Editing Sound on the Fly

Wed Jul 13 13:50:12 UTC 2016

Thanks for the pointer to the timemachine jack plugin. I remembered
there was such a thing, but I couldn't recall that it was for jack, and
it's kind of hard googling for timemachine because the predominant hits
are Macintosh related.

So, I appreciate the pointer very much.

Janina

Joel Roth writes:
> Janina Sajka wrote:
> > 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.
>  
> There exists a recording utility for that, a plugin that runs under JACK. 
> 
> http://plugin.org.uk/timemachine/
> 
>  
> > 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
> > > > > 
> > > > > _______________________________________________
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> > > > 
> > > > -- 
> > > > 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
> > 
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> 
> -- 
> Joel Roth
>   
> 
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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