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| <div class="refentry"> |
| <a name="gst-plugins-good-plugins-alpha"></a><div class="titlepage"></div> |
| <div class="refnamediv"><table width="100%"><tr> |
| <td valign="top"> |
| <h2><span class="refentrytitle"><a name="gst-plugins-good-plugins-alpha.top_of_page"></a>alpha</span></h2> |
| <p>alpha — Adds an alpha channel to video - uniform or via chroma-keying</p> |
| </td> |
| <td class="gallery_image" valign="top" align="right"></td> |
| </tr></table></div> |
| <div class="refsect1"> |
| <a name="gst-plugins-good-plugins-alpha.properties"></a><h2>Properties</h2> |
| <div class="informaltable"><table border="0"> |
| <colgroup> |
| <col width="150px" class="properties_type"> |
| <col width="300px" class="properties_name"> |
| <col width="200px" class="properties_flags"> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td class="property_type"><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a></td> |
| <td class="property_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha--alpha" title="The “alpha” property">alpha</a></td> |
| <td class="property_flags">Read / Write</td> |
| </tr> |
| <tr> |
| <td class="property_type"><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a></td> |
| <td class="property_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha--angle" title="The “angle” property">angle</a></td> |
| <td class="property_flags">Read / Write</td> |
| </tr> |
| <tr> |
| <td class="property_type"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlphaMethod" title="enum GstAlphaMethod"><span class="type">GstAlphaMethod</span></a></td> |
| <td class="property_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha--method" title="The “method” property">method</a></td> |
| <td class="property_flags">Read / Write</td> |
| </tr> |
| <tr> |
| <td class="property_type"><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a></td> |
| <td class="property_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha--noise-level" title="The “noise-level” property">noise-level</a></td> |
| <td class="property_flags">Read / Write</td> |
| </tr> |
| <tr> |
| <td class="property_type"><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a></td> |
| <td class="property_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha--target-b" title="The “target-b” property">target-b</a></td> |
| <td class="property_flags">Read / Write</td> |
| </tr> |
| <tr> |
| <td class="property_type"><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a></td> |
| <td class="property_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha--target-g" title="The “target-g” property">target-g</a></td> |
| <td class="property_flags">Read / Write</td> |
| </tr> |
| <tr> |
| <td class="property_type"><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a></td> |
| <td class="property_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha--target-r" title="The “target-r” property">target-r</a></td> |
| <td class="property_flags">Read / Write</td> |
| </tr> |
| <tr> |
| <td class="property_type"><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a></td> |
| <td class="property_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha--black-sensitivity" title="The “black-sensitivity” property">black-sensitivity</a></td> |
| <td class="property_flags">Read / Write</td> |
| </tr> |
| <tr> |
| <td class="property_type"><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a></td> |
| <td class="property_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha--white-sensitivity" title="The “white-sensitivity” property">white-sensitivity</a></td> |
| <td class="property_flags">Read / Write</td> |
| </tr> |
| <tr> |
| <td class="property_type"><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a></td> |
| <td class="property_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha--prefer-passthrough" title="The “prefer-passthrough” property">prefer-passthrough</a></td> |
| <td class="property_flags">Read / Write</td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <a name="GstAlpha"></a><div class="refsect1"> |
| <a name="gst-plugins-good-plugins-alpha.other"></a><h2>Types and Values</h2> |
| <div class="informaltable"><table width="100%" border="0"> |
| <colgroup> |
| <col width="150px" class="name"> |
| <col class="description"> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td class="datatype_keyword">struct</td> |
| <td class="function_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlpha-struct" title="struct GstAlpha">GstAlpha</a></td> |
| </tr> |
| <tr> |
| <td class="datatype_keyword">enum</td> |
| <td class="function_name"><a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlphaMethod" title="enum GstAlphaMethod">GstAlphaMethod</a></td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-good-plugins-alpha.object-hierarchy"></a><h2>Object Hierarchy</h2> |
| <pre class="screen"> <a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#GObject">GObject</a> |
| <span class="lineart">╰──</span> <a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#GInitiallyUnowned">GInitiallyUnowned</a> |
| <span class="lineart">╰──</span> <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstObject.html">GstObject</a> |
