Re: [ecasound] ecalength

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Subject: Re: [ecasound] ecalength
From: S. Massy (theanaloguekid@tak.net.dhis.org)
Date: Thu May 10 2001 - 20:57:11 EEST


On Thu, 26 Apr 2001, Kai Vehmanen wrote:

> On Wed, 4 Apr 2001, S. Massy wrote:
>
> > I've scribbled this little "program" to make it easy to retrieve the
> > length of a file from the command line. I post it here in the hope
> > that it might be useful to others too. Please note that I'm _not_ a
> > professional programmer, so be nice. :) Please post it back if you
> > bring any improvement to it.
>
> Actually I've been thinking about adding something like this to ecatools.
> I think 'ecalength' would fit to the current util set quite well. And it
> would be good to have a few ECI apps (both C and Python apps) in the
> ecatools set, just to show that not everything needs to be C++ and use
> libecasound directly.
>
> Few suggestions:
> - add support for new ai-* and ao-* commands sets ;)
Done... It was badly needed, of course.
> - usign the recently added ai-get-format/ao-get-format to
> also fetch audio format information
That was an excelent idea, I added it as well.
> - have separate switches for printing individual values;
> ie. by default ecalength/ecafile/ecasomething would
> print all info, but with..
> -l -> print only length in seconds
> -b -> print only sample resolution (bits)
> ... -> and son on
>
> Using the separate switches, you could easily use ecalength in scripts
> ('echo File length is `ecalength -l $1` seconds.).

Ok, here's the approach I took: The default behaviour is still the
exact same as it was except that there's a -t switch to have the
summed length, for when you have multiple files. If the -f switch is
specified the format string is printed as well. Now the -s switch
takes you in "script mode" (a sophisticated term to say that it
becomes script friendly). The default behaviour in -s mode is to print
the length in seconds, but if the -m switch is specified while in -s
mode you will have the time in minutes/seconds. If you specify the -f
switch in -s mode the info given now is the format string (think of it
as a "submode" to script mode). If you're in -sf mode you can have the
different parameters of the format string given to you. For example
-sfr will give you the file's sampling rate. I also made it possible
to set the assumed format (for headerless files). If switches are
specified out of their context (say you specify -r without -sf) they
are just ignored.
So, as an example, suppose that you just finished recording that guitar
take in a .raw file sampled at 48 khz and you want to know how long it is
in minutes and seconds, and nothing more, you would do:
$ ecalength -sma:16,2,48000 guittake.raw

I also tried to make it script friendly by giving different exit status.
-2 = One of the files could not be processed by ecasound.
-1 = One of the files couldn't be opened.
0 = Everything's fine.
1 = Nothing was done, error in command-line, etc.

Well, that's about it I think, you can get it at:
http://www.colba.net/~observer/progstuff

Warning: You might very well find my coding style unreadable, I tend to code
as I write... Oh well, I suppose writers make bad coders and coders bad
writers. :)

>
> > BTW, it would be really nice if it was possible to pass the command
> > and the argument separately. I believe there's already a version of
> > this for floats, couldn't there be one for strings as well? Or have I
> > just missed something?
>
> Even the float-thing is a bit messy, but it was desperately needed (you
> need quite a few bytes to textually represent 64bit floating point
> values). So at least now, I'd like to avoid adding any new ECI calls. But
> I have to think about this some more...
Well, it is not THAT much of an annoyance but it would certainly be nicer if
the args could be passed directly.

Regards,
S. Massy
>
> --
> http://www.eca.cx
> Audio software for Linux!
>
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