X-Git-Url: https://git.decadent.org.uk/gitweb/?p=lca-dvswitch.git;a=blobdiff_plain;f=index.html;h=063ac2a4c584f624ec46f4a8bc9ef7196d7679ce;hp=3c5d0a798791adf95ecfc6e970fe9cc85fb25a1d;hb=a3cdcaf7a9001392987cc34ad8b052e8753fb662;hpb=a45ddfd4426085bbe33df1129a34a78e9c4e2a32

diff --git a/index.html b/index.html
index 3c5d0a7..063ac2a 100644
--- a/index.html
+++ b/index.html
@@ -17,6 +17,12 @@
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 <link rel="stylesheet" href="s5-blank/ui/default/opera.css" type="text/css" media="projection" id="operaFix" />
+<style type="text/css">
+  .logo { position: absolute; right: 0; top: 0; height: 100% }
+  table { border-collapse: collapse }
+  th { border-bottom: 2pt solid black }
+  th, td { padding: 0 6pt }
+</style>
 <!-- S5 JS -->
 <script src="s5-blank/ui/default/slides.js" type="text/javascript"></script>
 </head>
@@ -25,7 +31,9 @@
 <div class="layout">
 <div id="controls"><!-- DO NOT EDIT --></div>
 <div id="currentSlide"><!-- DO NOT EDIT --></div>
-<div id="header"></div>
+<div id="header">
+  <object class="logo" data="lca2011.svg"></object>
+</div>
 <div id="footer">
 <h1>LCA2011</h1>
 <h2>DVswitch</h2>
@@ -42,6 +50,29 @@
 </div>
 
 
+<div class="slide">
+  <h1>The author</h1>
+  <ul class="incremental">
+    <li>
+      Professional software developer since 1998
+    </li>
+    <li>
+      Debian contributor since 2003
+    </li>
+    <li>
+      DebConf video team member since 2005
+    </li>
+    <li>
+      Started the VideoLink and DVswitch projects for use in DebConf
+      video production
+    </li>
+    <li>
+      Mostly working on kernel stuff
+    </li>
+  </ul>
+</div>
+
+
 <div class="slide">
   <h1>What is DVswitch?</h1>
   <ul class="incremental">
@@ -49,17 +80,28 @@
       A software system that supports video mixing, recording and streaming
     </li>
     <li>
-      Designed particularly for the needs of technical conferences that
-      want to record and stream on a limited budget.  Now used more
-      widely, often without streaming.
+      Primarily designed for free software conferences:
+      <ul class="incremental">
+	<li>
+	  Record and stream for maximum community benefit
+	</li>
+	<li>
+	  Budget is usually quite limited
+	</li>
+	<li>
+	  We have eager volunteers but not much time to train them
+	</li>
+      </ul>
+    <li>
+      Now used more widely, often without streaming
     </li>
     <li>
-      Mixing is <em>live</em> - a requirement for streaming, and a way to
-      avoid the need for extensive editing after the event
+      Mixing is <em>live</em> - required for streaming, and avoids the
+      need for extensive editing after the event
     </li>
     <li>
-      Mixing is <em>interactive</em> - a requirement for good coverage of
-      presenters, audience and slides, but very limited in other
+      Mixing is <em>interactive</em> - required for good coverage of
+      presenters, audience and slides; very limited in other
       streaming software
     </li>
   </ul>
@@ -76,7 +118,8 @@
       A general video editor
     </li>
     <li>
-      An audio mixer (but it does implement audio dubbing and level monitoring)
+      An audio mixer - audio functionality is limited to dubbing and
+      level monitoring
     </li>
     <li>
       A complete recording and publishing system
@@ -91,7 +134,7 @@
 <div class="slide">
   <h1>The 'DV' in DVswitch</h1>
   <p>
-    The name refers to the DV formats used by many video cameras:
+    The name refers to the DV format used by many video cameras:
   </p>
   <table>
     <tr>
@@ -140,7 +183,7 @@
   <p>
     A simplified view of the typical components:
   </p>
-  <object data="dvswitch-simple.svg" width="60%" height="60%"></object>
+  <object data="dvswitch-simple.dia.svg" width="60%" height="60%"></object>
 </div>
 
 <div class="slide">
@@ -162,10 +205,10 @@
 	  Requires a script to coordinate mixer and source startup -
 	  an annoying complication
 	</li>
-	<li>
-	  Improvement: tally lights
-	</li>
       </ul>
+    <li>
+      Later enhancement: tally lights
+    </li>
     <li>
       Next release: sources run as RTP/RTSP servers and mixer
       connects to them as a client
@@ -176,6 +219,12 @@
       </ul>
     </li>
   </ul>
+  <div class="handout">
+    <p>
+      DIF is the DV Interchange Format, sometimes referred to as 'raw
+      DV' although it is a container format in its own right.
+    </p>
+  </div>
 </div>
 
 <div class="slide">
@@ -191,12 +240,10 @@
     <li>
       Original protocol: mixer runs a network server; sinks run
       as clients and receive DIF over TCP
-      <ul class="incremental">
-	<li>
-	  Improvement: sink reports whether it will record; mixer can
-	  start, stop and cut recording
-	</li>
-      </ul>
+    </li>
+    <li>
+      Later enhancement: sink reports whether it will record;
+      mixer can start, stop and cut recording
     </li>
     <li>
       Next release: file and pipe sinks built into mixer along with an
@@ -206,13 +253,35 @@
 </div>
 
 <div class="slide">
-  <h1>Mixer</h1>
+  <h1>Mixer UI</h1>
   <object data="screenshot-1.png" width="50%"></object>
 </div>
 
 <div class="slide">
-  <h1>Mixer</h1>
-  <object data="screenshot-1-annotated.png" width="50%"></object>
+  <h1>Mixer UI, annotated</h1>
+  <object data="screenshot-1-annotated.xcf.png" width="50%"></object>
+</div>
+
+<div class="slide">
+  <h1>Mixer internals</h1>
+  <object data="dvswitch-internal.dia.svg" width="90%" height="90%"></object>
+  <div class="handout">
+    <p>
+      To simplify the diagram, I omitted connection setup, tally light
+      and recording control, and the internal sinks that haven't been
+      implemented yet.
+    </p>
+    <p>
+      All these interfaces have limited-length queues.  If a queue
+      fills up, frames have to be dropped - we must not block or use
+      unlimited memory!
+    </p>
+    <p>
+      The mixer clock thread maintains a frame clock at about 25 or
+      30&nbsp;Hz depending on the video system, constantly adjusted to
+      follow the audio source.
+    </p>
+  </div>
 </div>
 
 </body>