead I gave it from the comfort of my home office at the other end of the country.

  I used my laptop with in-built webcam and my Chrome browser to give this presentation. Beforehand, I had uploaded the presentation to a Web server and shared the link with the organiser of my speaker track, who was on site in Perth and had set up his laptop in the same fashion as myself. His screen was projecting the Chrome tab in which my slides were loaded and he had hooked up the audio output of his laptop to the room speaker system. His camera was pointed at the audience so I could see their reaction.

  I loaded a slide master URL :
  http://html5videoguide.net/presentations/lca_2014_webrtc/?master
  and the room loaded the URL without query string :
  http://html5videoguide.net/presentations/lca_2014_webrtc/.

  Then I gave my talk exactly as I would if I was in the same room. Yes, it felt exactly as though I was there, including nervousness and audience feedback.

  How did we do that ? WebRTC (Web Real-time Communication) to the rescue, of course !

  We used one of the modules of the rtc.io project called rtc-glue to add the video conferencing functionality and the slide navigation to deck.js. It was actually really really simple !

  Here are the few things we added to deck.js to make it work :

  • Code added to index.html to make the video connection work :

    <meta name="rtc-signalhost" content="http://rtc.io/switchboard/">
    
    <meta name="rtc-room" content="lca2014">
    
    ...
    
    <video id="localV" rtc-capture="camera" muted></video>
    
    <video id="peerV" rtc-peer rtc-stream="localV"></video>
    
    ...
    
    <script src="glue.js"></script>
    
    <script>
    
    glue.config.iceServers = [{ url: 'stun:stun.l.google.com:19302' }];
    
    </script>

    The iceServers config is required to punch through firewalls – you may also need a TURN server. Note that you need a signalling server – in our case we used http://rtc.io/switchboard/, which runs the code from rtc-switchboard.

  • Added glue.js library to deck.js :

    Downloaded from https://raw.github.com/rtc-io/rtc-glue/master/dist/glue.js into the source directory of deck.js.

  • Code added to index.html to synchronize slide navigation :

    glue.events.once('connected', function(signaller) {
    
      if (location.search.slice(1) !== '') {
    
        $(document).bind('deck.change', function(evt, from, to) {
    
          signaller.send('/slide', {
    
            idx: to,
    
            sender: signaller.id
    
          });
    
        });
    
      }
    
      signaller.on('slide', function(data) {
    
        console.log('received notification to change to slide: ', data.idx);
    
        $.deck('go', data.idx);
    
      });
    
    });

    This simply registers a callback on the slide master end to send a slide position message to the room end, and a callback on the room end that initiates the slide navigation.

  And that’s it !

  You can find my slide deck on GitHub.

  Feel free to write your own slides in this manner – I would love to have more users of this approach. It should also be fairly simple to extend this to share pointer positions, so you can actually use the mouse pointer to point to things on your slides remotely. Would love to hear your experiences !

  Note that the slides are actually a talk about the rtc.io project, so if you want to find out more about these modules and what other things you can do, read the slide deck or watch the talk when it has been published by LCA.

  Many thanks to Damon Oehlman for his help in getting this working.

  BTW : somebody should really fix that print style sheet for deck.js – I’m only ever getting the one slide that is currently showing.

• avcodec/libx265 : use x265 Multi-library Interface to query the API

  7 mai 2015, par Gopu Govindaswamy

  avcodec/libx265 : use x265 Multi-library Interface to query the API
  ffmpeg can now use the x265 multi-library interface to make a runtime
  
  selection between a number of libx265 libraries (perhaps 8bpp and 16bpp).
  ffmpeg will link to one build of libx265 (statically or
  
  dynamically) and this linked version of libx265 will support one
  
  bit-depth (8 or 10 bits). At runtime, ffmpeg now has the option to request the
  
  encoder to use a different bit depth(8 or 10). If the requested bitdepth
  
  is zero, or if it matches the bitdepth of the system default libx265 (the
  
  currently linked library), then this library will be used for encode.
  
