How to play audio: Difference between revisions

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Latest revision as of 13:46, 8 June 2022

Applicable for

STM32MP13x lines, STM32MP15x lines

1. Article purpose[edit source]

This article explains how to play audio through the ALSA audio framework in Linux^® OS context. The examples below, show how to play audio on the different audio hardware interfaces of the STM32MPU boards.

2. Audio playback overview[edit source]

The ALSA framework exposes audio devices associated to the board audio hardware interfaces.

The application audio streams are routed by default through the PulseAudio sound server. PulseAudio exposes audio profiles which are mapped on the ALSA sound card audio devices. The PulseAudio server provides a command line interface which allows to list audio profiles and to select a profile, to play on a specific audio interface.

Template:Warning

The audio playback examples in following sections are given for ALSA utilities. However, the audio playbacks can be launched by other applications, such as gstreamer multimedia framework.

3. Examples[edit source]

3.1. Audio playback on headset output[edit source]

3.1.1. Playback on ALSA device[edit source]

Run audio playback on 'playback_codec' ALSA device: Template:Info

Template:Board$ aplay -D playback_codec /usr/share/sounds/alsa/Front_Left.wav

3.1.2. Playback via PulseAudio[edit source]

Configure Pulseaudio

Change the Pulseaudio active profile of the sound card, to 'analog-stereo' profile: Template:Info Template:Info

Template:Board$ pactl set-card-profile 0 output:analog-stereo

Run audio playback:

Template:Board$ aplay /usr/share/sounds/alsa/Front_Left.wav

3.2. Audio playback on HDMI output[edit source]

Template:Warning

3.2.1. Playback on ALSA device[edit source]

Run audio playback on 'playback_hdmi' ALSA device: Template:Info

Template:Board$ aplay -D playback_hdmi /usr/share/sounds/alsa/Front_Left.wav

3.2.2. Playback via PulseAudio[edit source]

Configure Pulseaudio

Change the Pulseaudio active profile of the sound card, to 'hdmi-stereo' profile: Template:Info

Template:Board$ pactl set-card-profile 0 output:hdmi-stereo

Run audio playback:

Template:Board$ aplay /usr/share/sounds/alsa/Front_Left.wav

3.3. Audio playback on S/PDIF output[edit source]

Template:Warning Template:Info

3.3.1. Set IEC958 status bits[edit source]

Example: set IEC958 mode bit.

Template:Board$ iecset -c STM32MP1EV -n device=0 pro on

3.3.2. Playback on ALSA device[edit source]

Run audio playback on 'playback_spdif' ALSA device: Template:Info

Template:Board$ speaker-test -D playback_spdif -c 2 -F S32_LE -f 440 -t sine -l 1

3.3.3. Playback via PulseAudio[edit source]

Configure Pulseaudio

Change the sound card active profile, to S/PDIF 'iec958-stereo' profile. Template:Info

Template:Board$ pactl set-card-profile 0 output:iec958-stereo

Run audio playback:

