codec/h264/h264dec/decode.go: added picOrderCntType1 to derive topfieldOrderCnt and bottomFieldOrderCnt for when picOrderCntType == 1

codec/h264/h264dec/decode.go

@@ -26,13 +26,14 @@ package h264dec
 
 // picOrderCntType0 is used to return topFieldOrderCnt and bottomFieldOrderCnt
 // when pic_order_cnt_type i.e vid.PicOrderCntType == 0, using the process
-// defined in section 8.2.1.1 of the specifications.
-func picOrderCntType0(vid VideoStream, ctx SliceContext) (topFieldOrderCnt, bottomFieldOrderCnt int) {
+// defined in section 8.2.1.1 of the specifications. If topFieldOrderCnt or
+// bottomFieldOrderCnt are -1 they are unset.
+func picOrderCntType0(vid *VideoStream, ctx SliceContext) (topFieldOrderCnt, bottomFieldOrderCnt int) {
 	prevPicOrderCntMsb, prevPicOrderCntLsb := 0, 0
 	topFieldOrderCnt, bottomFieldOrderCnt = -1, -1
 
 	// NB: We're currently only handling IDRs so panic.
-	if !vid.currPic.isIDR {
+	if !vid.idrPicFlag {
 		panic("not implemented")
 	}
 
@@ -45,11 +46,9 @@ func picOrderCntType0(vid VideoStream, ctx SliceContext) (topFieldOrderCnt, bott
 		vid.picOrderCntMsb = prevPicOrderCntMsb
 	}
 
-	if !vid.currPic.isBottomField {
+	if !ctx.BottomField {
 		topFieldOrderCnt = vid.picOrderCntMsb + ctx.PicOrderCntLsb
-	}
-
-	if !vid.currPic.isTopField {
+	} else {
 		if !ctx.FieldPic {
 			bottomFieldOrderCnt = topFieldOrderCnt + ctx.DeltaPicOrderCntBottom
 		} else {
@@ -58,3 +57,54 @@ func picOrderCntType0(vid VideoStream, ctx SliceContext) (topFieldOrderCnt, bott
 	}
 	return
 }
+
+// picOrderCntType1 is used to return topFieldOrderCnt and bottomFieldOrderCnt
+// when vic.PicOrderCntType == 1 according to logic defined in section 8.2.1.2
+// of the specifications. If topFieldOrderCnt or bottomFieldOrderCnt are -1,
+// then they are considered unset.
+func picOrderCntType1(vid VideoStream, ctx SliceContext) (topFieldOrderCnt, bottomFieldOrderCnt int) {
+	topFieldOrderCnt, bottomFieldOrderCnt = -1, -1
+
+	// TODO: this will be prevFrameNum when we do frames other than IDR.
+	_ = vid.priorPic.FrameNum
+
+	if vid.idrPicFlag {
+		vid.frameNumOffset = 0
+	} else {
+		panic("not implemented")
+	}
+
+	absFrameNum := 0
+	if ctx.NumRefFramesInPicOrderCntCycle != 0 {
+		absFrameNum = vid.frameNumOffset + ctx.FrameNum
+	}
+
+	if ctx.RefIdc == 0 && absFrameNum > 0 {
+		absFrameNum = absFrameNum - 1
+	}
+
+	var expectedPicOrderCnt int
+	if absFrameNum > 0 {
+		picOrderCntCycleCnt := (absFrameNum - 1) / int(ctx.NumRefFramesInPicOrderCntCycle)
+		frameNumInPicOrderCntCycle := (absFrameNum - 1) % int(ctx.NumRefFramesInPicOrderCntCycle)
+		expectedPicOrderCnt = picOrderCntCycleCnt * vid.expectedDeltaPerPicOrderCntCycle
+		for i := 0; i <= frameNumInPicOrderCntCycle; i++ {
+			expectedPicOrderCnt = expectedPicOrderCnt + ctx.OffsetForRefFrameList[i]
+		}
+	}
+
+	if ctx.RefIdc == 0 {
+		expectedPicOrderCnt = expectedPicOrderCnt + int(ctx.OffsetForNonRefPic)
+	}
+
+	switch {
+	case !ctx.FieldPic:
+		topFieldOrderCnt = expectedPicOrderCnt + ctx.DeltaPicOrderCnt[0]
+		bottomFieldOrderCnt = topFieldOrderCnt + int(ctx.OffsetForTopToBottomField) + ctx.DeltaPicOrderCnt[1]
+	case !ctx.BottomField:
+		topFieldOrderCnt = expectedPicOrderCnt + ctx.DeltaPicOrderCnt[0]
+	default:
+		bottomFieldOrderCnt = expectedPicOrderCnt + int(ctx.OffsetForTopToBottomField) + ctx.DeltaPicOrderCnt[0]
+	}
+	return
+}

codec/h264/h264dec/slice.go

@@ -36,6 +36,7 @@ const (
 )
 
 type picture struct {
+	*SliceContext
 	isIDR         bool
 	isBottomField bool
 	isTopField    bool
@@ -47,12 +48,18 @@ type VideoStream struct {
 	Slices []*SliceContext
 
 	ChromaArrayType                  int
-	currPic           picture
+	priorPic                         *picture
+	currPic                          *picture
 	maxPicOrderCntLsb                int
 	picOrderCntMsb                   int
+	idrPicFlag                       bool
+	frameNumOffset                   int
+	expectedDeltaPerPicOrderCntCycle int
 }
 
 type SliceContext struct {
+	*SPS
+	*PPS
 	*NALUnit
 	*Slice
 }