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[maxxsid]

Hello,
It's a software question not hardware but still...
Just noticed this as I just started shooting HD movies with my camera.
Movies are QuickTime MOV (MPEG4 Video (H264) 1920x1080 29.97fps).
The movies look different when played on different players.
QuickTime Player (and Corel VideoStudio which uses QT engine) playback looks more natural too me.
The rest (MC, MPC, WMP, CyberLink) produce output which is much more contrasty and saturated.
If I convert to mp4 (MPEG4 Video (H264) 1920x1080 30fps) - all players play in the same way.
What's going on and which one is right?
Examples:
QuickTime/Corel

The rest


Any idea?
Thanks!
--max

[InflatableMouse]

MC of course 

Nah, just kidding. Interesting question though.

The top one has my preference as well but that doesn't mean anything. Given the fact that only QT renders it slightly less saturated I'm inclined to say may do some processing on it?

[maxxsid]

I just did some googling and it seems that there's a so called "gamma shift" in QT. Looks like QT applies a gamma shift (1.2 factor as I got from photoshop). In my case it produces good results but it actually changes the source...
Apple... meh..

[maxxsid]

Well, it's QT's (Apple's) fault for sure. Knowing this, I just need to apply "gamma -20" in Corel VideoStudio when editing/converting the videos. Or switch to some other video editing software (which sux) - tried CyberLink PowerDirector and it looks good.
The whole issue arose when I noticed that my edited videos looked lighter/washed-out after being processed by Corel VideoStudio (which uses QT)

--max

[maxxsid]

On the other hand... maybe my camera KNEW (or assumed) that the MOV files would be played with QT and made the movies with gamma 0.8 so that they would look good with gamma 1.2?

[InflatableMouse]

I wouldn't know, but doesn't repetitive processing result in loss of information? If that 1.2 gamma correction results in clipping, than bringing it back to 0.80 doesn't bring back the lost information, or doesn't it work that way? Is that a lossless process?

[maxxsid]

I don't think gamma does any clipping.
Well, I am not an expert here...
Hate moving away from VideoStudio but I think I need to.
Thanks!
--max

I wouldn't know, but doesn't repetitive processing result in loss of information? If that 1.2 gamma correction results in clipping, than bringing it back to 0.80 doesn't bring back the lost information, or doesn't it work that way? Is that a lossless process?

[InflatableMouse]

Glynor would know. Where is he when you need him    .

[Samson]

They say a picture is worth a thousand words, have a look at the range and distributions of tones on the histograms..... (OMG, as a "subjectivist" I am talking numbers and graphs  )

[maxxsid]

appreciate the histograms but they basically tell the same story as the pictures do.
the question is which one is the correct representation of a digital file....

[6233638]

There are a couple of reasons why videos might look different in QuickTime depending on the version, especially if you're on OS X.
And sometimes it's different in a "Good" way; newer versions of QuickTime - at least on OS X - are color managed applications, but older versions may be displaying the wrong thing for other reasons.
Generally it's not a bad idea to assume that QuickTime's output is wrong though.

However, because you are taking files from a video camera, it may actually be that it's a tagged file, and QuickTime is the only one that's displaying it correctly.
What does QuickTime's information window say about the file?

That said, my gut reaction from seeing the two images was "oh, it's not doing levels expansion" but from seeing the histogram, there are values outside 16-235 that would be clipped in that case.
The image from Media Center appears different to what it would look like if you just did levels expansion on that QuickTime image though.

What I'm wondering is if your video card is doing something to alter the image in some way.
With Nvidia cards, it would be set here:

[glynor]

Glynor would know. Where is he when you need him    .

Busy.

Sorry.  

Short answer?  With temporally compressed video like H264, there is no "right".  Different decoders interpret the standards in different ways, and apply different filtering depending on the whim of whatever engineer designed the system.

[maxxsid]

but it's like Apple vs all the others.
I am starting to suspect that QT is right here. It knows something the others don't. As 6233638 mentioned, MOV files (QT format) might containg some tags telling QT to up the gamma.
My still pictures of the same object look more like QT playback of the video.

[glynor]

I didn't realize you had the source files and that they were MOVs (sorry, I really was busy, I completely skimmed the thread).

Quicktime looks like it is using the proper Gamma, and the others aren't (or something like that).  OSX traditionally handles Gamma differently than Windows... Perhaps that's the reason?  I know Final Cut had Gamma issues with certain clips (it was frustrating till I figured out how to fix it).

MOV support in other engines is reverse engineered, I believe, so it wouldn't be shocking for it to be wrong in some ways (though it certainly got much easier when they used the MOV container as the basis for the MP4 container).

