[squeak-dev] Sound mixing makes nasty noises

K K Subbu kksubbu.ml at gmail.com
Sat Dec 26 06:28:41 UTC 2020


On 26/12/20 4:09 am, tim Rowledge wrote:
> I'd add files for the alsa Pi but I can't make arecord work at all. As usual, making sense of a man page is ridiculous.

;-). A man(ual) page is detailed spec. Reading all options can be quite 
intimidating. I just skip to the examples section in the beginning. I 
only use options to override defaults.

> arecord -d 5 -f cd -D -t wav output Pi4-alsa-1.wav
> ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM -t
> arecord: main:828: audio open error: No such file or directory

-D requires an argument.

$ arecord -d 5 -f cd Pi4-alsa-1.wav

will sample mic at 44khz (16-bit little endian) for 5 seconds and store 
it in wav format file (-t wav is the default anyway).

> arecord -d 5 -f cd -D output -t wav  Pi4-alsa-1.wav
> arecord: main:828: audio open error: No such file or directory

The "output" argument to -D is not a valid audio input device. What 
valid audio input devices does "arecord -l" show? You could also use 
alsamixer TUI to see all valid input/output devices, check their 
gain/vol settings and test recording and playback.

>   arecord -d 5 -f cd  -t wav  Pi4-alsa-1.wav
> ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM input
> arecord: main:828: audio open error: No such file or directory
> 
> arecord -d 5 -f cd  -t wav  foo
> ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM input
> arecord: main:828: audio open error: No such file or directory
> 
> arecord -d 5 -D output  -t wav  Pi4-alsa-1.wav
> arecord: main:828: audio open error: No such file or directory
> 
>   arecord -d 5 -D output  -t wav  ./Pi4-alsa-1.wav
> arecord: main:828: audio open error: No such file or directory
> 
>   arecord -d 5 foo.wav
> ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM input
> arecord: main:828: audio open error: No such file or directory

The default device is not available (bad driver?) or misconfigured. Try 
listing audio devices with arecord -l and then pick the appropriate name 
to use with -D.

HTH .. Subbu


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