[R] Limitations of audio processing in R

Thu Sep 22 00:23:30 CEST 2011

Once again, I would myself be inclined to farm this out
(in Linux) to the tools which come with the system. In this
case the command "dd" is useful (though one may need to be
careful about setting the options.

For instance,

  dd -bs=1 skip=54321 count=31415 if=infile of=outfile

would (having set block-size to bs=1 byte) copy count=31415
bytes (blocks) from the input file "infile" (if=infile),
starting at but position 54322 (skip=54321), and write
the result to "outfile" (of=outfile).

Ted.

On 21-Sep-11 22:08:02, Spencer Graves wrote:
> A more general question:  What tools are available in R for reading 
> parts of binary files?  'scan' allows you to 'skip' a certain number of
> records and read the next 'nlines'.  Unfortunately, scan only seems to 
> work for text files not binary, and I cannot find a comparable function
> that would work for binary files.  I tried library(sos);  (rb <- 
> findFn('read binary')).  This produced 299 matches.  Something there 
> might solve the problem, but I haven't taken the time to study it 
> carefully.  I hope someone else will know.
> 
> 
>        Spencer
> 
> 
> On 9/21/2011 2:15 PM, Ken wrote:
>> Also with Linux you can add more swap memory(which I'm pretty sure R
>> spills into if it hasn't reached it's  internal limits on 32 bit
>> installations). Windows pagefile is kind of obnoxious.
>>     Ken Hutchison
>>
>> On Sep 21, 2554 BE, at 5:05 PM, (Ted
>> Harding)<ted.harding at wlandres.net>  wrote:
>>
>>> Hi Ulisses!
>>> Yes, "get more creative" -- or "get more memory"!
>>>
>>> On the "creative" side, it may be worth thinking about
>>> using an independent (non-R) audio file editor. I'm
>>> writing from the standpoint of a Linux/Unixoid user
>>> here -- I wouldn;t know how to set ebout this in WIndows.
>>>
>>> You could use R to create a shell script which would run
>>> the editor in such a way as to extract your 6 random samples,
>>> and save them, where the script would be fed with the
>>> randomly-chosen 5-minute intervals decided by R. This
>>> could be done under the control of R, so you could set
>>> it up for your 1500 or so sets of samples, which (with
>>> the right editing program) could be done quite quickly.
>>>
>>> On Linux (also available for Windows) a flexible audio
>>> editor is 'sox' -- see:
>>>
>>>   http://en.wikipedia.org/wiki/SoX
>>>
>>> To take, say, a 5-minute sample starting at 1 hour,
>>> 10 min and 35sec into the audio file "infile.wav",
>>> and save this as "outfile.wav", you can execute
>>>
>>>   sox infile.wav outfile.wav trim 01:10:35 00:05:00
>>>
>>> and such a command could easily be generated by R and
>>> fed to a shell script (or simply executed from R by
>>> using the system() command). My test just now with
>>> a 5-minute long sample from a .wav file was completed
>>> in about 5 seconds, so it is quite efficient.
>>>
>>> There is a huge number of options for 'sox', allowing
>>> you to manipulate almost any aspect of the editing.
>>>
>>> Hoping this helps,
>>> Ted.
>>>
>>>
>>> On 21-Sep-11 19:55:22, R. Michael Weylandt wrote:
>>>> If you are running Windows it may be as simple as using
>>>> memory.limit() to allow R more memory -- if you are on
>>>> another OS, it may be possible to get the needed memory
>>>> by deleting various things in your workspace and running
>>>> gc()
>>>>
>>>> Of course, if your computer's memory is<3GB, you are
>>>> probably going to have trouble with R's keeping all objects
>>>> in memory and will have to get more creative.
>>>>
>>>> Michael
>>>>
>>>> On Wed, Sep 21, 2011 at 3:43 PM, Ulisses.Camargo<
>>>> moliterno.camargo at gmail.com>  wrote:
>>>>
>>>>> Hello everybody
>>>>>
>>>>> I am trying to process audio files in R and had some problems
>>>>> with files size. IÂ´m using R packages 'audio' and 'sound'.
>>>>> IÂ´m trying a really simple thing and it is working well with
>>>>> small sized .wav files. When I try to open huge audio files
>>>>> I received this error message: "cannot allocate vector of
>>>>> size 2.7 Gb". My job is open in R a 3-hour .wav file, make six
>>>>> 5-minute random audio subsamples, and than save these new files.
>>>>> I have to do the same process +1500 times. My problems is not
>>>>> in build the function to do the job, but in oppening the 3-hour
>>>>> files. Does anybody knows how to handle big audio files in R?
>>>>> Another package that allows me to do this work? I believe
>>>>> this is a really simple thing, but I really donÂ´t know what
>>>>> to do to solve that memory problem.
>>>>>
>>>>> Thank you very much for your answers,
>>>>> all the best!
>>>>>
>>>>> Ulisses
>>> --------------------------------------------------------------------
>>> E-Mail: (Ted Harding)<ted.harding at wlandres.net>
>>> Fax-to-email: +44 (0)870 094 0861
>>> Date: 21-Sep-11                                       Time: 22:05:55
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>>>
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>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
> 
> 
> -- 
> Spencer Graves, PE, PhD
> President and Chief Technology Officer
> Structure Inspection and Monitoring, Inc.
> 751 Emerson Ct.
> San JosÃ©, CA 95126
> ph:  408-655-4567
> web:  www.structuremonitoring.com

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E-Mail: (Ted Harding) <ted.harding at wlandres.net>
Fax-to-email: +44 (0)870 094 0861
Date: 21-Sep-11                                       Time: 23:23:23
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