You can set MC to use the Quicktime engine for MOV files.

[maxxsid]

Thank you guys for setting my head straight! I think I understand what's going on now.

[glynor]

Thank you guys for setting my head straight! I think I understand what's going on now.

Actually...  I looked it up.

It is actually that Quicktime is wrong.  Well, it interprets color values for MPEG-4 (ASP and AVC apparently) video "differently" than many other players.  It uses rec.601 pixel values, as opposed to "full range"(0-255) color values.  Depending on the way the video was encoded, this is either "right" or "wrong".  The right thing to do is probably up to interpretation, to some degree.

More info here:
http://vitrolite.wordpress.com/2010/12/31/quicktime_gamma_bug/

Anyway, my guess is that since they put it in a MOV container, the camera maker probably assumes that the user will be playing the files in Quicktime, and so encodes them with values that will look right in Quicktime (otherwise customers will call and complain).  You could transform the actual source files with an editor, or you can adjust the output format with many decoders.  I'm not sure how to make this adjustment accurately from inside Red October.  Perhaps someone could chime in?

[maxxsid]

That's actually my idea too.

And I do convert/edit my videos.
The thing is - Corel VideoEditor produces QT type of contrast, CyberLink PowerDirector and MS MovieMaker come out with lower gamma.
Just checked - Adobe Premiere Elements is also "QT friendly" (Corel and Adobe use QT engine to decode).

After conversion MOV to MP4 all players play the same way.

...
Anyway, my guess is that since they put it in a MOV container, the camera maker probably assumes that the user will be playing the files in Quicktime, and so encodes them with values that will look right in Quicktime (otherwise customers will call and complain)....

[Samson]

What disturbs me is the MC version seems to clip the darker tones losing shadow details. I could be wrong but gamma adjustments (of screen dislay) will affect mainly mid tone adjustments and therefore mid tone contrasts.Altering the gamma or mid tone slider in photoshop may bunch tones down one end but you shouldnt lose data, I woulnt have thought.

Levels adjustment shows the QT image just seems to have more data to work with and with shadow detail restored.

However, I cant then explain why converting both to MP4 all look the same if you are starting out with files containing fundamentally different amounts of info.

[maxxsid]

When converted from MOV to MP4 all videos play the same way in all players.
When I convert to mp4 using corel or adobe (they use QT engine to decode)  - videos look "QT like', i.e. lighter in all players.
When I convert to mp4 using cyberlink or ms (they use something else to decode)- videos look darker in all players.

However, I cant then explain why converting both to MP4 all look the same if you are starting out with files containing fundamentally different amounts of info.

[Samson]

okay so with different decoders the converted file plays differently and the difference is consostent in all players.

What still puzzles me (thats not hard to do ?) is the QT image is basically truncated at both ends, it does not appear to be a gamma issue per say.It will affect the overall contrast, difference between lightest and darkest tone.In my images I adjusted the "levels" accordingly to "fix" this.I didnt fiddle with mid tones.

On the other hand the MC image is "clipped" at the lower tones (Shadows). My adjusted "levels" pic required the highlights slider move to the left.

gamma should (I think) alter mainly mid tone shades. It shouldnt clip either end ??

So I fail to see how this is a "gamma" problem ( but I fail to see lots of things  ?)

Whatever the case.......Apparently it can be "fixed" inside QT Pro
From http://www.videocopilot.net/blog/2008/06/fix-quicktime-gamma-shift/

Using mp4 or h.264 when compressing through QuickTime can make the final video look washed out. This is a common problem that seemed to have no solution… until now. The gamma shift can actually be fixed inside QuickTime Pro without re-compressing your video by simply changing a few settings.
SOLUTION: After rendering into a QuickTime/h.264 file, open it up in QuickTime and select “Show Movie Properties.” Highlight the video track then click on the “Visual Settings” tab. Towards the bottom left you should see “Transparency” with a drop-down box next to it. Select “Blend” from the menu then move the “Transparency Level” slider to 100%. Choose “Straight Alpha” from the same drop-down and close the properties window and finally “Save.”

[maxxsid]

Yeah.. I saw this. Yes QT plays some videos lighter and this can be fixed in one way or another.
Some videos, however, really do need to have this gamma factor applied. This is exactly my case.

My camera (Fujifilm HS10) shoots QuickTime MOV movies in such a way that they are supposed to be played on QuickTime Player and they look true and natural there with the gamma applied.
One more proof of this is that when these movies are played directly from the camera via HDMI they look exactly as they look in QuickTime.

Thanks!
--max

Whatever the case.......Apparently it can be "fixed" inside QT Pro
From http://www.videocopilot.net/blog/2008/06/fix-quicktime-gamma-shift/