docs/plugins/html/gst-plugins-good-plugins-rganalysis.html

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
   2 <html>
   3 <head>
   4 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
   5 <title>rganalysis</title>
   6 <meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
   7 <link rel="home" href="index.html" title="GStreamer Good Plugins 0.10 Plugins Reference Manual">
   8 <link rel="up" href="ch01.html" title="gst-plugins-good Elements">
   9 <link rel="prev" href="gst-plugins-good-plugins-revtv.html" title="revtv">
  10 <link rel="next" href="gst-plugins-good-plugins-rglimiter.html" title="rglimiter">
  11 <meta name="generator" content="GTK-Doc V1.17 (XML mode)">
  12 <link rel="stylesheet" href="style.css" type="text/css">
  13 </head>
  14 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
  15 <table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="2">
  16 <tr valign="middle">
  17 <td><a accesskey="p" href="gst-plugins-good-plugins-revtv.html"><img src="left.png" width="24" height="24" border="0" alt="Prev"></a></td>
  18 <td><a accesskey="u" href="ch01.html"><img src="up.png" width="24" height="24" border="0" alt="Up"></a></td>
  19 <td><a accesskey="h" href="index.html"><img src="home.png" width="24" height="24" border="0" alt="Home"></a></td>
  20 <th width="100%" align="center">GStreamer Good Plugins 0.10 Plugins Reference Manual</th>
  21 <td><a accesskey="n" href="gst-plugins-good-plugins-rglimiter.html"><img src="right.png" width="24" height="24" border="0" alt="Next"></a></td>
  22 </tr>
  23 <tr><td colspan="5" class="shortcuts">
  24 <a href="#gst-plugins-good-plugins-rganalysis.synopsis" class="shortcut">Top</a>
  25                    |
  26                   <a href="#gst-plugins-good-plugins-rganalysis.description" class="shortcut">Description</a>
  27                    |
  28                   <a href="#gst-plugins-good-plugins-rganalysis.object-hierarchy" class="shortcut">Object Hierarchy</a>
  29                    |
  30                   <a href="#gst-plugins-good-plugins-rganalysis.properties" class="shortcut">Properties</a>
  31 </td></tr>
  32 </table>
  33 <div class="refentry">
  34 <a name="gst-plugins-good-plugins-rganalysis"></a><div class="titlepage"></div>
  35 <div class="refnamediv"><table width="100%"><tr>
  36 <td valign="top">
  37 <h2><span class="refentrytitle"><a name="gst-plugins-good-plugins-rganalysis.top_of_page"></a>rganalysis</span></h2>
  38 <p>rganalysis — Perform the ReplayGain analysis</p>
  39 </td>
  40 <td valign="top" align="right"></td>
  41 </tr></table></div>
  42 <div class="refsynopsisdiv">
  43 <a name="gst-plugins-good-plugins-rganalysis.synopsis"></a><h2>Synopsis</h2>
  44 <a name="GstRgAnalysis"></a><pre class="synopsis">struct              <a class="link" href="gst-plugins-good-plugins-rganalysis.html#GstRgAnalysis-struct" title="struct GstRgAnalysis">GstRgAnalysis</a>;
  45 </pre>
  46 </div>
  47 <div class="refsect1">
  48 <a name="gst-plugins-good-plugins-rganalysis.object-hierarchy"></a><h2>Object Hierarchy</h2>
  49 <pre class="synopsis">
  50   <a href="http://library.gnome.org/devel/gobject/unstable/gobject-The-Base-Object-Type.html#GObject">GObject</a>
  51    +----<a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstObject.html">GstObject</a>
  52          +----<a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html">GstElement</a>
  53                +----<a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-libs/html/GstBaseTransform.html">GstBaseTransform</a>
  54                      +----GstRgAnalysis
  55 </pre>
  56 </div>
  57 <div class="refsect1">
  58 <a name="gst-plugins-good-plugins-rganalysis.properties"></a><h2>Properties</h2>
  59 <pre class="synopsis">
