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<title>Speex: A free codec for free speech</title>
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<h1>Codec Quality Comparison</h1>
<p> Warning: these are machine-generated results (not from real listeners) and hence should be taken with a grain of salt.</p>
<p align="center"><a href="nb_codecs.png"><img src="nb_codecs_small.png" width="598" height="429"></a></p>
<h1>Codec Feature Comparison</h1>
<table border="2" cellpadding="2" width="100%">
<thead>
<tr>
<th>Codec</th>
<th>Rate (kHz)</th>
<th>bitrate (kbps)</th>
<th>delay frame+lookahead (ms)</th>
<th><a href="#multiRate">multi-rate</a></th>
<th><a href="#embedded">embedded</a></th>
<th><a href="#vbr"><abbr title="variable bitrate">VBR</abbr></a></th>
<th><a href="#plc"><abbr title="packet loss concealment">PLC</abbr></a></th>
<th><a href="#bitRobust">bit-robust</a></th>
<th>license</th>
</tr>
</thead>
<tbody>
<tr class="speex">
<td>Speex</td>
<td>8, 16, 32</td>
<td>
2.15-24.6 (<abbr title="narrowband">NB</abbr>)<br/>
4-44.2 (<abbr title="wideband">WB</abbr>)
</td>
<td>
20+10 (<abbr title="narrowband">NB</abbr>)<br/>
20+14 (<abbr title="wideband">WB</abbr>)
</td>
<td>yes</td>
<td>yes</td>
<td>yes</td>
<td>yes</td>
<td/>
<td>open-source/<br/>free software</td>
</tr>
<tr>
<td>iLBC</td>
<td>8</td>
<td>15.2 or 13.3</td>
<td>20+5 or 30+10</td>
<td/>
<td/>
<td/>
<td>yes</td>
<td/>
<td>no charge, but not open-source</td>
</tr>
<tr>
<td>AMR-NB</td>
<td>8</td>
<td>4.75-12.2</td>
<td>20+5?</td>
<td>yes</td>
<td/>
<td/>
<td>yes</td>
<td>yes</td>
<td>proprietary</td>
</tr>
<tr>
<td>AMR-<abbr title="wideband">WB</abbr><br/>(G.722.2)</td>
<td>16</td>
<td>6.6-23.85</td>
<td>20+5?</td>
<td>yes</td>
<td/>
<td/>
<td>yes</td>
<td>yes</td>
<td>proprietary</td>
</tr>
<tr>
<td>G.722.1 (Siren7)</td>
<td>16</td>
<td>(16) 24, 32</td>
<td>20+20</td>
<td>yes</td>
<td/>
<td/>
<td>yes</td>
<td>yes</td>
<td>no charge, but not open-source</td>
</tr>
<tr>
<td>G.729</td>
<td>8</td>
<td>8</td>
<td>10+5</td>
<td/>
<td/>
<td/>
<td>yes</td>
<td>yes</td>
<td>proprietary</td>
</tr>
<tr>
<td><a href="http://kbs.cs.tu-berlin.de/~jutta/toast.html">GSM-FR</a></td>
<td>8</td>
<td>13</td>
<td>20+?</td>
<td/>
<td/>
<td/>
<td>?</td>
<td>?</td>
<td>patented?</td>
</tr>
<tr>
<td>GSM-EFR</td>
<td>8</td>
<td>12.2</td>
<td>20+?</td>
<td/>
<td/>
<td/>
<td>yes</td>
<td>yes</td>
<td>proprietary</td>
</tr>
<tr>
<td>G.723.1</td>
<td>8</td>
<td>5.3 6.3</td>
<td>37.5</td>
<td/>
<td/>
<td/>
<td>yes</td>
<td>?</td>
<td>proprietary</td>
</tr>
<tr>
<td>G.728</td>
<td>8</td>
<td>16</td>
<td>0.625</td>
<td/>
<td/>
<td/>
<td/>
<td/>
<td>proprietary</td>
</tr>
<tr>
<td>G.722</td>
<td>16</td>
<td>48 56 64</td>
<td>?</td>
<td/>
<td>yes</td>
<td/>
<td/>
<td>?</td>
<td>?</td>
</tr>
</tbody>
</table>
<h2>Definitions</h2>
<dl>
<dt><dfn id="multiRate">multi-rate</dfn></dt>
<dd>
Allows the codec to change bitrate
dynamically, at any moment
</dd>
<dt><dfn id="embedded">embedded</dfn></dt>
<dd>
A codec that embeds narrowband
bitstreams in wideband bitstreams
</dd>
<dt><dfn id="vbr"><abbr title="variable bitrate">VBR</abbr></dfn></dt>
<dd>
Variable bitrate
</dd>
<dt><dfn id="plc"><abbr title="packet loss concealment">PLC</abbr></dfn></dt>
<dd>
Packet loss concealment
</dd>
<dt><dfn id="bitRobust">bit-robust</dfn></dt>
<dd>
Robust to corruption at the bit level,
as found on wireless networks
</dd>
</dl>
<h2>Special Features</h2>
<dl>
<dt>Speex</dt>
<dd>
Speex supports intensity stereo encoding
and 32 kHz sampling
</dd>
<dt>iLBC</dt>
<dd>
iLBC frames are encoded completely
independently; while this provides better
quality when 10% (or more) of the packets
are being dropped, this makes the codec
suboptimal for clean line conditions.
</dd>
</dl>
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