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Small manual changes.

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Original commit message from CVS:
Small manual changes.
Added a section about autoplugging.
This commit is contained in:
Wim Taymans 2001-05-02 23:46:27 +00:00
parent a7566d4158
commit 08bb61fd3c
8 changed files with 126 additions and 67 deletions
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1
docs/manual/Makefile.am
View file

@ -3,6 +3,7 @@ htmlname = index.html
sgml_files = gstreamer-manual.sgml \
advanced.sgml \
autoplugging.sgml \
bins.sgml \
buffers.sgml \
components.sgml \

99
docs/manual/autoplugging.sgml Normal file
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@ -0,0 +1,99 @@
<chapter id="cha-autoplug">
<title>Autoplugging</title>
<para>
<application>GStreamer</application> provides an API to automatically
construct complex pipelinebased on source and destination capabilities.
This feature is very usefull if you want to convert type X to type Y but
don't care about the plugins needed to accomplish this task. The
autoplugger will consult the plugin repository, select and connect the
elements needed for the conversion.
</para>
<para>
The autoplugger API is implemented in an abstract class. Autoplugger implementations
reside in plugins and are therefore optional and can be optimized for a specific
task. Two types of autopluggers exist: renderer ones and non
renderer ones. the renderer autopluggers will not have any src pads while the
non renderer ones do. The renderer autopluggers are mainly used for media
playback while the non renderer ones are used for arbitrary format conversion.
</para>
<sect1>
<title>Using autoplugging</title>
<para>
You first need to create a suitable autoplugger with gst_autoplugfactory_make().
The name of the autoplugger must be one of the registered autopluggers..
</para>
<para>
A list of all available autopluggers can be obtained with gst_autoplugfactory_get_list().
</para>
<para>
If the autoplugger supports the RENDERER API, use gst_autoplug_to_renderers() call to
create a bin that connectes the src caps to the specified render elements. You can
then add the bin to a pipeline and run it.
<programlisting>
GstAutoplug *autoplug;
GstElement *element;
GstElement *sink;
/* create a static autoplugger */
autoplug = gst_autoplugfactory_make ("staticrender");
/* create an osssink */
sink = gst_elementfactory_make ("osssink", "our_sink");
/* create an element that can play audio/mp3 through osssink */
element = gst_autoplug_to_renderers (autoplug,
gst_caps_new (
"sink_audio_caps",
"audio/mp3",
NULL
),
sink,
NULL);
/* add the element to a bin and connect the sink pad */
...
</programlisting>
</para>
<para>
If the autoplugger supports the CAPS API, use the gst_autoplug_to_caps() function to
connect the src caps to the destination caps. The created bin will have src and sink
pads compatible with the provided caps.
<programlisting>
GstAutoplug *autoplug;
GstElement *element;
/* create a static autoplugger */
autoplug = gst_autoplugfactory_make ("static");
/* create an element that converts audio/mp3 to audio/raw */
element = gst_autoplug_to_caps (autoplug,
gst_caps_new (
"sink_audio_caps",
"audio/mp3",
NULL
),
gst_caps_new (
"src_audio_caps",
"audio/raw",
NULL
),
NULL);
/* add the element to a bin and connect the src/sink pads */
...
</programlisting>
</para>
</sect1>
<sect1>
<title>A complete autoplugging example</title>
<para>
We will create and explain how a complete media player can be built with the
autoplugger.
</para>
</sect1>
</chapter>

2
docs/manual/bins.sgml
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@ -34,7 +34,7 @@
<listitem>
<para>
A thread (<classname>GstThread</classname>). All the elements in the thread bin will
run in a separate thread. You will haver to use this bin if you carfully have to
run in a separate thread. You will have to use this bin if you carfully have to
synchronize audio and video for example. You will learn more about threads in.. <!-- FIXME -->
</para>
</listitem>

18
docs/manual/buffers.sgml
View file

@ -27,17 +27,6 @@
will be used to destroy the buffer when no element is having a reference to it.
</para>
</listitem>
<listitem>
<para>
A list of metadata that describes the context of the buffers memory. In the case
of audio data, for example, it would provide the samplerate, depth and channel
count.
</para>
<para>
GStreamer provides a registry where different metadata types can be registered
so that everybody is talking about the same data.
</para>
</listitem>
</itemizedlist>
</para>
@ -67,11 +56,4 @@
situation.
</para>
<para>
Before an element can operate on the buffers memory, is has to check the metadata
attached to it (if any). An MPEG audio decoder has to ignore a buffer with video
metadata (in which case the pipeline is probably constructed by connecting the
wrong elements, anyway).
</para>
</chapter>

