Fix timestamp processing for HTTP-FLV

pkg/flv/flv_test.go

@@ -0,0 +1,21 @@
+package flv
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestTimeToRTP(t *testing.T) {
+	// Reolink camera has 20 FPS
+	// Video timestamp increases by 50ms, SampleRate 90000, RTP timestamp increases by 4500
+	// Audio timestamp increases by 64ms, SampleRate 16000, RTP timestamp increases by 1024
+	frameN := 1
+	for i := 0; i < 32; i++ {
+		// 1000ms/(90000/4500) = 50ms
+		require.Equal(t, uint32(frameN*4500), TimeToRTP(uint32(frameN*50), 90000))
+		// 1000ms/(16000/1024) = 64ms
+		require.Equal(t, uint32(frameN*1024), TimeToRTP(uint32(frameN*64), 16000))
+		frameN *= 2
+	}
+}

pkg/flv/producer.go

@@ -299,8 +299,12 @@ func (c *Producer) readPacket() (*rtp.Packet, error) {
 	return pkt, nil
 }
 
-func TimeToRTP(timeMS uint32, clockRate uint32) uint32 {
-	return timeMS * clockRate / 1000
+// TimeToRTP convert time in milliseconds to RTP time
+func TimeToRTP(timeMS, clockRate uint32) uint32 {
+	// for clockRates 90000, 16000, 8000, etc. - we can use:
+	//     return timeMS * (clockRate / 1000)
+	// but for clockRates 44100, 22050, 11025 - we should use:
+	return uint32(uint64(timeMS) * uint64(clockRate) / 1000)
 }
 
 func isExHeader(data []byte) bool {