https://wiki.xiph.org/index.php?action=history&feed=atom&title=CELT%2FIETF 2026-05-29T21:54:44Z Revision history for this page on the wiki MediaWiki 1.45.1 https://wiki.xiph.org/index.php?title=CELT/IETF&diff=16390&oldid=prev 2016-06-23T12:30:33Z

<p>Add notice that CELT was merged into Opus</p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:30, 23 June 2016</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td> <td colspan="2" class="diff-lineno">Line 1:</td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{{Obsolete|The CELT codec has been merged into the IETF [[Opus]] codec and is now obsolete}}</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Intro ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Intro ==</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* CELT description and design goals</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* CELT description and design goals</div></td></tr> <!-- diff cache key xiphwiki:diff:1.41:old-15964:rev-16390:php=table --> </table>

EPirat https://wiki.xiph.org/index.php?title=CELT/IETF&diff=15964&oldid=prev 2015-08-18T23:13:28Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 23:13, 18 August 2015</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l62">Line 62:</td> <td colspan="2" class="diff-lineno">Line 62:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* Complete RTP profile</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* Complete RTP profile</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* Possible standardization (IETF or other)</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* Possible standardization (IETF or other)</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[Category:Opus]]</ins></div></td></tr> </table>

MrZeus https://wiki.xiph.org/index.php?title=CELT/IETF&diff=10093&oldid=prev 2009-03-11T14:58:45Z

<p></p> <p><b>New page</b></p><div>== Intro ==<br /> * CELT description and design goals<br /> * CELT RTP profile<br /> * Open issues<br /> <br /> == About CELT ==<br /> * Two types of codecs<br /> ** Speech codecs with low-medium quality and low delay<br /> ** Music codecs with high quality and high delay<br /> * CELT aims for both high quality and &#039;&#039;&#039;very&#039;&#039;&#039; low delay<br /> * Perceptual transform (MDCT) codec<br /> * Developped within the Xiph.Org Foundation<br /> * Reference implementation is open source (BSD-licensed)<br /> * No royalties, avoids known patents in the field<br /> <br /> == Why low delay? ==<br /> * Low delay is critical to live interactions<br /> ** Prevents collisions during conversations (higher sense of presence)<br /> ** Reduces or remove the need for acoustic echo cancellation<br /> ** Allows synchronization for live music performance<br /> * Increased range<br /> ** 1ms reduction = 200 km more in fiber<br /> <br /> == CELT features ==<br /> * Sampling rates from 32 kHz to 48 kHz<br /> * Total algorithmic delay from 2ms to 20 ms (8 ms typical)<br /> * Configurable frame size from 64 samples to 512 samples<br /> * Bit-stream &#039;&#039;not frozen yet&#039;&#039;<br /> <br /> == Comparison with existing codecs ==<br /> * Summary of quality figures, along with delay and bit-rate<br /> <br /> == draft -- Important Facts ==<br /> * The bit-rate is implicitly encoded in the size of the compressed data<br /> * The decoder must know:<br /> ** The frame size (decompressed samples) being transmitted<br /> ** The size of each compressed packet<br /> <br /> == RTP ==<br /> * Lacing values and all?<br /> <br /> == SDP ==<br /> * SDP parameters<br /> ** ptime<br /> ** b=AS: ?<br /> * CELT-specific parameters<br /> ** frame-size=<br /> ** mapping=<br /> ** low-overhead=<br /> <br /> == Examples ==<br /> <br /> == Open issues ==<br /> * Need to negotiate the frame size<br /> * CELT would be more flexible with configuration data (~100 bytes)<br /> ** Configuration packet transmitted at regular interval<br /> ** Incrmentally tramsmitted (one byte at a time)<br /> ** base64-encoded in SDP parameters<br /> <br /> == Future work ==<br /> * Freeze the bit-stream<br /> * Complete RTP profile<br /> * Possible standardization (IETF or other)</div>

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