My action cam is producing out of alignment channels

[GonzoRibbons]

Hi video peeps,

I'm searching for some guidance, and hoped there would be someone in the forums that had seen this type of issue before.. here is a frame grab from some recent footage. All seems to be the same.



I seem to have an issue with my action camera. The colour channels seem to be mis aligned, causing visual ghosting and unusable footage. Does anyone know if this is a hardware issue or a codec/software issue, and can it be fixed using Adobe or DaVinci resolve?

thanks in anticipation

[jagabo]

There's probably nothing wrong with the video, you just have a decoding problem. Upload a short video sample directly from the camera (don't reencode). It would also help if there are large patches of highly saturated colors. Something like this:

[GonzoRibbons]

Thanks jagabo,

posted 2 videos from the same camera. All videos recorded on a recent trip have the problem, recording a clip today had no issues.

https://files.videohelp.com/u/302977/ANMR0094.mp4
https://files.videohelp.com/u/302977/ANMR0001.mp4

Seems very odd.

[jagabo]

There does indeed appear to be a problem with the 0094 clip. And it is as simple as the chroma channels being shifted right and down. You can fix that by shifting the chroma left and up but there's no easy way to get the correct chroma for the right and bottom edges.

source frame:

[Attachment 65810 - Click to enlarge]

after shifting chroma:

[Attachment 65811 - Click to enlarge]

Since there aren't any correct colors for the right and bottom edges you could just crop them away:

[Attachment 65812 - Click to enlarge]

I did the chroma shift with AviSynth:

LWLibavVideoSource("ANMR0094.mp4") 
MergeChroma(last, Overlay(last, last, x=-576, y=-320))
Crop(0,0,-576,-320)

You can probably do something similar with other software. In theory, you can get some of the colors for the right and bottom edges from past and future frames (given the way the camera is panning around) but that's a lot more difficult.

[GonzoRibbons]

Thanks for the direction. I'll give it a try, much appreciated, I might be able to salvage something.


Do you think it was hardware/software/card problem? These were straight off the TF card. Will have to keep an eye on it.

Anyway, many thanks for the assist

regards
GR

[jagabo]

This is probably a bug in the camera's firmware. I don't see any way a bad flash card could cause it. The chroma is fine other than the offset with the luma. I don't know of the offset will be the same with all the videos so you may need to make individual adjustments.

[GonzoRibbons]

OK, huge learning curve. Installed all the necessary to get AviSynth to work. It processes the file, aligns and crops as advertised. How do I save it out? Opening the file doesn't seem to have changed anything. Sorry, real noob.

Is there a script line to save out to a finished folder?
Can I increment the filename automatically to batch process?

Many thanks in anticipation. Huge respect for such a quick response.

[jagabo]

OK, huge learning curve. Installed all the necessary to get AviSynth to work. It processes the file, aligns and crops as advertised. How do I save it out?

AviSynth is basically a filtering system. You need to open the script in an editor that support AVS scripts as input. Then save from there. You could VirtualDub2 (also good for viewing the results of your scripts). In VirtualDub use File -> Open Video File to open your AVS script. Note, the script I gave you doesn't include the audio. You need a few more commands to include the audio (it will be reencoded though):

a = LWLibavAudioSource("ANMR0094.mp4", cache=false) 
v = LWLibavVideoSource("ANMR0094.mp4", cache=false) 
AudioDub(v,a)
MergeChroma(last, Overlay(last.GreyScale(), last, x=-576, y=-320))

You can batch process a bunch of files in a folder (and subfolders if necessary). But lets get AviSynth working for you first. By the way, I recommend using 64 bit AviSynth Plus. You will need the LSMASHSource filter in addition to a default AviSynth+ installation.

https://www.videohelp.com/software/AviSynth-Plus
http://avisynth.nl/index.php/LSMASHSource

[GonzoRibbons]

As luck would have it, I installed AviSynth+ after watching some YouTube videos. I've also downloaded VirtualDub, AvsPmod, ffmpeg-master, LSMASH and Python. I think I have them all installed properly. For good measure, I also got the PremiereAVSPlugin to see if any of this can be done in Premiere Pro.

