h264: improve performance of SPS parser (#152)

bluenviron · Oct 20, 2024 · 058cf2b · 058cf2b
1 parent 8883ba8
commit 058cf2b
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Showing 2 changed files with 9 additions and 8 deletions.
diff --git a/pkg/codecs/h264/emulation_prevention.go b/pkg/codecs/h264/emulation_prevention.go
@@ -14,6 +14,7 @@ func EmulationPreventionRemove(nalu []byte) []byte {
 	for i := 2; i < l; i++ {
 		if nalu[i-2] == 0 && nalu[i-1] == 0 && nalu[i] == 3 {
 			n--
+			i += 2
 		}
 	}
 
@@ -25,6 +26,7 @@ func EmulationPreventionRemove(nalu []byte) []byte {
 		if nalu[i-2] == 0 && nalu[i-1] == 0 && nalu[i] == 3 {
 			pos += copy(ret[pos:], nalu[start:i])
 			start = i + 1
+			i += 2
 		}
 	}
 

diff --git a/pkg/codecs/h264/sps.go b/pkg/codecs/h264/sps.go
@@ -68,26 +68,25 @@ func (h *SPS_HRD) unmarshal(buf []byte, pos *int) error {
 	h.BitRateScale = uint8(bits.ReadBitsUnsafe(buf, pos, 4))
 	h.CpbSizeScale = uint8(bits.ReadBitsUnsafe(buf, pos, 4))
 
+	h.BitRateValueMinus1 = make([]uint32, h.CpbCntMinus1+1)
+	h.CpbSizeValueMinus1 = make([]uint32, h.CpbCntMinus1+1)
+	h.CbrFlag = make([]bool, h.CpbCntMinus1+1)
+
 	for i := uint32(0); i <= h.CpbCntMinus1; i++ {
-		var v uint32
-		v, err = bits.ReadGolombUnsigned(buf, pos)
+		h.BitRateValueMinus1[i], err = bits.ReadGolombUnsigned(buf, pos)
 		if err != nil {
 			return err
 		}
-		h.BitRateValueMinus1 = append(h.BitRateValueMinus1, v)
 
-		v, err = bits.ReadGolombUnsigned(buf, pos)
+		h.CpbSizeValueMinus1[i], err = bits.ReadGolombUnsigned(buf, pos)
 		if err != nil {
 			return err
 		}
-		h.CpbSizeValueMinus1 = append(h.CpbSizeValueMinus1, v)
 
-		var vb bool
-		vb, err = bits.ReadFlag(buf, pos)
+		h.CbrFlag[i], err = bits.ReadFlag(buf, pos)
 		if err != nil {
 			return err
 		}
-		h.CbrFlag = append(h.CbrFlag, vb)
 	}
 
 	err = bits.HasSpace(buf, *pos, 5+5+5+5)