Last edited 2 years ago

How to record audio: Difference between revisions

Visual
imported>Frq08988
mNo edit summary
 
Registered User
mNo edit summary
 
(18 intermediate revisions by 3 users not shown)
Line 1: Line 1:
<noinclude>
<noinclude>{{ApplicableFor
{{ArticleMainWriter | OlivierM}}
|MPUs list=STM32MP13x, STM32MP15x
{{ArticleApprovedVersion | OlivierM | ArnaudP(Passed, 30Janv'18) | No previous approved version | LagoutteJM - 6Feb'19 - 10588 | 6Feb'19}}
|MPUs checklist=STM32MP13x,STM32MP15x
[[Category:How to run use cases]]
}}</noinclude>
[[Category:ALSA]]
</noinclude>
 
== Article purpose ==
== Article purpose ==
This article explains how to record audio via the kernel [[ALSA overview|ALSA]] audio framework in '''Linux® OS''' context.
This article explains how to record audio via the kernel [[ALSA overview|ALSA]] audio framework in '''Linux® OS''' context.
Line 13: Line 10:
The [[ALSA overview|ALSA]] framework exposes audio devices associated to the board audio hardware interfaces.  
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 to list audio profiles and to select one, in order to record from 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 to list audio profiles and to select one, in order to record from 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 record examples in following sections are based on [[ALSA_overview#How_to_use|ALSA utilities]]. Some input paths are configured through ALSA controls. These configurations are detailed in [[Soundcard_configuration|sound card configuration]] article. If an error is issued when running an example, please refer to [[Audio troubleshooting grid]] article for debug.
The audio record examples in following sections are based on [[ALSA_overview#How_to_use|ALSA utilities]]. Some input paths are configured through ALSA controls. These configurations are detailed in [[Soundcard_configuration|sound card configuration]] article. If an error is issued when running an example, please refer to [[Audio troubleshooting grid]] article for debug.
Line 20: Line 21:


=== Audio record from headset microphone input ===
=== Audio record from headset microphone input ===
* '''Record from ALSA device'''
 
Launch audio record from 'record_codec' ALSA device:
==== Record from ALSA device ====
Start audio record from 'record_codec' ALSA device:
 
{{Info|'record_codec' is an alias defined in /etc/asound.conf, for headset microphone input device.}}
{{Info|'record_codec' is an alias defined in /etc/asound.conf, for headset microphone input device.}}
  {{Board$}} arecord -D record_codec -f S16_LE -d 10 /tmp/rec.wav
  {{Board$}} arecord -D record_codec -f S16_LE -d 10 /tmp/rec.wav


* '''Record via PulseAudio'''
==== Record via PulseAudio ====
Change 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.}}
* '''Configure Pulseaudio :'''
{{Info|Example below is given for {{highlight|sound card index 0}}. Check sound cards index with "''pactl list cards short''" command.}}
Change Pulseaudio default input source to 'analog_input':
  {{Board$}} pacmd set-card-profile 0 output:analog-stereo+input:analog-stereo
{{Info|The Pulseaudio analog_input is defined in /etc/pulse/system.pa configuration file.}}
  {{Board$}} pactl set-default-source analog_input


Launch audio record:
* '''Start audio record :'''
{{Info|The Pulseaudio device is the default one, so "-D pulse" option can be omitted in the record command.}}
  {{Board$}} arecord -d 10 /tmp/rec.wav
  {{Board$}} arecord -d 10 /tmp/rec.wav


Line 37: Line 42:
{{Warning|The support of digital microphone input is board dependent. Please, check available inputs with "''arecord -l''" command.}}
{{Warning|The support of digital microphone input is board dependent. Please, check available inputs with "''arecord -l''" command.}}


