<div dir="ltr"><div>Is there any info how much bandwidth is required for 48kHz audio? How CPU hungry is downsampling to 8kHz G711?<br></div>According to <a href="http://opus-codec.org">opus-codec.org</a>, opus can use sampling rates from 8kHz, not just 48kHz. In cases when the call ends in PSTN, won't be appropriate to support 8kHz sampling rate in FS too?<br>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Aug 1, 2013 at 9:18 PM, Anthony Minessale <span dir="ltr"><<a href="mailto:anthony.minessale@gmail.com" target="_blank">anthony.minessale@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><p dir="ltr">Opus always uses 48khz </p>
<div class="gmail_quote"><div><div class="h5">On Aug 1, 2013 2:15 PM, "Dimosthenis Arkoudeas" <<a href="mailto:dimosthenis@arkoudeas.com" target="_blank">dimosthenis@arkoudeas.com</a>> wrote:<br type="attribution">
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
<div link="#0563C1" vlink="#954F72" lang="EL">
<div>
<p class="MsoNormal"><span lang="EN-US">Hi all,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">Playing with mod_opus came up with the following.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">I am trying to recompile the codec with 8Khz and 40ms ptime. I am not familiar with the codec internals and not really sure what parameters should I change…<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">In mod_opus.c :<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">Line 59:<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US">int bitrate_bps = codec->implementation->bits_per_second;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"> int use_vbr = 1;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"> int complexity = 10;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"> int use_inbandfec = 1;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"> int use_dtx = 1;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"> int bandwidth = OPUS_BANDWIDTH_FULLBAND;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"> </span><span style="font-size:10.0pt;font-family:"Courier New"">int err;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US">I suppose that the bandwidth must be changed to OPUS_BANDWIDTH_NARROWBAND and use_vbr=0 and I haven’t found yet whether the FEC parameter is passed
to opus encoder.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US">And in Line 184 , I think the following parameters must be changed<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"><u></u> <u></u></span></p>
<pre><span lang="EN-US"> </span><span><span lang="EN-US">switch_codec_interface_t</span></span><span lang="EN-US"> *</span><span><span lang="EN-US">codec_interface</span></span><span lang="EN-US">;<u></u><u></u></span></pre>
<pre><span lang="EN-US"> <span>int</span> </span><span><span lang="EN-US">samples</span></span><span lang="EN-US"> = <span>480</span>;<u></u><u></u></span></pre>
<pre><span lang="EN-US"> <span>int</span> </span><span><span lang="EN-US">bytes</span></span><span lang="EN-US"> = <span>960</span>;<u></u><u></u></span></pre>
<pre><span lang="EN-US"> <span>int</span> </span><span><span lang="EN-US">mss</span></span><span lang="EN-US"> = <span>10000</span>;<u></u><u></u></span></pre>
<pre><span lang="EN-US"> <span>int</span> </span><span><span lang="EN-US">x</span></span><span lang="EN-US"> = <span>0</span>;<u></u><u></u></span></pre>
<pre><span lang="EN-US"> <span>int</span> </span><span><span lang="EN-US">rate</span></span><span lang="EN-US"> = <span>48000</span>;<u></u><u></u></span></pre>
<pre><span lang="EN-US"> <span>int</span> </span><span><span lang="EN-US">bits</span></span><span lang="EN-US"> = <span>32000</span>;<u></u><u></u></span></pre>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US">Can you propose any values about these parameters to achieve 8khz with 40ms packet time?
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"" lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">Thanks for any help,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">Dimosthenis<u></u><u></u></span></p>
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