DefaultMP4Segmenter
class DefaultMP4Segmenter(hasAudio: Boolean, hasVideo: Boolean, numOfAudioSampleInSegment: Int = DEFAULT_NUM_OF_AUDIO_SAMPLE_IN_SEGMENT) : MP4Segmenter(source)
Default implementation of MP4Segmenter. Return the order to write segment when:
Audio only: every numOfAudioSampleInSegment audio frames
else, when video frame is a key frame (except the first one)