  If ffmpeg requests a different bit-depth, the linked libx265 will attempt
  
  to dynamically bind a shared library with the requested bit-depth from the install
  
  location (default or user-specified).
  new x265 API :
  
       const x265_api* api = x265_api_get(int bitDepth) ;
  
       x265_api - holds the libx265 public API functions
  
       bitDepth - requested API for 8bpp or 16bpp
       note : Use 0 to indicate native bit depth of the linked libx265 and
  
             x265_api_get(0) is guaranteed to return a non-null pointer
  Signed-off-by : Gopu Govindaswamy <gopu@multicorewareinc.com>
  
  Signed-off-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  

  • [DH] configure
  • [DH] libavcodec/libx265.c

• ffserver streams webm data, but nothing is displayed

  2 novembre 2015, par Daniël Bakker

  I’m trying to stream webcam data over the internet on a lubuntu machine. To achieve this, I’ve installed ffmpeg and ffserver. However, I can’t seem to get this to work.
  I would like to use the webm format to integrate it as an HTML5 video. I found several examples of this on the internet, so that is where I based my settings on. This is the ffserver config I have at the moment :

  HTTPPort 8090                      # Port to bind the server to
  
  HTTPBindAddress 0.0.0.0
  
  MaxHTTPConnections 2000
  
  MaxClients 1000
  
  MaxBandwidth 10000             # Maximum bandwidth per client
  
                                 # set this high enough to exceed stream bitrate
  
  CustomLog -
  
  #NoDaemon                       # Remove this if you want FFserver to daemonize after start
  
  
  
  <feed>               # This is the input feed where FFmpeg will send
  
     File ./feed1.ffm            # video stream.
  
     FileMaxSize 5M              # Maximum file size for buffering video
  
     ACL allow 127.0.0.1         # Allowed IPs
  
  </feed>
  
  
  
  <stream>              # Output stream URL definition
  
     Feed feed1.ffm              # Feed from which to receive video
  
     Format webm
  
  
  
     # Audio settings
  
     #AudioCodec vorbis
  
     #AudioBitRate 64             # Audio bitrate
  
     NoAudio
  
  
  
     # Video settings
  
     VideoCodec libvpx
  
     VideoSize 640x480           # Video resolution
  
     VideoFrameRate 2           # Video FPS
  
     AVOptionVideo flags +global_header  # Parameters passed to encoder
  
                                         # (same as ffmpeg command-line parameters)
  
     #AVOptionVideo cpu-used 0
  
     AVOptionVideo qmin 1
  
     AVOptionVideo qmax 42
  
     #AVOptionVideo quality good
  
     AVOptionAudio flags +global_header
  
     #PreRoll 1
  
     #StartSendOnKey
  
     VideoBitRate 400            # Video bitrate
  
  </stream>
  
  
  
  <stream>            # Server status URL
  
     Format status
  
     # Only allow local people to get the status
  
     ACL allow localhost
  
     ACL allow 192.168.0.0 192.168.255.255
  
  </stream>
  
  
  
  <redirect>    # Just an URL redirect for index
  
     # Redirect index.html to the appropriate site
  
     URL http://www.ffmpeg.org/
  
  </redirect>

  I put the FPS at 2 seconds, pretty much the maximum the computer I’m using can achieve is 4 for some reason. I then start ffmpeg with the following command :

  ffmpeg -f video4linux2 -s 640x480 -r 2 -i /dev/video0 -c:v libvpx http://localhost:8090/feed1.ffm. 

  The input is a standard UVC webcam that wprks properly (tested with cheese), ffmpeg seems to work (setting a file as ouput works properly) and the link to ffserver seems to work, the two programs regocnize each other. If an application requests the ffserver stream, it does receive data. wget for example results in a file of the size you would expect with the given bitrate. However, opening the stream in a webpage does not work.
  I tried it in two ways : simply browsing to the webm link. firefox indicates it’s receiving some data, but nothing is displayed. ffserver also indicates that a normal amount of data is transferred. The second option I tried was webpage with video tags for the video stream :

  <video with="640" height="480" autoplay="autoplay">
  
    <source src="http://localhost:8090/camera1.webm" type="video/webm">
  
  </source></video>

  but this works neither.
  Who has any idea where I went wrong ?