support for negative strides

Originally committed as revision 3989 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/libpostproc/postprocess.c

@@ -1051,18 +1051,20 @@ void  pp_postprocess(uint8_t * src[3], int srcStride[3],
 	int mbHeight= (height+15)>>4;
 	PPMode *mode = (PPMode*)vm;
 	PPContext *c = (PPContext*)vc;
-        int minStride= MAX(srcStride[0], dstStride[0]);
+	int minStride= MAX(ABS(srcStride[0]), ABS(dstStride[0]));
+	int absQPStride = ABS(QPStride);
 
-	if(c->stride < minStride || c->qpStride < QPStride)
+	// c->stride and c->QPStride are always positive
+	if(c->stride < minStride || c->qpStride < absQPStride)
 		reallocBuffers(c, width, height, 
 				MAX(minStride, c->stride), 
-				MAX(c->qpStride, QPStride));
+				MAX(c->qpStride, absQPStride));
 
 	if(QP_store==NULL || (mode->lumMode & FORCE_QUANT)) 
 	{
 		int i;
 		QP_store= c->forcedQPTable;
-		QPStride= 0;
+		absQPStride = QPStride = 0;
 		if(mode->lumMode & FORCE_QUANT)
 			for(i=0; i<mbWidth; i++) QP_store[i]= mode->forcedQuant;
 		else
@@ -1072,7 +1074,7 @@ void  pp_postprocess(uint8_t * src[3], int srcStride[3],
 
 	if(pict_type & PP_PICT_TYPE_QP2){
 		int i;
-		const int count= mbHeight * QPStride;
+		const int count= mbHeight * absQPStride;
 		for(i=0; i<(count>>2); i++){
 			((uint32_t*)c->stdQPTable)[i] = (((uint32_t*)QP_store)[i]>>1) & 0x7F7F7F7F;
 		}
@@ -1080,6 +1082,7 @@ void  pp_postprocess(uint8_t * src[3], int srcStride[3],
 			c->stdQPTable[i] = QP_store[i]>>1;
 		}
                 QP_store= c->stdQPTable;
+		QPStride= absQPStride;		
 	}
 
 if(0){
@@ -1095,6 +1098,7 @@ for(y=0; y<mbHeight; y++){
 
 	if((pict_type&7)!=3)
 	{
+		if (QPStride >= 0) {
 			int i;
 			const int count= mbHeight * QPStride;
 			for(i=0; i<(count>>2); i++){
@@ -1103,6 +1107,14 @@ for(y=0; y<mbHeight; y++){
 			for(i<<=2; i<count; i++){
 				c->nonBQPTable[i] = QP_store[i] & 0x3F;
 			}
+		} else {
+			int i,j;
+			for(i=0; i<mbHeight; i++) {
+		    		for(j=0; j<absQPStride; j++) {
+					c->nonBQPTable[i*absQPStride+j] = QP_store[i*QPStride+j] & 0x3F;
+				}
+			}
+		}
 	}
 
 	if(verbose>2)
@@ -1125,8 +1137,8 @@ for(y=0; y<mbHeight; y++){
 	}
 	else if(srcStride[1] == dstStride[1] && srcStride[2] == dstStride[2])
 	{
-		memcpy(dst[1], src[1], srcStride[1]*height);
-		memcpy(dst[2], src[2], srcStride[2]*height);
+		linecpy(dst[1], src[1], height, srcStride[1]);
+		linecpy(dst[2], src[2], height, srcStride[2]);
 	}
 	else
 	{

libavcodec/libpostproc/postprocess_internal.h

@@ -160,3 +160,11 @@ typedef struct PPContext{
 } PPContext;
 
 
+static inline void linecpy(void *dest, void *src, int lines, int stride)
+{
+	if (stride > 0) {
+		memcpy(dest, src, lines*stride);
+	} else {
+		memcpy(dest+(lines-1)*stride, src+(lines-1)*stride, -lines*stride);
+	}
+}

libavcodec/libpostproc/postprocess_template.c

@@ -3366,8 +3366,8 @@ static void RENAME(postProcess)(uint8_t src[], int srcStride, uint8_t dst[], int
 
