In my experience suppress_cng did work but only prevented sending CNG packet.

freeswitch would ignore the late packets because it thought the cng packet had been sent out. it makes a hole in the seq number in B-leg.

So later I modified the switch_rtp.c to change this mechanism. 

On Tue, Feb 5, 2013 at 11:32 AM, Xijing Dai <dxj19831029@gmail.com> wrote:

I see.

 

I did set it suppress_cng=true, and it did not help. No difference at all.

This happens inside LAN.

When talking about the jitter buffer, we want to enable it on client, and disable it inside freeswitch. 

Therefore, in this case, should freeswitch do nothing?

Cheers

On Tue, Feb 5, 2013 at 11:35 PM, Anthony Minessale <anthony.minessale@gmail.com> wrote:

Don't negotiate CNG in the SDP and it won't use it or disable it with suppress_cng=true in your channel or global vars.

On Tue, Feb 5, 2013 at 4:32 AM, Steven Ayre <steveayre@gmail.com> wrote:

Because if a RTP packet is due and hasn't arrived yet you need something to play. Audio isn't like TCP where you dropped packets can be retransmitted, if it hasn't arrived by the time you want to play it it's too late and you have to play silence to handle it.

Your audio problems are more likely due to packet loss or jitter which is why the RTP packet is overdue, not the CNG itself.

It jitter's the problem enabling the jitterbuffer might help (at the expense of increased lag). If loss is the problem there's no way to handle that except as silence for the missing interval, you need to fix whatever is causing the loss.

-Steve

On 5 February 2013 10:23, Xijing Dai <dxj19831029@gmail.com> wrote:

Hey all,

Inside code

switch_rtp.c file:

   static int rtp_common_read(switch_rtp_t *rtp_session, switch_payload_t *payload_type, switch_frame_flag_t *flags, switch_io_flag_t io_flags)
                 ................
                 if (check || (bytes && !switch_test_flag(rtp_session, SWITCH_RTP_FLAG_USE_TIMER))) {
if (!bytes && switch_test_flag(rtp_session, SWITCH_RTP_FLAG_USE_TIMER)) { /* We're late! We're Late! */
if (!switch_test_flag(rtp_session, SWITCH_RTP_FLAG_NOBLOCK) && status == SWITCH_STATUS_BREAK) {
switch_cond_next();
continue;
}

return_cng_frame();  <------- this lane to return cng frame if late.
}
}

Could someone explain why we want to return cng frame when package is late? this is caused for me to hear very bad noise audio.

Can I disable return CNG frame?

Cheers

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