IDR frame alignment
Stream encoders should produce IDR frame alignment across bitrates per the targeted segment duration. For example, if an encoder is generating maximum supported 10-second segments, then every 10 seconds there must be timestamp-aligned IDR frames across streams.
There must be an IDR frame at the beginning of the segment; otherwise, the audio and video might deviate and drop out of synchronization.
IDR frames must be at the very beginning of the segment, not in the middle or end of the segment.