  60   "<a class="link" href="gst-plugins-good-plugins-rganalysis.html#GstRgAnalysis--forced" title='The "forced" property'>forced</a>"                   <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>              : Read / Write
  61   "<a class="link" href="gst-plugins-good-plugins-rganalysis.html#GstRgAnalysis--num-tracks" title='The "num-tracks" property'>num-tracks</a>"               <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write
  62   "<a class="link" href="gst-plugins-good-plugins-rganalysis.html#GstRgAnalysis--reference-level" title='The "reference-level" property'>reference-level</a>"          <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a>               : Read / Write
  63   "<a class="link" href="gst-plugins-good-plugins-rganalysis.html#GstRgAnalysis--message" title='The "message" property'>message</a>"                  <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>              : Read / Write / Construct
  64 </pre>
  65 </div>
  66 <div class="refsect1">
  67 <a name="gst-plugins-good-plugins-rganalysis.description"></a><h2>Description</h2>
  68 <p>
  69 This element analyzes raw audio sample data in accordance with the proposed
  70 <a class="ulink" href="http://replaygain.org" target="_top">ReplayGain standard</a> for
  71 calculating the ideal replay gain for music tracks and albums.  The element
  72 is designed as a pass-through filter that never modifies any data.  As it
  73 receives an EOS event, it finalizes the ongoing analysis and generates a tag
  74 list containing the results.  It is sent downstream with a tag event and
  75 posted on the message bus with a tag message.  The EOS event is forwarded as
  76 normal afterwards.  Result tag lists at least contain the tags
  77 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstTagList.html#GST-TAG-TRACK-GAIN:CAPS"><span class="type">GST_TAG_TRACK_GAIN</span></a>, <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstTagList.html#GST-TAG-TRACK-PEAK:CAPS"><span class="type">GST_TAG_TRACK_PEAK</span></a> and <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstTagList.html#GST-TAG-REFERENCE-LEVEL:CAPS"><span class="type">GST_TAG_REFERENCE_LEVEL</span></a>.
  78 </p>
  79 <p>
  80 Because the generated metadata tags become available at the end of streams,
  81 downstream muxer and encoder elements are normally unable to save them in
  82 their output since they generally save metadata in the file header.
  83 Therefore, it is often necessary that applications read the results in a bus
  84 event handler for the tag message.  Obtaining the values this way is always
  85 needed for <a class="link" href="gst-plugins-good-plugins-rganalysis.html#GstRgAnalysis--num-tracks" title='The "num-tracks" property'>album processing</a>
  86 since the album gain and peak values need to be associated with all tracks of
  87 an album, not just the last one.
  88 </p>
  89 <p>
  90 </p>
  91 <div class="refsect2">
  92 <a name="idp20743456"></a><h3>Example launch lines</h3>
  93 <div class="informalexample">
  94   <table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
  95     <tbody>
  96       <tr>
  97         <td class="listing_lines" align="right"><pre>1</pre></td>
  98         <td class="listing_code"><pre class="programlisting">gst<span class="gtkdoc opt">-</span>launch <span class="gtkdoc opt">-</span>t audiotestsrc wave<span class="gtkdoc opt">=</span>sine num<span class="gtkdoc opt">-</span>buffers<span class="gtkdoc opt">=</span><span class="number">512</span> <span class="gtkdoc opt">!</span> rganalysis <span class="gtkdoc opt">!</span> fakesink</pre></td>
  99       </tr>
 100     </tbody>
 101   </table>
 102 </div>
 103  Analyze a simple test waveform
 104 <div class="informalexample">
 105   <table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
 106     <tbody>
 107       <tr>
