[alsa-devel] Direct use of the DMA buffer?

Pavel Hofman pavel.hofman at ivitera.com
Mon Feb 20 10:25:57 CET 2012

Dne 20.2.2012 10:21, Jaroslav Kysela napsal(a):
>> Clemens, thanks a lot for the information. How does it work when the
>> alsa-lib chain contains plugins, such as plug, rate, etc.? I would
>> assume the application circumvents these.
> Nope. The mmap commit mechanism was introduced to keep the plugin
> interface functional. The direct mmap access to the DMA buffer is only
> applied for the direct hw: devices. If a plugin is used inside alsa-lib,
> the application talks to the plugin chain (it means that an intermediate
> buffer for samples can be allocated to let things working).

Jaroslav, thanks a lot for the clarification.


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