* '''Record from ALSA device'''
==== Record from ALSA device ====
Launch audio record from 'record_dfsdm0' ALSA device:
Start mono audio record from 'record_dfsdm0' ALSA device:
{{Info|'record_dfsdm0' is an alias defined in /etc/asound.conf, for digital microphone U1 input device.}}
{{Info|'record_dfsdm0' is an alias defined in /etc/asound.conf, for digital microphone U1 input device.}}
  {{Board$}} arecord -D record_dfsdm0 -r 16000 -f S32_LE -c 1 -d 10 /tmp/rec.wav
  {{Board$}} arecord -D record_dfsdm0 -r 16000 -f S32_LE -c 1 -d 10 /tmp/rec.wav
==== Record multiple digital microphones from a virtual ALSA device ====
Start stereo audio record from 'multi' ALSA device:
{{Info|'multi' device, based on ALSA multi plugin<ref>[https://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html ALSA PCM plugins]</ref>, has to be defined in /etc/asound.conf file.}}
{{Board$}} arecord -D multi -r 16000 -f S32_LE -c 2 -d 10 /tmp/rec.wav
==== Record via PulseAudio ====
* '''Configure Pulseaudio'''
Change Pulseaudio default input source to 'dmic1_input':
{{Info|The Pulseaudio dmic1_input is defined in /etc/pulse/system.pa configuration file.}}
{{Board$}} pactl set-default-source dmic1_input
* '''Start audio record :'''
{{Info|The Pulseaudio device is the default one, so "-D pulse" option can be omitted in the record command.}}
{{Board$}} arecord -r 48000 -f S32_LE -c 2 -d 10 /tmp/rec.wav


=== Audio record from S/PDIF input ===
=== Audio record from S/PDIF input ===
{{Warning|The support of S/PDIF input is board dependent. Please, check available inputs with "''arecord -l''" command.}}
{{Warning|The support of S/PDIF input is board dependent. Please, check available inputs with "''arecord -l''" command.}}


* '''Record from ALSA device'''
==== Get IEC958 status bits ====
Launch audio record from 'record_spdif' ALSA device:
Some restrictions may apply to IEC958 control, depending on the SPDIFRX device configuration as it is explained in [[SPDIFRX device tree configuration]] and [[SPDIFRX Linux driver]] articles.
 
{{Board$}} amixer -c STM32MP1EV cget iface=PCM,name='IEC958 Capture Default'
 
==== Record from ALSA device ====
Start audio record from 'record_spdif' ALSA device:
{{Info|'record_spdif' is an alias defined in /etc/asound.conf, for S/PDIF input device.}}
{{Info|'record_spdif' is an alias defined in /etc/asound.conf, for S/PDIF input device.}}
{{Info|A S/PDIF signal must be available on S/PDIF RCA input connector before launching the record command. The record rate must be set according to S/PDIF signal sampling rate.}}
{{Info|A S/PDIF signal must be available on S/PDIF RCA input connector before starting the record command. The record rate must be set according to S/PDIF signal sampling rate.}}
  {{Board$}} arecord -D record_spdif -f S32_LE -c 2 -r 48000 -d 10 /tmp/rec.wav
  {{Board$}} arecord -D record_spdif -f S32_LE -c 2 -r 48000 -d 10 /tmp/rec.wav
==== Record via PulseAudio ====
* '''Configure Pulseaudio'''
Change Pulseaudio default input source to 'iec958_input':
{{Info|The Pulseaudio iec958_input is defined in /etc/pulse/system.pa configuration file.}}
{{Board$}} pactl set-default-source iec958_input
* '''Start audio record :'''
{{Info|The Pulseaudio device is the default one, so "-D pulse" option can be omitted in the record command.}}
{{Board$}} arecord -r 48000 -f S32_LE -c 2 -d 10 /tmp/rec.wav
== References ==
<references />
<noinclude>
{{PublicationRequestId | 10588 | 2019-02-06}}
[[Category:How to run use cases]]
[[Category:ALSA]]
</noinclude>

Latest revision as of 12:35, 8 June 2022↑

Applicable for STM32MP13x lines, STM32MP15x lines

1. Article purpose↑

This article explains how to record audio via the kernel ALSA audio framework in Linux® OS context. The examples below, show how to record audio from the different audio hardware interfaces of the STM32MPU boards.

2. Audio record overview↑

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 to list audio profiles and to select one, in order to record from a specific audio interface.

