Date: Mon, 15 May 2006 14:03:45 +0200 From: Hans Petter Selasky <hselasky@c2i.net> To: Dirk =?iso-8859-1?q?Thannh=E4user?= <dt@dtinnovations.com> Cc: freebsd-isdn@freebsd.org Subject: Re: Sound delay in i4b Message-ID: <200605151403.47796.hselasky@c2i.net> In-Reply-To: <CE5A2D0A-B91D-423C-B1C2-80A74F8EA873@dtinnovations.com> References: <0CDCE7F4-A7D2-4379-9560-516FFF3350C6@dtinnovations.com> <200605150938.28035.hselasky@c2i.net> <CE5A2D0A-B91D-423C-B1C2-80A74F8EA873@dtinnovations.com>
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On Monday 15 May 2006 12:20, Dirk Thannh=E4user wrote:
> On May 15, 2006, at 9:38 AM, Hans Petter Selasky wrote:
> > Hi,
> >
> > On Sunday 14 May 2006 22:57, Dirk Thannh=E4user wrote:
> >> On May 14, 2006, at 3:18 PM, Hans Petter Selasky wrote:
> >>> Do you have SVN installed?
> >>
> >> yes i have. I checked out the version which included both, the i4b
> >> and the chan_capi. Is ist possible that my version was to old?
> >> I just did a new checkout.
> >> Subversion says "Checked out revision 264."
> >
> > That should be the latest version. It was fixed in "Revision 257",
> > which was
> > after that I released Version 1.6.0 in April.
>
> Hmm. i compiled the latest release (i4b and chan_capi) yesterday and
> tested it with the echo test application. The delay is the same as
> before.
> When I call the server internal (My Phone -> ISDNCard(NT) -> Asterisk
> (1.2.4) (isdnd not running. cards set to TE/NT mode via "isdnconfig"
> command . The delay in the echo test application remains unchanged at
> about 250ms to half a second. (not measured, it's just my feeling,
> but i know the difference to the zaptel FreeBSD driver). My machine
> is a Siemens Scenic L (1.6Ghz/512MB RAM). That schould be enough
> power to get low latency.
Sure, but that is only when the computer is not loaded. 50ms interrupts wer=
e=20
chosen because it will allow one to heavily load the computer without loosi=
ng=20
any data.
> How easy would it be to play around with changing latencey. Should i
> take a look to the chan_capi sources to get latency changed?
>
It is not very difficult to play around to get the latency down.
Edit: /usr/src/sys/i4b/layer1/ihfc2/i4b_ihfc2_drv.c
Change:
=2Es_ctmt_pci =3D 0x00 | 0x17, /* t50ms + trans */
Into:
=2Es_ctmt_pci =3D 0x00 | 0x13, /* t25ms + trans */
And change:
/* default AUDIO limit =3D=3D 100ms of data */
/* limit fifo usage to 800 bytes(100ms)
* - Assuming that about 400 bytes(50ms)
* is needed for each interrupt:
*/
f->Z_min_free -=3D 800;
Into:
/* default AUDIO limit =3D=3D 100ms of data */
/* limit fifo usage to 800 bytes(100ms)
* - Assuming that about 400 bytes(50ms)
* is needed for each interrupt:
*/
f->Z_min_free -=3D 400;
> >> Are there any "cheap" HFC-4S cards out there for testing?
> >
> > There exist some developer kits, but they are not so easy to get a
> > hand on.
> > The only place I know that sales HFC-4S are:
>
> A developer Kit would be the card of my choice.
> Does Bero sell them or shoud i contact colognechip?
I don't know.
>
> > http://shop.beronet.com
> >
> > And maybe "http://www.junghanns.net/".
> >
> >> I think that this also means that i am not able to run one card
> >> (HFC-1S) in slave mode, getting the clock from the other to keep them
> >> in sync without soldering.
> >
> > Yes.
> >
> >> For Voice over IP a huger delay might be ok. thats also my opinion.
> >> but what about Faxing over ISDN. Here I think latency is an important
> >> issue. (didn't test the CAPI Fax receiption, yet)
> >
> > Faxing works, but really you need to use line interconnect to get
> > faxing
> > working reliably. Or you can receive the fax in asterisk. That also
> > works.
>
> Does it also work with about 250ms delay? (it exists on both sides
> from my NT-Card to asterisk and also from the TE-Card to asterisk
> may be that i did something wrong compiling the sources although i
> cleaned the BSD sourcetree applied the patches again an then started
> compiling the get a "fresh" state an no confusion with the older
> release which was installed before.
Yes, faxing works with 250ms delay.
=2D-HPS
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