From reading around it seems hls iptv input shouldn't work or is possibly new to tvheadend? I have an m3u file generated by Channels DVR that contains hls streams of my channels, when importing 100 channels about half are OK and the other half OK(partial) with 4 showing as failed. When watching them using Kodi most of the channels start and then freeze after 2 seconds, a few of them will pause after 2 seconds then resume and continue on without issue, others just show an initial image then freeze.
2019-06-12 18:27:01.587 mpegts: channels.m3u - CH1 in Test - tuning on IPTV
2019-06-12 18:27:01.587 subscription: 00DB: "HTTP" subscribing on channel "CH1", weight: 100, adapter: "IPTV", network: "Test", mux: "channels.m3u - CH1", provider: "FFmpeg", service: "Service01", profile="pass", hostname="X.X.X.X", username="user", client="TvhClient/224 LibVLC/3.0.2"
2019-06-12 18:27:03.309 iptv: m3u contents parsing failed
2019-06-12 18:27:24.961 mpegts: channels.m3u - CH2 in Test - tuning on IPTV
2019-06-12 18:27:24.961 subscription: 00DC: "HTTP" subscribing on channel "CH2", weight: 100, adapter: "IPTV", network: "Test", mux: "channels.m3u - CH2", provider: "FFmpeg", service: "Service01", profile="pass", hostname="X.X.X.X", username="test", client="TvhClient/224 LibVLC/3.0.2"
2019-06-12 18:27:56.866 subscription: 00DC: "HTTP" unsubscribing from "CH2", hostname="X.X.X.X", username="test", client="TvhClient/224 LibVLC/3.0.2"
Also, with the automatic import, about 20 of the channels are imported with the servicename=channelname and a blank channel name, the rest import with servicename=Service01 and the channel name properly filled in. There is no formatting different in the m3u file to explain this.
