blog/archive/2016/06/06.rss

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   4                 <title>Petter Reinholdtsen - Entries from June 2016</title>
   5                 <description>Entries from June 2016</description>
   6                 <link>http://www.hungry.com/~pere/blog/</link>
   7
   8
   9         <item>
  10                 <title>The new &quot;best&quot; multimedia player in Debian?</title>
  11                 <link>http://www.hungry.com/~pere/blog/The_new__best__multimedia_player_in_Debian_.html</link>
  12                 <guid isPermaLink="true">http://www.hungry.com/~pere/blog/The_new__best__multimedia_player_in_Debian_.html</guid>
  13                 <pubDate>Mon, 6 Jun 2016 12:50:00 +0200</pubDate>
  14                 <description>&lt;p&gt;When I set out a few weeks ago to figure out
  15 &lt;a href=&quot;https://people.skolelinux.org/pere/blog/What_is_the_best_multimedia_player_in_Debian_.html&quot;&gt;which
  16 multimedia player in Debian claimed to support most file formats /
  17 MIME types&lt;/a&gt;, I was a bit surprised how varied the sets of MIME types
  18 the various players claimed support for.  The range was from 55 to 130
  19 MIME types.  I suspect most media formats are supported by all
  20 players, but this is not really reflected in the MimeTypes values in
  21 their desktop files.  There are probably also some bogus MIME types
  22 listed, but it is hard to identify which one this is.&lt;/p&gt;
  23
  24 &lt;p&gt;Anyway, in the mean time I got in touch with upstream for some of
  25 the players suggesting to add more MIME types to their desktop files,
  26 and decided to spend some time myself improving the situation for my
  27 favorite media player VLC.  The fixes for VLC entered Debian unstable
  28 yesterday. The complete list of MIME types can be seen on the
  29 &lt;a href=&quot;https://wiki.debian.org/DebianMultimedia/PlayerSupport&quot;&gt;Multimedia
  30 player MIME type support status&lt;/a&gt; Debian wiki page.&lt;/p&gt;
  31
  32 &lt;p&gt;The new &quot;best&quot; multimedia player in Debian?  It is VLC, followed by
  33 totem, parole, kplayer, gnome-mpv, mpv, smplayer, mplayer-gui and
  34 kmplayer.  I am sure some of the other players desktop files support
  35 several of the formats currently listed as working only with vlc,
  36 toten and parole.&lt;/p&gt;
  37
  38 &lt;p&gt;A sad observation is that only 14 MIME types are listed as
  39 supported by all the tested multimedia players in Debian in their
  40 desktop files: audio/mpeg, audio/vnd.rn-realaudio, audio/x-mpegurl,
  41 audio/x-ms-wma, audio/x-scpls, audio/x-wav, video/mp4, video/mpeg,
  42 video/quicktime, video/vnd.rn-realvideo, video/x-matroska,
  43 video/x-ms-asf, video/x-ms-wmv and video/x-msvideo.  Personally I find
  44 it sad that video/ogg and video/webm is not supported by all the media
  45 players in Debian.  As far as I can tell, all of them can handle both
  46 formats.&lt;/p&gt;
  47 </description>
  48         </item>
  49
  50         <item>
  51                 <title>A program should be able to open its own files on Linux</title>
  52                 <link>http://www.hungry.com/~pere/blog/A_program_should_be_able_to_open_its_own_files_on_Linux.html</link>
  53                 <guid isPermaLink="true">http://www.hungry.com/~pere/blog/A_program_should_be_able_to_open_its_own_files_on_Linux.html</guid>
  54                 <pubDate>Sun, 5 Jun 2016 08:30:00 +0200</pubDate>
  55                 <description>&lt;p&gt;Many years ago, when koffice was fresh and with few users, I
  56 decided to test its presentation tool when making the slides for a
  57 talk I was giving for NUUG on Japhar, a free Java virtual machine.  I
  58 wrote the first draft of the slides, saved the result and went to bed
  59 the day before I would give the talk.  The next day I took a plane to
  60 the location where the meeting should take place, and on the plane I
  61 started up koffice again to polish the talk a bit, only to discover
  62 that kpresenter refused to load its own data file.  I cursed a bit and
  63 started making the slides again from memory, to have something to
  64 present when I arrived.  I tested that the saved files could be
  65 loaded, and the day seemed to be rescued.  I continued to polish the
  66 slides until I suddenly discovered that the saved file could no longer
  67 be loaded into kpresenter.  In the end I had to rewrite the slides
  68 three times, condensing the content until the talk became shorter and
  69 shorter.  After the talk I was able to pinpoint the problem &amp;ndash;
  70 kpresenter wrote inline images in a way itself could not understand.
