[LAU] How is the bass mixed? Per-channel frequency analysis? Histogram?

[Dan S]

Hi Matt,

Here's a Python script which analyses a set of files in a specified
folder. They have to be file formats understood by libsndfile - which
allows for flac/wav/aiff and some others, but not mp3. It takes maybe
5 to 10 seconds per track, but eventually it produces a plot as a PNG
file.

https://gist.github.com/danstowell/8872466

(Also blogged: <http://mcld.co.uk/blog/blog.php?417>)

Best
Dan

2014-02-05 Matt Garman <matthew.garman at gmail.com>:
>
> I have a collection of FLAC files, all ripped from my CD collection
> What I would like to do is run an analysis across all the music to
> determine how the bass/lower frequencies are generally mixed.  For
> example, how much content below (for example) 150 Hz is on the left
> channel versus the right channel?
>
> I'm not sure if "histogram" is the right word, but in my mind what
> I'd like to see, per-channel, is something like this:
>
> 150--125 Hz: x samples
> 125--100 Hz: y samples
> 100--80  Hz: z samples
> ...
>
> Then I can look at the two channels of a song, and if the histograms
> are approximately the same, I can assume the bass was mixed equally
> to both channels.
>
> I am a programmer, and thought it would be easy to quickly hack
> something up that would do this, but I have no experience with
> signal processing, and as I started reading about this, I quickly
> got in over my head!  So I was hoping there might already exist a
> tool that has this functionality.
>
> Note that I don't need any kind of graphical output, as this needs
> to be wrapped up in some kind of batch processing script---I have
> about 11,000 files to analyze!
>
> The motivation for this is: I have a hardware DAC (digital audio
> converter) in one part of my house, and a subwoofer in another.
> There is a single coax run between the DAC and subwoofer, so I can
> only send one channel.  If the overwhelming majority of my music has
> the bass mixed equally, sending only one channel isn't a problem.
> But if I choose the "L" channel to send to the sub, and much music
> has the bass mixed only to the "R" channel, then I won't be able to
> hear the low frequencies.  I want to find out how often this might
> happen.
>
> Thanks,
> Matt
>
>
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