Subject: [linux-audio-dev] laaga, round 2
From: Paul Davis (pbd_AT_Op.Net)
Date: Tue May 08 2001 - 16:19:30 EEST
i grow tired of debating with abramo (as i'm sure he does with me). so
i am going to try to summarize what i think are the basics, as best as
i can from my highly non-objective point of view.
AES worldview
The server presents an abstraction of an audio interface to
dynamically loaded (in-process) clients. That abstraction consists of
some number of "channels" for capture, and some number for
playback. Each channel can be used as a data source or data
destination by using functions provided by the server. All data read
from or written to a channel is in mono IEEE 32 bit float format. The
server "executes" plugins on a periodic basis by calling a function
that they provide, passing it a single argument, the number of frames
of audio that they should process/generate. Some of the channels
provided by the server function as shared data areas allowing plugins
to read and write each others audio data if they so choose.
alsa-lib worldview
Everything is an ALSA PCM stream. Components that have streams
available for capture are called "producers"; those with streams
available for playback are called consumers. When connecting two
components together, it is necessary to ensure that their parameters
match or that some converter component is inserted between them. Each
component has its own set of pre-conditions to be satisfied before it
is possible to read/write audio data from/to it. a component may
represent a real hardware audio interface or a pure software model, or
some combination of both. an organizing object called an engine is
responsible for ensuring that calls to check the pre-conditions for
each component are made. components access each other directly, using
calls from the ALSA PCM API to transfer data.
[ not clear: what drives the engine?
can a component be a producer and a consumer? ]
I've tried to be as fair as I can in presenting these summaries. What
do you think?
--p
This archive was generated by hypermail 2b28 : Tue May 08 2001 - 16:42:47 EEST