| <span class="lineart">╰──</span> <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html">GstElement</a> |
| <span class="lineart">╰──</span> <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-libs/html/GstBaseTransform.html">GstBaseTransform</a> |
| <span class="lineart">╰──</span> <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstvideofilter.html#GstVideoFilter">GstVideoFilter</a> |
| <span class="lineart">╰──</span> GstAlpha |
| </pre> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-good-plugins-alpha.description"></a><h2>Description</h2> |
| <p>The alpha element adds an alpha channel to a video stream. The values |
| of the alpha channel can be either be set to a constant or can be |
| dynamically calculated via chroma keying, e.g. blue can be set as |
| the transparent color.</p> |
| <p>Sample pipeline:</p> |
| <div class="informalexample"> |
| <table class="listing_frame" border="0" cellpadding="0" cellspacing="0"> |
| <tbody> |
| <tr> |
| <td class="listing_lines" align="right"><pre>1 |
| 2 |
| 3</pre></td> |
| <td class="listing_code"><pre class="programlisting">gst<span class="gtkdoc opt">-</span>launch<span class="gtkdoc opt">-</span><span class="number">1.0</span> videotestsrc pattern<span class="gtkdoc opt">=</span>smpte75 <span class="gtkdoc opt">!</span> alpha method<span class="gtkdoc opt">=</span>green <span class="gtkdoc opt">!</span> \ |
| videomixer name<span class="gtkdoc opt">=</span>mixer <span class="gtkdoc opt">!</span> videoconvert <span class="gtkdoc opt">!</span> autovideosink \ |
| videotestsrc pattern<span class="gtkdoc opt">=</span>snow <span class="gtkdoc opt">!</span> mixer<span class="gtkdoc opt">.</span></pre></td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| |
| <p> This pipeline adds a alpha channel to the SMPTE color bars |
| with green as the transparent color and mixes the output with |
| a snow video stream.</p> |
| <div class="refsynopsisdiv"> |
| <h2>Synopsis</h2> |
| <div class="refsect2"> |
| <a name="id-1.2.7.7.5.1.1"></a><h3>Element Information</h3> |
| <div class="variablelist"><table border="0" class="variablelist"> |
| <colgroup> |
| <col align="left" valign="top"> |
| <col> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td><p><span class="term">plugin</span></p></td> |
| <td> |
| <a class="link" href="gst-plugins-good-plugins-plugin-alpha.html#plugin-alpha">alpha</a> |
| </td> |
| </tr> |
| <tr> |
| <td><p><span class="term">author</span></p></td> |
| <td>Wim Taymans <wim.taymans@gmail.com> |
| Edward Hervey <edward.hervey@collabora.co.uk> |
| Jan Schmidt <thaytan@noraisin.net></td> |
| </tr> |
| <tr> |
| <td><p><span class="term">class</span></p></td> |
| <td>Filter/Effect/Video</td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="id-1.2.7.7.5.1.2"></a><h3>Element Pads</h3> |
| <div class="variablelist"><table border="0" class="variablelist"> |
| <colgroup> |
| <col align="left" valign="top"> |
| <col> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td><p><span class="term">name</span></p></td> |
| <td>sink</td> |
| </tr> |
| <tr> |
| <td><p><span class="term">direction</span></p></td> |
| <td>sink</td> |
| </tr> |
| <tr> |
| <td><p><span class="term">presence</span></p></td> |
| <td>always</td> |
| </tr> |
| <tr> |
| <td><p><span class="term">details</span></p></td> |
| <td>video/x-raw, format=(string){ AYUV, ARGB, BGRA, ABGR, RGBA, Y444, xRGB, BGRx, xBGR, RGBx, RGB, BGR, Y42B, YUY2, YVYU, UYVY, I420, YV12, Y41B }, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]</td> |
| </tr> |
| </tbody> |
| </table></div> |
| <div class="variablelist"><table border="0" class="variablelist"> |
| <colgroup> |
| <col align="left" valign="top"> |
| <col> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td><p><span class="term">name</span></p></td> |
| <td>src</td> |
| </tr> |
| <tr> |
| <td><p><span class="term">direction</span></p></td> |
| <td>source</td> |
| </tr> |
| <tr> |
| <td><p><span class="term">presence</span></p></td> |
| <td>always</td> |
| </tr> |
| <tr> |
| <td><p><span class="term">details</span></p></td> |
| <td>video/x-raw, format=(string){ AYUV, ARGB, BGRA, ABGR, RGBA, Y444, xRGB, BGRx, xBGR, RGBx, RGB, BGR, Y42B, YUY2, YVYU, UYVY, I420, YV12, Y41B }, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]</td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| </div> |
| <p> |
| </p> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-good-plugins-alpha.functions_details"></a><h2>Functions</h2> |
| <p></p> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-good-plugins-alpha.other_details"></a><h2>Types and Values</h2> |
| <div class="refsect2"> |
| <a name="GstAlpha-struct"></a><h3>struct GstAlpha</h3> |
| <pre class="programlisting">struct GstAlpha;</pre> |
| <p> |
| </p> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstAlphaMethod"></a><h3>enum GstAlphaMethod</h3> |
| <div class="refsect3"> |
| <a name="id-1.2.7.9.3.3"></a><h4>Members</h4> |
| <div class="informaltable"><table width="100%" border="0"> |
| <colgroup> |
| <col width="300px" class="enum_members_name"> |
| <col class="enum_members_description"> |
| <col width="200px" class="enum_members_annotations"> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td class="enum_member_name"><p><a name="ALPHA-METHOD-SET:CAPS"></a>ALPHA_METHOD_SET</p></td> |