  71 Eventually that bug was fixed and kpresenter ended up being a great
  72 program to make slides.  The point I&#39;m trying to make is that we
  73 expect a program to be able to load its own data files, and it is
  74 embarrassing to its developers if it can&#39;t.&lt;/p&gt;
  75
  76 &lt;p&gt;Did you ever experience a program failing to load its own data
  77 files from the desktop file browser?  It is not a uncommon problem.  A
  78 while back I discovered that the screencast recorder
  79 gtk-recordmydesktop would save an Ogg Theora video file the KDE file
  80 browser would refuse to open.  No video player claimed to understand
  81 such file.  I tracked down the cause being &lt;tt&gt;file --mime-type&lt;/tt&gt;
  82 returning the application/ogg MIME type, which no video player I had
  83 installed listed as a MIME type they would understand.  I asked for
  84 &lt;a href=&quot;http://bugs.gw.com/view.php?id=382&quot;&gt;file to change its
  85 behavour&lt;/a&gt; and use the MIME type video/ogg instead.  I also asked
  86 several video players to add video/ogg to their desktop files, to give
  87 the file browser an idea what to do about Ogg Theora files.  After a
  88 while, the desktop file browsers in Debian started to handle the
  89 output from gtk-recordmydesktop properly.&lt;/p&gt;
  90
  91 &lt;p&gt;But history repeats itself.  A few days ago I tested the music
  92 system Rosegarden again, and I discovered that the KDE and xfce file
  93 browsers did not know what to do with the Rosegarden project files
  94 (*.rg).  I&#39;ve reported &lt;a href=&quot;http://bugs.debian.org/825993&quot;&gt;the
  95 rosegarden problem to BTS&lt;/a&gt; and a fix is commited to git and will be
  96 included in the next upload.  To increase the chance of me remembering
  97 how to fix the problem next time some program fail to load its files
  98 from the file browser, here are some notes on how to fix it.&lt;/p&gt;
  99
 100 &lt;p&gt;The file browsers in Debian in general operates on MIME types.
 101 There are two sources for the MIME type of a given file.  The output from
 102 &lt;tt&gt;file --mime-type&lt;/tt&gt; mentioned above, and the content of the
 103 shared MIME type registry (under /usr/share/mime/).  The file MIME
 104 type is mapped to programs supporting the MIME type, and this
 105 information is collected from
 106 &lt;a href=&quot;https://www.freedesktop.org/wiki/Specifications/desktop-entry-spec/&quot;&gt;the
 107 desktop files&lt;/a&gt; available in /usr/share/applications/.  If there is
 108 one desktop file claiming support for the MIME type of the file, it is
 109 activated when asking to open a given file.  If there are more, one
 110 can normally select which one to use by right-clicking on the file and
 111 selecting the wanted one using &#39;Open with&#39; or similar.  In general
 112 this work well.  But it depend on each program picking a good MIME
 113 type (preferably
 114 &lt;a href=&quot;http://www.iana.org/assignments/media-types/media-types.xhtml&quot;&gt;a
 115 MIME type registered with IANA&lt;/a&gt;), file and/or the shared MIME
 116 registry recognizing the file and the desktop file to list the MIME
 117 type in its list of supported MIME types.&lt;/p&gt;
 118
 119 &lt;p&gt;The &lt;tt&gt;/usr/share/mime/packages/rosegarden.xml&lt;/tt&gt; entry for
 120 &lt;a href=&quot;http://www.freedesktop.org/wiki/Specifications/shared-mime-info-spec&quot;&gt;the
 121 Shared MIME database&lt;/a&gt; look like this:&lt;/p&gt;
 122
 123 &lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
 124 &amp;lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&amp;gt;
 125 &amp;lt;mime-info xmlns=&quot;http://www.freedesktop.org/standards/shared-mime-info&quot;&amp;gt;
 126   &amp;lt;mime-type type=&quot;audio/x-rosegarden&quot;&amp;gt;
 127     &amp;lt;sub-class-of type=&quot;application/x-gzip&quot;/&amp;gt;
 128     &amp;lt;comment&amp;gt;Rosegarden project file&amp;lt;/comment&amp;gt;
 129     &amp;lt;glob pattern=&quot;*.rg&quot;/&amp;gt;
 130   &amp;lt;/mime-type&amp;gt;
 131 &amp;lt;/mime-info&amp;gt;
 132 &lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;
 133
 134 &lt;p&gt;This states that audio/x-rosegarden is a kind of application/x-gzip
 135 (it is a gzipped XML file).  Note, it is much better to use an
 136 official MIME type registered with IANA than it is to make up ones own
 137 unofficial ones like the x-rosegarden type used by rosegarden.&lt;/p&gt;
 138
 139 &lt;p&gt;The desktop file of the rosegarden program failed to list
 140 audio/x-rosegarden in its list of supported MIME types, causing the
 141 file browsers to have no idea what to do with *.rg files:&lt;/p&gt;
 142
 143 &lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
 144 % grep Mime /usr/share/applications/rosegarden.desktop
 145 MimeType=audio/x-rosegarden-composition;audio/x-rosegarden-device;audio/x-rosegarden-project;audio/x-rosegarden-template;audio/midi;
 146 X-KDE-NativeMimeType=audio/x-rosegarden-composition
 147 %
 148 &lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;
 149
 150 &lt;p&gt;The fix was to add &quot;audio/x-rosegarden;&quot; at the end of the
 151 MimeType= line.&lt;/p&gt;
 152
 153 &lt;p&gt;If you run into a file which fail to open the correct program when
 154 selected from the file browser, please check out the output from
 155 &lt;tt&gt;file --mime-type&lt;/tt&gt; for the file, ensure the file ending and
 156 MIME type is registered somewhere under /usr/share/mime/ and check
 157 that some desktop file under /usr/share/applications/ is claiming
 158 support for this MIME type.  If not, please report a bug to have it
 159 fixed. :)&lt;/p&gt;
 160 </description>
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