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>13.2. The Mixer interface</A
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> The mixer interface provides a uniform way to control the volume on a
hardware (or software) mixer. The interface is primarily intended to
be implemented by elements for audio inputs and outputs that talk
directly to the hardware (e.g. OSS or ALSA plugins).
</P
><P
> Using this interface, it is possible to control a list of tracks
(such as Line-in, Microphone, etc.) from a mixer element. They can
be muted, their volume can be changed and, for input tracks, their
record flag can be set as well.
</P
><P
> Example plugins implementing this interface include the OSS elements
(osssrc, osssink, ossmixer) and the ALSA plugins (alsasrc, alsasink
and alsamixer).
</P
><P
> You should not use this interface for volume control in a playback
application. Either use a <CODE
CLASS="classname"
>volume</CODE
> element or use
<CODE
CLASS="classname"
>playbin</CODE
>'s <SPAN
CLASS="QUOTE"
>"volume"</SPAN
> property, or use
the <CODE
CLASS="classname"
>audiosink</CODE
>'s <SPAN
CLASS="QUOTE"
>"volume"</SPAN
> property (if it has one).
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> In order for the <A
HREF="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstmixer.html"
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><CODE
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>GstMixer</CODE
></A
>
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 <CODE
CLASS="classname"
>GST_STATE_READY</CODE
>
before you can use this interface. You will get confusing warnings
if the element is not in the right state when the interface is used.
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