For some movies I have audio, but no video on IOS 10. Logs show no indicators why. Looks to me like IOS10 doesn't support the video format, but plex doesn't transcode for some reason. Video works when I go to IOS app > settings > Quality > Home Streaming > 720p.
ffmpeg -i of problematic video:
Input #0, mpegts, from '00000.MTS':
Duration: 00:02:58.88, start: 1.040000, bitrate: 17172 kb/s
Stream #0:0[0x1011]: Video: h264 (High) (HDMV / 0x564D4448), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
Stream #0:1[0x1100]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, stereo, fltp, 256 kb/s
Stream #0:2[0x1200]: Subtitle: hdmv_pgs_subtitle ( / 0x0090), 1920x1080
How can I force plex to transcode this for IOS, without losing quality like with the workaround mentioned above ?