 108         <td class="listing_lines" align="right"><pre>1
 109 2</pre></td>
 110         <td class="listing_code"><pre class="programlisting">gst<span class="gtkdoc opt">-</span>launch <span class="gtkdoc opt">-</span>t filesrc location<span class="gtkdoc opt">=</span>filename<span class="gtkdoc opt">.</span>ext <span class="gtkdoc opt">!</span> decodebin \
 111     <span class="gtkdoc opt">!</span> audioconvert <span class="gtkdoc opt">!</span> audioresample <span class="gtkdoc opt">!</span> rganalysis <span class="gtkdoc opt">!</span> fakesink</pre></td>
 112       </tr>
 113     </tbody>
 114   </table>
 115 </div>
 116  Analyze a given file
 117 <div class="informalexample">
 118   <table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
 119     <tbody>
 120       <tr>
 121         <td class="listing_lines" align="right"><pre>1
 122 2</pre></td>
 123         <td class="listing_code"><pre class="programlisting">gst<span class="gtkdoc opt">-</span>launch <span class="gtkdoc opt">-</span>t gnomevfssrc location<span class="gtkdoc opt">=</span>http<span class="gtkdoc opt">:</span><span class="gtkdoc slc">//replaygain.hydrogenaudio.org/ref_pink.wav \</span>
 124     <span class="gtkdoc opt">!</span> wavparse <span class="gtkdoc opt">!</span> rganalysis <span class="gtkdoc opt">!</span> fakesink</pre></td>
 125       </tr>
 126     </tbody>
 127   </table>
 128 </div>
 129  Analyze the pink noise reference file
 130 <p>
 131 The above launch line yields a result gain of +6 dB (instead of the expected
 132 +0 dB).  This is not in error, refer to the <a class="link" href="gst-plugins-good-plugins-rganalysis.html#GstRgAnalysis--reference-level" title='The "reference-level" property'><span class="type">"reference-level"</span></a>
 133 property documentation for more information.
 134 </p>
 135 </div>
 136 <p>
 137 </p>
 138 <hr>
 139 <div class="refsect2">
 140 <a name="idp16371872"></a><h3>Acknowledgements</h3>
 141 <p>
 142 This element is based on code used in the <a class="ulink" href="http://sjeng.org/vorbisgain.html" target="_top">vorbisgain</a> program and many
 143 others.  The relevant parts are copyrighted by David Robinson, Glen Sawyer
 144 and Frank Klemm.
 145 </p>
 146 </div>
 147 <p>
 148 </p>
 149 <div class="refsynopsisdiv">
 150 <h2>Synopsis</h2>
 151 <div class="refsect2">
 152 <a name="idp15916432"></a><h3>Element Information</h3>
 153 <div class="variablelist"><table border="0">
 154 <col align="left" valign="top">
 155 <tbody>
 156 <tr>
 157 <td><p><span class="term">plugin</span></p></td>
 158 <td>
 159             <a class="link" href="gst-plugins-good-plugins-plugin-replaygain.html#plugin-replaygain">replaygain</a>
 160           </td>
 161 </tr>
 162 <tr>
 163 <td><p><span class="term">author</span></p></td>
 164 <td>René Stadler &lt;mail@renestadler.de&gt;</td>
 165 </tr>
 166 <tr>
 167 <td><p><span class="term">class</span></p></td>
 168 <td>Filter/Analyzer/Audio</td>
 169 </tr>
 170 </tbody>
 171 </table></div>
 172 </div>
 173 <hr>
 174 <div class="refsect2">
 175 <a name="idp16103152"></a><h3>Element Pads</h3>
 176 <div class="variablelist"><table border="0">
 177 <col align="left" valign="top">
 178 <tbody>
 179 <tr>
 180 <td><p><span class="term">name</span></p></td>
 181 <td>sink</td>
 182 </tr>
 183 <tr>
 184 <td><p><span class="term">direction</span></p></td>
 185 <td>sink</td>
 186 </tr>
 187 <tr>
 188 <td><p><span class="term">presence</span></p></td>
 189 <td>always</td>
 190 </tr>
 191 <tr>
 192 <td><p><span class="term">details</span></p></td>
 193 <td>audio/x-raw-float, width=(int)32, endianness=(int)1234, channels=(int){ 1, 2 }, rate=(int){ 8000, 11025, 12000, 16000, 22050, 24000, 32000, 44100, 48000 }</td>
 194 </tr>
 195 <tr>
 196 <td><p><span class="term"></span></p></td>