| <td class="enum_member_description"> |
| <p>Set/adjust alpha channel</p> |
| </td> |
| <td class="enum_member_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="enum_member_name"><p><a name="ALPHA-METHOD-GREEN:CAPS"></a>ALPHA_METHOD_GREEN</p></td> |
| <td class="enum_member_description"> |
| <p>Chroma Key green</p> |
| </td> |
| <td class="enum_member_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="enum_member_name"><p><a name="ALPHA-METHOD-BLUE:CAPS"></a>ALPHA_METHOD_BLUE</p></td> |
| <td class="enum_member_description"> |
| <p>Chroma Key blue</p> |
| </td> |
| <td class="enum_member_annotations"> </td> |
| </tr> |
| <tr> |
| <td class="enum_member_name"><p><a name="ALPHA-METHOD-CUSTOM:CAPS"></a>ALPHA_METHOD_CUSTOM</p></td> |
| <td class="enum_member_description"> |
| <p>Chroma Key on target_r/g/b</p> |
| </td> |
| <td class="enum_member_annotations"> </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| </div> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-good-plugins-alpha.property-details"></a><h2>Property Details</h2> |
| <div class="refsect2"> |
| <a name="GstAlpha--alpha"></a><h3>The <code class="literal">“alpha”</code> property</h3> |
| <pre class="programlisting"> “alpha” <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a></pre> |
| <p>The value for the alpha channel.</p> |
| <p>Flags: Read / Write</p> |
| <p>Allowed values: [0,1]</p> |
| <p>Default value: 1</p> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstAlpha--angle"></a><h3>The <code class="literal">“angle”</code> property</h3> |
| <pre class="programlisting"> “angle” <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a></pre> |
| <p>Size of the colorcube to change.</p> |
| <p>Flags: Read / Write</p> |
| <p>Allowed values: [0,90]</p> |
| <p>Default value: 20</p> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstAlpha--method"></a><h3>The <code class="literal">“method”</code> property</h3> |
| <pre class="programlisting"> “method” <a class="link" href="gst-plugins-good-plugins-alpha.html#GstAlphaMethod" title="enum GstAlphaMethod"><span class="type">GstAlphaMethod</span></a></pre> |
| <p>How the alpha channels should be created.</p> |
| <p>Flags: Read / Write</p> |
| <p>Default value: Set/adjust alpha channel</p> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstAlpha--noise-level"></a><h3>The <code class="literal">“noise-level”</code> property</h3> |
| <pre class="programlisting"> “noise-level” <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a></pre> |
| <p>Size of noise radius.</p> |
| <p>Flags: Read / Write</p> |
| <p>Allowed values: [0,64]</p> |
| <p>Default value: 2</p> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstAlpha--target-b"></a><h3>The <code class="literal">“target-b”</code> property</h3> |
| <pre class="programlisting"> “target-b” <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a></pre> |
| <p>The blue color value for custom RGB chroma keying.</p> |
| <p>Flags: Read / Write</p> |
| <p>Allowed values: <= 255</p> |
| <p>Default value: 0</p> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstAlpha--target-g"></a><h3>The <code class="literal">“target-g”</code> property</h3> |
| <pre class="programlisting"> “target-g” <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a></pre> |
| <p>The green color value for custom RGB chroma keying.</p> |
| <p>Flags: Read / Write</p> |
| <p>Allowed values: <= 255</p> |
| <p>Default value: 255</p> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstAlpha--target-r"></a><h3>The <code class="literal">“target-r”</code> property</h3> |
| <pre class="programlisting"> “target-r” <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a></pre> |
| <p>The red color value for custom RGB chroma keying.</p> |
| <p>Flags: Read / Write</p> |
| <p>Allowed values: <= 255</p> |
| <p>Default value: 0</p> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstAlpha--black-sensitivity"></a><h3>The <code class="literal">“black-sensitivity”</code> property</h3> |
| <pre class="programlisting"> “black-sensitivity” <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a></pre> |
| <p>Sensitivity to dark colors.</p> |
| <p>Flags: Read / Write</p> |
| <p>Allowed values: <= 128</p> |
| <p>Default value: 100</p> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstAlpha--white-sensitivity"></a><h3>The <code class="literal">“white-sensitivity”</code> property</h3> |
| <pre class="programlisting"> “white-sensitivity” <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a></pre> |
| <p>Sensitivity to bright colors.</p> |
| <p>Flags: Read / Write</p> |
| <p>Allowed values: <= 128</p> |
| <p>Default value: 100</p> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstAlpha--prefer-passthrough"></a><h3>The <code class="literal">“prefer-passthrough”</code> property</h3> |
| <pre class="programlisting"> “prefer-passthrough” <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a></pre> |
| <p>Don't do any processing for alpha=1.0 if possible.</p> |
| <p>Flags: Read / Write</p> |
| <p>Default value: FALSE</p> |
| </div> |
| </div> |
| </div> |
| <div class="footer"> |
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