Because if a RTP packet is due and hasn&#39;t arrived yet you need something to play. Audio isn&#39;t like TCP where you dropped packets can be retransmitted, if it hasn&#39;t arrived by the time you want to play it it&#39;s too late and you have to play silence to handle it.<div>

<br></div><div>Your audio problems are more likely due to packet loss or jitter which is why the RTP packet is overdue, not the CNG itself.</div><div><br></div><div>It jitter&#39;s the problem enabling the jitterbuffer might help (at the expense of increased lag). If loss is the problem there&#39;s no way to handle that except as silence for the missing interval, you need to fix whatever is causing the loss.</div>

<div><br></div><div>-Steve</div><div><br></div><div><br><div class="gmail_quote">On 5 February 2013 10:23, Xijing Dai <span dir="ltr">&lt;<a href="mailto:dxj19831029@gmail.com" target="_blank">dxj19831029@gmail.com</a>&gt;</span> wrote:<br>

<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hey all,<div><br></div><div><br></div><div>Inside code</div><div><br></div><div>switch_rtp.c file:</div><div><br></div>

<blockquote>   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)<br>
                 ................<br>                 if (check || (bytes &amp;&amp; !switch_test_flag(rtp_session, SWITCH_RTP_FLAG_USE_TIMER))) {<br><span style="white-space:pre-wrap">			</span>if (!bytes &amp;&amp; switch_test_flag(rtp_session, SWITCH_RTP_FLAG_USE_TIMER)) {<span style="white-space:pre-wrap">	</span>/* We&#39;re late! We&#39;re Late! */<br>


<span style="white-space:pre-wrap">				</span>if (!switch_test_flag(rtp_session, SWITCH_RTP_FLAG_NOBLOCK) &amp;&amp; status == SWITCH_STATUS_BREAK) {<br><span style="white-space:pre-wrap">					</span>switch_cond_next();<br>


<span style="white-space:pre-wrap">					</span>continue;<br><span style="white-space:pre-wrap">				</span>}<br><span style="white-space:pre-wrap">				<br></span><span style="white-space:pre-wrap">				</span>return_cng_frame();  &lt;------- this lane to return cng frame if late.<br>


<span style="white-space:pre-wrap">			</span>}<br><span style="white-space:pre-wrap">		</span>}<br><br><br></blockquote>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.<div>


<br></div><div>Can I disable return CNG frame?<br><div><br></div><div><br></div><div>Cheers<br><blockquote><br><br><br><br></blockquote></div></div>
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