 197 <td> audio/x-raw-int, width=(int)16, depth=(int)[ 1, 16 ], signed=(boolean)true, endianness=(int)1234, channels=(int){ 1, 2 }, rate=(int){ 8000, 11025, 12000, 16000, 22050, 24000, 32000, 44100, 48000 }</td>
 198 </tr>
 199 </tbody>
 200 </table></div>
 201 <div class="variablelist"><table border="0">
 202 <col align="left" valign="top">
 203 <tbody>
 204 <tr>
 205 <td><p><span class="term">name</span></p></td>
 206 <td>src</td>
 207 </tr>
 208 <tr>
 209 <td><p><span class="term">direction</span></p></td>
 210 <td>source</td>
 211 </tr>
 212 <tr>
 213 <td><p><span class="term">presence</span></p></td>
 214 <td>always</td>
 215 </tr>
 216 <tr>
 217 <td><p><span class="term">details</span></p></td>
 218 <td>audio/x-raw-float, width=(int)32, endianness=(int)1234, channels=(int){ 1, 2 }, rate=(int){ 8000, 11025, 12000, 16000, 22050, 24000, 32000, 44100, 48000 }</td>
 219 </tr>
 220 <tr>
 221 <td><p><span class="term"></span></p></td>
 222 <td> audio/x-raw-int, width=(int)16, depth=(int)[ 1, 16 ], signed=(boolean)true, endianness=(int)1234, channels=(int){ 1, 2 }, rate=(int){ 8000, 11025, 12000, 16000, 22050, 24000, 32000, 44100, 48000 }</td>
 223 </tr>
 224 </tbody>
 225 </table></div>
 226 </div>
 227 </div>
 228 <p>
 229 </p>
 230 </div>
 231 <div class="refsect1">
 232 <a name="gst-plugins-good-plugins-rganalysis.details"></a><h2>Details</h2>
 233 <div class="refsect2">
 234 <a name="GstRgAnalysis-struct"></a><h3>struct GstRgAnalysis</h3>
 235 <pre class="programlisting">struct GstRgAnalysis;</pre>
 236 <p>
 237 Opaque data structure.
 238 </p>
 239 </div>
 240 </div>
 241 <div class="refsect1">
 242 <a name="gst-plugins-good-plugins-rganalysis.property-details"></a><h2>Property Details</h2>
 243 <div class="refsect2">
 244 <a name="GstRgAnalysis--forced"></a><h3>The <code class="literal">"forced"</code> property</h3>
 245 <pre class="programlisting">  "forced"                   <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>              : Read / Write</pre>
 246 <p>
 247 Whether to analyze streams even when ReplayGain tags exist.
 248 </p>
 249 <p>
 250 For assisting transcoder/converter applications, the element can silently
 251 skip the processing of streams that already contain the necessary tags.
 252 Data will flow as usual but the element will not consume CPU time and will
 253 not generate result tags.  To enable possible skipping, set this property
 254 to <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#FALSE:CAPS"><span class="type">FALSE</span></a>.
 255 </p>
 256 <p>
 257 If used in conjunction with <a class="link" href="gst-plugins-good-plugins-rganalysis.html#GstRgAnalysis--num-tracks" title='The "num-tracks" property'>album
 258 processing</a>, the element will skip the number of remaining album
 259 tracks if a full set of tags is found for the first track.  If a subsequent
 260 track of the album is missing tags, processing cannot start again.  If this
 261 is undesired, the application has to scan all files beforehand and enable
 262 forcing of processing if needed.
 263 </p>
 264 <p>Default value: TRUE</p>
 265 </div>
 266 <hr>
 267 <div class="refsect2">
 268 <a name="GstRgAnalysis--num-tracks"></a><h3>The <code class="literal">"num-tracks"</code> property</h3>
 269 <pre class="programlisting">  "num-tracks"               <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write</pre>
 270 <p>
 271 Number of remaining album tracks.
 272 </p>
 273 <p>
 274 Analyzing several streams sequentially and assigning them a common result
 275 gain is known as "album processing".  If this gain is used during playback
 276 (by switching to "album mode"), all tracks of an album receive the same
 277 amplification.  This keeps the relative volume levels between the tracks
 278 intact.  To enable this, set this property to the number of streams that
 279 will be processed as album tracks.
