muxer: remove useless check

muxer_segmenter_fmp4.go

@@ -325,22 +325,18 @@ func (m *muxerSegmenterFMP4) writeVideo(
 	forceSwitch bool,
 	sample *augmentedSample,
 ) error {
-	// add a starting DTS to avoid a negative BaseTime
+	// add a starting DTS to avoid a negative audio BaseTime
 	sample.dts += fmp4StartDTS
 
-	// BaseTime is still negative, this is not supported by fMP4. Reject the sample silently.
-	if (sample.dts - m.startDTS) < 0 {
-		return nil
-	}
-
 	// put samples into a queue in order to
 	// - compute sample duration
 	// - check if next sample is IDR
 	sample, m.nextVideoSample = m.nextVideoSample, sample
 	if sample == nil {
 		return nil
 	}
-	sample.Duration = uint32(durationGoToMp4(m.nextVideoSample.dts-sample.dts, 90000))
+	duration := m.nextVideoSample.dts - sample.dts
+	sample.Duration = uint32(durationGoToMp4(duration, 90000))
 
 	// create first segment
 	if m.currentSegment == nil {
@@ -368,7 +364,7 @@ func (m *muxerSegmenterFMP4) writeVideo(
 		}
 	}
 
-	m.adjustPartDuration(m.nextVideoSample.dts - sample.dts)
+	m.adjustPartDuration(duration)
 
 	err := m.currentSegment.writeVideo(sample, m.nextVideoSample.dts, m.adjustedPartDuration)
 	if err != nil {
@@ -424,7 +420,7 @@ func (m *muxerSegmenterFMP4) writeVideo(
 }
 
 func (m *muxerSegmenterFMP4) writeAudio(sample *augmentedSample) error {
-	// add a starting DTS to avoid a negative BaseTime
+	// add a starting DTS to avoid a negative audio BaseTime
 	sample.dts += fmp4StartDTS
 
 	// BaseTime is still negative, this is not supported by fMP4. Reject the sample silently.
@@ -444,7 +440,8 @@ func (m *muxerSegmenterFMP4) writeAudio(sample *augmentedSample) error {
 	if sample == nil {
 		return nil
 	}
-	sample.Duration = uint32(durationGoToMp4(m.nextAudioSample.dts-sample.dts, m.audioTimeScale))
+	duration := m.nextAudioSample.dts - sample.dts
+	sample.Duration = uint32(durationGoToMp4(duration, m.audioTimeScale))
 
 	if m.videoTrack == nil {
 		// create first segment