[SOLVED] sox, arecord both produce blank recordings

porphyry5 · 06-14-2012, 04:47 PM

I stream my local radio with

Code:

mpg123 -b 2048 -C -@ http://war.str3am.com:8250/listen.pls

It plays fine but both

Code:

rec -c 2 radio.wav trim 0 00:15
arecord -f cd -d 15 radio.wav

produce blank recordings.

I've also tried recording from my mp3 player feeding into Front Mic and Line-In, with the same result.

My sound card settings are

Code:

~ $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC662 rev1 Analog [ALC662 rev1 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: ALC662 rev1 Digital [ALC662 rev1 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
~ $

In alsamixer I have set both columns that would toggle to CAPTURE, and both are set to 81

I made some progress when I added the line

Code:

amixer -c 0 sset Line,0 80%,80% unmute cap

Now, instead of getting a blank recording, I get a noisy recording of static.
I tried

Code:

amixer contents

and decided that the problem must lie with these items that it listed

Quote:

numid=17,iface=MIXER,name='Input Source'
; type=ENUMERATED,access=rw------,values=1,items=3
; Item #0 'Rear Mic'
; Item #1 'Front Mic'
; Item #2 'Line'
: values=0
numid=18,iface=MIXER,name='Input Source',index=1
; type=ENUMERATED,access=rw------,values=1,items=3
; Item #0 'Rear Mic'
; Item #1 'Front Mic'
; Item #2 'Line'
: values=0

so I changed them with

Code:

root@a:/home/g# amixer -c 0 cset numid=17,iface=MIXER,name='Input Source' 2
numid=17,iface=MIXER,name='Input Source'
  ; type=ENUMERATED,access=rw------,values=1,items=3
  ; Item #0 'Rear Mic'
  ; Item #1 'Front Mic'
  ; Item #2 'Line'
  : values=2
root@a:/home/g# amixer -c 0 cset numid=18,iface=MIXER,name='Input Source',index=1 2
numid=18,iface=MIXER,name='Input Source',index=1
  ; type=ENUMERATED,access=rw------,values=1,items=3
  ; Item #0 'Rear Mic'
  ; Item #1 'Front Mic'
  ; Item #2 'Line'
  : values=2

but nothing changed, still just static

adamk75 · 06-16-2012, 06:42 AM

If you want to record the audio you are playing, I suggest installing pavucontrol, and then using that to select the "Monitor" of your audio device when you record. Fewer and fewer audio devices these days have the ability to record what you hear.

Adam

jlinkels · 06-16-2012, 07:09 AM

I don't know exactly the properties of your audio chip, but I have a number of Intel audio chips and none of them allow capturing a playback stream. Best results with capturing for me is using $9.99 SoundBlaster el cheapo clone cards.

However, I would not install Pavucontrol as I also found that pulse usually screws up what you painstakingly got working in Alsa.

What I do with radio streams is recording them to file and play back that file. Much easier.

jlinkels

porphyry5 · 06-16-2012, 10:16 AM

Quote:

Originally Posted by adamk75

Fewer and fewer audio devices these days have the ability to record what you hear.

Adam

Quote:

I don't know exactly the properties of your audio chip, but I have a number of Intel audio chips and none of them allow capturing a playback stream. Best results with capturing for me is using $9.99 SoundBlaster el cheapo clone cards.

jlinkels

Aah, thank you both. I'd never thought about the actual process of producing sound on a computer before, but what you're saying means that the player app does not actually produce the sounds, it simply converts the mp3 or wav to a stream format that the sound chip can interpret, so

Quote:

What I do with radio streams is recording them to file and play back that file. Much easier.

jlinkels

Yes indeed, thank you very much.