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PostPosted: Wed Oct 20, 2021 9:31 am 
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I took a short clip of a girl flipping her hair and want to do an Instagram Boomerang effect on it. So I copied the clip in the timeline and checked the box to play backward. The problem is when it plays backward the colors are washed out. Take a look. https://youtu.be/h6S54EqxIJQ Does anyone know how to fix it?

This is a 4k video shot with a Canon R5 with Log turned off.


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PostPosted: Sat Oct 23, 2021 1:16 am 
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is the R5 shooting 10bit? I wonder if the reversed clip is rendered as 8bit.... can you see in the clip properties? highlight the clip, tap the "i" and tap the 3 dots to expand the info panel.

Perhaps the grade from the original clip doesn't translate well when applied to a lower bit depth reversed clip....

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PostPosted: Thu Nov 25, 2021 9:53 pm 
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Quote:
is the R5 shooting 10bit? I wonder if the reversed clip is rendered as 8bit.... can you see in the clip properties? highlight the clip, tap the "i" and tap the 3 dots to expand the info panel.

Perhaps the grade from the original clip doesn't translate well when applied to a lower bit depth reversed clip....
Sorry it took me so long to reply, but I must have missed the notification that you replied.

I don't see bit depth on the list. It does say the Video is H.264 Rec. 709 469.3MBits/s 29.97 fps.

It also has a warning at the top that says This clip is not fully compatible with this iOS device and may cause crashes and playback issues.


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PostPosted: Fri Nov 26, 2021 3:04 am 
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I checked the specs. From the bitrate, I think you're shooting "All Intra" 4:2:2...

Typical H264 encodes video with an "I" frame which captures the whole frame, then the in-between frames are the difference from frame to frame until the next "I" frame comes along.

All-I only encodes the full frame, none of the inbetween 'difference' frames which gives a fantastic image at the expense of large and hard to edit files. I've read that Canon's implementation of h.264 breaks the spec quite a bit.

It's great that Apple devices can even play and edit that footage at all! Some x86 machines struggle to just play that footage smoothly. You might consider transcoding that footage to something more manageable like ProRes 422 which will keep all your colour information and be easier to edit - It might not even be that much larger than All-I. If on the other hand you're happy with the responsiveness of Lumafusion with your original All-I footage, see if transcoding helps where you want to reverse the footage.

That said, reversing encodes a brand new file....
One of the Luma team might be able to answer how Lumafusion encodes the reversed clips. Do the reversed clips match the chroma subsampling, colour space and bit depth of the original file or does the encoding fall back to something like 8bit 4:2:0 bt709? That alone might be the reason the colours don't match.

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PostPosted: Fri Nov 26, 2021 3:32 am 
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Fixes for pro res reverse clips coming in next update (soon)

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PostPosted: Fri Nov 26, 2021 6:48 pm 
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Quote:
I checked the specs. From the bitrate, I think you're shooting "All Intra" 4:2:2...

Typical H264 encodes video with an "I" frame which captures the whole frame, then the in-between frames are the difference from frame to frame until the next "I" frame comes along.

All-I only encodes the full frame, none of the inbetween 'difference' frames which gives a fantastic image at the expense of large and hard to edit files. I've read that Canon's implementation of h.264 breaks the spec quite a bit.

It's great that Apple devices can even play and edit that footage at all! Some x86 machines struggle to just play that footage smoothly. You might consider transcoding that footage to something more manageable like ProRes 422 which will keep all your colour information and be easier to edit - It might not even be that much larger than All-I. If on the other hand you're happy with the responsiveness of Lumafusion with your original All-I footage, see if transcoding helps where you want to reverse the footage.

That said, reversing encodes a brand new file....
One of the Luma team might be able to answer how Lumafusion encodes the reversed clips. Do the reversed clips match the chroma subsampling, colour space and bit depth of the original file or does the encoding fall back to something like 8bit 4:2:0 bt709? That alone might be the reason the colours don't match.
Yes I do shoot in All I which Canon recommends if you are going to edit the video. So which ProRes 422 do you recommend? I picked 422 HQ and this issue went away so thank you for that. I guess there is a bug in the way LumaFusion reverses the file with the original file out of the camera. Thanks again.


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PostPosted: Mon Nov 29, 2021 2:48 am 
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422HQ is described as visually lossless - 422 is a good amount smaller with a tiny loss in quality which you might need good eyes to be able to spot. That might suit if the final export is only for social media.

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Lumafusion on 2020 iPad Pro (with FCPXML export)
Davinci Resolve Studio on M1 MBP
Windows laptop for emergencies


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