[Bash] sox convert for loop

[sunrat]

I have a for loop to batch resample .wav files. convert to flac, normalize, and move to a new directory.
Command is:

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mkdir 16bit && for file in *.wav; do sox -SG "$file" -b 16 16bit/"$file".flac norm -1.0; done

This works fine except the resulting files have suffix ".wav.flac"
How can I avoid the superfluous ".wav"?

[steve_v]

I'm too lazy to test with your exact case, but I'd probably just use a simple bash string manipulation here, e.g. something like
Substring replacement:

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mkdir 16bit && for file in *.wav; do sox -SG "$file" -b 16 16bit/"${file/.wav/.flac}" norm -1.0; done

That will replace the first occurrence of ".wav" in $file so it'll be a little fragile, but close enough for government work assuming your input filenames aren't too funky.

Or better, substring removal:

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mkdir 16bit && for file in *.wav; do sox -SG "$file" -b 16 16bit/"${file%.wav}.flac" norm -1.0; done

That'll cut the shortest match for ".wav" off the end of $file, so it should be more resilient.

I find the ${var%string} construct (and it's front-cut counterpart ${var#string}) extremely handy for separating filenames from extensions in general.


Many ways to skin that one, how many cats do you have?

[sunrat]

The second one works a treat. I was thinking along those lines but wasn't sure of exact syntax. Thank you @steve_v !

My cat left for cat heaven several years ago but I'm sure she would have been happy about that.

[steve_v]

Bash sure is a screwey language, but it's surprising what it can do natively.

Aside, I find iterating over filenames in for loops to be a real PITA, particularly when they contain whitespace. In your case it's probably fine, but there are other, more space-tolerant and less variable-quoting sensitive ways to loop over arbitrary filenames.
Traditionally one might use a while | read loop or the -exec function of find, but now that bash has arrays... IMHO bash arrays are pretty mint for dealing with filenames.

Just a thought, if you too have the tendency to succumb to script-OCD

[kent_dorfman766]

flacfile=${file/.wav/.flac}

Should do it...but I see steve beat me to the punch. You may be able to anchor the search to the right end of the string using "$", or that may just work in PERL. cannot remember. I usually use the above instead of the % form he mentioned.

[sunrat]

I've used a similar for loop to convert sample rate/bit depth many times but have never used it to convert formats before and this was a quest to find how to do it all in one. sox is great for lots of things and it makes it easy that the specified output file just needs to have the target format suffix and it converts. Spaces are handled, no problem. sox also dithers by default when bit depth is lowered which was a factor in using it rather than ffmpeg.
Achievement unlocked! Thanks again.

[kent_dorfman766]

sox kicks a$$! if you need a low level swiss army knife there is nothing better, IMHO...

I am very partial to ecasound because of the GUI to visualize the waveforms though, and I don't have to remember sox command line params.

[sunrat]

sox kicks a$$! if you need a low level swiss army knife there is nothing better, IMHO...

I am very partial to ecasound because of the GUI to visualize the waveforms though, and I don't have to remember sox command line params.

ecasound is cli. What GUI do you use?
sox can do spectrograms:

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sox <file> -n spectrogram

I used to use Spek which was great except it was left behind in Bullseye with library upgrades but it's coming back for Bookworm.

Mostly for recording I use Harrison Mixbus 32C, Ardour, or Qtractor. For edits and vinyl rips mainly Audacity. But sox is best for samplerate conversions and batch processing.
Unfortunately Linux still doesn't have a comprehensive audio restoration program. Audacity can do a bit, but usually I use Izotope RX in Windows which still astounds me in quality particularly for the vinyl to digital conversion project I'm doing now.

[kent_dorfman766]

ecasound is cli. What GUI do you use?

brain says one thing and fingers say another. I meant audacity, but since I pull it from an X11 pulldown menu, I'm like "dangit...what's it called this week?"