[alsa-devel] Asynchronous notification in ALSA - I/O Plugin - Pulseaudio

Takashi Iwai tiwai at suse.de
Tue May 20 13:07:49 CEST 2008

At Mon, 19 May 2008 12:38:39 +0300 (EEST),
Juha Erkkilä wrote:
> I'm trying to get Abode Flash Player working properly on a thin client,
> with sound, using Pulseaudio as a sound server.  I'm using ALSA
> version 1.10.15 and Pulseaudio version 0.9.10 on Ubuntu Hardy, with
> Pulseaudio server running as a system-wide daemon on the thin client.
> I already outlined the issues on Pulseaudio mailing list on this post:
> https://tango.0pointer.de/pipermail/pulseaudio-discuss/2008-May/001793.html,
> see also Lennart Poettering's answer:
> https://tango.0pointer.de/pipermail/pulseaudio-discuss/2008-May/001796.html.
> I feel the proper solution would involve writing support for
> asynchronous notification into ALSA library and I/O-plugin layer.
> Currently, Pulse I/O-plugin does not work in the Flash case, because
> Flash requires the asynchronous API.  On the other hand, Pulse requires
> the I/O-plugin layer to work.  See the posts by Alexander Indenbaum,
> http://mailman.alsa-project.org/pipermail/alsa-devel/2008-April/007033.html,
> and Takashi Iwai,
> http://mailman.alsa-project.org/pipermail/alsa-devel/2008-April/007335.html,
> on this subject.
> I tried to tackle this issue, and did get the signal handling code to
> call the Flash audio callback, but I'm new to both ALSA and Pulseaudio,
> and it appears there are some issues with it I don't fully understand.
> Thus I'm asking: are there any other people who have been looking into
> this, or anyone who can tell whether this is a sane thing to do or not,
> will it require some nasty hack, or can help with some pointers to
> relevant information?
> I'm hoping that implementing the asynchronous API on I/O-plugin layer
> would not only fix Flash audio, but might help some other programs too
> to achieve network transparent audio.

Yeah, the async support is a big missing piece in ioplug.  I didn't
think it be so important until someone told me that flash player uses
it.  Sigh.

I have experimental patches to add async support to ioplug.  With a
quick test using jack plugin, it seems working somehow.  Will post
them alsa-devel now.



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