Re: [alsa-devel] Re: [linux-audio-dev] Re: Toward a modularizationof audio component

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Subject: Re: [alsa-devel] Re: [linux-audio-dev] Re: Toward a modularizationof audio component
From: Abramo Bagnara (abramo_AT_alsa-project.org)
Date: Fri May 04 2001 - 23:07:21 EEST


Kai Vehmanen wrote:
>
> On Fri, 4 May 2001, Abramo Bagnara wrote:
>
> - we don't have a standard API for accessing sound hardware
> (standard = used by most audio apps); on the contrary most
> popular audio apps have support for multiple different APIs

And here ALSA PCM API may already play a very good role. One API,
different backends. The backend is writed once.

>
> So there's plenty of work even in the ridicilously-high-latency,
> nano-bandwidth audio world. :) And one point to remember is that _we
> always need an API to access the audio hardware_. Without ALSA and OSS
> LAAGA wouldn't be of much use.
>
> As for LAAGA, I like to view it as a "monolithic audio app" design, where
> the main app is build from independent audio consumer and producer
> components. The only catch is that our main app (the LAAGA server) must
> follow the single-thread audio engine design. Now it might be that this is
> not the only way to write efficient audio applications, but still, this
> design seems to work in practise:

Please remember that ALSA PCM API can work in both way:
- single-thread audio engine design (using ALSA PCM API as a
communication interface between in core components and an engine that
gives the impulses)
- multi-threaded/multi-process components (linked together using pcm_shm
and pcm_lbserver pairs)

>
> Would it be possible to to use multiple individual apps (= multiple GUIs),
> together and still take advantage of the single-audio-server approach? Now
> that's what LAAGA is all about. It clearly is not meant to be a new
> general API for writing audio apps. At least now, the actual APIs are not
> the main interest. It's the basic concepts that should be discussed...
>
> Whether there will ever be real LAAGA client apps is still uncertain to
> me. It might turn out that it's easier to write custom servers
> (Ardour/Aes+Quasimodo, aRts/Noatun+Khdrec, gstreamer/sinks,
> ecasound/audioplugins), which again use the ALSA/OSS APIs...

I have to say that my aim is more ambitious: reusable audio components.

- audio file format encoder/decoders
- audio file dropout free reader/writer
- FX
- visual scopes
- etc.

I think that now we have enough experience (distributed on several
brains, as we like it ;-) to design an architecture that permit all this
and I'm sure that this would bring great benefits for consumer audio and
*huge* benefits for professional audio.

I think that you can help yourself to understand the impact of such an
architecture making a parallel with the impact of pipes on Unix world.

-- 
Abramo Bagnara                       mailto:abramo_AT_alsa-project.org

Opera Unica Phone: +39.546.656023 Via Emilia Interna, 140 48014 Castel Bolognese (RA) - Italy

ALSA project http://www.alsa-project.org It sounds good!


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