Fixes #624164.
</para>
<sect1 id="section-mime">
- <title>MIME-types as a way to identity streams</title>
+ <title>MIME-types as a way to identify streams</title>
<para>
We have previously introduced the concept of capabilities as a way
for elements (or, rather, pads) to agree on a media type when
<para>
By doing all this, we will be able to make a simple autoplugger that
can automatically setup a pipeline for any media type. In the example
- below, we will do this for audio only. However, we can also do this
+ above, we did this for audio only. However, we can also do this
for video to create a player that plays both audio and video.
</para>
<!-- example-begin dynamic.c d --><!--
shortest-path-finding to make sure the most optimal pipeline is chosen,
and so on. Basically, the features that you implement in an autoplugger
depend on what you want to use it for. For full-blown implementations,
- see the <quote>playbin</quote> and <quote>decodebin</quote> elements.
+ see the <quote>playbin</quote> and <quote>decodebin</quote> elements in
+ <xref linkend="chapter-components"/>.
</para>
</sect1>
</chapter>
need to start at 0. The pipeline, which contains the global clock that
all elements in the pipeline will use, in addition has a <quote>base
time</quote>, which is the clock time at the the point where media time
- is starting from zero. This timestamp is subctracted from the clock
+ is starting from zero. This timestamp is subtracted from the clock
time, and that value is returned by <function>_get_time ()</function>.
</para>
<para>
in your application.
</para>
<note><para>
- New API is being developed at the moment to make data insertion and
- extraction less painful for applications. It can be found as GstAppSrc
- and GstAppSink in the gst-plugins-bad module. At the time of writing
- (October 2007), this API is not quite stable and ready yet, even though
- it may work fine for your purposes.
+ <ulink type="http"
+ url="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gstreamer-app.html">New
+ API</ulink> was developed to make data insertion and extraction easy
+ for applications. It can be found as GstAppSrc and GstAppSink in the
+ <ulink type="http"
+ url="http://gstreamer.freedesktop.org/modules/gst-plugins-base.html">
+ gst-plugins-base</ulink> module.
</para></note>
<para>
After all those disclaimers, let's start. There's three possible
pipeline, and how to set negotiation.
</para>
<para>
- Those who're paying close attention, will notice that the purpose
+ Those who're paying close attention will notice that the purpose
of identity is almost identical to that of probes. Indeed, this is
true. Probes allow for the same purpose, and a bunch more, and
with less overhead plus dynamic removing/adding of handlers, but
specifying a <classname>GstCaps</classname> as
<quote>caps</quote> property on this element. It will then
only allow types matching that specified capability set for
- negotiation.
+ negotiation. See also <xref linkend="section-caps-filter"/>.
</para>
</sect2>
<chapter id="chapter-dparams">
<title>Dynamic Controllable Parameters</title>
-
- <sect1 id="section-dparams-getting-started">
- <title>Getting Started</title>
- <para>
+ <para>
The controller subsystem offers a lightweight way to adjust gobject
properties over stream-time.
It works by using time-stamped value pairs that are queued for
element-properties.
- At run-time the elements continously pull values changes for the
+ At run-time the elements continously pull value changes for the
current stream-time.
- </para>
+ </para>
+
+ <sect1 id="section-dparams-getting-started">
+ <title>Getting Started</title>
<para>
This subsystem is contained within the
<filename>gstcontroller</filename> library.
interaction between applications and elements. This method suffices for
the simple'n'straight settings, but fails for anything more complicated
than a getter and setter. For the more complicated use cases, &GStreamer;
- uses interfaces based on the Glib <classname>GInterface</classname> type.
+ uses interfaces based on the GObject <ulink type="http"
+ url="http://library.gnome.org/devel/gobject/stable/gtype-non-instantiable-classed.html"><classname>GTypeInterface</classname></ulink>
+ type.
</para>
<para>
You should not use this interface for volume control in a playback
application. Either use a <classname>volume</classname> element or use
<classname>playbin</classname>'s <quote>volume</quote> property, or use
- the audiosink's <quote>volume</quote> property (if it has one).
+ the <classname>audiosink</classname>'s <quote>volume</quote> property (if it has one).
</para>
<note>
<para>
- In order for the <classname>GstMixer</classname> interface to be
+ In order for the <ulink type="http"
+ url="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstmixer.html"><classname>GstMixer</classname></ulink>
+ interface to be
usable, the element implementing it needs to be in the right state,
so that the underlying mixer device is open. This usually means the
element needs to be at least in <classname>GST_STATE_READY</classname>
</para>
<para>
Using this interface, it is possible to select one track from a list
- of tracks supported by that tuner-element. The tuner will than select
+ of tracks supported by that tuner-element. The tuner will then select
that track for media-processing internally. This can, for example, be
used to switch inputs on a TV-card (e.g. from Composite to S-video).
</para>
</para>
<note>
<para>
- In order for the <classname>GstTuner</classname> interface to be
+ In order for the <ulink type="http"
+ url="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gsttuner.html"><classname>GstTuner</classname></ulink>
+ interface to be
usable, the element implementing it needs to be in the right state,
so that the underlying device is open. This usually means the
element needs to be at least in <classname>GST_STATE_READY</classname>
<para>
The colorbalance interface is a way to control video-related properties
on an element, such as brightness, contrast and so on. It's sole
- reason for existance is that, as far as its authors know, there's no
+ reason for existence is that, as far as its authors know, there's no
way to dynamically register properties using
<classname>GObject</classname>.
