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    SubjectRe: [OT] ALSA userspace API complexity
    On Sun, 8 Jan 2006, Olivier Galibert wrote:

    > On Sun, Jan 08, 2006 at 03:26:18AM +0100, Martin Drab wrote:
    > > On Sun, 8 Jan 2006, Olivier Galibert wrote:
    > >
    > > > > And if the application doesn't support, who and where converts it?
    > > > > With OSS API, it's a job of the kernel.
    > > >
    > > > Once again no. Nothing prevents the kernel to forward the data to
    > > > userland daemons depending on a userspace-uploaded configuration.
    > >
    > > I think that the point was, that switching from userspace to kernelspace
    > > then to userspace again and back to kernelspace in order to do something,
    > > that could have been done directly in the userspace, and though could save
    > > those two unnecessary switches, is an unnecessary overhead, which may not
    > > necessarily be that insignificant if it's done so often (which for
    > > streaming audio is the case).
    > You all seem to forget that dmix is in userspace in a different task
    > too.

    Because it is really not. The mixing is done directly to the mmaped DMA

    > > Why doing things complicated when there is no evident gain from it,
    > > or is there?
    > No evident gain? Wow. What about:
    > - stopping crippling the OSS api

    We're not doing that. We're just showing that OSS API and useability has
    it's own problems, too.

    > - having a real kernel api for which you can make different libraries
    > depending on the need of the users
    > - stop making a fundamentally unsecure shared library mandatory

    ALSA kernel API is real and binary compatible. If someone require to
    write an own library, we will document this API, of course, too.

    > - opening the possibility of writing plugins to people without a PhD
    > in lattice QCD.

    Already done. We have official plugin SDK in alsa-lib to create user space
    drivers. If you have some questions or bug-reports (missing docs etc),
    please, fill a bug report.

    Also, you can use very simple LADSPA plugin style, because alsa-lib can
    use LADSPA plugins directly, too.


    Jaroslav Kysela <>
    Linux Kernel Sound Maintainer
    ALSA Project, SUSE Labs
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