[ml] Tonight

John Hurliman jhurliman at cull.tv
Tue Mar 20 00:27:05 PDT 2012


I wrote a simple ffmpeg wrapper for extracting audio recently (
https://github.com/jhurliman/node-pcm). It's a node.js library but here is
the relevant ffmpeg command:

var ffmpeg = spawn('ffmpeg', ['-i',filename,'-f','s16le','-ac',channels,
'-acodec','pcm_s16le','-ar',sampleRate,'-y','pipe:1']);

Then read in stdout as a stream of 16-bit signed little endian integers and
divide each by 32767.0 to convert to floating point. Hope that helps, and
with any luck I'll make it this Thursday.

Best,
John Hurliman

On Mon, Mar 19, 2012 at 10:57 PM, gershon bialer
<gershon.bialer at gmail.com>wrote:

> Hi Steve,
>
> Thats cool that you wrote that Stack Overflow answer.
>
> PyMIR looks like a good start. I see that Jeremy has a nice hack for
> importing from ffmpeg. I suppose we could try using ffmpeg's API
> directly, although that can be a tricky API to work with. I'd like to
> be able to play this at least as a sanity check. I suppose you might
> be able to play it with audiolab, but I think that requires converting
> from int16 to float. I suppose float might be better for fft and such,
> anyway. I tried feeding it back to ffplay with:
>   ffmpeg = Popen([
>            "ffplay",
>            "-i -"],
>            stdin=PIPE, stderr=open(os.devnull,"w"))
>   ffmpeg.communicate(mp3Array.tostring())
> but that doesn't seem to work. What do you think is the best way to do
> this?
>
> MFCC would be cool to work with. Is it invertible? How does it sound
> inverted?
>
> Does NMF give a sparse representation? What is a good reference on NMF?
>
> Thanks,
> Gershon Bialer
>
> On Mon, Mar 19, 2012 at 4:33 PM, Steve Tjoa <stjoa at izotope.com> wrote:
> > Hello Gershon, others,
> >
> > Lurker here. That happens to be my code and Stack Overflow answer that
> you
> > linked to!
> >
> > Regarding concerns in this email thread:
> >
> > 1. Despite that "Python in Music" page, the lack of basic, simple
> > audio/music processing libraries in Python has motivated my friend
> Jeremy to
> > begin a Github repo for that very purpose named PyMIR:
> > (http://jsawruk.com/?p=141). Feel free to use or contribute.
> >
> > 2. In there, you will find an MP3 importer that Jeremy wrote.
> >
> > 3. I have custom-brewed stuff for audio feature extraction operations,
> > including MFCCs. I also have sparse coding and NMF stuff.  If there are
> > specific requests that I can fulfill, I will add them to the repo.
> >
> > Please feel free to ask if you have any questions.
> >
> > Steve
> > http://stevetjoa.com
> >
> >
> > On Sun, Mar 18, 2012 at 10:59 PM, gershon bialer <
> gershon.bialer at gmail.com>
> > wrote:
> >>
> >> Yeah, thursday would be cool.
> >>
> >> Friture looks interesting, I'll have to see I found some code at
> >> http://stackoverflow.com/questions/2459295/stft-and-istft-in-python
> >> for doing the spectogram. I couldn't find a good library for importing
> >> mp3's into python. Although, I suppose we can work with wav files for
> >> now.
> >>
> >> On Sun, Mar 18, 2012 at 10:50 PM, Mike Schachter
> >> <mschachter at eigenminds.com> wrote:
> >> > Hey Gershon,
> >> >
> >> > Do you want to meet up this Thursday and talk about
> >> > time-frequency representations for sound? I'm looking
> >> > at various packages in python. One that struck my eye
> >> > was a real-time spectrogram package:
> >> >
> >> > http://tlecomte.github.com/friture/
> >> >
> >> > Anyone else interested in this kind of stuff too? I could
> >> > put something on the calendar and make an official-like
> >> > announcement.
> >> >
> >> >  mike
> >> >
> >> > On Thu, Mar 15, 2012 at 12:00 PM, Mike Schachter
> >> > <mschachter at eigenminds.com> wrote:
> >> >> That's awesome Gershon!
> >> >>
> >> >> I can't come out tonight, but how about we meet
> >> >> up next Thursday and have a discussion about using
> >> >> deep nets for sound feature extraction? Spectrograms
> >> >> are also be invertible feature representation, as long
> >> >> as you use the overlapping windows for the FFT.
> >> >>
> >> >>  mike
> >> >>
> >> >>
> >> >>
> >> >> On Thu, Mar 15, 2012 at 11:42 AM, gershon bialer
> >> >> <gershon.bialer at gmail.com> wrote:
> >> >>> Hi,
> >> >>>
> >> >>> Do you want to meet again tonight?
> >> >>>
> >> >>> I played a bit with trying to build a generative model for creating
> >> >>> music like we were talking about. I also read the papers and looked
> at
> >> >>> the tutorial on deep learning.
> >> >>>
> >> >>> I think the first step is to find an invertible, sparse, feature,
> >> >>> representation. I think this would be MFCC or some sort of linear
> >> >>> predictive coding. I suppose you could then apply some of the deep
> >> >>> learning stuff to it for a generative model. Any thoughts?
> >> >>> --
> >> >>> ---------------------
> >> >>> Gershon Bialer
> >> >>> _______________________________________________
> >> >>> ml mailing list
> >> >>> ml at lists.noisebridge.net
> >> >>> https://www.noisebridge.net/mailman/listinfo/ml
> >>
> >>
> >>
> >> --
> >> ---------------------
> >> Gershon Bialer
> >> _______________________________________________
> >> ml mailing list
> >> ml at lists.noisebridge.net
> >> https://www.noisebridge.net/mailman/listinfo/ml
> >
> >
>
>
>
> --
> ---------------------
> Gershon Bialer
> _______________________________________________
> ml mailing list
> ml at lists.noisebridge.net
> https://www.noisebridge.net/mailman/listinfo/ml
>
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