Re: Adjusting write buffer for recording

[Shane Blaser <shane.blaser@callfire.com>]

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Thanks Jan,

Just to confirm there is no way to have rec not pause once it has started?

I could use silence detection to start the recording then record everything
until we see the set number of seconds of silence ?

Thanks again

Shane


On Mon, Aug 12, 2013 at 10:11 AM, Jan Stary <hans@stare.cz> wrote:

> 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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