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<div id="preamble">
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<div id="preamble">
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<div class="sectionbody">
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<div class="sectionbody">
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<div class="paragraph"><p>General information about <strong>upmpdcli</strong> support for <strong>Songcast</strong> can be found
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<div class="paragraph"><p>General information about <strong>upmpdcli</strong> support for <strong>Songcast</strong> can be found
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<a href="sc2mpd.html">here</a>. This page explains how to set up a multiroom
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<a href="sc2mpd.html">here</a>. This page explains how to set up a multiroom
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synchronized audio system using <strong>upmpdcli</strong> and <strong>Songcast</strong>.</p></div>
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synchronized audio system using <strong>upmpdcli</strong> and <strong>Songcast</strong>.</p></div>


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<div class="admonitionblock">






  
  

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<table><tr>






  
  

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<td class="icon">






  
  

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<div class="title">Note</div>






  
  

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</td>






  
  

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<td class="content">multicast and WIFI don&#8217;t mix well in many cases. If you have






  
  

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wireless Receivers experiencing sound drop issues, try selecting unicast in






  
  

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the Songcast advanced configuration panel on the desktop.</td>






  
  

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</tr></table>






  
  

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</div>






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</div>


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</div>






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</div>


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</div>






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<div class="sect1">


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<div class="sect1">






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<h2 id="_multiple_receivers">Multiple Receivers</h2>


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<h2 id="_multiple_receivers">Multiple Receivers</h2>






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<div class="sectionbody">


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<div class="sectionbody">






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<div class="paragraph"><p>Multiple <strong>Songcast</strong> <em>Receiver</em> hosts can connect to the same <em>Sender</em>, so


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<div class="paragraph"><p>Multiple <strong>Songcast</strong> <em>Receiver</em> hosts can connect to the same <em>Sender</em>, so






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that they will all be playing the same audio.</p></div>


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that they will all be playing the same audio. They form a group only in the






  
  

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sense that they play from the same URI, and are not otherwise linked.</p></div>






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<div class="paragraph"><p>The Mac and Windows <strong>Songcast</strong> apps only let you activate one


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<div class="paragraph"><p>The Mac and Windows <strong>Songcast</strong> apps only let you activate one






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<em>Receiver</em> though.</p></div>


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<em>Receiver</em> though.</p></div>






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<div class="paragraph"><p><strong>upmpdcli</strong> now includes a small application which can list the state of


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<div class="paragraph"><p>The <strong>upmpdcli</strong> package now includes the <strong>scctl</strong> command line utility, which






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the local <strong>Songcast</strong> Receivers, make a Receiver play from the same URI as


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can list the state of the local <strong>Songcast</strong> <em>Receivers</em>, make a <em>Receiver</em>






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another one (for building multiroom groups), or return a Media Renderer


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play from the same URI as another one (for building multi-room groups), or






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from Receiver to normal operation.</p></div>


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return a <em>Media Renderer</em> from <em>Receiver</em> to normal operation.</p></div>






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<div class="paragraph"><p>The functions can be accessed either from the <strong>scctl</strong> command line utility,


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<div class="paragraph"><p>As the Songcast application is only available on Windows or Mac desktops,






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or from a local Web application (as Songcast is mostly used from a Windows


  
  





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or Mac PC, it would be inconvenient to have to access the Linux command


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it would be inconvenient to have to access the Linux command line to






  
  

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control the multi-room groups, and the <strong>upmpdcli</strong> package also includes a






  
  

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small Web application which can be accessed from a desktop web browser to






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line to control the multiroom groups).</p></div>


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control the groups.</p></div>






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<div class="paragraph"><p>This has only be tested with <strong>upmpdcli</strong> and its <a href="sc2mpd.html">sc2mpd</a>


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<div class="paragraph"><p>This has only be tested with <strong>upmpdcli</strong> and its <a href="sc2mpd.html">sc2mpd</a>






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<strong>Songcast</strong> auxiliary process as Receiver implementation, but I&#8217;d guess that


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<strong>Songcast</strong> auxiliary process as Receiver implementation, but I&#8217;d guess that






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there is a good chance it would work with others.</p></div>


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there is a good chance it would work with others.</p></div>






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</div>


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</div>






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</div>


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</div>






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<div class="sect1">


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<div class="sect1">






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<h2 id="_synchronisation_issues">Synchronisation issues</h2>


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<h2 id="_synchronisation_issues">Synchronisation issues</h2>






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<div class="sectionbody">


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<div class="sectionbody">






  773
  
<div class="paragraph"><p>The short version is: all sc2mpd instances must be configured to play


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<div class="paragraph"><p>The short version is: all <strong>sc2mpd</strong> instances must be configured to play






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directly to Alsa. See the <a href="sc2mpd.html#Configuration">configuration


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directly to Alsa. See the <a href="sc2mpd.html#Configuration">configuration






