Hi All,
What are your comments about the following conversation regarding T.38
support for PJSIP.
Regards,
Sandeep Malik
---------- Forwarded message ----------
From: Sandeep Mailk <malik.mca@xxxxxxxxx>
Date: Thu, Feb 19, 2009 at 8:26 PM
Subject: Re: Regarding T.38 Fax
To: Gang Liu <gangban.lau at gmail.com>
Hi Gang,
You are right the PJSUA api don't export the API's for handling our own SDP
so what I have done is as follows:
For Tx side:
I had to Tap the pjsua_call_set_hold function and wrote a new function named
pjsua_media_channel_create_T38sdp which is similar to the
pjsua_media_channel_create_sdp.
For Rx side:
I had to tap the on_rx_offer function which again uses the
pjsua_media_channel_create_T38sdp function to create the T.38 sdp
The function pjsua_media_channel_create_T38sdp internally calls another
function named pjmedia_endpt_create_T38sdp which does the creation of T.38
SDP and is a modified version of pjmedia_endpt_create_sdp.
Now I am able to send the updated SDP with T.38 parameters in reInvite but
the issue comes while processing the offer. When an offer is processed
function pjmedia_session_info_from_sdp is called which does parsing of offer
recieved in SDP. But since the T.38 is not supported as a standard part of
PJSIP the stack send BYE.
To solve this one way would be to write another function which does parsing
of recieved offer but if you can suggest a better way it would be good for
me. I just started working on PJSIP so don't have much idea about the
consequences of all such modifications.
Regards,
Sandeep Malik
On Thu, Feb 19, 2009 at 4:07 PM, Gang Liu <gangban.lau at gmail.com> wrote:
> I used my own function to handle re-INVITE because my apps need wait
> some time to get related media information. And I can't block at
> on_rx_offer().
> I think it is more better to use on_rx_offer if you can.
>
> I am using pjsip-ua, not pjsua api.
>
> As I remember, pjsua api don't export function for handling our own
> SDP. So maybe it need
> patch pjsua api for T.38 fax handling. Correct me if I am wrong.
>
>
> regards,
> Gang
>
> On Wed, Feb 18, 2009 at 6:48 PM, Sandeep Mailk <malik.mca at gmail.com>
> wrote:
> > Hi Gang,
> >
> > And when are you calling this function to create the SDP offer/answer? I
> > mean have you written your own function to override the
> > pjsua_call_on_rx_offer function or you are calling this from inside of
> that
> > function?
> >
> > Regards,
> > Sandeep Malik
> >
> > On Tue, Feb 3, 2009 at 12:08 PM, Gang Liu <gangban.lau at gmail.com> wrote:
> >>
> >> I create my own SDP offer/answer for T.38 fax like below:
> >>
> >> CallRec is my own struct. And some value for t38 params are hardcoded.
> >>
> >> /*
> >> * Create SDP offer/answer for T.38 FAX.
> >> * is_sdp_answer, whether SDP answer or offer
> >> */
> >> int sdp_t38_create(CallRec * call, pjmedia_sdp_session **p_sdp,
> >> pj_bool_t is_sdp_answer)
> >> {
> >> pj_pool_t *pool;
> >> pjmedia_sdp_session *sdp;
> >> pjmedia_sdp_media *m;
> >> pjmedia_sdp_attr *attr;
> >>
> >> if (call->data.is_assigned && call->data.inv)
> >> pool = call->data.inv->dlg->pool;
> >> else
> >> return -1;
> >>
> >> /* Create and initialize basic SDP session */
> >> sdp = (pjmedia_sdp_session *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_session));
> >>
> >> sdp_set_origin(call, sdp);
> >>
> >> sdp->name = pj_str("SIP CALL");
> >>
> >> /* Since we only support one media stream at present, put the
> >> * SDP connection line in the session level.
> >> */
> >> sdp->conn = (pjmedia_sdp_conn *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_conn));
> >> sdp->conn->net_type = pj_str("IN");
> >> sdp->conn->addr_type = pj_str("IP4");
> >> sdp->conn->addr = pj_str(call->data.local_sdp_audio_ip);
> >>
> >> /* SDP time */
> >> sdp->time.start = sdp->time.stop = 0;
> >>
> >> /* Create media stream 0: */
> >> sdp->media_count = 1;
> >> m = (pjmedia_sdp_media *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_media));
> >> sdp->media[0] = m;
> >>
> >> /* Standard media info: */
> >> m->desc.media = pj_str("image");
> >> m->desc.port = call->data.local_sdp_audio_port;
> >> m->desc.port_count = 1;
> >> m->desc.transport = pj_str("udptl");
> >>
> >> /* Add format and rtpmap for each codec. */
> >> m->desc.fmt_count = 0;
> >> m->attr_count = 0;
> >>
> >> m->desc.fmt[m->desc.fmt_count++] = pj_str("t38");
> >>
> >> if (is_sdp_answer)
> >> {
> >>
> >> {
> >> attr = (pjmedia_sdp_attr *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_attr));
> >> attr->name = pj_str("T38FaxVersion");
> >>
> >> char ptstr[10];
> >> snprintf(ptstr, sizeof(ptstr), "%d", 0);
