Applying correction and normalization to audio files.

[Jonathanese]

I wasn't quite sure where to put this, since this is less about any sort of hardware, and more about software tools.

I recently got a Tesla Model Y. While it has an amazing stock sound system, there is still a lot of correction I want to do. However, all the car gives you is a 5-band fixed-band EQ, so you can only make super broad ham-fisted adjustments. REW has been spoiling me. So I've heard some software can let you do convolution offline to the audio file itself.

So what I'm wanting to work on is a pipeline:
1. Upload a sweep to a USB drive.
2. Record the sweep with a UMIK-1
3. Upload the sweep to REW to generate a corrective EQ
4. Export the EQ as an impulse response for correction.

And then when I go to upload music files to my car:
1. Gather the music I want to upload
2. Convolve the music with the corrective EQ impulse response as an entire batch.
3. Normalize the music as an entire batch
4. Toss the result on to a USB drive to listen in the car. With EQ correction and normalization.

The originals are all FLAC, so keeping them in a lossless format would be preferred, but it's also car audio, so I'm not entirely bummed if the result is MP3. I would just save that for the last step before normalizing.

So what tools would help me with this? For the files, I know Audacity can do convolution, but that would be one file at a time. I also know it can do normalization, but I would prefer that to be handled by the replaygain parameter to minimize loss of fidelity.

For the calibration, I think I know how I could perform all the steps. You can import both sweeps and sweep response files, so I can just record from several locations, process them together in REW, and export the IIR/FIR.

 

[DanDan]

Intriguing plan. I believe it should work to a large extent. However I do believe a regular DRC system applies the IR of the filter to the speaker and thus the room. I view it like an active damper on the ringing. Shortens the modes a bit.

 

[ddude003]

Things that come to mind in no particular order... Have a look at SoX (Sound eXchange)... I seem to recall that it has the ability to do some EQ and Filters as well resampling which you may want to do to take that load off your DAC/Player...

You might also look at HQPlayer... Lots of filtering, resampling and convolution... Although this seems to be used mostly for on-the-fly streaming conversion, I am pretty sure there is a way to save the output as files...

And there is the Pan Galactic Gargle Blaster (PGGB), otherwise known as Remastero, a file based remastering utility that does resampling and reconstruction, Convolution filters for EQ and Noise shaping and digital volume control...

You could even use something like Audacity with a EQ Convolution plugin... I use Reverberate... Don't remember if you can run this in a "batch" mode using "macros"...

Reaper DAW + your favorite EQ Convolution plugin... As above...

SoX is free while HQPlayer and PGGB are not...
As always, Google is your frenemy...

 

[jtalden]

Another Option:
I have used Foobar2000 to convert batches of files of music in various ways.
It is capable of convolving music files in batch mode using a specified FIR filter. It requires the Free Encoder Pack add-in to support flac and several other file types. The foo_convolve add-in component is also loaded separately. I found it very confusing to setup file conversion using the convolver originally, but once the the settings are correctly configured it works very well. I can help with the setup if you go this way.