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From: info <info@dressmaker.ca>
To: alsa-devel@alsa-project.org
Subject: Discover a microphone device, to later discover if it is receiving input
Date: Sun, 4 Oct 2020 12:22:43 -0400	[thread overview]
Message-ID: <de6ebf17-8f71-c497-28bc-7819338baddb@dressmaker.ca> (raw)

Hi all,


I am writing a program that aims to auto-discover the microphone device 
that the user is speaking into. I started off by querying device hints 
and collected all devices with the IO types of null, since I have not 
found any devices with the type of Input. I am puzzled how it is 
possible that there is no Input, where a microphone device should not be 
able to emit sound. This is the list on my particular machine:

Name of device: sysdefault:CARD=SB
Description of device: HDA ATI SB, ALC892 Analog
Default Audio Device
I/O type of device: (null)

Name of device: front:CARD=SB,DEV=0
Description of device: HDA ATI SB, ALC892 Analog
Front speakers
I/O type of device: (null)

Name of device: surround21:CARD=SB,DEV=0
Description of device: HDA ATI SB, ALC892 Analog
2.1 Surround output to Front and Subwoofer speakers
I/O type of device: Output

Name of device: surround41:CARD=SB,DEV=0
Description of device: HDA ATI SB, ALC892 Analog
4.1 Surround output to Front, Rear and Subwoofer speakers
I/O type of device: Output

Name of device: surround50:CARD=SB,DEV=0
Description of device: HDA ATI SB, ALC892 Analog
5.0 Surround output to Front, Center and Rear speakers
I/O type of device: Output

Name of device: surround71:CARD=SB,DEV=0
Description of device: HDA ATI SB, ALC892 Analog
7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
I/O type of device: Output

Name of device: sysdefault:CARD=SB
Description of device: HDA ATI SB, ALC892 Analog
Default Audio Device
I/O type of device: (null)

Name of device: front:CARD=SB,DEV=0
Description of device: HDA ATI SB, ALC892 Analog
Front speakers
I/O type of device: (null)

Now, I am more puzzled, because none of them is a microphone device 
explicitly. How can my program determine which of them is actually a 
microphone?

Also, why are devices are duplicated in the output from 
snd_device_name_hint()? The very first device is also repeated as the 
2nd last one...


Regards,
Alex


             reply	other threads:[~2020-10-04 16:23 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-04 16:22 info [this message]
2020-10-04 21:17 ` Dead link in wiki under Tutorials info
2020-10-16 17:33   ` info
2020-10-09 12:39 ` Discover a microphone device, to later discover if it is receiving input info
2020-10-09 14:07   ` Jaroslav Kysela
2020-10-09 15:35 ` Takashi Iwai
2020-10-09 16:11   ` info

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