1

I am trying to convert a sample video to 1080p size from 4K. My TV is HD that can support FULL HD playback via USB. It's an LG Smart TV from 2017 that can even play HEVC 1080p. But any video that I convert or encode via ffmpeg is not working. I tried numerous settings. Currently, this is what I used:

ffmpeg -i input.mp4 -c:v libx264 -vf scale=-1:1080,scale=out_color_matrix=bt709 -color_primaries bt709 -color_trc bt709 -colorspace bt709 -pix_fmt yuv420p -crf 18 -preset veryslow -c:a copy output.mp4

The TV does display the thumbnail, but unable to play. I even tried separating the audio to see if that was causing the issue, but it didn't work either. However, if I conver it via online software, a simple one, it works. However not able to set the quality according to my need.

It's a 4K video that I want to convert to Full HD keeping the highest quality of video.

Improve this question
5
  • It might be worth it to include an analysis with ffprobe of the same example file that does and doesn't work depending on the tool you used.
    – Anaksunaman
    Commented Jun 23, 2021 at 2:59
  • 3
    veryslow preset will try to use upto 16 refs but your TV may not support that. Add -refs 2 -bf 2 and check.
    – Gyan
    Commented Jun 23, 2021 at 4:20
  • @Gyan please post this as an answer. This worked
    – 4-K
    Commented Jun 24, 2021 at 9:20
  • Related to this, can we use a semi-lossless conversion from previous veryslow preset to the new refs ? So ffmpeg accepts prior compression with valid refs and only re-converts with refs > 2
    – moi
    Commented Apr 22, 2023 at 11:57
  • For example I have a prior file converted using veryslow that does not play - so I use 'ffmpeg -i input.mp4 -c:v libx264 -refs 2 -bf 2 -crf 18 -preset veryslow -c:a copy output.mp4' - this will reconvert everything.
    – moi
    Commented Apr 22, 2023 at 13:16

1 Answer 1

Reset to default
6

The veryslow preset for the libx264 encoder will try to use upto 16 refs but your TV may not support that. Add -refs 2 -bf 2 to limit to a sane number of reference frames.

Improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .