Table of Contents
Advertisement
amixer, alsactl) for controlling and accessing the audio hardware from user applications or the console. Please
refer to the official ALSA webpage for a full documentation:
I
http://www.alsa-project.org
For a quick start here are three short examples of how to play/record an audio file and how to adjust the playback
volume.
Example 1: Play the audio file
root@vincell:~# aplay my_audio_file.wav
Example 2: Record the audio file
root@vincell:~# arecord -f cd -t wav > my_recorded_audio_file.wav
Example 3: Set the playback volume to half of the maximum:
root@vincell:~# amixer sset 'PCM' 50%
The
amixer
command can be used for several settings regarding the audio hardware. Called without parameters,
it gives a list of all available settings along with their possible values.
ALSA is also used in conjuction with playing multimedia files with GStreamer via the
ing the audio data from an audio stream.
Example 4: Play a sine signal with a frequency of 440 Hz (default settings) with GStreamer's
alsasink
plugins:
root@vincell:~# gst-launch audiotestsrc ! audioconvert ! alsasink
6.15 SRAM
The battery-backed SRAM is controlled by the MTD subsystem in the Linux kernel. Therefore, it can be handled
like a typical MTD device via the device handles
of the device. This number can be found by executing:
root@vincell:~# cat /proc/mtd | grep SRAM
Per default, the SRAM is located at /dev/mtd0.
A very common use of the SRAM in conjuction with the MTD subsystem is to create a file system on top of it, like
shown in the following example.
Example: Create a JFFS2 file system on
root@vincell:~# flash_eraseall /dev/mtd0
root@vincell:~# mkfs.jffs2 /dev/mtdblock0
root@vincell:~# mount /dev/mtdblock0 -t jffs2 /mnt
6.16 HDMI
The HDMI port can be used as primary or secondary display on VINCELL. Furthermore, an audio-enabled HDMI
device can be used as secondary sound card.
There are a few different use case for the HDMI display:
6.16.1 HDMI as primary display
To start the X-Server on the HDMI output only, no display configuration should be enabled in the system. This
way the hdmi screen is set as primary screen in the system.
my_audio_file.wav
from the console using aplay:
my_recorded_audio_file.wav
/dev/mtdX
/dev/mtd0
with the mtd-utils and mount it to
GUF-Yocto-34.0-r5756-0
from the console using arecord:
alsasink
and /dev/mtdblockX, where
VINCELL
User Manual
¡
¡
plugin after decod-
adiotestsrc
and
X
is the logical number
/mnt
33
Advertisement
Table of Contents
