[x265] [PATCH] x265: implemented crf-min that specifies a minimum rate factor value for encode

[gopu at multicorewareinc.com]

# HG changeset patch
# User Gopu Govindaswamy
# Date 1399524053 -19800
#      Thu May 08 10:10:53 2014 +0530
# Node ID 7a3657ff29e24b7832002b76b3f9096736d20a36
# Parent  6494bb2e64253fc0f9413b88933634d1f37c4881
x265: implemented crf-min that specifies a minimum rate factor value for encode

diff -r 6494bb2e6425 -r 7a3657ff29e2 source/common/param.cpp
--- a/source/common/param.cpp	Wed May 07 14:03:25 2014 -0500
+++ b/source/common/param.cpp	Thu May 08 10:10:53 2014 +0530
@@ -604,6 +604,7 @@
     OPT("vbv-bufsize") p->rc.vbvBufferSize = atoi(value);
     OPT("vbv-init")    p->rc.vbvBufferInit = atof(value);
     OPT("crf-max")     p->rc.rfConstantMax = atof(value);
+    OPT("crf-min")     p->rc.rfConstantMin = atoi(value);
     OPT("crf")
     {
         p->rc.rfConstant = atof(value);
diff -r 6494bb2e6425 -r 7a3657ff29e2 source/encoder/encoder.cpp
--- a/source/encoder/encoder.cpp	Wed May 07 14:03:25 2014 -0500
+++ b/source/encoder/encoder.cpp	Thu May 08 10:10:53 2014 +0530
@@ -1342,6 +1342,12 @@
         x265_log(p, X265_LOG_WARNING, "Support for interlaced video is experimental\n");
     }
 
+    if (p->rc.rfConstantMin > p->rc.rfConstant)
+    {
+        x265_log(param, X265_LOG_WARNING, "CRF min must be less than CRF\n");
+        p->rc.rfConstantMin = 0;
+    }
+
     m_bframeDelay = p->bframes ? (p->bBPyramid ? 2 : 1) : 0;
 
     //====== Coding Tools ========
diff -r 6494bb2e6425 -r 7a3657ff29e2 source/encoder/ratecontrol.cpp
--- a/source/encoder/ratecontrol.cpp	Wed May 07 14:03:25 2014 -0500
+++ b/source/encoder/ratecontrol.cpp	Thu May 08 10:10:53 2014 +0530
@@ -207,6 +207,7 @@
     param->rc.rfConstant = Clip3((double)-QP_BD_OFFSET, (double)51, param->rc.rfConstant);
     param->rc.rfConstantMax = Clip3((double)-QP_BD_OFFSET, (double)51, param->rc.rfConstantMax);
     rateFactorMaxIncrement = 0;
+    rateFactorMaxDecrement = 0;
 
     if (param->rc.rateControlMode == X265_RC_CRF)
     {
@@ -226,6 +227,8 @@
                 rateFactorMaxIncrement = 0;
             }
         }
+        if (param->rc.rfConstantMin)
+            rateFactorMaxDecrement = param->rc.rfConstant - param->rc.rfConstantMin;
     }
 
     isAbr = param->rc.rateControlMode != X265_RC_CQP; // later add 2pass option
@@ -851,10 +854,15 @@
     /* tweak quality based on difference from predicted size */
     double prevRowQp = qpVbv;
     double qpAbsoluteMax = MAX_MAX_QP;
+    double qpAbsoluteMin = MIN_QP;
     if (rateFactorMaxIncrement)
         qpAbsoluteMax = X265_MIN(qpAbsoluteMax, rce->qpNoVbv + rateFactorMaxIncrement);
+
+    if (rateFactorMaxDecrement)
+        qpAbsoluteMin = X265_MAX(qpAbsoluteMin, rce->qpNoVbv - rateFactorMaxIncrement);
+
     double qpMax = X265_MIN(prevRowQp + param->rc.qpStep, qpAbsoluteMax);
-    double qpMin = X265_MAX(prevRowQp - param->rc.qpStep, MIN_QP);
+    double qpMin = X265_MAX(prevRowQp - param->rc.qpStep, qpAbsoluteMin);
     double stepSize = 0.5;
     double bufferLeftPlanned = rce->bufferFill - rce->frameSizePlanned;
 
@@ -922,6 +930,12 @@
             qpVbv = Clip3(prevRowQp + 1.0f, qpMax, (prevRowQp + qpVbv) * 0.5);
             return -1;
         }
+
+        if (qpVbv < qpMin && prevRowQp > qpMin && canReencodeRow)
+        {
+            qpVbv = Clip3(prevRowQp + 1.0f, (prevRowQp + qpVbv) * 0.5, qpMin);
+            return -1;
+        }
     }
     else
     {
diff -r 6494bb2e6425 -r 7a3657ff29e2 source/encoder/ratecontrol.h
--- a/source/encoder/ratecontrol.h	Wed May 07 14:03:25 2014 -0500
+++ b/source/encoder/ratecontrol.h	Thu May 08 10:10:53 2014 +0530
@@ -96,6 +96,7 @@
     double vbvMinRate;       /* in kbps */
     bool singleFrameVbv;
     double rateFactorMaxIncrement; /* Don't allow RF above (CRF + this value). */
+    double rateFactorMaxDecrement; /* don't allow RF below (this value). */
     bool isVbv;
     Predictor pred[5];
     Predictor predBfromP;
diff -r 6494bb2e6425 -r 7a3657ff29e2 source/x265.cpp
--- a/source/x265.cpp	Wed May 07 14:03:25 2014 -0500
+++ b/source/x265.cpp	Thu May 08 10:10:53 2014 +0530
@@ -129,6 +129,7 @@
     { "weightb",              no_argument, NULL, 0 },
     { "crf",            required_argument, NULL, 0 },
     { "crf-max",        required_argument, NULL, 0 },
+    { "crf-min",        required_argument, NULL, 0 },
     { "vbv-maxrate",    required_argument, NULL, 0 },
     { "vbv-bufsize",    required_argument, NULL, 0 },
     { "vbv-init",       required_argument, NULL, 0 },
@@ -360,6 +361,8 @@
     H0("   --crf <float>                 Quality-based VBR (0-51). Default %f\n", param->rc.rfConstant);
     H0("   --crf-max <float>             With CRF+VBV, limit RF to this value. 0 for no limit (default)\n");
     H0("                                 May cause VBV underflows!\n");
+    H0("   --crf-min <float>             With CRF+VBV, limit RF to this value. 0 for no limit (default)\n");
+    H0("                                 this specifies a minimum rate factor value for encode!\n");
     H0("   --vbv-maxrate <integer>       Max local bitrate (kbit/s). Default %d\n", param->rc.vbvMaxBitrate);
     H0("   --vbv-bufsize <integer>       Set size of the VBV buffer (kbit). Default %d\n", param->rc.vbvBufferSize);
     H0("   --vbv-init <float>            Initial VBV buffer occupancy (fraction of bufsize or in kbits). Default %f\n", param->rc.vbvBufferInit);
diff -r 6494bb2e6425 -r 7a3657ff29e2 source/x265.h
--- a/source/x265.h	Wed May 07 14:03:25 2014 -0500
+++ b/source/x265.h	Thu May 08 10:10:53 2014 +0530
@@ -703,6 +703,9 @@
 
         /* In CRF mode, maximum CRF as caused by VBV. 0 implies no limit */
         double    rfConstantMax;
+
+        /* In CRF mode, minimum CRF as caused by VBV */
+        double    rfConstantMin;
     } rc;
 
     /*== Video Usability Information ==*/