Command line for HD preview and 4K final rendering

Hi there,

I’m trying to use the melt to render the files exported from Shotcut.
Having the .mlt project file would like to have a command-line command which renders the .mlt for preview as a fullHD, this will save some time on rendering.
When all the edits are done and the project is approved would be good to have another command line that renders the same .mlt at the final 4K resolution.

For fullHD this command is working for me:
melt - progress shotcut-iIOuUF.mlt -consumer avformat:output-hd.mp4 vpre=veryfast preset=fast movflags=+faststart f=mp4 acodec=aac channels=2 ar=48000 ab=384k vcodec=h264_nvenc
qp=18 vq=18 g=15 bf=2 width=1920 height=1080

For 4k I have modified this to:
melt - progress shotcut-iIOuUF.mlt -consumer avformat:output-4k.mp4 vpre=veryfast preset=fast movflags=+faststart f=mp4 acodec=aac channels=2 ar=48000 ab=384k vcodec=h264_nvenc
qp=18 vq=18 g=15 bf=2 width=3840 height=2160
[ this would be ideal ]
This says that:
[h264_nvenc @ 0x7f150c201d80] Interlaced encoding is not supported. Supported level: 0
[h264_nvenc @ 0x7f150c201d80] No capable devices found
also the rendered output-4k.mp4 doesn’t have any video in it.

Any idea/help would be appreciated.

Why are you using preset=veryfast again? We already established that doesn’t work and breaks the export.

It’s also lacking progressive=1.

Remove vpre. It is deprecated and replaced by preset.

Hey Austin,

Have missed the preset=veryfast, changed to preset=fast.
When I’ve added the progressive=1 the sound became choppy, so dropped that one.
From what I found out, having vpre doesn’t hurt at all, can live with preset

This shouldn’t be related to interlace vs progressive. Something else may be in play, like 60.00 vs 59.94 fps, although even that is a stretch. Are any of the source clips from cell phones that weren’t converted to edit-friendly? Choppy audio is typical of VFR files.

It doesn’t provided it matches preset if both are specified. If they are in conflict, results could be unpredictable.

Have redone my tests and … having vpre didn’t made the rendering faster, so will drop that one :slight_smile:

As for the sound & video sources, they are very mixed, to say at least, ranging from 23.98 up to 60.00

Until now, the single solution I found is to do 2 different temporary .mlt files, one for HD and one for 4K, and render them.

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