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section</a>.</p></div>


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section</a>.</p></div>






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<div class="paragraph"><p>Longer version: Songcast is a real-time audio stream. As the Sender and


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<div class="paragraph"><p>Longer version: <strong>Songcast</strong> is a real-time audio stream. As the <em>Sender</em> and






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Receiver sample clocks (the 44.1 or 48 KHz clocks) are independant, audio


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<em>Receiver</em> sample clocks (the 44.1 or 48 KHz clocks) are independant, audio






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reproduction on the two systems will slowly drift. If nothing is done,


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reproduction on the two systems will slowly drift. If nothing is done,






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after a time, the Receiver will have to skip samples or add a period of


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after a time, the <em>Receiver</em> will have to skip samples or add a period of






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silence (depending if its clock is slower or faster), which is quite


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silence (depending if its clock is slower or faster), which is quite






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audible and ennoying, and will happen "from time to time", depending of how


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audible and ennoying, and will happen "from time to time", depending of how






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much the clocks differ.</p></div>


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much the clocks differ.</p></div>






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<div class="paragraph"><p>The only way to control this is to adjust the rate of reproduction on the


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<div class="paragraph"><p>The only way to control this is to adjust the rate of reproduction on the






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Receiver, which can be done in two ways:</p></div>


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<em>Receiver</em>, which can be done in two ways:</p></div>






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<div class="ulist"><ul>


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<div class="ulist"><ul>






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<li>


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<li>






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<p>


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<p>






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Linn hardware uses timestamps embedded in the audio stream to adjust


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<strong>Linn</strong> hardware uses timestamps embedded in the audio stream to adjust






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   their hardware sample clock.


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   their hardware sample clock.






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</p>


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</p>






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</li>


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</li>






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<li>


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<li>






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<p>


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<p>






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sc2mpd in Alsa mode uses sample rate conversion to adjust the stream.


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<strong>sc2mpd</strong> in <em><tt>alsa</tt></em> mode uses sample rate conversion to adjust the stream.






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</p>


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</p>






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</li>


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</li>






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</ul></div>


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</ul></div>






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<div class="paragraph"><p>This is not specific to Songcast of course, all real time audio network


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<div class="paragraph"><p>This is not specific to <strong>Songcast</strong> of course, all real time audio network






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transports have to do something similar.</p></div>


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transports have to do something similar.</p></div>






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<div class="paragraph"><p>Independantly of the clock issue, all Receivers should use approximately


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<div class="paragraph"><p>Independantly of the clock issue, all <em>Receivers</em> should use approximately






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the same amount of buffering for the audio to be reasonably synchronous


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the same amount of buffering for the audio to be reasonably synchronous






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(with no more shifts than moving around would produce anyway). This is


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(with no more shifts than moving around would produce anyway). This is






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impossible to achieve when going through mpd, and the second reason why


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impossible to achieve when going through mpd, and the second reason why






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sc2mpd must be set in Alsa mode for multiroom setups. In mpd mode, the


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<strong>sc2mpd</strong> must be set in <em><tt>alsa</tt></em> mode for multiroom setups. In <em><tt>mpd</tt></em>






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receivers can be out of sync by several seconds.</p></div>


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mode, the <em>Receivers</em> can be out of sync by several seconds.</p></div>






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</div>


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</div>






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</div>


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</div>






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<div class="sect1">


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<div class="sect1">






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<h2 id="_setting_things_up">Setting things up</h2>


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<h2 id="_setting_things_up">Setting things up</h2>






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<div class="sectionbody">


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<div class="sectionbody">






  
  
...

  
  
...





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<tt>friendlyname</tt>, this is quite useful when managing several systems.


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<tt>friendlyname</tt>, this is quite useful when managing several systems.






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</p>


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</p>






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</li>


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</li>






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<li>


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<li>






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<p>


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<p>






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<tt>scplaymethod</tt> = alsa


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<tt>scplaymethod</tt> = <em><tt>alsa</tt></em>






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</p>


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</p>






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</li>


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</li>






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<li>


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<li>






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<p>


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<p>






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<tt>scalsadevice</tt>: use <tt>aplay -L</tt> to chose an appropriate device.


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<tt>scalsadevice</tt>: use <tt>aplay -L</tt> to chose an appropriate device.






  
  
...

  
  
...





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</li>


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</li>






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</ul></div>


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</ul></div>






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</li>


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</li>






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<li>


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<li>






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<p>


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<p>






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Activate the web interface on one of the Receivers (or on any machine


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Activate the web interface on one of the <em>Receivers</em> (or on any machine






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   with upmpdcli installed actually). Edit <tt>/etc/default/scweb</tt> to


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   with upmpdcli installed actually). Edit <tt>/etc/default/scweb</tt> to






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   configure the interface (see comments in there) and start it with


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   configure the interface (see comments in there) and start it with






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   <tt>/etc/init.d/scweb-service start</tt>.


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   <tt>service scweb start</tt>.






