mpegts: change TimeDecoder2 signature (#151)

bluenviron · Oct 7, 2024 · 8883ba8 · 8883ba8
1 parent 6b36e89
commit 8883ba8
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Showing 3 changed files with 27 additions and 11 deletions.
diff --git a/pkg/formats/mpegts/time_decoder.go b/pkg/formats/mpegts/time_decoder.go
@@ -27,8 +27,11 @@ type TimeDecoder struct {
 //
 // Deprecated: replaced by NewTimeDecoder2.
 func NewTimeDecoder(start int64) *TimeDecoder {
+	td := NewTimeDecoder2()
+	td.Decode(start)
+
 	return &TimeDecoder{
-		wrapped: NewTimeDecoder2(start),
+		wrapped: td,
 	}
 }
 

diff --git a/pkg/formats/mpegts/time_decoder2.go b/pkg/formats/mpegts/time_decoder2.go
@@ -7,19 +7,23 @@ const (
 
 // TimeDecoder2 is a MPEG-TS timestamp decoder.
 type TimeDecoder2 struct {
-	overall int64
-	prev    int64
+	initialized bool
+	overall     int64
+	prev        int64
 }
 
 // NewTimeDecoder2 allocates a TimeDecoder.
-func NewTimeDecoder2(start int64) *TimeDecoder2 {
-	return &TimeDecoder2{
-		prev: start,
-	}
+func NewTimeDecoder2() *TimeDecoder2 {
+	return &TimeDecoder2{}
 }
 
 // Decode decodes a MPEG-TS timestamp.
 func (d *TimeDecoder2) Decode(ts int64) int64 {
+	if !d.initialized {
+		d.initialized = true
+		d.prev = ts
+	}
+
 	diff := (ts - d.prev) & maximum
 
 	// negative difference

diff --git a/pkg/formats/mpegts/time_decoder2_test.go b/pkg/formats/mpegts/time_decoder2_test.go
@@ -7,9 +7,12 @@ import (
 )
 
 func TestTimeDecoder2NegativeDiff(t *testing.T) {
-	d := NewTimeDecoder2(64523434)
+	d := NewTimeDecoder2()
 
-	ts := d.Decode(64523434 - 90000)
+	ts := d.Decode(64523434)
+	require.Equal(t, int64(0), ts)
+
+	ts = d.Decode(64523434 - 90000)
 	require.Equal(t, int64(-90000), ts)
 
 	ts = d.Decode(64523434)
@@ -23,7 +26,10 @@ func TestTimeDecoder2NegativeDiff(t *testing.T) {
 }
 
 func TestTimeDecoder2Overflow(t *testing.T) {
-	d := NewTimeDecoder2(0x1FFFFFFFF - 20)
+	d := NewTimeDecoder2()
+
+	ts := d.Decode(0x1FFFFFFFF - 20)
+	require.Equal(t, int64(0), ts)
 
 	i := int64(0x1FFFFFFFF - 20)
 	secs := int64(0)
@@ -49,11 +55,14 @@ func TestTimeDecoder2Overflow(t *testing.T) {
 }
 
 func TestTimeDecoder2OverflowAndBack(t *testing.T) {
-	d := NewTimeDecoder2(0x1FFFFFFFF - 90000 + 1)
+	d := NewTimeDecoder2()
 
 	ts := d.Decode(0x1FFFFFFFF - 90000 + 1)
 	require.Equal(t, int64(0), ts)
 
+	ts = d.Decode(0x1FFFFFFFF - 90000 + 1)
+	require.Equal(t, int64(0), ts)
+
 	ts = d.Decode(90000)
 	require.Equal(t, int64(2*90000), ts)