 	//FIXME remove
 	uint64_t * const yHistogram= c.yHistogram;
-	uint8_t * const tempSrc= c.tempSrc;
-	uint8_t * const tempDst= c.tempDst;
+	uint8_t * const tempSrc= srcStride > 0 ? c.tempSrc : c.tempSrc - 23*srcStride;
+	uint8_t * const tempDst= dstStride > 0 ? c.tempDst : c.tempDst - 23*dstStride;
 	//const int mbWidth= isColor ? (width+7)>>3 : (width+15)>>4;
 
 #ifdef HAVE_MMX
@@ -3529,8 +3529,8 @@ static void RENAME(postProcess)(uint8_t src[], int srcStride, uint8_t dst[], int
 			dstBlock+=8;
 			srcBlock+=8;
 		}
-		if(width==dstStride)
-			memcpy(dst, tempDst + 9*dstStride, copyAhead*dstStride);
+		if(width==ABS(dstStride))
+			linecpy(dst, tempDst + 9*dstStride, copyAhead, dstStride);
 		else
 		{
 			int i;
@@ -3552,7 +3552,7 @@ static void RENAME(postProcess)(uint8_t src[], int srcStride, uint8_t dst[], int
 		uint8_t *tempBlock2= c.tempBlocks + 8;
 #endif
 		int8_t *QPptr= &QPs[(y>>qpVShift)*QPStride];
-		int8_t *nonBQPptr= &c.nonBQPTable[(y>>qpVShift)*QPStride];
+		int8_t *nonBQPptr= &c.nonBQPTable[(y>>qpVShift)*ABS(QPStride)];
 		int QP=0;
 		/* can we mess with a 8x16 block from srcBlock/dstBlock downwards and 1 line upwards
 		   if not than use a temporary buffer */
@@ -3561,19 +3561,19 @@ static void RENAME(postProcess)(uint8_t src[], int srcStride, uint8_t dst[], int
 			int i;
 			/* copy from line (copyAhead) to (copyAhead+7) of src, these will be copied with
 			   blockcopy to dst later */
-			memcpy(tempSrc + srcStride*copyAhead, srcBlock + srcStride*copyAhead,
-				srcStride*MAX(height-y-copyAhead, 0) );
+			linecpy(tempSrc + srcStride*copyAhead, srcBlock + srcStride*copyAhead,
+				MAX(height-y-copyAhead, 0), srcStride);
 
 			/* duplicate last line of src to fill the void upto line (copyAhead+7) */
 			for(i=MAX(height-y, 8); i<copyAhead+8; i++)
-				memcpy(tempSrc + srcStride*i, src + srcStride*(height-1), srcStride);
+				memcpy(tempSrc + srcStride*i, src + srcStride*(height-1), ABS(srcStride));
 
 			/* copy up to (copyAhead+1) lines of dst (line -1 to (copyAhead-1))*/
-			memcpy(tempDst, dstBlock - dstStride, dstStride*MIN(height-y+1, copyAhead+1) );
+			linecpy(tempDst, dstBlock - dstStride, MIN(height-y+1, copyAhead+1), dstStride);
 
 			/* duplicate last line of dst to fill the void upto line (copyAhead) */
 			for(i=height-y+1; i<=copyAhead; i++)
-				memcpy(tempDst + dstStride*i, dst + dstStride*(height-1), dstStride);
+				memcpy(tempDst + dstStride*i, dst + dstStride*(height-1), ABS(dstStride));
 
 			dstBlock= tempDst + dstStride;
 			srcBlock= tempSrc;
@@ -3785,8 +3785,8 @@ static void RENAME(postProcess)(uint8_t src[], int srcStride, uint8_t dst[], int
 		if(y+15 >= height)
 		{
 			uint8_t *dstBlock= &(dst[y*dstStride]);
-			if(width==dstStride)
-				memcpy(dstBlock, tempDst + dstStride, dstStride*(height-y));
+			if(width==ABS(dstStride))
+				linecpy(dstBlock, tempDst + dstStride, height-y, dstStride);
 			else
 			{
 				int i;