Re: Adjusting write buffer for recording

[Jan Stary <hans@stare.cz>]

On Aug 12 09:16:32, shane.blaser@callfire.com wrote:
> > On Aug 12 07:31:24, shane.blaser@callfire.com wrote:
> > > Yes i am calling stat,
> >
> > Wouldn't it be easire to just write to a pipe,
> > and have your application read from that pipe?
> >
> Maybe not sure the file seems to work.

No doubt, but you have to call stat() in a loop
to find out whether the file has grown; with a pipe,
you would just be read()ing and getting the data (or not).

> > > 1. rec listening with silence detection
> > > 2. Call comes in and recording starts.
> > > 3. Caller id is between 1st and second ring.
> > > (ok this is were the issue comes in)
> > > after the first ring I get the first part of the caller id signal written
> > > to disk (call it 1/2 of the caller id signal).
> >
> > Let me understand this: in the phone calls you are recording,
> > there is a piece of _audio_ signal, comming between the
> > first and second ring, which carries the caller's ID.
> > Is that right? Can you please elaborate? I never knew
> > there is something like that coming on a phone line.
> >
> yes it is audible and it sounds like a fax machine or modem ..

> > > But not until after the second ring
> > > do I get the audio for the rest of the caller id written to disk.
> > > Can I have rec write silence to the file after the recording starts?
> >
> > Of course: just rec(1) everything,
> > without using the 'silence' effect.
> 
> > What you are doing now is the exact opposite:
> > you are telling rec(1) _not_ to write until
> > a certain treshold of 'silence' is surpassed.
> >
> > I am too lazy now to look up your exact 'silence' parameters,
> > but could it be that the caller ID audio signal contains
> > enough 'silence' so that rec(1) pauses?
> >
> After the caller id signal there is a silence until the next ring ...
> 
> Do you see any way for me to adjust the write buffers, if I can make them
> smaller I think this issue will fall away ...?

This has nothing to do with buffers.

You are running rec(1) with the silence effect.
That makes rec(1) pause when it sees the silence.
Just run rec(1) without the silence effect - that
way, rec will just write everything, without pausing
at the 'silent' moments.

The writing will of course be buffered, and you can play
with --buffer to make the continuous writing more smooth.
But that's not your problem now: rec waits with writing
because you are telling it to wait (for a non-silence).

	Jan


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