Editing Sound on the Fly

Tue Jul 12 13:47:27 UTC 2016

Am I missing the obvious? Or is the obvious not stated in the
requirements?

What i mean is that by the time you hear something interesting, it's too
late to start recording. That part of the stream has passed.

In other words, you need to copy from a stream that's buffered by some
amount of time. What amount of time is whatever you judge to be a
sufficient interval of time in order to judge that something is
interesting. I believe radio stations typically use a 7 second delay
where they're taking live calls on air -- in order to edit out people
trying to say nasties on air. That kind of fifo buffer for the stream
should work here, too.

Of course, you have a similar problem at the end of "interesting
segment" You need to make certain you don't cut off the copy too soon.
So, either you brute force by waiting a compensatory of additional time,
or have some way to switch to monitoring the buffered recording in order
to know when to stop copying.

hth

Janina

Willem van der Walt writes:
> Hi,
> Hart mentioned my program called dae (short for digital audio editor), so I
> will try and explain to what extent it might do Martin's job.
> If you convert  your 8-bit raw audio into a wav file using sox or similar,
> you can use dae on it.
> Dae will start playing the file when it is loaded and, while playing, one
> can press a button, f5, to mark the start of a block. This will be when you
> reach the audio that is interesting.
> One can then press f6 when the interesting part is passed.  That block can
> then be written out to a separate file using f8, which allow you to specify
> a file name for the block.
> Alternatively, while the file is playing, one can press p which marks a
> position in the file. Each time you want to have a track boundary, you press
> p.  once you are done, you can press S to split up the file into the tracks
> defined by the marked positions.
> 
> This might almost do what you want, but maybe not quite.
> Dae uses ecasound for the heavy lifting and is written in python.
> HTH, Willem
> 
> 
> On Mon, 11 Jul 2016, Joel Roth wrote:
> 
> > Hi Martin,
> > 
> > > From what you write, I think you want to extract interesting
> > parts of an audio file to another audio file, although you
> > could mean extracting parts of an audio *stream* to a file.
> > 
> > I looked at ecasound. I came up with a plan, but I think it
> > won't work because I don't see an easy way to append output to an
> > existing file.
> > 
> > Nama (which uses ecasound) is another possibility. Nama can
> > extract parts of an audio file, and has some special
> > features for that purpose. Basically, you drop marks in
> > pairs, create a sequence using the content between the
> > marks, and then export the desired audio via mixdown. Right
> > now you have to specify the list of marks to use, but we
> > might find ways to simplify that when dealing with large
> > numbers of marks.
> > 
> > regards,
> > 
> > Joel
> > 
> > Martin McCormick wrote:
> > > 	I am always looking for the easiest way to do things but
> > > am also aware of that quotation which goes "The lazy man works
> > > the hardest."
> > > 
> > > 	I want to play a file which is usually 8-bit audio at
> > > a sampling rate of 8000 samples per second, sometimes called raw
> > > 8-bit audio. If I hear something worth saving, I would like to
> > > copy that part of the stream to a new file and then stop the copy
> > > when the good stuff has passed, just like dubbing from one tape
> > > recorder to another.
> > > 
> > > 	I just installed ecasound as it should be able to
> > > accomplish this task but the question is will mplayer also do this?
> > 
> > > 	The idea is one listens, hears something interesting to
> > > save, starts the recording at the right time and then stops it
> > > after the gem has been saved while the master continues to play.
> > > If a new treasure comes by, start recording again and save that
> > > in the same new file or maybe a series of files depending upon
> > > what one wants.
> > > 
> > > 	Thanks for any suggestions. This audio is radio traffic
> > > so it doesn't need to be high fidelity. One usually wants the
> > > most audio crammed in to the least space.
> > > 
> > > Thanks for all good ideas.
> > > 
> > > Martin WB5AGZ
> > > 
> > > _______________________________________________
> > > Blinux-list mailing list
> > > Blinux-list at redhat.com
> > > https://www.redhat.com/mailman/listinfo/blinux-list
> > 
> > -- 
> > Joel Roth
> > 
> > 
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> > 
> > 
> 
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-- 

Janina Sajka,	Phone:	+1.443.300.2200
			sip:janina at asterisk.rednote.net
		Email:	janina at rednote.net

Linux Foundation Fellow
Executive Chair, Accessibility Workgroup:	http://a11y.org

The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI)
Chair, Accessible Platform Architectures	http://www.w3.org/wai/apa