Forgive me for I'm new to here, but I've been searching for solutions all the day, yet still puzzled by this problem. I try to downscale a 3840*2160 video to 1080p, and here's what I first did:

ffmpeg -i original.mkv -vf scale=1920:-1 downscaled.mkv

And here are the results:

Original: Original video screenshot

Downscaled: Downscaled video screenshot

At first, I thought it's because I didn't apply the correct settings to my video player (potplayer), but even I set exactly the same splitter/decoder/renderer/..., it still didn't work.

Then I searched and tried different ways like pix_fmt yuv444p10le which is from a post here, and later defined encoders, crf...... but all didn't work.

Could anyone please help me, many thanks!

Add: I then used HandBrake, a GUI video transcoder, to downscale the original video, it worked well, at least, looks a lot better. Downscaled video using HandBrake screenshot

  • Interesting. I suspect it has something to do with the color-space you're in. The original footage might have been in srgb but then got converted into an ACES colorspace (for example), and thus the values for each color shifted a bit. You might want to try to find out the color-space of your original footage and then setting it during the downscaling with ffmpeg. Feb 21 '20 at 11:28
  • Share the readout of ffmpeg -i original.mkv
    – Gyan
    Feb 21 '20 at 14:07
  • @Gyan too long to comment, so I'll separately comment.
    – Xiaobao
    Feb 22 '20 at 2:41
  • Metadata: title : Frozen.II.2019.2160p.BluRay.REMUX.HEVC.DTS-HD.MA.TrueHD.7.1.Atmos-FGT ENCODER : Lavf58.35.101 Duration: 00:01:40.64, start: 0.000000, bitrate: 68129 kb/s Chapter #0:0: start 0.000000, end 100.000000 Metadata: title : Chapter 15 Stream #0:0(eng): Video: hevc (Main 10), yuv420p10le(tv, bt2020nc/bt2020/smpte2084), 3840x2160 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 23.98 tbc
    – Xiaobao
    Feb 22 '20 at 2:43
  • Metadata: title : Frozen.II.2019.2160p.BluRay.REMUX.HEVC.DTS-HD.MA.TrueHD.7.1.Atmos-FGT BPS-eng : 60669047 DURATION-eng : 01:43:13.646000000 NUMBER_OF_FRAMES-eng: 148499 NUMBER_OF_BYTES-eng: 46970325317 _STATISTICS_WRITING_APP-eng: mkvmerge v43.0.0 ('The Quartermaster') 64-bit _STATISTICS_WRITING_DATE_UTC-eng: 2020-02-15 09:08:44 _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES DURATION : 00:01:40.642000000 Stream #0:1(eng): Audio: truehd, 48000 Hz, 7.1, s32 (24 bit) (default)
    – Xiaobao
    Feb 22 '20 at 2:44

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