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--></style></head><body lang="EN-US" link="#0563C1" vlink="#954F72"><div class="WordSection1"><p class="MsoNormal"><span style="color:#1f497d">Hi Damian,</span></p><p class="MsoNormal"><span style="color:#1f497d">We have a team that is also working on improving analysis save/load/refine, for a variety of interesting applications (not just multi-bitrate encoding). We would be interested in evaluating your contributions for possible inclusion in x265, but we would first need you to sign our <a href="https://bitbucket.org/multicoreware/x265/downloads/x265ContributorAgreement.pdf">Contributor License Agreement</a>.</span></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="color:#1f497d">If you would like to collaborate directly with our team, we would be happy to arrange a phone call to discuss.</span></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="color:#1f497d">Best regards,</span></p><p class="MsoNormal"><span style="color:#1f497d">Tom</span></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:10.5pt;color:black">-- </span><span style="color:#1f497d"></span></p><p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1c53b9">Tom Vaughan | VP and GM, Video | MulticoreWare, Inc. </span></p><p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Verdana","sans-serif";color:#1c53b9">12930 Saratoga Avenue, Suite B1, Saratoga, CA 95070 USA </span><span style="color:#1f497d"></span></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p><div><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in 0in"><p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> x265-devel [mailto:<a href="mailto:x265-devel-bounces@videolan.org">x265-devel-bounces@videolan.org</a>] <b>On Behalf Of </b>Schroeder, Damien<br><b>Sent:</b> Wednesday, August 10, 2016 6:13 AM<br><b>To:</b> <a href="mailto:x265-devel@videolan.org">x265-devel@videolan.org</a><br><b>Subject:</b> [x265] multi-rate feature</span></p></div></div><p class="MsoNormal"> </p><p class="MsoNormal">Hello,<span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal">I recently implemented a „multi-rate“ feature for x265 based on the latest x265 version. The target application is adaptive HTTP streaming, where you need the same video encoded at different representations. Basically, if you need to encode the same video at different bitrates (different qualities), the multi-rate method allows you to pass some analysis info from a high-quality reference encoding to lower quality dependent encodings, which is then used to constrain the RDO (and thus, this leads to a speed-up).<span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal">This is similar to the analysis-mode option already existing in x265. However, this analysis-mode option is not targeted at encodings at different qualities (the rate-distortion performance is degraded if you use this option across different qualities).<span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal">I put my code on github for the moment: <a href="https://github.com/damjeux/multi-rate-x265">https://github.com/damjeux/multi-rate-x265</a><span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal">When mr-mode is 1, the CU structure of each CTU is stored in an external file called analysisData.bin<span lang="DE"></span></p><p class="MsoNormal">When mr-mode is 2, analysisData.bin is loaded and the loaded CU structure is used to constrain the RDO by stopping the recursion in the different compressInterCU and compressIntraCU functions in analysis.cpp<span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal">I have posted some results in a blog post: <a href="https://damienschroeder.wordpress.com/2016/08/10/multi-rate-hevc-with-x265-for-adaptive-http-streaming/">https://damienschroeder.wordpress.com/2016/08/10/multi-rate-hevc-with-x265-for-adaptive-http-streaming/</a><span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal">The implemented method performs better for high rd-levels (--rd 5 and 6), because the compressInterCU_rd0_4() function already constrains the CTU quadtree by using a minDepth.<span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal">For example, with --rd 6, I get an average reduction in encoding time of 10% with no rate-distortion performance decrease (BD-rate -0.002%) in the case where I encode four representations with fixed QP 22, 27, 32, and 37.<span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal">With crf 22, 27, 32, and 37, I get an average encoding time reduction of 19% and the rate-distortion performance is slightly degraded (BD-rate 0.9%).<span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal">Not sure if there is interest to include such a feature in the official x265, but I thought I should mention this.<span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal">Best regards,<span lang="DE"></span></p><p class="MsoNormal">Damien Schroeder<span lang="DE"></span></p><p class="MsoNormal"> <span lang="DE"></span></p><p class="MsoNormal"><span lang="DE"> </span></p><p class="MsoNormal"><i><span lang="DE" style="font-size:9.0pt">Dipl.-Ing. Damien Schroeder</span></i><span lang="DE"></span></p><p class="MsoNormal"><i><span lang="DE" style="font-size:9.0pt;color:black">Technische Universität München</span></i><span lang="DE"></span></p><p class="MsoNormal"><i><span lang="DE" style="font-size:9.0pt">Lehrstuhl für Medientechnik</span></i><span lang="DE"></span></p><p class="MsoNormal"><i><span lang="DE" style="font-size:9.0pt;color:black">Chair of Media Technology</span></i><span lang="DE"></span></p><p class="MsoNormal"><i><span lang="DE" style="font-size:9.0pt;color:black">Arcisstr. 21, 80333 München</span></i><span lang="DE"></span></p><p class="MsoNormal"><i><span style="font-size:9.0pt;color:black">Building 9, Room 1934</span></i><span lang="DE"></span></p><p class="MsoNormal"><i><span style="font-size:9.0pt;color:black">Phone:</span></i><i><span style="font-size:9.0pt"> <span style="color:black">+49 89 289 23507</span></span></i><span lang="DE"></span></p><p class="MsoNormal"><i><span style="font-size:9.0pt;color:black">Fax:</span></i><i><span style="font-size:9.0pt"> <span style="color:black">+49 89 289 23523</span></span></i><span lang="DE"></span></p><p class="MsoNormal"><i><span style="font-size:9.0pt;color:black">Email:</span></i><i><span style="font-size:9.0pt"> <span style="color:black"><a href="mailto:damien.schroeder@tum.de"><span style="color:blue">damien.schroeder@tum.de</span></a></span></span></i><span lang="DE"></span></p><p class="MsoNormal"><i><span style="font-size:9.0pt;color:black">Web: <a href="http://www.lmt.ei.tum.de/"><span style="color:blue">www.lmt.ei.tum.de</span></a></span></i><span lang="DE"></span></p><p class="MsoNormal"><span lang="DE"> </span></p><p class="MsoNormal"> <span lang="DE"></span></p></div></body></html>