--- vop_type_decision.c	2003/09/10 22:19:00	1.1.2.1
+++ vop_type_decision.c	2003/12/04 12:08:03	1.1.2.6
@@ -19,7 +19,7 @@
  *  along with this program ; if not, write to the Free Software
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  *
- * $Id: vop_type_decision.c,v 1.1.2.1 2003/09/10 22:19:00 edgomez Exp $
+ * $Id: vop_type_decision.c,v 1.1.2.6 2003/12/04 12:08:03 syskin Exp $
  *
  ****************************************************************************/
 
@@ -33,12 +33,21 @@
 #include "motion_inlines.h"
 
 
-#define INTRA_THRESH	2200
+#define INTRA_THRESH	2000
 #define INTER_THRESH	40
-#define INTRA_THRESH2	95
+#define INTRA_THRESH2	90
+
+/* when we are in 1/I_SENS_TH before forced keyframe, we start to decrese i-frame threshold */
+#define I_SENS_TH		3 
+
+/* how much we subtract from each p-frame threshold for 2nd, 3rd etc. b-frame in a row */
+#define P_SENS_BIAS		18
+
+/* .. but never below INTER_THRESH_MIN */
+#define INTER_THRESH_MIN 5
 
 static void
-CheckCandidate32I(const int x, const int y, const SearchData * const data, const unsigned int Direction)
+CheckCandidate32I(const int x, const int y, SearchData * const data, const unsigned int Direction)
 {
 	/* maximum speed */
 	int32_t sad;
@@ -52,7 +61,7 @@
 	if (sad < *(data->iMinSAD)) {
 		*(data->iMinSAD) = sad;
 		data->currentMV[0].x = x; data->currentMV[0].y = y;
-		*data->dir = Direction;
+		data->dir = Direction;
 	}
 	if (data->temp[0] < data->iMinSAD[1]) {
 		data->iMinSAD[1] = data->temp[0]; data->currentMV[1].x = x; data->currentMV[1].y = y; }
@@ -115,7 +124,7 @@
 			CheckCandidate32I(pmv[2].x, pmv[2].y, Data, 2);
 
 		if (*Data->iMinSAD > 500) { /* diamond only if needed */
-			unsigned int mask = make_mask(pmv, 3, *Data->dir);
+			unsigned int mask = make_mask(pmv, 3, Data->dir);
 			xvid_me_DiamondSearch(Data->currentMV->x, Data->currentMV->y, Data, mask, CheckCandidate32I);
 		} else simplicity++;
 
@@ -137,42 +146,44 @@
 MEanalysis(	const IMAGE * const pRef,
 			const FRAMEINFO * const Current,
 			const MBParam * const pParam,
-			const int maxIntra, //maximum number if non-I frames
-			const int intraCount, //number of non-I frames after last I frame; 0 if we force P/B frame
-			const int bCount, // number of B frames in a row
-			const int b_thresh)
+			const int maxIntra, /* maximum number if non-I frames */
+			const int intraCount, /* number of non-I frames after last I frame; 0 if we force P/B frame */
+			const int bCount, /* number of B frames in a row */
+			const int b_thresh,
+			const MACROBLOCK * const prev_mbs)
 {
 	uint32_t x, y, intra = 0;
 	int sSAD = 0;
 	MACROBLOCK * const pMBs = Current->mbs;
 	const IMAGE * const pCurrent = &Current->image;
-	int IntraThresh = INTRA_THRESH, InterThresh = INTER_THRESH + b_thresh;
-	int blocks = 0;
+	int IntraThresh = INTRA_THRESH, 
+		InterThresh = INTER_THRESH + b_thresh,
+		IntraThresh2 = INTRA_THRESH2;
+		
+	int blocks = 10;
 	int complexity = 0;
 
