2020-12-08, 10:39
(2020-12-08, 06:53)lmyllari Wrote: What are the known issues with N2+ Coreelec image quality? I'm running 9.2.5 and have had a frustrating start.
First I noticed issues with chroma test patterns having weird temporal artifacts. After disabling noise reduction in Coreelec settings, 4k playback seems good. (This also fixed loss of detail.)
Lower resolutions are giving me issues though. It looks like some progressive content is handled as interlaced, and there is loss of vertical resolution. I tried the `echo 1 > /sys/module/di/parameters/bypass_all` setting, but that didn't seem to have any effect. When playing a 1080p25 or 1080p29.97 video, `/sys/devices/platform/deinterlace/deinterlace/di0/frame_format` shows `interlace`.
Not sure if this is relevant - but Blu-rays of content shot at 1080p25 are released 1080i25 interlaced - the Blu-ray spec only included support for 1080p24, 1080i25 and 1080i30 (*) 1080 line formats (no 1080p25).
Lossless rips of TV series shot p25 will be released on HD Blu-rays usually as i25 (even though the content is 25fps progressive with no intra-frame motion between fields). Some are slowed down to p24 and released as 1080p24 (first series of Downton Abbey is one example)
(And yes - the noise reduction adds some pretty nasty artefacts - it's the first thing I check is disabled on AMLogic platforms)
My main sources viewed on AMLogic devices are actually 1080i and 576i DVB TV streams - so I guess I've never looked to closely at what it does with native progressive content.