 280 </p>
 281 <p>
 282 Every time an EOS event is received, the value of this property is
 283 decremented by one.  As it reaches zero, it is assumed that the last track
 284 of the album finished.  The tag list for the final stream will contain the
 285 additional tags <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstTagList.html#GST-TAG-ALBUM-GAIN:CAPS"><span class="type">GST_TAG_ALBUM_GAIN</span></a> and <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstTagList.html#GST-TAG-ALBUM-PEAK:CAPS"><span class="type">GST_TAG_ALBUM_PEAK</span></a>.  All other
 286 streams just get the two track tags posted because the values for the album
 287 tags are not known before all tracks are analyzed.  Applications need to
 288 ensure that the album gain and peak values are also associated with the
 289 other tracks when storing the results.
 290 </p>
 291 <p>
 292 If the total number of album tracks is unknown beforehand, just ensure that
 293 the value is greater than 1 before each track starts.  Then before the end
 294 of the last track, set it to the value 1.
 295 </p>
 296 <p>
 297 To perform album processing, the element has to preserve data between
 298 streams.  This cannot survive a state change to the NULL or READY state.
 299 If you change your pipeline's state to NULL or READY between tracks, lock
 300 the element's state using <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html#gst-element-set-locked-state"><code class="function">gst_element_set_locked_state()</code></a> when it is in
 301 PAUSED or PLAYING.
 302 </p>
 303 <p>Allowed values: &gt;= 0</p>
 304 <p>Default value: 0</p>
 305 </div>
 306 <hr>
 307 <div class="refsect2">
 308 <a name="GstRgAnalysis--reference-level"></a><h3>The <code class="literal">"reference-level"</code> property</h3>
 309 <pre class="programlisting">  "reference-level"          <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a>               : Read / Write</pre>
 310 <p>
 311 Reference level [dB].
 312 </p>
 313 <p>
 314 Analyzing the ReplayGain pink noise reference waveform computes a result of
 315 +6 dB instead of the expected 0 dB.  This is because the default reference
 316 level is 89 dB.  To obtain values as lined out in the original proposal of
 317 ReplayGain, set this property to 83.
 318 </p>
 319 <p>
 320 Almost all software uses 89 dB as a reference however, and this value has
 321 become the new official value.  That is to say, while the change has been
 322 acclaimed by the author of the ReplayGain proposal, the <a class="ulink" href="http://replaygain.org" target="_top">webpage</a> is still outdated at the time
 323 of this writing.
 324 </p>
 325 <p>
 326 The value was changed because the original proposal recommends a default
 327 pre-amp value of +6 dB for playback.  This seemed a bit odd, as it means
 328 that the algorithm has the general tendency to produce adjustment values
 329 that are 6 dB too low.  Bumping the reference level by 6 dB compensated for
 330 this.
 331 </p>
 332 <p>
 333 The problem of the reference level being ambiguous for lack of concise
 334 standardization is to be solved by adopting the <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstTagList.html#GST-TAG-REFERENCE-LEVEL:CAPS"><span class="type">GST_TAG_REFERENCE_LEVEL</span></a>
 335 tag, which allows to store the used value alongside the gain values.
 336 </p>
 337 <p>Allowed values: [0,150]</p>
 338 <p>Default value: 89</p>
 339 </div>
 340 <hr>
 341 <div class="refsect2">
 342 <a name="GstRgAnalysis--message"></a><h3>The <code class="literal">"message"</code> property</h3>
 343 <pre class="programlisting">  "message"                  <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>              : Read / Write / Construct</pre>
 344 <p>Post statics messages.</p>
 345 <p>Default value: FALSE</p>
 346 </div>
 347 </div>
 348 <div class="refsect1">
 349 <a name="gst-plugins-good-plugins-rganalysis.see-also"></a><h2>See Also</h2>
 350 <a class="link" href="gst-plugins-good-plugins-rgvolume.html#GstRgVolume"><span class="type">GstRgVolume</span></a>
 351 </div>
 352 </div>
 353 <div class="footer">
 354 <hr>
 355           Generated by GTK-Doc V1.17</div>
 356 </body>
 357 </html>