Console audio recording, editing, mixing for garabe rock'n'roll

icovnik · 08-24-2021, 08:33 AM

Hello,

Does anyone use linux for music mastering? You know, you record some tracks in a garage jam session (4x drums, guitar, bass, voice) on some digital mixer. Transfer recorded wav files to linux. Fire Audacity. Apply some filters to some tracks, other filters to other tracks. Nothing fancy, we are lo-fi garage band having fun

Then join input into some songs to listen to. Then practice and repeat the same on next jam session.

OK, everything is fine. Except I am not really happy with my audio workflow. I am heavy console user and working with Audacity isn't really best for me. I was wondering, is there a way to use some console-oriented programs to process audio? E.g. normalize input (each track differently), use some compressor, some low-pass filters, high-pass filters, amplify something, mix together, use fade-out, .... you name it. Something like write some common parameters to some bash script, then run that script. It applies all filters and does everything. Then listen to output, change some presets in script, run again... etc.

So are there command-line programs to do this stuf? Or is there a way to control Audacity, Ardour, .. another program to do this in batch mode? Just fire the script, wait some, get results. Or are there some audio filters/effects I can use at command-line and script them by myself?

Thanks for any advice!

ico

ondoho · 08-24-2021, 01:34 PM

You can definitely use ffmpeg and/or sox for all of this.
https://trac.ffmpeg.org/wiki
https://ffmpeg.org/ffmpeg.html
http://sox.sourceforge.net/
Random search result for downmixing with ffmpeg:
https://stackoverflow.com/questions/...ms-into-stereo

icovnik · 08-28-2021, 01:18 PM

ondoho: Wow, I did some video recodings with ffmpeg but I didn't dive too much into it. And now after learning more about ffmpeg's filters I am truly impressed! That's the advice I was asking. Thank you!

Just quick question about ffmpeg's pan filter. I am trying to create stereo output from some mono wav files (and position it "in space") but I am unable to do it. It allways ends with error "Too many inputs specified for the "pan" filter.". My command:

ffmpeg -i ch1.wav -i ch2.wav -filter_complex "[0:0][1:0]pan=2c|c0=c0|c1=c1" -ac 2 out.wav

What is wrong with my command?

Thanks

ondoho · 08-28-2021, 01:55 PM

I'm sorry but I have no idea.
I always do web searches that suggest commands. Lots of stuff on stackoverflow.com

rokytnji · 08-28-2021, 02:01 PM

Nixcraft is another source for good scripts.
https://www.cyberciti.biz/faq/page/191/

Shotgun link

teckk · 08-28-2021, 04:37 PM

Quote:

I am trying to create stereo output from some mono wav files

Let me make a couple of .wav files.

Examples:

Code:

mplayer myfile1.mp3 -vc dummy -vo null -ao pcm:file=audio1.wav
mplayer myfile2.mp3 -vc dummy -vo null -ao pcm:file=audio2.wav

ffprobe audio1.wav
...
Input #0, wav, from 'audio1.wav':
  Duration: 00:26:30.00, bitrate: 1024 kb/s
  Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 32000 Hz, 2 channels, s16, 1024 kb/s
  

ffmpeg -i audio1.wav -i audio2.wav -filter_complex amerge -c:a libmp3lame -b:a 128k -vn audio1.mp3

ffprobe audio1.mp3
...
Input #0, mp3, from 'audio1.mp3':
  Metadata:
    encoder         : Lavf58.76.100
  Duration: 00:26:30.05, start: 0.034531, bitrate: 128 kb/s
  Stream #0:0: Audio: mp3, 32000 Hz, stereo, fltp, 128 kb/s
    Metadata:
      encoder         : Lavc58.13

Also

Code:

sox -M audio1.wav audio2.wav audio3.wav delay .05 0 0

icovnik · 08-29-2021, 12:40 PM

Thank you for your help. It proves again that it pays off to study a bit

teck: I was struggling with creating stereo from multiple instruments with pan filter, which can place respective instruments (mono source streams) "in space" - guitar 75% to left channel, 25% to right, kick drum 50-50, voice a bit to the right... etc. Now I found out that if I first "amerge" all separate streams, then feed amerge's output into pan filter. I don't know whether it is the right way to do it but it works for me. Like this:

Code:

ffmpeg -hide_banner \
-i kick.wav -i snare.wav -i cymbals.wav -i guitar.wav \
-filter_complex \
" \
    [0:0][1:0][2:0][3:0]amerge=inputs=4, \
    pan='stereo| \
        c0 = c0+c1+1.1*c2+0.7*c3 | \
        c1 = c0+c1+0.9*c2+1.3*c3 \
    ' \
" \
-ac 2 \
out.wav

So - we have 4x 1-channel streams, join it into 1x 4-channel stream with amerge, then place those into output stereo channels with pan filter. I was unable to use pan without this step.

For someone searching for similar help - pan filter doesn't like output channel layout with a space before | (e.g. "stereo |..." isn't OK, "stereo|.." is, spaces in outdef is OK). "," between filters connects output from 1st filter to input of 2nd. If you use ";" between filters, it is something like a sequence of filters - run this filter; then run that; ...