Hi, Im trying to use ios15.0 client to play LL-HLS media stream. I provide a media playlist to the player but find it seems that PART-HOLD-BACK tag, mentioned in LL-HLS, failes to task effect. In other words, the player fails to follow PART-HOLD-BACK's behavior mentioned in LL-HLS documentation when playing the media. Anyone can help me check whether there needs some change to my media playlist? Or there is something stubborn in LL-HLS protocol itself, lol. #EXT-X-TARGETDURATION:2 #EXT-X-VERSION:9 #EXT-X-SERVER-CONTROL:CAN-BLOCK-RELOAD=YES,PART-HOLD-BACK=0.640 #EXT-X-MAP:URI="audio_sample.m4i" #EXT-X-PART-INF:PART-TARGET=0.213 #EXT-X-MEDIA-SEQUENCE:818343598 #EXT-X-PROGRAM-DATE-TIME:2021-11-12T03:19:56.330Z #EXTINF:2.005, audio_sample-147301847669700-PolicyMode_llhls9_2_cmaf-0.m4a? #EXT-X-PROGRAM-DATE-TIME:2021-11-12T03:19:58.335Z #EXTINF:2.005, audio_sample-147301847850180-PolicyMode_llhls9_2_cmaf-0.m4a? #EXT-X-PROGRAM-DATE-TIME:2021-11-12T03:20:00.340Z #EXTINF:2.005, audio_sample-147301848030660-PolicyMode_llhls9_2_cmaf-0.m4a? #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848211140-part_0.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848211140-part_1.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848211140-part_2.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848211140-part_3.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848211140-part_4.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848211140-part_5.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848211140-part_6.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848211140-part_7.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848211140-part_8.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.064,URI="audio_sample-147301848211140-part_9.m4a?",INDEPENDENT=YES #EXT-X-PROGRAM-DATE-TIME:2021-11-12T03:20:02.346Z #EXTINF:1.984, audio_sample-147301848211140-PolicyMode_llhls9_2_cmaf-0.m4a? #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848389700-part_0.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848389700-part_1.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848389700-part_2.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848389700-part_3.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848389700-part_4.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848389700-part_5.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848389700-part_6.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848389700-part_7.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848389700-part_8.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.085,URI="audio_sample-147301848389700-part_9.m4a?",INDEPENDENT=YES #EXT-X-PROGRAM-DATE-TIME:2021-11-12T03:20:04.330Z #EXTINF:2.005, audio_sample-147301848389700-PolicyMode_llhls9_2_cmaf-0.m4a? #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848570180-part_0.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848570180-part_1.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848570180-part_2.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848570180-part_3.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848570180-part_4.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848570180-part_5.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848570180-part_6.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848570180-part_7.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848570180-part_8.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.085,URI="audio_sample-147301848570180-part_9.m4a?",INDEPENDENT=YES #EXT-X-PROGRAM-DATE-TIME:2021-11-12T03:20:06.335Z #EXTINF:2.005, audio_sample-147301848570180-PolicyMode_llhls9_2_cmaf-0.m4a? #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848750660-part_0.m4a?",INDEPENDENT=YES #EXT-X-PART:DURATION=0.213,URI="audio_sample-147301848750660-part_1.m4a?",INDEPENDENT=YES #EXT-X-PRELOAD-HINT:TYPE=PART,URI="audio_sample-147301848750660-part_2.m4a?"

Im a developer for Low-Latency HLS protocol. I found some doubts when reading contents about preload hint/blocking. Suppose that a media segment of 2 seconds long is divided into 10 partial segments, which means that each part segment is 0.2 second long. At the point the last part segment is completed, how should I provide a preload hint? Should I give a preload hint for 11-th part, although it will never generate? or first part for next media segment? How should I write a rate index file when facing this situation? https://developer.apple.com/documentation/http_live_streaming/enabling_low-latency_hls