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X-T3 Apple Compressor Not Transcoding Properly


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Hi All:

I am having an issue when using Apple's Compressor version 4.4.6 and transcoding .h264,UHD, fLog from an X-T3 to Prores 422.  It appears as through the transcoding process that compressor is changing the brightness values of the transcoded file.  Please see attached.

Top image is the neat file from the X-T3.  Middle image is the Prores 422 transcoded file with Video Pass Through (VPT) left unchecked.  This is the way I normally transcode.  Notice how the that the histogram is shifted up significantly.  The bottom image is transcoded Prores 422 with the VPT checked.  While the histogram is unshifted, unfortunately the file ends up not being transcoded Prores 422.

Does anyone have thoughts on what might be occurring?

Thank you in advance for your help.

Don Barar

ETTR No LUT.jpg

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Hi All:

I need to amend my initial comments.  The above represent .h265 10 bit 420.  Compressor does not properly transcode this to Prores 422 and imparts a significant shift in the histogram.  On the other had, Compressor does properly transcode to Prores 422 files that are h264 8 bit 420.

Sorry for any confusion.

Don Barar

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21 hours ago, dgbarar said:

Hi All:

 

Top image is the neat file from the X-T3.  Middle image is the Prores 422 transcoded file with Video Pass Through (VPT) left unchecked.  This is the way I normally transcode.  Notice how the that the histogram is shifted up significantly.  The bottom image is transcoded Prores 422 with the VPT checked.  While the histogram is unshifted, unfortunately the file ends up not being transcoded Prores 422.

 

1. Are you on OSX Mojave or Catalina? Mojave did not display Fuji H265 correctly.

2. I am not a compressor user, but a "pass through" is usually for leaving part of a file unchanged, such as transcoding only the audio track but not the video track.

I would have read "video pass through" as a way of re-encoding the audio (say from 48khz to 44.1khz) but not the video,

which would remain the same H265 track. So I find your results puzzling.

The compressor user guide at

https://support.apple.com/en-mide/guide/compressor/cpsrf44b12ac/mac

mentions this:

"Video properties

Enable video pass-through: Select this checkbox to copy the source video unmodified to the destination file. When this checkbox is selected, all the other settings in the Video Properties area are disabled."

Is codec selection (Prores 422) included in the Video Properties? so would that be disabled?

 

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Hi Jay,

Thanks for writing.

I am using MacOS 10.15.6 Catalina on a late 2016 MBP15.  That is what I found with Video Pass Through.  It leaves the video untouched and does not transcode to Prores 422--even through it still names the file Prores 422.

However, the main issue remains as to why Compressor shifts the RGB parade up for when transcoding to Prores 422 from .h265, 10 bit, 420 files.

As an experiment, I tried transcoding to Prores 422 the same .h265, 10 bit, 420 file using Adobe Media Encoder.  It seems to process the files just fine without shifting the RGB parade up.

I am at a loss as to what to do other than file a bug report with Apple.

Don

 

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18 hours ago, dgbarar said:

As an experiment, I tried transcoding to Prores 422 the same .h265, 10 bit, 420 file using Adobe Media Encoder.  It seems to process the files just fine without shifting the RGB parade up.

I am at a loss as to what to do other than file a bug report with Apple.

Don

 

Glad you found a workaround. This made me curious about some other transcoder results with raw Fuji H.265 Eterna so I tested the latest version of Shutter Encoder (free) and EditReady (trial) for Fuji H.265 Eterna to Prores 422. I am on Catalina 10.15,  FCPX 10.4.7 - not upgraded to the latest but I am wary of fixing what ain't broke.

I found both those encoders to result in higher contrast Prores files, similar to what FCP used to do to Fuji HEVC in the older OSX Mojave.  There is still something funky about Fuji H.265 compared to other cameras. Luckily the FCPX renders of Fuji HEVC shots to Prores 422 look fine, no shifting.  Which is how I render out my final cut master to be encoded to MP4 in Handbrake. (And even Handbrake compressor if given a raw Fuji H.265 results in higher contrast output.)

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Hi Jay,

Thank you for performing these additional tests.  Hmmm.  I am beginning wonder if this is a Fuji bug or if companies not properly updating their software to properly handle 10 bit HEVC.

Any one out there with a camera brand other than Fuji that can test 10 bit HEVC to see if when transcoding to Prores 422 there is shift up in the RGB parade?

Don Barar

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  • 2 months later...

HI Majkel:

The solution is to transcode to Prores 422 in FCPX.  This is how I do it.  When you import your files, allow FCPX to generate optimized files.  Optimized files are a Prores 422 transcode.  Do your editing.  Then when you complete your project, delete the optimized files to conserve storage space.

For some reason Compressor is not properly transcoding to Prores 422 and with my X-T3 exposure was being added..  However, optimized files in FCPX do not have this problem.  I have written to Apple on their bug reporting and they have never responded.

If you are an FCPX user, this is a far better process than first transcoding to Prores using Compressor or any other transcoding software.  Why? because when you are done with your project you do not have large Prores files to store.

Hope this helps.

Don Barar

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Hi Xavier:

Thank you for pointing this out as a possibility.  I was unaware of the possibilities of mis-match between full levels for 8 bit.  Why would applications make this change?  What applications are you aware of that do this?  Do they have a way to toggle on/off?

BTW.  The examples captured in 10 bit.

Don

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