I ran mediastreamvalidator on HLS output that we produce. Our custom encoder ensures that all segment boundaries for video are aligned. When I look at the PTS and DTS I see that all variants that are using HIGH or MAIN h264 match but the BASELINE does not. It appears the startTime used is DTS/90000 where it would be more accurate to use PTS/90000 because of b-frames.
mediastreamvalidator gives all variants must start at the same time when using b-frames
Please file a report using the feedback assistant. In the report, please include the version of mediastreamvalidator, a sample of an HLS stream, the observed validation output and detail the validation output that you are expecting.