Re: [Rhythmbox-devel] Crossfading Support?

["Ernst Persson" <ernstp gmail com>]

Gstreamer has an element called "adder" that mixes an arbitrary number of streams together.
Here's the "documentation" :-) 
http://webcvs.freedesktop.org/gstreamer/gst-plugins-base/gst/adder/gstadder.c?revision=1.88&view=markup

That should be perfect, right?
 * <refsect2>
 * The Adder allows to mix several streams into one by adding the data.
 * Mixed data is clamped to the min/max values of the data format.
 * <title>Example launch line</title>
 * <para>
 * <programlisting>
 * gst-launch audiotestsrc freq=100 ! adder name=mix ! audioconvert ! alsasink audiotestsrc freq=500 ! mix.
 * </programlisting>
 * This pipeline produces two sine waves mixed together.
 * </para>
 * <para>
 * The Adder currently mixes all data received on the sinkpads as soon as possible
 * without trying to synchronize the streams.
 * </para>
 * </refsect2>
BR
/Ernst

On 11/15/06, Frank Altpeter <frank altpeter de > wrote:

By the way - i found this discussion about crossfading support in
rhythmbox - is there any news about that?


On Sat, 8 Nov 2003, Mike Hearn wrote:
> I looked into this a bit a few weeks ago. Basically:
>
> * We'd need to write a new crossfader element. It has two input pads, one
> output pad. Rhythmbox sets up and maintains TWO pipelines at once, feeding
> into the crossfader. IE the crossfader element would be compulsory, not
> optional without major hackage inside RB - that doesn't mean you have to
> have the effect enabled though.
>
> * The crossfader element would pull N seconds of audio into itself and
> then have two internal volume elements and an adder element. You could use
> the sine function to splice between them, which is easy enough, the hard
> bit is pulling the right amount of audio I think. GStreamer 0.7 supports
> querying a buffer for its duration.
>
> * We could also use this element to implement gapless playback as it'd
> buffer a small amount on the alternate pipeline before doing the switch.
> Once the switch between the pads has occurred, the element could emit a
> signal that RB would attach to and rejig the pipelines.
>
> * Maybe a weekend or twos work. Unfortunately I am already committed to
> too much stuff elsewhere in linuxland, so I can't do this....
>
> thanks -mike


Le deagh dhùraghd,

        Frank Altpeter

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