HELP ! Vidcoder resize change colors !!!

[Ginosergio]

Hi
I am resizing some mp4 files from 5400x2700 to 4096x2048. I also need to add sharpness. Look at the settings here below. The problem is that the resulting file loose contrast/saturation. Why ??? What can I do ? For "TUNE" I use NONE, also tried FILM, but the result is the same.
Please help.
thank you
Ginosergio


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[hello_hello]

The encoding itself won't change the colors, although a sharpening filter might change them a little bit. Nothing like your screenshots though.

YUV video normally uses "limited range" levels (16-235 represents black to white) whereas RGB, computers and some (I think) cameras use full range levels (0-255 represents black to white). When you view a limited range video on a PC the levels should be expanded to full range, or they'll look washed out. Likewise when you convert RGB to YUV for encoding, the full range levels are normally converted to limited range. I don't know your source is RGB but things can go wrong when you view the source on a PC, and when you view the encode, so it'd probably pay to upload a small sample of the original video, otherwise there's too much guessing involved. The original may be displaying correctly on your PC but not the encoded version.

To get it back to the original colors (or pretty close) I had to convert the jpeg to YUV without converting it to limited range (jpegs are full range), then I had to do another limited to full range conversion, so there's something wrong that isn't the encoding as such. All that's easy to do using Avisynth.

Edit: I don't use it, but I think VidCoder has a section for displaying a log file (Handbrake does). It might pay to see if you can't find the information regarding the source, or maybe copy the whole thing to a text file and attach it to a post with a sample of the source, and maybe even a sample of the encoded version.

[Ginosergio]

Hi hello_hello
Thank you for your answer, you are an expert, for sure!


For playback I am using MPC-HC.
With MPC-HC, checking the video track, it shows...
ORIGINAL: Alias Data Handler [eng] (HEVC Main, yuv420p, 5400x2700...
RESIZED: h264 high L4.1, yuv420p, 4096x2048...

With MPC-HC, I have played with renderer settings:
- Output interval was originally at 0-255, but setting to 16-255 does nothing
- Checking Presentation: Output 10bit RGB, does nothing
- Checking Presentation: Force input 10bit RGB, does nothing

Further inspection with MEDIAINFO. the obvious differences are:
ORIGINAL video: encoding Main @L6 - Colour range: Full
RESIZED video: encoding High @L4.1 - Colour Range: Limited

Some time ago I have changed the encoding because the default (I don't remember what was) does not allow 30Mb/s.

Today with some googling I have found some suggestion to obtain full color range in output. The suggestion was to add some parameters to the encoding.
I added these to Vidcoder, but from the LOG it seems to reject them.
Look at the enclosed pictures.

P.S.1 Does Vidcoder use FFMPEG ????
P.S.2 Tried to do this work with Handbrake, but it seems I can not set an output width greater than 1920 !



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[hello_hello]

If changing the output levels in MPC-HC has no effect, it probably means your video card is expanding the levels as required. That's not necessarily a bad thing, but if the video card is set to output full range for video (the video setting is often independent of everything else), your monitor should be set to expect a full range input. For DVI and VGA, the input should be full range, but many monitors default to limited range for HDMI inputs. If the output is full range and the input limited range, the picture will look darker. It doesn't matter too much if the output/input are limited or full range, as long as they match.

Is there any picture enhancing crap enabled in the video card's control panel aside from a levels conversion? Dynamic contrast etc?

yuvj420p is normally full range, but the video might still be limited range, or a player/decoder might be assuming.
Normally Vidcoder would convert a full range source to limited range, and I'm not sure you can tell it not to. If that conversion shouldn't happen because the source is really limited range, then the encode will look washed out, or lighter. The fact that the encode appears to be two "full range" to "limited range" conversions away from the source would suggest a combination of a playback and conversion problems, but I can't quite get my head around how it might happen that way.

Sorry, but it's just guessing without a sample, and last time I was involved in a discussion like this one, I think I discovered full range video wasn't displaying correctly on this PC. It looked too dark, like the crappy Nvidia drivers were expanding it incorrectly (I'm using very old drivers with XP), but maybe someone else will be able to take a look. I haven't investigated as a almost never work with full range sources. I don't use Vidcoder either, but I don't think there's any way to tell it not to change the levels, or to tell it to save full range or limited range info for a player, but I could be wrong. Maybe the Handbrake forum might be the place to ask?

[Ginosergio]

Hi, thank you for your answer!

I do not have any enhancement set in my Nvidia control panel; anyway this will not solve my problem because I am resizing videos to watch them in my Oculus GO.

Sorry, did you read the Mediainfo value that I reported ? The 2 files are different as the original has Color Range FULL, the resized has color range LIMITED. Do you know a method to obtain "FULL" in the output file ? It would be a good start.

Last, I was trying Vidcoder because it seems the fastest, but I can use *ANY* recoding software if it can do what I need:

- resize (reduce) resolution of an MP4 with a given target bitrate
- add some sharpness
- obtain a file similar to the original for quality, keyframes, codec....

you can suggest me anything ! Thank you.
Ginosergio