differences in preview (vitrtaldub,aviutl,avidemux and xvid4psp)

[smartel]

When i preview avisynth scripts in different software i get different results (blacks, saturation etc..)

how can i be sure my editing app is correctly setup?

[Bernix]

Hi,
dont know about other programs, but in Avidemux can be issue checked play filtered. And also I would disable post processing under video in top menu.

Bernix

[jagabo]

ConvertToRGB(marix="X") at the end of your script to check the colors. After checking colors, remove the ConvertToRGB().

[smartel]

Avidemux only support YV12

and i was thinking it was an overlay , directx or GPU decoding issue or something ...

will try the ConvertToRGB(matrix="X") thing ..

[smartel]

string matrix =

"X" meaning .. "Rec601" or "Rec709" or "Rec2020" or "PC.601" or "PC.709" or "Average" ??????
otherwise "X" is an unknown colormatrix parameter ..

[jagabo]

string matrix =

"X" meaning .. "Rec601" or "Rec709" or "Rec2020" or "PC.601" or "PC.709" or "Average" ??????

Yes, whichever is appropriate for your video. The point is for you to control the conversion to RGB, not the graphics card or editor (which may or may not do it correctly).

[smartel]

So if i understand well it's not a renderer or overlay issue but a colorspace issue supported by the app or suited for the content ?

that must go the same way for media players ..

[jagabo]

For you to see YUV video it has to be converted to RGB. That can happen anywhere between the file and the monitor (including the monitor). It's up to you to figure out how each program, renderer, overlay, device... handles the conversion. This can be complicated because some programs/device may use different matrices depending on the container, resolution, etc. If you handle the conversion in AviSynth and only give RGB to other programs/devices you know how the conversion was done.

[hello_hello]

Check your video card settings in it's control panel. On a PC, video should be converted to full range levels for viewing (although it seems PC monitors defaulting to limited range input are becoming more common). I think AMD still defaults to converting to YCbCr444 for some reason, but make sure any video "enhancing" options are disabled. You'll possibly find the video card is fiddling with the picture when it can, or not as the case may be, but it mightn't be effecting all the players you've tried.

As long as the luminance levels look okay I tend to ignore any slight colour differences cause by a rec.601/rec,709 difference when previewing. If the source is YV12 and it's being encoded as YV12 and there's no filtering converting to RGB in the encoding chain, it'll just be encoded "as-is" so in that respect it doesn't matter if the preview is lying to you. Of course if you want to adjust the colour etc that's a different story.

MPC-HC is fairly trustworthy. A script should look the same as the source video (they don't show up in the "File/Quick Open File" menu unless you select "all files" when the navigation window opens). If you adjust the levels with your video card and you play a video with black borders, if you change the video card's setting from full to limited range (for example) and the borders turn greyish, then full range was correct for your display's input. If you change it from limited to full range and the video gets darker but the black doesn't get blacker, then limited was correct. Once you have that sorted you should at least have a reference for what's correct to bother your other software with.

I should add.... keep in mind that depending on the OS/renderer, MPC-HC might be adjusting the luminance levels itself (View/Renderer Settings/Output Range). If it's set to full range, then setting your video card to full range as well won't change the levels (they won't be expanded to full range twice).

The Nvidia system is explained here, even though that's a bit old. https://pcmonitors.info/articles/correcting-hdmi-colour-on-nvidia-and-amd-gpus.
I think it's still fairly retarded though. If it sees your monitor as a TV (depending on the resolution/refresh rate) and the output is RGB, it'll possibly insist on reverting back to limited range every time you reboot. It's something that's worth keeping an eye on.

[smartel]

Well thanks to bernix,jagabo and hello_helllo

i'm actually color correcting a 16-235 SD vidéo and don't want my preview stretched to 0-355 #will it?
i'd ratther do it myself (if i needed to)..

MPC-HC 64bits didn't worked with avisynth but the 32bits version did.

i always have to double check things

Thx again

[jagabo]

i'm actually color correcting a 16-235 SD vidéo and don't want my preview stretched to 0-355 #will it?

It should. 0-255 is the normal range for RGB. In RGB 0,0,0 is defined as black and 255,255,255 is defined as white. In YUV Y=16 is defined as black, Y=235 is deinfed as white. A normal conversion from YUV (Y=16-235) to RGB for viewing results in RGB 0-255. Conversely RGB 0-255 is reduced to YUV 0-235. This is the industry standard for broadcast TV, DVD, Blu-ray, youtube, etc.

[smartel]

this link shows options mainly with ffdshow and avisynth inside ffdshow ...

http://avisynth.nl/index.php/Colorimetry#How_can_I_use_the_correct_standard_upon_playback.3F