4
docs/manual/elements.sgml
View file

@ -1,8 +1,8 @@
<chapter id="cha-elements">
<title>GstElement</title>
<para>
The most important object in GStreamer for the application programmer is
the GstElement object.
The most important object in <application>GStreamer</application> for the
application programmer is the <classname>GstElement</classname> object.
</para>
<sect1 id="sec-elements-design">

3
docs/manual/gstreamer-manual.sgml
View file

@ -12,6 +12,7 @@
<!ENTITY HELLOWORLD SYSTEM "helloworld.sgml">
<!ENTITY FACTORIES SYSTEM "factories.sgml">
<!ENTITY AUTOPLUGGING SYSTEM "autoplugging.sgml">
<!ENTITY HELLOWORLD2 SYSTEM "helloworld2.sgml">
<!ENTITY THREADS SYSTEM "threads.sgml">
@ -130,6 +131,8 @@
&FACTORIES;
&AUTOPLUGGING;
&HELLOWORLD2;
</part>

51
docs/manual/helloworld.sgml
View file

@ -19,17 +19,6 @@
#include &lt;gst/gst.h&gt;
gboolean playing;
/* eos will be called when the src element has an end of stream */
void
eos (GstSrc *src)
{
g_print ("have eos, quitting\n");
playing = FALSE;
}
int
main (int argc, char *argv[])
{
@ -48,8 +37,6 @@ main (int argc, char *argv[])
/* create a disk reader */
disksrc = gst_elementfactory_make ("disksrc", "disk_source");
gtk_object_set (GTK_OBJECT (disksrc),"location", argv[1], NULL);
gtk_signal_connect (GTK_OBJECT (disksrc), "eos",
GTK_SIGNAL_FUNC (eos), NULL);
/* now it's time to get the parser */
parse = gst_elementfactory_make ("mp3parse", "parse");
@ -75,11 +62,7 @@ main (int argc, char *argv[])
/* start playing */
gst_element_set_state (bin, GST_STATE_PLAYING);
playing = TRUE;
while (playing) {
gst_bin_iterate (GST_BIN (bin));
}
while (gst_bin_iterate (GST_BIN (bin)));
/* stop the bin */
gst_element_set_state (bin, GST_STATE_NULL);
@ -150,14 +133,7 @@ main (int argc, char *argv[])
/* create a disk reader */
disksrc = gst_elementfactory_make ("disksrc", "disk_source");
gtk_object_set (GTK_OBJECT (disksrc),"location", argv[1], NULL);
gtk_signal_connect (GTK_OBJECT (disksrc), "eos",
GTK_SIGNAL_FUNC (eos), NULL);
</programlisting>
<para>
We also connected the eos signal to our function. When the
disk source has reached an end-of-stream, this function will be called.
We will use it to set a gboolean value to FALSE;
</para>
<note>
<para>
You can check if the disksrc != NULL to verify the creation of the
@ -165,20 +141,6 @@ main (int argc, char *argv[])
</para>
</note>
<programlisting>
gboolean playing;
...
/* eos will be called when the src element has an end of stream */
void
eos (GstSrc *src)
{
g_print ("have eos, quitting\n");
playing = FALSE;
}
</programlisting>
<para>
We now create the MP3 decoder element. <application>GStreamer</application> requires you
to put a parser in front of the decoder. This parser will
@ -249,7 +211,6 @@ eos (GstSrc *src)
/* start playing */
gst_element_set_state (bin, GST_STATE_PLAYING);
playing = TRUE;
</programlisting>
<note>
<para>
@ -263,14 +224,12 @@ eos (GstSrc *src)
call gst_bin_iterate() to execute one iteration of the bin.
</para>
<programlisting>
while (playing) {
gst_bin_iterate (GST_BIN (bin));
}
while (gst_bin_iterate (GST_BIN (bin)));
</programlisting>
<para>
Remember that the variable playing will become false if the disk source
has reached an end-of-file. When that happens, the follwing code takes
care of the cleanup:
The gst_bin_iterate() function will return TRUE as long as something interesting
happended inside the bin. When the end-of-file has been reached the _iterate
function will return FALSE and we can end the loop.
</para>
<programlisting>
/* stop the bin */

15
docs/manual/pads.sgml
View file

@ -276,6 +276,21 @@ Pads:
A list value: the property can take any value from a list.
</para>
</listitem>
<listitem>
<para>
A float value: the property has this exact floating point value.
</para>
</listitem>
<listitem>
<para>
A float range value: denotes a range of possible floating point values.
</para>
</listitem>
<listitem>
<para>
A string value.
</para>
</listitem>
</itemizedlist>
</sect2>