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

Just to mention: someone pointed out a glitch in my code (actually, in
the underlying "audiolab" module, or so it seems) - code updated:
https://gist.github.com/danstowell/8872466

Dan

2014-02-07 Dan S <danstowell+lxau@email-addr-hidden>:
> 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@email-addr-hidden>:
>>
>> 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
>>
>>
>> _______________________________________________
>> Linux-audio-user mailing list
>> Linux-audio-user@email-addr-hidden
>> http://lists.linuxaudio.org/listinfo/linux-audio-user
>
>
>
> --
> http://www.mcld.co.uk

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