State of Linux Audio in 2009 - Linux Plumbers Conference 2009State of Linux Audio in 2009 Linux...

State of Linux Audio in 2009

Linux Plumbers Conference 2009

Lennart Poetteringlennart@poettering.net

September 2009

Lennart Poettering State of Linux Audio in 2009

Who Am I?

Software Engineer at Red Hat, Inc.

Developer of PulseAudio, Avahi and a few other Free Softwareprojects

http://0pointer.de/lennart/

lennart@poettering.net

IRC: mezcalero

Perspective

So, what happened since last LPC?

RIP: EsounD is officially gone.

RIP: OSS is officially gone.

(at least on Fedora)

RIP: OSS is officially gone. (at least on Fedora)

Audio API Guide

http://0pointer.de/blog/projects/guide-to-sound-apis

We now use realtime scheduling on the desktop by default.

Wealso make use of high-resolution timers on the desktop by default.

We now use realtime scheduling on the desktop by default. Wealso make use of high-resolution timers on the desktop by default.

2s Buffers

We moved a couple of things into the audio server:

Timer-based audio scheduling; mixing; flat volume/volume rangeand granularity extension; integration of volume sliders; mixer

abstraction; monitoring

Mixer abstraction? Due to user-friendliness, i18n, meta data(icons, ...)

We moved a couple of things into the audio server:

Timer-based audio scheduling; mixing; flat volume/volume rangeand granularity extension; integration of volume sliders; mixer

abstraction; monitoring

Mixer abstraction? Due to user-friendliness, i18n, meta data(icons, ...)

udev integration: meta data, by-path/by-id/...

Bluetooth Audio, A2DP, HSP/HFP, Lip-Sync!

ALSA mixer initialization database

Other: Drivers for X-Fi, LSB work

What are the challenges to tackle until next LPC?

Drivers: Power saving distortions

Drivers: Incorrect dB information

Drivers: Wrong mixer element names

Drivers: Missing/broken device strings

Drivers: Non-standard negotiation logic

Drivers: Missing from mixer initialization database

Drivers: Broken timing

snd pcm delay(), snd pcm avail()

ALSA API addition:

Multi-PCM clock synchronization

ALSA API addition:

Routing/PCM-to-mixer-element mapping/auto discovery

Current system depends on assumptions made based on consumerhardware, which doesn’t scale to professional and embedded

hardware

ALSA API addition:

Jack sensing, labelling, colouring, matching

Mixed HW/SW switching

ALSA API addition:

Timing/data transfer granularity

ALSA API addition:

Channel mapping, current system does not scale

ALSA API addition:

Latency control, Hifi DSP

HDMI negotiation

Atomic status updates

Atomic mixer updates?

PCM synchronized mixer updates?

General:

Codec pass-through for A2DP, SPDIF, HDMI, embedded

General:

Simpler, high-level PCM API

General:

20s Buffering

General:

Revoking, synchronous session switching

That’s all, folks.

Any questions?

That’s all, folks.

Any questions?

State of Linux Audio in 2009 - Linux Plumbers Conference 2009State of Linux Audio in 2009 Linux...

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