use dvh1 tag for DV P5 & P8.1 and keep hvc1 for P7 & P8.4

[DrHurt]

AVplayer needs dvh1 to properly recognise DV P5 & P8.1

P8.4 requires hvc1 to work with AVPlayer

P7 is NOT natively supported by AVPlayer & QT and must use hvc1 to force HDR10 fallback

Additionally, it would help if Subler recognises when an mp4 with hev1 is loaded and change that to hvc1 when saving. This will ensure mp4 is Apple-compatible.