<div dir="ltr">Santhoshini,<br><br>I-slice clipping has been removed only if it is not the first keyframe. I havent touched the newly introduced logic which clips all concurrent frames at the beginning.<br><div class="gmail_extra">
<br><div class="gmail_quote">On Thu, Apr 10, 2014 at 1:54 PM, Santhoshini Sekar <span dir="ltr"><<a href="mailto:santhoshini@multicorewareinc.com" target="_blank">santhoshini@multicorewareinc.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><br><div class="gmail_extra"><br><br><div class="gmail_quote"><div><div class="h5">On Thu, Apr 10, 2014 at 12:57 PM, <span dir="ltr"><<a href="mailto:deepthi@multicorewareinc.com" target="_blank">deepthi@multicorewareinc.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"># HG changeset patch<br>
# User Deepthi Nandakumar <<a href="mailto:deepthi@multicorewareinc.com" target="_blank">deepthi@multicorewareinc.com</a>><br>
# Date 1397114813 -19800<br>
# Node ID 1c0f1a4ce209badcca1272f87c3917ec69ee1cc7<br>
# Parent 83ccf2f1453ffd91c9fd8b84b72e3d3daacba6c6<br>
ratecontrol: prevent one layer of non-zero I-slice qp clipping [CHANGES OUTPUT].<br>
<br>
This seems to have been an error importing RC code from x264. It could be responsible<br>
for error reports on I-slices (after POC 0) having much higher QP/low visual quality.<br>
Needs review.<br>
<br>
diff -r 83ccf2f1453f -r 1c0f1a4ce209 source/encoder/ratecontrol.cpp<br>
--- a/source/encoder/ratecontrol.cpp Thu Apr 10 11:17:46 2014 +0530<br>
+++ b/source/encoder/ratecontrol.cpp Thu Apr 10 12:56:53 2014 +0530<br>
@@ -554,33 +554,34 @@<br>
q = x265_qp2qScale(accumPQp / accumPNorm);<br>
q /= fabs(param->rc.ipFactor);<br>
}<br>
-<br>
- if (param->rc.rateControlMode != X265_RC_CRF)<br>
+ else if(framesDone > 0)<br></blockquote></div></div></div></div></div></blockquote><div><br></div><div>The above else if part is the only real addition. The remaining stuff is as is. Diff makes it harder to review the exact change. Pls apply the patch and you can see the exact change. <br>
</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div><div class="h5"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
{<br>
- double lqmin = 0, lqmax = 0;<br>
- if (totalBits == 0 && !isVbv)<br>
+ if (param->rc.rateControlMode != X265_RC_CRF)<br>
{<br>
- lqmin = x265_qp2qScale(ABR_INIT_QP_MIN) / lstep;<br>
- lqmax = x265_qp2qScale(ABR_INIT_QP_MAX) * lstep;<br>
- q = Clip3(lqmin, lqmax, q);<br>
- }<br>
- else if (totalBits > 0 || (isVbv && framesDone > 0))<br>
- {<br>
- lqmin = lastQScaleFor[sliceType] / lstep;<br>
- lqmax = lastQScaleFor[sliceType] * lstep;<br>
- if (overflow > 1.1 && framesDone > 3)<br>
- lqmax *= lstep;<br>
- else if (overflow < 0.9)<br>
- lqmin /= lstep;<br>
- q = Clip3(lqmin, lqmax, q);<br>
+ double lqmin = 0, lqmax = 0;<br>
+ if (totalBits == 0 && !isVbv)<br>
+ {<br>
+ lqmin = x265_qp2qScale(ABR_INIT_QP_MIN) / lstep;<br>
+ lqmax = x265_qp2qScale(ABR_INIT_QP_MAX) * lstep;<br>
+ q = Clip3(lqmin, lqmax, q);<br>
+ }<br></blockquote></div></div><div>The above clipping logic is not present in x264. This was consciously introduced only in x265 to clip I slice's qp along with N concurrent frames' qp when frame parallelism is enabled. If I slice's clipping is removed then we need to remove the above piece of code as well. Otherwise the frames following the I frame might have qp that gets clipped - lower than the I frame's qp.</div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="">
+ else if (totalBits > 0 || (isVbv && framesDone > 0))<br>
+ {<br>
+ lqmin = lastQScaleFor[sliceType] / lstep;<br>
+ lqmax = lastQScaleFor[sliceType] * lstep;<br>
+ if (overflow > 1.1 && framesDone > 3)<br>
+ lqmax *= lstep;<br>
+ else if (overflow < 0.9)<br>
+ lqmin /= lstep;<br>
+ q = Clip3(lqmin, lqmax, q);<br>
+ }<br>
}<br>
}<br>
- else<br>
+ else if (qCompress != 1 && param->rc.rateControlMode == X265_RC_CRF)<br>
{<br>
- if (qCompress != 1 && framesDone == 0)<br>
- q = x265_qp2qScale(ABR_INIT_QP) / fabs(param->rc.ipFactor);<br>
+ q = x265_qp2qScale(ABR_INIT_QP) / fabs(param->rc.ipFactor);<br>
}<br>
-<br>
+<br>
q = Clip3(MIN_QPSCALE, MAX_MAX_QPSCALE, q);<br>
qpNoVbv = x265_qScale2qp(q);<br>
<br></div>
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