[Asterisk-Dev] Re: Audio delay in MeetMe using SIP when not 'q' mode

[Tony Mountifield]

In article <cuqnpq$qj9$1 at softins.clara.co.uk>,
Tony Mountifield <tony at softins.clara.co.uk> wrote:
> In article <4210DE98.9070302 at starnetworks.us>,
> Kevin P. Fleming <kpfleming at starnetworks.us> wrote:
> > Tony Mountifield wrote:
> > 
> > > I am suspecting that the problem is something to do with the conf_play()
> > > of the enter and leave sounds. My guess is that by writing that raw data
> > > into the pseudo device fd, it causes a backlog that never drains, because
> > > the device is only getting emptied at the same rate as the conference is
> > > filling it.
> > 
> > That's very interesting... it certainly seems possible that it could be 
> > the case. It would be pretty simple to test, just replace the "conf 
> > enter" sound with something quite a bit longer (4 or 5 seconds) and 
> > determine if the delay increases accordingly.
> 
> Well I've tried the next best thing: commented out the careful_write that
> is in conf_play(). The delay then went away, even on non-q confs.

I've just had an idea how to fix it.

a) Have conf_play() return the length of the data it wrote.

b) Have a variable 'skiplen', and write the ENTER sound as:

    skiplen += conf_play(conf, ENTER);

c) In the main loop, when processing the voice frames, do this:

    } else if (using_pseudo) {
        if (f->frametype == AST_FRAME_VOICE) {
            if (f->subclass == AST_FORMAT_SLINEAR) {
                /* Carefully write */
                if (skiplen == 0)
                    careful_write(fd, f->data, f->datalen);
                else if (skiplen >= f->datalen)
                    skiplen -= f->datalen;
                else {
                    careful_write(fd, f->data + skiplen, f->datalen - skiplen);
                    skiplen = 0;
                }
            } else
                ast_log(LOG_WARNING, "Huh?  Got a non-linear (%d) frame in the conference\n", f->subclass);
        }
    }

This would then throw away the voice bytes that would have occupied the
space now taken by the Enter sound.

I haven't tested it yet. Will do shortly.

Cheers
Tony
-- 
Tony Mountifield
Work: tony at softins.co.uk - http://www.softins.co.uk
Play: tony at mountifield.org - http://tony.mountifield.org