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203 lines
7.3 KiB
XML
203 lines
7.3 KiB
XML
<sect1 id="chapter-using">
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<title id="title-using">Using GStreamer</title>
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<qandaset defaultlabel="qanda">
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<qandaentry>
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<question id="using-getting-started">
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<para>Ok, I've installed GStreamer. What can I do next ?</para>
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</question>
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<answer>
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<para>
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First of all, verify that you have a working registry and that you can
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inspect them by typing
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<programlisting>
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$ gst-inspect-1.0 fakesrc
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</programlisting>
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This should print out a bunch of information about this particular element.
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If this tells you that there is "no such element or plugin", you haven't
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installed GStreamer correctly. Please check
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<link linkend="chapter-getting">how to get GStreamer</link>
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If this fails with any other message, we would appreciate a
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<link linkend="using-bugs-where">bug report</link>.
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</para>
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<para>
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It's time to try out a few things. Start with gst-launch and two plug-ins
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that you really should have : fakesrc and fakesink. They do nothing except
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pass empty buffers. Type this at the command-line :
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<programlisting>
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$ gst-launch-1.0 -v fakesrc silent=0 num-buffers=3 ! fakesink silent=0
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</programlisting>
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This will print out output that looks similar to this :
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<programlisting>
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RUNNING pipeline ...
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fakesrc0: last-message = "get ******* (fakesrc0:src)gt; (0 bytes, 0) 0x8057510"
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fakesink0: last-message = "chain ******* (fakesink0:sink)lt; (0 bytes, 0) 0x8057510"
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fakesrc0: last-message = "get ******* (fakesrc0:src)gt; (0 bytes, 1) 0x8057510"
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fakesink0: last-message = "chain ******* (fakesink0:sink)lt; (0 bytes, 1) 0x8057510"
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fakesrc0: last-message = "get ******* (fakesrc0:src)gt; (0 bytes, 2) 0x8057510"
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fakesink0: last-message = "chain ******* (fakesink0:sink)lt; (0 bytes, 2) 0x8057510"
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execution ended after 5 iterations (sum 301479000 ns, average 60295800 ns, min 3000 ns, max 105482000 ns)
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</programlisting>
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(Some parts of output have been removed for clarity) If it looks similar, then
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GStreamer itself is running correctly.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question id="using-sound">
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<para>Can my system play sound through GStreamer ?</para>
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</question>
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<answer>
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<para>
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You can test this by trying to play a sine tone. For this, you need to
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link the audiotestsrc element to an output element that matches your hardware.
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A (non-complete) list of output plug-ins for audio is
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<itemizedlist>
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<listitem><para>pulsesink for Pulseaudio output</para></listitem>
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<listitem><para>osssink for OSS output</para></listitem>
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<listitem><para>esdsink for ESound output</para></listitem>
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<listitem><para>alsasink for ALSA output</para></listitem>
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<listitem><para>alsaspdifsink for ALSA S/PDIF output</para></listitem>
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<listitem><para>jackaudiosink for JACK output</para></listitem>
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</itemizedlist>
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First of all, run gst-inspect-1.0 on the output plug-in you want to use to
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make sure you have it installed. For example, if you use Pulseaudio, run
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<programlisting>
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$ gst-inspect-1.0 pulsesink
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</programlisting>
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and see if that prints out a bunch of properties for the plug-in.
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</para>
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<para>
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Then try to play the sine tone by running
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<programlisting>
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$ gst-launch-1.0 audiotestsrc ! audioconvert ! audioresample ! pulsesink
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</programlisting>
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and see if you hear something. Make sure your volume is turned up,
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but also make sure it is not too loud and you are not wearing your headphones.
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</para>
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<para>
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In GNOME, you can configure audio output for most applications by running
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<programlisting>
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$ gstreamer-properties
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</programlisting>
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which can also be found in the start menu (Applications -> Preferences ->
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Multimedia Systems Selector). In KDE, there is not yet a shared way of
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setting audio output for all applications; however, applications such
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as Amarok allow you to specify an audio output in their preferences dialog.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question id="using-gst-inspect">
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<para>How can I see what GStreamer plugins I have on my system ?</para>
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</question>
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<answer>
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<para>
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To do this you use the gst-inspect
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command-line tool, which comes standard with GStreamer.
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Invoked without any arguments,
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<programlisting>
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$ gst-inspect-1.0
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</programlisting>
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will print out a listing of installed plugins.
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To learn more about a particular plugin, pass its name on the command line.
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For example,
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<programlisting>
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$ gst-inspect-1.0 volume
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</programlisting>
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will give you information about the volume plugin.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question id="using-bugs-where">
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<para>Where should I report bugs ?</para>
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</question>
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<answer>
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<para>
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Bug management is now hosted on GNOME's Bugzilla at
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<ulink url="http://bugzilla.gnome.org">http://bugzilla.gnome.org</ulink>,
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under the product GStreamer.
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Using bugzilla you can view past bug history, report new bugs, etc.
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Bugzilla requires you to make an account here, which might seem cumbersome,
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but allows us to at least have a chance at contacting you for further
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information, as we will most likely have to.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question id="using-bugs-how">
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<para>How should I report bugs ?</para>
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</question>
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<answer>
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<para>
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When doing a bug report, you should at least describe
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<itemizedlist>
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<listitem><para>your distribution</para></listitem>
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<listitem><para>
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how you installed GStreamer (from git, source, packages, which ?)</para></listitem>
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<listitem><para>if you installed GStreamer before</para></listitem>
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</itemizedlist>
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</para>
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<para>
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If the application you are having problems with is segfaulting, then
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provide us with the necessary gdb output. See
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<xref linkend="troubleshooting-segfault" endterm="troubleshooting-segfault"/>
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question id="using-gst-launch">
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<para>How do I use the GStreamer command line interface ?</para>
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</question>
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<answer>
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<para>
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You access the GStreamer command line interface using the command gst-launch.
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To decode an mp3 and play it through Pulseaudio, you could use
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<programlisting>
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gst-launch-1.0 filesrc location=thesong.mp3 ! mad ! pulsesink
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</programlisting>.
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More examples can be found in the gst-launch man page.
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</para>
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<para>
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To automatically detect the right codec in a pipeline, try
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<programlisting>
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gst-launch-1.0 filesrc location=my-random-media-file.mpeg ! decodebin !
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pulsesink
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</programlisting>.
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or
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<programlisting>
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gst-launch-1.0 filesrc location=my-random-media-file.mpeg ! decodebin !
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videoconvert ! xvimagesink
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</programlisting>
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Something more complicated:
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<programlisting>
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gst-launch-1.0 filesrc location=my-random-media-file.mpeg ! decodebin name=decoder
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decoder. ! videoconvert ! xvimagesink
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decoder. ! audioconvert ! pulsesink
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</programlisting>
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</para>
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<para>
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We also have a basic media playing plugin that will take care of most things
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for you. This plugin is called playbin. Try this:
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<programlisting>
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gst-launch-1.0 playbin uri=file:///home/joe/my-random-media-file.mpeg
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</programlisting>
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This should play the file if the format is supported, ie. you have all the
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necessary demuxing and decoding and some output plugins installed.
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</para>
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</answer>
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</qandaentry>
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</qandaset>
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</sect1>
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