Hello!
I'm trying to encode 1080i h264 MBAFF sat feed with 10-bit color and 4:2:2 chroma to 1080p50 h265 with 10-bit color and 4:2:0 chroma because that seems to be the only 10-bit format supported by my TV set and original feed won't play. I tried using StaxRip 2.1.8.0 with QTGMC Medium deinterlacing and x265 crf18 Medium for encoding and got something that plays but with faulty frame order in some situations. In first attempt I got chroma issues because StaxRip had added conversion to 4:2:0 chroma before deinterlacing, so I had to move that conversion after deinterlacing to get correct frames. I can't use 4:2:2 output because that's not supported by my TV set, but progressive 4:2:0 should be good enough. However, while viewing frames with mpv at the 3 fps speed of my encode I noticed cars in this Formula1 race sometimes jumping backwards between two frames. This wrong frame order appears usually only when camera is stationary and cars move and it's visible with both mpv and TV set. Source feed plays fine in mpv after cutting 4 min sample and remuxing from .ts with mkvtoolnix, but I can't check it with TV set and VLC is too slow to decode it. Does anyone have any idea why this frame order issue could happen and how to fix it?
That crf18 gives 18 Mbps from 14 Mbps source, so maybe I should use crf20-22 instead, but should that have any noticeable difference in quality? I'm new to x265, so I don't know yet what kind of artifacts to look for. Then that 3 fps encoding speed is quite annoying for some seasons of 2h+ races, but maybe using faster settings causes some visible issues. Threaded QTGMC likely won't help much because I already get 60-90% CPU usage. I'm getting quite annoying deinterlacing issues with thin almost horizontal lines and at least source matching doesn't seem to help there, but is there any trick to improve that? Or maybe those are just too difficult to deinterlace properly with any method because I haven't seen good results with those yet.
Hopefully I can somehow fix the stutters so that I wouldn't have to use x264 instead and drop to 8-bit color.
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Can you provide a sample of the source, at least 10 seconds, something showing steady movement
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OK, here is one minute source sample as attachment. First stutter is around 5 seconds when Ferraris drive towards the camera and there's more to come whenever camera stops moving. I tried to encode this with slow QTGMC and x265 presets at crf20, but that doesn't seem to affect the stutters although encoding runs only at 2 fps then instead 3 fps of medium preset. I also checked that one stutter frame by frame in mpv and almost all frames look fine but in wrong order with cars moving backwards four times within short interval and also skipping frames forwards. However, I found a couple frames with messed up car detail and attached screenshot of one, so maybe QTGMC assumes that's some still frame when camera stops panning and enters some wrong mode to cause stutter. Hopefully this sample helps someone know why such stutters happen and how to fix it because otherwise I'm quite happy with the quality. My settings may still need some refining, though, but this is my first attempt with x265 and some help with settings would be great.
Last edited by BirdmanF1; 31st Mar 2021 at 21:20.
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Actually, my earlier encode with QTGMC medium doesn't have that messed up car detail in the attached screenshot from slow encode although frame order is similarly faulty. So likely the problem happens before some extra processing in QTGMC slow messes up the car detail.
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Source looks ok around 5 seconds, no problems. Whole clip is ok in terms of motion, except for the first few frames (maybe from the way it was cut)
What source filter was used ? Post your log file -
I used the default FFVideoSource and no extra parameters anywhere because this is my first attempt. I just had to move ConvertToYUV420() in the script after QTGMC to fix chroma issues. Anyway, I attached my log file from slow test encode with sample and screenshot I posted here. After some more comparison of single frames I couldn't really see any improvement from slow QTGMC except somewhat sharper detail and messed up car detail during stutter that both I don't really like. Maybe QTGMC medium is better for me then because fine detail disappears anyway in motion and I don't want to sharpen imperfections of onboard footage. However, I noticed some glitches in crf20 encode compared to crf18, so maybe I should just use crf18 with higher bitrate because source has so high quality (up to 27 Mbps first generation encode for some seasons) and I'm trying to compete with quality of later 4K races. Hopefully I can somehow fix those stutters and maybe improve deinterlacing of thin almost horizontal lines because otherwise result looks nice already.
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I get jerky results with FFVideoSource too , try lsmash , works ok for me
LWLibavVideoSource()
You can use ConvertToYUV420(interlaced=true) if you apply it before deinterlacing -
LWLibavVideoSource indeed fixes all the stutters, so Thank You a lot! I somehow didn't expect that source filter could just give frames in wrong order for processing. I'm now getting useful output with my settings, but maybe I should still test some more options before encoding dozens of races with two days of CPU time per race. Do you have any useful tips for better settings or any idea how aliasing of thin almost horizontal lines could be fixed? Now QTGMC gives quite annoying result with many thin almost vertical lines stacked although otherwise it works great.
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