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.hard...@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.cama...@gmail.com> wrote:
Hello everybody
I am trying to process audio files in R and had some problems
with files size. I´m using R packages 'audio' and 'sound'.
I´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 don´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.hard...@wlandres.net>
Fax-to-email: +44 (0)870 094 0861
Date: 21-Sep-11 Time: 22:05:55
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