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</p>


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</p>






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</li>


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</li>






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<li>


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<li>






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<p>


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<p>






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Activate a Receiver from the PC <strong>Songcast</strong> interface. Play something and


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Activate a <em>Receiver</em> from the PC <strong>Songcast</strong> interface. Play something and






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   leave it playing.


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   leave it playing.






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</p>


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</p>






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</li>


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</li>






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<li>


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<li>






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<p>


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<p>






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Connect to the Web interface (host and port chosen above) with a


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Connect to the Web interface (host and port chosen above) with a






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   browser, and use it to list, activate, or disconnect the Receivers.


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   browser, and use it to list, activate, or disconnect the <em>Receivers</em>.






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</p>


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</p>






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</li>


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</li>






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</ul></div>


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</ul></div>






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<div class="paragraph"><p>Once the slave Receivers are associated with the Sender, they should stay


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<div class="paragraph"><p>Once the slave <em>Receivers</em> are associated with the <em>Sender</em>, they should stay






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in this state until you change it. So you can stop/start Songcast on the


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in this state until you change it. So you can stop/start <strong>Songcast</strong> on the






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PC, and they will usually just follow.</p></div>


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PC, and they will usually just follow.</p></div>






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<div class="paragraph"><p>An "associated" Receiver is just one which plays from the same URI, it


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<div class="paragraph"><p>An "associated" <em>Receiver</em> is just one which plays from the same URI, it






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keeps no other relation to the "Master". Only one Receiver is a bit special


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keeps no other relation to the "Master". Only one <em>Receiver</em> is a bit special






  861
  
because it is the one known from the PC, but there is no specific reason to


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because it is the one known from the PC, but there is no specific reason to






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use it as Master, the Master is only used to get the URI. Avoid changing


  874
  
use it as Master, the Master is only used to get the URI. Avoid changing






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the state of the "PC"'s Receiver from outside the PC <strong>Songcast</strong> interface,


  875
  
the state of the "PC"'s <em>Receiver</em> from outside the PC <strong>Songcast</strong> interface,






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this can only confuse things.</p></div>


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this can only confuse things.</p></div>






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</div>


  877
  
</div>






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</div>


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</div>






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<div class="sect1">


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<div class="sect1">






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<h2 id="_more_detail_about_the_web_interface">More detail about the Web interface</h2>


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<h2 id="_more_detail_about_the_web_interface">More detail about the Web interface</h2>






  
  
...

  
  
...





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interface:</p></div>


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interface:</p></div>






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<div class="literalblock">


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<div class="literalblock">






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<div class="content">


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<div class="content">






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<pre><tt>python2 ./scweb-standalone.py</tt></pre>


  894
  
<pre><tt>python2 ./scweb-standalone.py</tt></pre>






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</div></div>


  895
  
</div></div>






  884
  
<div class="paragraph"><p>This will start a server on localhost, on port 8780 by default which is


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<div class="paragraph"><p>This will start a server on localhost, on port 8680 by default which is






  885
  
good for testing, but not very useful. Use the -a 0.0.0.0 option to let the


  897
  
good for testing, but not very useful. Use the -a 0.0.0.0 option to let the






  886
  
server answer on all local addresses (or specify the address to use a


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server answer on all local addresses (or specify the address to use a






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specific interface):</p></div>


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specific interface):</p></div>






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<div class="literalblock">


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<div class="literalblock">






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<div class="content">


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<div class="content">






  890
  
<pre><tt>python2 ./scweb-standalone.py -a 0.0.0.0</tt></pre>


  902
  
<pre><tt>python2 ./scweb-standalone.py -a 0.0.0.0</tt></pre>






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</div></div>


  903
  
</div></div>






  892
  
<div class="paragraph"><p>-p can be used to specify a port.</p></div>


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<div class="paragraph"><p>-p can be used to specify a port.</p></div>






  893
  
<div class="paragraph"><p>Once started, connecting to the server from any browser should hopefully


  905
  
<div class="paragraph"><p>Once started, connecting to the server from any browser should hopefully






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display a reasonably self-explanatory interface.</p></div>


  906
  
display a reasonably self-explanatory interface.</p></div>






  
  

  907
  
<div class="paragraph"><p>Recent <strong>upmpdcli</strong> packages install the web app as a service named






  
  

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<strong>scweb</strong>. The service is not started by default though, you need to edit






  
  

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<tt>/etc/default/scweb</tt>.</p></div>






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</div>


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</div>






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</div>


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</div>






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</div>


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</div>






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<div id="footnotes"><hr /></div>


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<div id="footnotes"><hr /></div>






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<div id="footer">


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<div id="footer">






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<div id="footer-text">


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<div id="footer-text">






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Last updated 2015-05-06 10:18:31 CEST


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Last updated 2015-05-19 16:15:38 CEST






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</div>


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</div>






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</div>


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</div>






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</body>


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</body>






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</html>


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</html>