audio redirection into fifo

kzo81 · 10-09-2019, 03:41 AM

Hi,

I'd like to stream and record at the same time on my laptop, first I'd devide the audio to 2 fifos:

Code:

#!/bin/bash

rm -rf /tmp/streaming 2 >/dev/null && mkfifo /tmp/recording 2 >/dev/null
rm -rf /tmp/recording 2 >/dev/null &&mkfifo /tmp/recording 2 >/dev/null

arecord -c 2 -f S16_LE -r 48000 | ffmpeg -i - -f wav pipe:3 -f wav pipe:4 3> /tmp/recording 4> /tmp/streaming &

Here is my only working solution, but it has way to much overhead, it consumes the CPU cores:
https://pastebin.com/mub4HCjM

and than I would test the fifos one-by-one:

Code:

cat /tmp/recording_fifo > arecord -c 2 -f S16_LE -r 48000 -d 10 /mnt/data/recordings/2019-10-09/recording_fifo_test.wav

I got this error: -sh: arecord: Text file busy

Could you please help me a bit?

Shadow_7 · 10-09-2019, 03:55 AM

Why? There's snd-aloop that creates a dummy soundcard who's output is it's input.

There's also tee.

$ arecord | tee file.raw | ffmpeg .....

With whatever parameters you desire.

Shadow_7 · 10-09-2019, 03:58 AM

I've used the tee method to record a high quality wav file and an mp3 file to another device at the same time. Hand the crappy mp3 on a usb stick to the event organizer on the way out the door, take my "good" recording home.

kzo81 · 10-09-2019, 04:13 AM

Quote:

Originally Posted by Shadow_7

Why? There's snd-aloop that creates a dummy soundcard who's output is it's input.

There's also tee.

$ arecord | tee file.raw | ffmpeg .....

With whatever parameters you desire.

Interesting. This way file.raw will grow and eventually fill the disk.

I'd like 5 minutes segment recording to wav and in the meantime, stream with ffmpeg or vlc via http

Shadow_7 · 10-09-2019, 04:42 AM

Well yes, files tend to do that. Disks are relatively cheap. It doesn't have to be .raw, it could be .mp3 or other compressed formats. It doesn't have to be arecord, it could be rec from sox, or other options. Even if you're making a high quality recording of about 1GB a minute, a 2TB HDD would give you 2000 minutes, well past 24 hours of audio. Perhaps not good enough for a security system where you need 24/7 recording of at least a 30 day loop. But even that is just a storage limitation. Throw enough $$$ at the issue and you could have petabyte(s) of space.

Sox has a trim option to break segments into specified duration's as it records. Or tail -f file.raw in another thread to do that. Lots of options.