Warning white.png 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 record examples in following sections are based on ALSA utilities. Some input paths are configured through ALSA controls. These configurations are detailed in sound card configuration article. If an error is issued when running an example, please refer to Audio troubleshooting grid article for debug.

3. Examples↑

3.1. Audio record from headset microphone input↑

3.1.1. Record from ALSA device↑

Start audio record from 'record_codec' ALSA device:

Info white.png Information
'record_codec' is an alias defined in /etc/asound.conf, for headset microphone input device. 
 arecord -D record_codec -f S16_LE -d 10 /tmp/rec.wav

3.1.2. Record via PulseAudio↑

  • Configure Pulseaudio :

Change Pulseaudio default input source to 'analog_input':

Info white.png Information
The Pulseaudio analog_input is defined in /etc/pulse/system.pa configuration file. 
 pactl set-default-source analog_input
  • Start audio record :
Info white.png Information
The Pulseaudio device is the default one, so "-D pulse" option can be omitted in the record command. 
 arecord -d 10 /tmp/rec.wav

3.2. Audio record from digital microphone input↑

Warning white.png Warning
The support of digital microphone input is board dependent. Please, check available inputs with "arecord -l" command.

3.2.1. Record from ALSA device↑

Start mono audio record from 'record_dfsdm0' ALSA device:

Info white.png Information
'record_dfsdm0' is an alias defined in /etc/asound.conf, for digital microphone U1 input device. 
 arecord -D record_dfsdm0 -r 16000 -f S32_LE -c 1 -d 10 /tmp/rec.wav

3.2.2. Record multiple digital microphones from a virtual ALSA device↑

Start stereo audio record from 'multi' ALSA device:

Info white.png Information
'multi' device, based on ALSA multi plugin[1], has to be defined in /etc/asound.conf file. 
 arecord -D multi -r 16000 -f S32_LE -c 2 -d 10 /tmp/rec.wav

3.2.3. Record via PulseAudio↑

  • Configure Pulseaudio

Change Pulseaudio default input source to 'dmic1_input':

Info white.png Information
The Pulseaudio dmic1_input is defined in /etc/pulse/system.pa configuration file. 
 pactl set-default-source dmic1_input
  • Start audio record :
Info white.png Information
The Pulseaudio device is the default one, so "-D pulse" option can be omitted in the record command. 
 arecord -r 48000 -f S32_LE -c 2 -d 10 /tmp/rec.wav

3.3. Audio record from S/PDIF input↑

Warning white.png Warning
The support of S/PDIF input is board dependent. Please, check available inputs with "arecord -l" command.

3.3.1. Get IEC958 status bits↑

Some restrictions may apply to IEC958 control, depending on the SPDIFRX device configuration as it is explained in SPDIFRX device tree configuration and SPDIFRX Linux driver articles. 

 amixer -c STM32MP1EV cget iface=PCM,name='IEC958 Capture Default'

3.3.2. Record from ALSA device↑

Start audio record from 'record_spdif' ALSA device:

Info white.png Information
'record_spdif' is an alias defined in /etc/asound.conf, for S/PDIF input device.
Info white.png Information
A S/PDIF signal must be available on S/PDIF RCA input connector before starting the record command. The record rate must be set according to S/PDIF signal sampling rate. 
 arecord -D record_spdif -f S32_LE -c 2 -r 48000 -d 10 /tmp/rec.wav

3.3.3. Record via PulseAudio↑

  • Configure Pulseaudio

Change Pulseaudio default input source to 'iec958_input':

Info white.png Information
The Pulseaudio iec958_input is defined in /etc/pulse/system.pa configuration file. 
 pactl set-default-source iec958_input
  • Start audio record :
Info white.png Information
The Pulseaudio device is the default one, so "-D pulse" option can be omitted in the record command. 
 arecord -r 48000 -f S32_LE -c 2 -d 10 /tmp/rec.wav

4. References↑

  1. ↑ ALSA PCM plugins



Retrieved from "https://wiki.stmicroelectronics.cn/stm32mpu-ecosystem-v4/index.php?title=How_to_record_audio&oldid=85529"