9 Feb
2014
9 Feb
'14
10:33 p.m.
Hi Dan,
Thank you for taking the time to put that together! Looks like I have
a fair amount of learning to do before I can make sense of exactly
what's going on (I mean, I get the gist at a very high level, but
don't understand the details enough to hack the code).
I ran it on a few tracks that I thought would be interesting. Clearly
this list has a number of folks with mixing experience and/or
knowledge, maybe they can comment on what I'm seeing:
1. Leo Kottke "The Driving of the Year Nail" - first track from 6- and
12-String Guitar. Looks like there's a definite bias towards the left
channel.
http://raw-sewage.net/images/stereoscope/kottke.png
I would have expected both channels to be perfectly equal, since this
is exactly one instrument. (I have no mixing or studio experience,
keep in mind, just a guy who likes music. So this is what my
uninformed intuition says.)
2. The Beatles "While My Guitar Gently Weeps" - from The While Album.
http://raw-sewage.net/images/stereoscope/beatles.png
I picked this since there was a mention of Beatles albums having the
bass mixed only to one side. If I could hack the code to do a low
pass filter, this might be an interesting track. But, it appears to
me there's a definite bias for the lowest frequencies to be panned to
the right side.
3. Above & Beyond "Let Go" - from Anjunabeats Vol 8.
http://raw-sewage.net/images/stereoscope/above_beyond.png
Just curious what some electronic music looked like... This could well
be a mono mix?
4. Beethoven "Moonlight Sonata" - from a collection of Beethoven's
piano sonatas (not sure who the performer is or label, too lazy to go
pull the CD)
http://raw-sewage.net/images/stereoscope/beethoven.png
This graph looks kind of weird. Is there really that little
high-frequency information?
Anyway, thanks again Dan! I'll keep playing with the tool and trying
to learn to see if I can come up with any more interesting info.
-Matt
On Fri, Feb 7, 2014 at 3:43 PM, Dan S <danstowell+lxau(a)gmail.com> wrote:
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(a)gmail.com>om>:
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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