h265: improve DTS extractor performance (#99)

bluenviron · Nov 17, 2023 · dd5555b · dd5555b
1 parent 151a3cb
commit dd5555b
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Showing 3 changed files with 16 additions and 11 deletions.
diff --git a/pkg/codecs/h265/dts_extractor.go b/pkg/codecs/h265/dts_extractor.go
@@ -9,17 +9,22 @@ import (
 	"github.com/bluenviron/mediacommon/pkg/codecs/h264"
 )
 
+const (
+	maxBytesToGetPOC = 12
+)
+
 func getPTSDTSDiff(buf []byte, sps *SPS, pps *PPS) (uint32, error) {
-	if len(buf) < 12 {
-		return 0, fmt.Errorf("not enough bits")
-	}
+	typ := NALUType((buf[0] >> 1) & 0b111111)
 
-	buf = h264.EmulationPreventionRemove(buf[:12])
+	buf = buf[1:]
+	lb := len(buf)
 
-	typ := NALUType((buf[0] >> 1) & 0b111111)
+	if lb > maxBytesToGetPOC {
+		lb = maxBytesToGetPOC
+	}
 
-	buf = buf[2:]
-	pos := 0
+	buf = h264.EmulationPreventionRemove(buf[:lb])
+	pos := 8
 
 	firstSliceSegmentInPicFlag, err := bits.ReadFlag(buf, &pos)
 	if err != nil {

diff --git a/pkg/codecs/h265/pps.go b/pkg/codecs/h265/pps.go
@@ -27,8 +27,8 @@ func (p *PPS) Unmarshal(buf []byte) error {
 		return fmt.Errorf("not a PPS")
 	}
 
-	buf = h264.EmulationPreventionRemove(buf[2:])
-	pos := 0
+	buf = h264.EmulationPreventionRemove(buf[1:])
+	pos := 8
 
 	var err error
 	p.ID, err = bits.ReadGolombUnsigned(buf, &pos)

diff --git a/pkg/codecs/h265/sps.go b/pkg/codecs/h265/sps.go
@@ -569,8 +569,8 @@ func (s *SPS) Unmarshal(buf []byte) error {
 		return fmt.Errorf("not a SPS")
 	}
 
-	buf = h264.EmulationPreventionRemove(buf[2:])
-	pos := 0
+	buf = h264.EmulationPreventionRemove(buf[1:])
+	pos := 8
 
 	err := bits.HasSpace(buf, pos, 8)
 	if err != nil {