-	int32_t iMinSAD[5], temp[5];
-	uint32_t dir;
-	VECTOR currentMV[5];
 	SearchData Data;
 	Data.iEdgedWidth = pParam->edged_width;
-	Data.currentMV = currentMV;
-	Data.iMinSAD = iMinSAD;
 	Data.iFcode = Current->fcode;
-	Data.temp = temp;
-	Data.dir = &dir;
 	Data.qpel = (pParam->vol_flags & XVID_VOL_QUARTERPEL)? 1: 0;
 	Data.qpel_precision = 0;
 
 	if (intraCount != 0) {
-		if (intraCount < 10) // we're right after an I frame
-			IntraThresh += 15* (intraCount - 10) * (intraCount - 10);
-		else
-			if ( 5*(maxIntra - intraCount) < maxIntra) // we're close to maximum. 2 sec when max is 10 sec
-				IntraThresh -= (IntraThresh * (maxIntra - 8*(maxIntra - intraCount)))/maxIntra;
+		if (intraCount < 30) {
+			/* we're right after an I frame 
+			   we increase thresholds to prevent consecutive i-frames */
+			if (intraCount < 10) IntraThresh += 15*(10 - intraCount)*(10 - intraCount);
+			IntraThresh2 += 4*(30 - intraCount);
+		} else if (I_SENS_TH*(maxIntra - intraCount) < maxIntra) {
+			/* we're close to maximum. we decrease thresholds to catch any good keyframe */
+			IntraThresh -= IntraThresh*((maxIntra - I_SENS_TH*(maxIntra - intraCount))/maxIntra);
+			IntraThresh2 -= IntraThresh2*((maxIntra - I_SENS_TH*(maxIntra - intraCount))/maxIntra);
+		}
 	}
 
-	InterThresh -= 20 * bCount;
-	if (InterThresh < 10 + b_thresh) InterThresh = 10 + b_thresh;
+	InterThresh -= P_SENS_BIAS * bCount;
+	if (InterThresh < INTER_THRESH_MIN) InterThresh = INTER_THRESH_MIN;
 
 	if (sadInit) (*sadInit) ();
 
@@ -182,11 +193,11 @@
 			blocks += 10;
 
 			if (bCount == 0) pMBs[x + y * pParam->mb_width].mvs[0] = zeroMV;
-			else { //extrapolation of the vector found for last frame
+			else { /* extrapolation of the vector found for last frame */
 				pMBs[x + y * pParam->mb_width].mvs[0].x =
-					(pMBs[x + y * pParam->mb_width].mvs[0].x * (bCount+1) ) / bCount;
+					(prev_mbs[x + y * pParam->mb_width].mvs[0].x * (bCount+1) ) / bCount;
 				pMBs[x + y * pParam->mb_width].mvs[0].y =
-					(pMBs[x + y * pParam->mb_width].mvs[0].y * (bCount+1) ) / bCount;
+					(prev_mbs[x + y * pParam->mb_width].mvs[0].y * (bCount+1) ) / bCount;
 			}
 
 			MEanalyzeMB(pRef->y, pCurrent->y, x, y, pParam, pMBs, &Data);
@@ -205,9 +216,9 @@
 
 				if (pMB->mvs[0].x == 0 && pMB->mvs[0].y == 0)
 					if (dev > 1000 && pMB->sad16 < 1000)
-						sSAD += 1000;
+						sSAD += 512;
 
-				sSAD += (dev < 4000) ? pMB->sad16 : pMB->sad16/2; /* blocks with big contrast differences usually have large SAD - while they look very good in b-frames */
+				sSAD += (dev < 3000) ? pMB->sad16 : pMB->sad16/2; /* blocks with big contrast differences usually have large SAD - while they look very good in b-frames */
 			}
 		}
 	}
@@ -215,8 +226,8 @@
 
 	sSAD /= complexity + 4*blocks;
 
-	if (intraCount > 80 && sSAD > INTRA_THRESH2 ) return I_VOP;
-	if (sSAD > InterThresh ) return P_VOP;
+	if (sSAD > IntraThresh2) return I_VOP;
+	if (sSAD > InterThresh) return P_VOP;
 	emms();
 	return B_VOP;
 }