Thanks again

[rrats]

Decoding problem

[jagabo]

It's definitely not a decoding problem. It happened before the video was encoded within the camera.

[jagabo]

As luck would have it, I installed AviSynth+ after watching some YouTube videos. I've also downloaded VirtualDub, AvsPmod, ffmpeg-master, LSMASH and Python. I think I have them all installed properly. For good measure, I also got the PremiereAVSPlugin to see if any of this can be done in Premiere Pro.

Have you tried the script yet?

[GonzoRibbons]

The code in AvsPmod seems to work

a = LWLibavAudioSource("C:\Working Folder VIDEO\Test folder\ANMR0094.mp4", cache=false)
v = LWLibavVideoSource("C:\Working Folder VIDEO\Test folder\ANMR0094.mp4", cache=false)
AudioDub(v,a)
MergeChroma(last, Overlay(last.GreyScale(), last, x=-576, y=-320))
Crop(0,0,-576,-320)

In the preview it aligns chroma and luma channels and crops.... is this correct? Am I just testing the script before I put it into action? Do I run this script in something else? Sorry to be a klutz, but I'm new to this, and have only worked in Premiere Pro, and I'm no expert in that.

[Attachment 65847 - Click to enlarge]

Thank you for your patience.

[jagabo]

The code in AvsPmod seems to work

a = LWLibavAudioSource("C:\Working Folder VIDEO\Test folder\ANMR0094.mp4", cache=false)
v = LWLibavVideoSource("C:\Working Folder VIDEO\Test folder\ANMR0094.mp4", cache=false)
AudioDub(v,a)
MergeChroma(last, Overlay(last.GreyScale(), last, x=-576, y=-320))
Crop(0,0,-576,-320)

In the preview it aligns chroma and luma channels and crops.... is this correct?

Yes. If you don't want to crop you can remove the last line. Or disable it by putting a # at the start of the line. If you want to leave the misaligned colors at the bottom and right edges you can remove the ".GreyScale()", leaving the "last". If you want to crop but restore the original frame size add Spline36Resize(3840, 2160) at the end of the script.

Am I just testing the script before I put it into action? Do I run this script in something else?

I don't really use Avspmod but I know it has the ability to encode the script. Use the Tools menu. That's as much as I know about that. I usually use a command line encoder, x264 or ffmpeg (I see that Avspmod uses ffmpeg). You can also open the script in VirtualDub2 (File -> Open Video File) and encode with that. Select Video and Audio codecs, configure them, and File -> Save Video... That should be enough to get you started.

[rrats]

The code in AvsPmod seems to work

a = LWLibavAudioSource("C:\Working Folder VIDEO\Test folder\ANMR0094.mp4", cache=false)
v = LWLibavVideoSource("C:\Working Folder VIDEO\Test folder\ANMR0094.mp4", cache=false)
AudioDub(v,a)
MergeChroma(last, Overlay(last.GreyScale(), last, x=-576, y=-320))
Crop(0,0,-576,-320)

In the preview it aligns chroma and luma channels and crops.... is this correct? Am I just testing the script before I put it into action? Do I run this script in something else? Sorry to be a klutz, but I'm new to this, and have only worked in Premiere Pro, and I'm no expert in that.

[Attachment 65847 - Click to enlarge]

Thank you for your patience.

Can such filters be used to align chroma on badly deinterlaced video? You know, when idiots convert interlaced video to lossless progressive 4:2:0 (on the fly) and it all looks wrong.

[jagabo]

Can such filters be used to align chroma on badly deinterlaced video? You know, when idiots convert interlaced video to lossless progressive 4:2:0 (on the fly) and it all looks wrong.

Usually not. The problem there isn't that the chroma is shifted. It's that the chroma of two different fields (different points in time) are blended together.