Template:Board$ speaker-test -c 2 -F S32_LE -f 440 -t sine -l 1

@@ Line 1: / Line 1: @@
-<noinclude>
+<noinclude>{{ApplicableFor
-{{ArticleMainWriter | OlivierM}}
+|MPUs list=STM32MP13x, STM32MP15x
-{{ArticleApprovedVersion | OlivierM | ArnaudP(Passed 17Janv'19) | No previous approved version | AlainF - 21Jan'19 - 10391 | 21Jan'19}}
+|MPUs checklist=STM32MP13x,STM32MP15x
-[[Category:How to run use cases]]
+}}</noinclude>
-[[Category:ALSA]]
-</noinclude>
 == Article purpose ==
 This article explains how to play audio through the [[ALSA overview|ALSA]] audio framework in '''Linux<sup>&reg;</sup> OS''' context.
@@ Line 13: / Line 10: @@
 The [[ALSA overview|ALSA]] framework exposes audio devices associated to the board audio hardware interfaces.
-The application audio streams are routed  by default through the [[PulseAudio]] sound server. PulseAudio exposes audio profiles which are mapped on the ALSA sound card audio devices. The PulseAudio server provides a command line interface which allows to list audio profiles and to select a profile, to play on a specific audio interface.
+The application audio streams are routed  by default through the PulseAudio sound server. PulseAudio exposes audio profiles which are mapped on the ALSA sound card audio devices. The PulseAudio server provides a command line interface which allows to list audio profiles and to select a profile, to play on a specific audio interface.
+{{Warning|The applications interacting with Weston framework have to be launched as "Weston" user instead of "root" user. The Pulseaudio commands can, for instance, be launched as follows:
+ su -l "weston" -c "pactl info"
+}}
 The audio playback examples in following sections are given for [[ALSA_overview#How_to_use|ALSA utilities]]. However, the audio playbacks can be launched by other applications, such as [[Gst-play|gstreamer]] multimedia framework.
@@ Line 21: / Line 22: @@
 === Audio playback on headset output ===
-* '''Playback on ALSA device'''
+==== Playback on ALSA device ====
 Run audio playback on 'playback_codec' ALSA device:
 {{Info|'playback_codec' is an alias defined in /etc/asound.conf, for headset output device.}}
   {{Board$}} aplay -D playback_codec /usr/share/sounds/alsa/Front_Left.wav
-* '''Playback via PulseAudio'''
+==== Playback via PulseAudio ====
+* '''Configure Pulseaudio'''
 Change the Pulseaudio active profile of the sound card, to 'analog-stereo' profile:
 {{Info|The Pulseaudio analog-stereo profile is the default profile. So next command is not required after boot.}}
 {{Info|Example below is given for {{highlight|sound card index 0}}. Check sound cards index with "''pactl list cards short''" command.}}
-  {{Board$}} pacmd set-card-profile 0 output:analog-stereo+input:analog-stereo
+  {{Board$}} pactl set-card-profile 0 output:analog-stereo
-Run audio playback:
+* '''Run audio playback:'''
   {{Board$}} aplay /usr/share/sounds/alsa/Front_Left.wav
@@ Line 38: / Line 41: @@
 {{Warning|The support of HDMI output is board dependent. Please, check available outputs with "''aplay -l''" command.}}
-* '''Playback on ALSA device'''
+==== Playback on ALSA device ====
 Run audio playback on 'playback_hdmi' ALSA device:
 {{Info|'playback_hdmi' is an alias defined in /etc/asound.conf, for hdmi output device.}}
   {{Board$}} aplay -D playback_hdmi /usr/share/sounds/alsa/Front_Left.wav
-* '''Playback via PulseAudio'''
+==== Playback via PulseAudio ====
+* '''Configure Pulseaudio'''
 Change the Pulseaudio active profile of the sound card, to 'hdmi-stereo' profile:
 {{Info|Example below is given for {{highlight|sound card index 0}}. Check sound card index with "''pactl list cards short''" command.}}
-  {{Board$}} pacmd set-card-profile 0 output:hdmi-stereo
+  {{Board$}} pactl set-card-profile 0 output:hdmi-stereo
-Run audio playback:
+* '''Run audio playback:'''
   {{Board$}} aplay /usr/share/sounds/alsa/Front_Left.wav
@@ Line 55: / Line 60: @@
 {{Info|S/PDIF ALSA device supports only {{highlight|32-bit audio streams}}. As 32-bit wave files are not provided in sample sound files, speaker-test is used instead of aplay, for convenience, here. Speaker-test generates a 440Hz sine wave in following examples.}}
-* '''Playback on ALSA device'''
+==== Set IEC958 status bits ====
+Example: set IEC958 mode bit.
+ {{Board$}} iecset -c STM32MP1EV -n device=0 pro on
+==== Playback on ALSA device ====
 Run audio playback on 'playback_spdif' ALSA device:
 {{Info|'playback_spdif' is an alias defined in /etc/asound.conf, for S/PDIF output device.}}
   {{Board$}} speaker-test -D playback_spdif -c 2 -F S32_LE -f 440 -t sine -l 1
-* '''Playback via PulseAudio'''
+==== Playback via PulseAudio ====
+* '''Configure Pulseaudio'''
 Change the sound card active profile, to S/PDIF 'iec958-stereo' profile.
 {{Info|Example below is given for {{highlight|sound card index 0}}. Check sound card index with "''pactl list cards short''" command.}}
-  {{Board$}} pacmd set-card-profile 0 output:iec958-stereo
+  {{Board$}} pactl set-card-profile 0 output:iec958-stereo
-Run audio playback:
+* '''Run audio playback:'''
   {{Board$}} speaker-test -c 2 -F S32_LE -f 440 -t sine -l 1
+<noinclude>
+{{PublicationRequestId | 10391 | 2019-01-21}}
+[[Category:How to run use cases]]
+[[Category:ALSA]]
+</noinclude>