cr2hdr vs mlv_dump: Black/white levels

[Oedipax]

Like a lot of you, I've been experimenting the past few days with the new 3k/4k modes in crop_rec and really loving the results I'm getting.

At first I was using mlv_dump in the command line to output DNG files one at a time. The files I got opened up and played back fine in Resolve without any issues.

After a bit, I decided to check out cr2hdr and really like the batch processing it does. However, my DNGs from cr2hdr end up having flickering frames where I'm guessing either the white or black level has fluctuated slightly.

I searched around the forum a bit and found a post referencing setting blacks to 2048 and whites to 16383. So I reprocessed one of my MLV files using these values in cr2hdr, but I'm still getting the flickering issues in Resolve.

Does anyone know why mlv_dump on the command line is giving me perfect results right out of the gate without any manual settings (just -o to specify output name and --dng) but cr2hdr even with settings dialed in still results in flicker frames?

I really want an easy way to batch footage, rather than do it one at a time! Thanks for any help.

[Oedipax]

Dug around a little more and realized the flickering is only happening on certain shots - most of the batch-processed clips from cr2hdr are fine as well.

Maybe it's just a fluke? I can process these trouble clips in the command line, I suppose...

I can upload one of the problem MLV files in question if someone wants to look into it.

[DeafEyeJedi]

...I can upload one of the problem MLV files in question if someone wants to look into it.

Please do.

[MitchLally]

I had a similar flickering issue in Resolve – it looked more like white balance flickering from 2000 to 5600 – only on certain clips. I think it has something to do with resolve reading the dngs. Have you tried viewing the dngs in ACR?

[Danne]

Hi Oedipax. Please upload a clip with the flickering issue. You could also upload some dng files if you can locate which ones are causing it to flicker.
cr2hdr.app is adding back the white balance tag to to compressed raw dng files. If that tag isn,t being readded to all the files that might be causing this to happen but it,s just a wild guess. It could be a number of different things.
You could also try and disable the dualiso automation from the mlv_dump menu and see if that works better.
(10) disable dualiso automation
Here is the cr2hdr.app thread.
http://www.magiclantern.fm/forum/index.php?topic=15108.0

[Oedipax]

Thanks for the replies! Here is one MLV that comes out of cr2hdr with flickering, but does not when using plain mlv_dump in the command line:

https://drive.google.com/open?id=0B_GaTvWvQ0BfVzcwZF9XNC1kM2c (~800mb)

If I get some time later I'll try to isolate a few of the processed DNGs as well and upload those here.

[Danne]

How are you previewing this clip? I couldn,t see any flicker ing over here but then again couldn,t get any realtime previewing. Is the clip flickery also after export to let´s say a prores file?

[Oedipax]

I'm getting it when I load the DNGs generated with cr2hdr into Resolve and either preview it there, or export to prores (same result either way).

[Danne]

I see. If you can find some dng files samples it would be great

[Danne]

I prepared a command script which will check for differences in metadata in your files. It will check the static ones.

You,ll need exiftool installed on your computer.
http://www.sno.phy.queensu.ca/~phil/exiftool/ExifTool-10.49.dmg

1 - Download and put the script next to your dng files. The files has to been processed in cr2hdr.app or with the any mlv_dump version.
https://bitbucket.org/Dannephoto/magic-lantern/downloads/A_metachecker.command

2 - Give the script permission before you double click it. In terminal write following:
chmod u=rwx and then drag the A_metachecker.command into terminal press enter. Should look like this in terminal
chmod u=rwx drag/A_metachecker.command/here
press enter

3 - Now double click the A_metachecker.command inside the folder with dng files. You´ll see in terminal what´s going on. Please post your findings.


I excluded Strip byte counts and Strip offsets. these tag differs from file to file coming from compressed raw. The tag is static for uncompressed 14bit files. I couldn´t see any difference in those tags with dng files processed in cr2hdr.app or directly with the compressed mlv_dump binary so left these ones tag out.


One other tag that differs is this:
Baseline Exposure               : undef

Undefined in compressed raw and set to 0 for uncompressed. This tag could change exposure causing fluctuations in brightness. Not sure what undef will do, maybe defaults to 0.