> >> pj_strdup2(pool, &attr->value, ptstr);
> >>
> >> m->attr[m->attr_count++] = attr;
> >> }
> >>
> >> {
> >> attr = (pjmedia_sdp_attr *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_attr));
> >> attr->name = pj_str("T38MaxBitRate");
> >>
> >> char ptstr[10];
> >> snprintf(ptstr, sizeof(ptstr), "%d",
> >> globaldata.t38_max_bit_rate);
> >> pj_strdup2(pool, &attr->value, ptstr);
> >>
> >> m->attr[m->attr_count++] = attr;
> >> }
> >>
> >> {
> >> attr = (pjmedia_sdp_attr *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_attr));
> >> attr->name = pj_str("T38FaxFillBitRemoval");
> >>
> >> char ptstr[10];
> >> snprintf(ptstr, sizeof(ptstr), "%d", 0);
> >> pj_strdup2(pool, &attr->value, ptstr);
> >>
> >> m->attr[m->attr_count++] = attr;
> >> }
> >>
> >> {
> >> attr = (pjmedia_sdp_attr *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_attr));
> >> attr->name = pj_str("T38FaxTranscodingMMR");
> >>
> >> char ptstr[10];
> >> snprintf(ptstr, sizeof(ptstr), "%d", 0);
> >> pj_strdup2(pool, &attr->value, ptstr);
> >>
> >> m->attr[m->attr_count++] = attr;
> >> }
> >>
> >> {
> >> attr = (pjmedia_sdp_attr *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_attr));
> >> attr->name = pj_str("T38FaxTranscodingJBIG");
> >>
> >> char ptstr[10];
> >> snprintf(ptstr, sizeof(ptstr), "%d", 0);
> >> pj_strdup2(pool, &attr->value, ptstr);
> >>
> >> m->attr[m->attr_count++] = attr;
> >> }
> >>
> >> {
> >> attr = (pjmedia_sdp_attr *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_attr));
> >> attr->name = pj_str("T38FaxRateManagement");
> >>
> >> char ptstr[32];
> >> snprintf(ptstr, sizeof(ptstr), "%s",
> >> "transferredTCF");
> >> pj_strdup2(pool, &attr->value, ptstr);
> >>
> >> m->attr[m->attr_count++] = attr;
> >> }
> >>
> >> {
> >> attr = (pjmedia_sdp_attr *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_attr));
> >> attr->name = pj_str("T38FaxMaxBuffer");
> >>
> >> char ptstr[10];
> >> snprintf(ptstr, sizeof(ptstr), "%d",
> >> globaldata.t38_fax_max_buf);
> >> pj_strdup2(pool, &attr->value, ptstr);
> >>
> >> m->attr[m->attr_count++] = attr;
> >> }
> >>
> >> {
> >> attr = (pjmedia_sdp_attr *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_attr));
> >> attr->name = pj_str("T38FaxMaxDatagram");
> >>
> >> char ptstr[10];
> >> snprintf(ptstr, sizeof(ptstr), "%d",
> >> globaldata.t38_fax_max_datagram);
> >> pj_strdup2(pool, &attr->value, ptstr);
> >>
> >> m->attr[m->attr_count++] = attr;
> >> }
> >>
> >> {
> >> attr = (pjmedia_sdp_attr *)pj_pool_zalloc(pool,
> >> sizeof(pjmedia_sdp_attr));
> >> attr->name = pj_str("T38FaxUdpEC");
> >>
> >> char ptstr[32];
> >> snprintf(ptstr, sizeof(ptstr), "%s",
> >> "t38UDPRedundancy");
> >> pj_strdup2(pool, &attr->value, ptstr);
> >>
> >> m->attr[m->attr_count++] = attr;
> >> }
> >>
> >> }
> >>
> >> /* Done */
> >> *p_sdp = sdp;
> >>
> >> return PJ_SUCCESS;
> >> }
> >>
> >> On Tue, Feb 3, 2009 at 1:14 PM, Sandeep Mailk <malik.mca at gmail.com>
> wrote:
> >> > Hi Gang,
> >> >
> >> > Thank you for response. Can you please share the sample code
> >> > demonstrating
> >> > how the implementation is being done for T.38 which we can use as a
> >> > reference?
> >> >
> >> > Regards,
> >> > Sandeep Malik
> >> >
> >> > On Tue, Feb 3, 2009 at 10:40 AM, Gang Liu <gangban.lau at gmail.com>
> wrote:
> >> >>
> >> >> What issues?
> >> >> It is ok for me pjsip 0.9.0-release. I use pjsip-ua api.
> >> >>
> >> >> regards,
> >> >> Gang
> >> >>
> >> >> On Fri, Jan 30, 2009 at 3:20 PM, Sandeep Mailk <malik.mca at gmail.com>
> >> >> wrote:
> >> >> > Hi,
> >> >> >
> >> >> > I am using PJSIP version 0.7 and trying to send T.38 Fax but I am
> >> >> > facing
> >> >> > some issues. Do we have some working example of T.38 fax integrated
> >> >> > with
> >> >> > PJSIP?
> >> >> >
> >> >> > --
> >> >> > Regards,
> >> >> > Sandeep Malik
> >> >> > +919818184745
> >> >> >
> >> >> > _______________________________________________
> >> >> > Visit our blog: http://blog.pjsip.org
> >> >> >
> >> >> > pjsip mailing list
> >> >> > pjsip at lists.pjsip.org
> >> >> > http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org
> >> >> >
> >> >> >
> >> >>
> >> >> _______________________________________________
> >> >> Visit our blog: http://blog.pjsip.org
> >> >>
> >> >> pjsip mailing list
> >> >> pjsip at lists.pjsip.org
> >> >> http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org
> >> >
> >> >
> >> >
> >
> >
>
--
Regards,
Sandeep Malik
+919818184745
--
Regards,
Sandeep Malik
+919818184745
--
Regards,
Sandeep Malik
+919818184745
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