genode/repos/dde_bsd

This repository contains device drivers ported from OpenBSD.

Audio
#####

The audio driver is ported from OpenBSD 6.6 and includes support for
Intel HD Audio devices. The HDA driver works on real hardware and
supposedly in VirtualBox.


Usage and configuration
=======================

You have to prepare the contrib sources for this repository by
executing _./tool/ports/prepare_port dde_bsd_. Also you need to make
sure to add the 'dde_bsd' repository to the REPOSITORIES variable
in your 'etc/build.conf'.

Reporting of the mixer state is enabled by adding the 'report_mixer'
attribute to the drivers configuration and setting its value to 'yes'.

The following snippets illustrates the format of the report:

!<mixer_state>
!  <mixer field="inputs.beep" value="108"/>
!  <mixer field="outputs.hp_sense" value="plugged"/>
!  <mixer field="outputs.master" value="128,128"/>
!  <mixer field="outputs.mic_sense" value="unplugged"/>
!  <mixer field="outputs.spkr_muters" value="hp,mic"/>
!</mixer_state>

The mixer state may expose other mixer fields as well, depending on the
used sound card. The naming scheme of the attributes intentionally
matches the naming scheme of OpenBSD's mixerctl(1) program.

Each 'mixer' node can be used to configure the audio driver by using it
in its configuration, e.g.:

!<config report_mixer="yes">
!  <mixer field="outputs.master" value="255,255"/>
!</config>

This configuration will set the output volume to the highest possible
value. Although it is now also possible to update the configuration
at run-time it should not be done while the driver is currently playing
or recording because it may provoke the generation of artefacts.

The following configures the driver of playback and recording:

! <start name="audio_out_drv">
!   <resource name="RAM" quantum="8M"/>
!   <provides>
!     <service name="Audio_out"/>
!     <service name="Audio_in"/>
!   </provides>
!   <config>
!     <mixer field="outputs.master" value="255"/>
!     <mixer field="record.enable" value="on"/>
!     <mixer field="record.adc-0:1_source" value="mic3"/>
!     <mixer field="record.volume" value="128"/>
!   </config>
! </start>

It is vital to enable recording by setting 'record.enable' to 'on' as
otherwise only silence will be delievered to the Audio_in session.
In addition to selecting the recording source, the playback as well as the
recording volume are set. When a single value is given the same value is
used for all channels. Depending on the used HDA device or rather the used
codec the available fields might differ and a different recording source
must be set for 'adc-0:1'. For example on a Thinkpad X220 the source must
be set to 'mic3' to select the internal microphone.

Information about the available mixers and settings in general
may be obtained by setting the 'verbose' to 'yes' in the config
node.


Examples
========

Playback can be tested by executing the run script
'repos/dde_bsd/run/audio_out.run'.
It will play a raw sample file in a loop. The file format is header less
two channel float 32 at 44100 Hz. You may use the 'sox' utility to create
such an audio file:

! sox -c 2 -r 44100 foo.wav foo.f32

Recording, on the other hand, can be tested by executing the run script
'repos/dde_bsd/run/audio_in.run'.

It will use a simply audio monitor test component that records samples
and plays them back immediately.