</para>
<title>Metadata reading</title>
<para>
- Stream information can most easily be read by reading them from a
+ Stream information can most easily be read by reading it from a
<classname>GstPad</classname>. This has already been discussed before
in <xref linkend="section-caps-metadata"/>. Therefore, we will skip
it here. Note that this requires access to all pads of which you
<title>Tag writing</title>
<para>
- Tag writing is done using the <classname>GstTagSetter</classname>
+ Tag writing is done using the <ulink type="http"
+ url="&URLAPI;GstTagSetter.html"><classname>GstTagSetter</classname></ulink>
interface. All that's required is a tag-set-supporting element in
your pipeline. In order to see if any of the elements in your
pipeline supports tag writing, you can use the function
(if configured to do so) drop data.
</para>
<para>
- To use a queues (and therefore force the use of two distinct threads
+ To use a queue (and therefore force the use of two distinct threads
in the pipeline), one can simply create a <quote>queue</quote> element
and put this in as part of the pipeline. &GStreamer; will take care of
all threading details internally.
return 0;
}
]]><!-- example-end elementget.c --></programlisting>
- <para>
+ <para>
Most plugins provide additional properties to provide more information
- about their configuration or to configure the element.
+ about their configuration or to configure the element.
<command>gst-inspect</command> is a useful tool to query the properties
of a particular element, it will also use property introspection to give
a short explanation about the function of the property and about the
- parameter types and ranges it supports. See the appendix for details
- about <command>gst-inspect</command>.
- </para>
- <para>
+ parameter types and ranges it supports. See
+ <xref linkend="section-applications-inspect"/>
+ in the appendix for details about <command>gst-inspect</command>.
+ </para>
+ <para>
For more information about <classname>GObject</classname>
properties we recommend you read the <ulink
url="http://developer.gnome.org/doc/API/2.0/gobject/index.html"
The Glib Object system</ulink>.
</para>
<para>
- A <ulink type="http" url="&URLAPI;gstreamer/html/GstElementFactory.html">
+ A <ulink type="http" url="&URLAPI;GstElementFactory.html">
<classname>GstElement</classname></ulink> also provides various
<classname>GObject</classname> signals that can be used as a flexible
callback mechanism. Here, too, you can use <command>gst-inspect</command>
<sect2 id="section-caps-structure">
<title>Dissecting capabilities</title>
<para>
- A pads capabilities are described in a <classname>GstCaps</classname>
+ A pad's capabilities are described in a <classname>GstCaps</classname>
object. Internally, a <ulink type="http"
url="../../gstreamer/html/gstreamer-GstCaps.html"><classname>GstCaps</classname></ulink>
will contain one or more <ulink type="http"
accept vorbis-encoded audio data, with the mime-type
<quote>audio/x-vorbis</quote>. The source pad will be used
to send raw (decoded) audio samples to the next element, with
- a raw audio mime-type (in this case,
- <quote>audio/x-raw-int</quote>) The source pad will also
+ a raw audio mime-type (in this case,
+ <quote>audio/x-raw-float</quote>). The source pad will also
contain properties for the audio samplerate and the amount of
channels, plus some more that you don't need to worry about
for now.
</programlisting>
This will force the data flow between those two elements to
a certain video format, width, height and framerate (or the linking
- will fail if that cannot be achieved in the context of the elments
+ will fail if that cannot be achieved in the context of the elements
involved). Keep in mind that when you use <function>
gst_element_link_filtered ()</function> it will automatically create
a <classname>capsfilter</classname> element for you and insert it into
</programlisting>
<para>
See the API references for the full API of
- <classname>GstStructure</classname> and
- <classname>GstCaps</classname>.
+ <ulink type="http"
+ url="&URLAPI;GstStructure.html"><classname>GstStructure</classname></ulink>
+ and <ulink type="http"
+ url="&URLAPI;GstCaps.html"><classname>GstCaps</classname></ulink>.
</para>
</sect2>
</sect1>
through one or more <emphasis>sink pads</emphasis>. Source and sink
elements have only source and sink pads, respectively. Data usually
means buffers (described by the <ulink type="http"
- url="&URLAPI;/gstreamer-GstBuffer.html"><classname>GstBuffer
+ url="&URLAPI;gstreamer-GstBuffer.html"><classname>GstBuffer
</classname></ulink> object) and events (described by the <ulink
- type="http" url="&URLAPI;/gstreamer-GstEvent.html"><classname>
+ type="http" url="&URLAPI;gstreamer-GstEvent.html"><classname>
GstEvent</classname></ulink> object).
</para>
</sect1>
<para>
Some parts of this part will serve mostly as an explanation of
how &GStreamer; works internally; they are not actually needed for
- actual application development. This includes chapter such as the
+ actual application development. This includes chapters such as the
ones covering scheduling, autoplugging and synchronization. Other
chapters, however, discuss more advanced ways of
pipeline-application interaction, and can turn out to be very useful
for certain applications. This includes the chapters on metadata,
querying and events, interfaces, dynamic parameters and pipeline
data manipulation.
- </para>
+ </para>
</partintro>
&QUERYEVENTS;
projects / platform / upstream / gstreamer.git / commitdiff