Ok, done my homework (Job has bitched about Gamma shifts a lot in the past….)
It is simple: (Nah, it never is :-)
A QT file can have an clrn atom (an atom is a piece of info)
In there are three parameters:
-Colour Primaries (You see I'm using BBC language :-)
-Transfer Function
-Colour Matrix
Apps that are 'ColorSync aware' will adjust the display based on what is in this atom.
Now it is very easy for me to add something to QT change that will alter these values, but I have NO CLUE on what setting will solve what issue.
I would think that 'pro' apps will totally ignore whatever is in there, or at least let you override ColorSync stuff.
So writing 'something' in the manual is impossible without some additional help.
And, I need some additional info on 2.4 gamma…
And, I need to know if this is a stupid issue from the past that only affects users using steam powered stuff.
(In that case it still might help here and there, but if close to no-one uses it, no need to clutter the interface with stuff no-one uses.)
So, if anyone can help? (Or send (small) testfiles with what to expect / what goes wrong where.)
Some nice video about the subject:
https://player.vimeo.com/video/349868875
Bouke / edit 'B
videotoolshed.com
Van Oldenbarneveltstraat 33
6512 AS Nijmegen, the Netherlands
+31 6 21817248
If you want to send me large files, please use:
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> On 17 Mar 2023, at 23:39, Dave Hogan via groups.io <mactvman=yahoo.com@groups.io> wrote:
>
> Not on that system right now, but let me see if I can come up with a couple short files to send you in a day or two.
>
> Not sure if QT Pro would do it. I'll give that a shot as well.
>
> Dave
>
>> On Mar 17, 2023, at 3:52 AM, bouke <bouke@editb.nl> wrote:
>>
>> QTchange can't do this right now.
>> Was QT pro able to do this in the old days?
>>
>> If i have the same file twice, but with only this flag changed, I know where to look for.
>>
>> Bouke
>>
>
>
>
>
>
>
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Saturday, March 18, 2023
Friday, March 17, 2023
Re: [Avid-L2] Quicklimes with wrong levels flags.
I know that in some cases it doesn't scale the video level. Way back when I had to deliver XDCam 50 files and it was when Adobe Media Encoder would accept QT reference files. I would export a QT Ref from Avid. I found AME would export incorrect level XDCam50 files if I left the checkbox set to legal or back then I think they called Rec 709 in the checkbox. If I set the check box to old name RGB/Full Range in today's term then the XDCam 50 would export correctly. Given I was sending AME a QT reference the video essence from the Avid timeline was all legal level regardless of which checkbox I selected on Avid export. It was AME that must have seen the flag or something change and interpreted it differently. IIRC when exported as legal/Rec709 the AME export was low but when exported from Avid at Full Range/RGB the AME export was proper legal level. I only figured out the pattern of behavior by trial and error.
Over the years I've been told from the Avid Camp that if I link to a file then check in source settings that there are no color adapters or scalers it should output the true video essence level of that file but again I've had times especially when using some Avid native codecs that when linking back into Avid it really seemed like there were some under the hood flags being read and interpreted.
On the Arri sight their LUT maker a few years back assumed all the camera material was legal level and that was the only choice you could choose on the production side of the LUT builder. I assumed from that the the files from Arri Log C were supposed to be legal level and their LogC to Rec 709 LUT worked well in my experience as did the one Avid came up with IIRC. It seems most other Cameras/Codecs create their log video essence in Full Range. It seems weird because the Log signal never even reaches legal level in actual value is way inside legal level on scopes so it always amused me as to what was legal vs full range in the log world. How Avid handles level scaling on the input side to LUTs has also been confusing and hard to pin down. I remember back in the 8.4/8.5 Avid days different versions of Avid would input scale LUTs differently. I experienced that on Panasonic Varicam 35 using the Panny Vlog to Rec 709 LUT. I don't know why there isn't some visible way to see these aspects of under the hood level scaling before and after LUTs or color adapters.
Groups.io Links:
Over the years I've been told from the Avid Camp that if I link to a file then check in source settings that there are no color adapters or scalers it should output the true video essence level of that file but again I've had times especially when using some Avid native codecs that when linking back into Avid it really seemed like there were some under the hood flags being read and interpreted.
On the Arri sight their LUT maker a few years back assumed all the camera material was legal level and that was the only choice you could choose on the production side of the LUT builder. I assumed from that the the files from Arri Log C were supposed to be legal level and their LogC to Rec 709 LUT worked well in my experience as did the one Avid came up with IIRC. It seems most other Cameras/Codecs create their log video essence in Full Range. It seems weird because the Log signal never even reaches legal level in actual value is way inside legal level on scopes so it always amused me as to what was legal vs full range in the log world. How Avid handles level scaling on the input side to LUTs has also been confusing and hard to pin down. I remember back in the 8.4/8.5 Avid days different versions of Avid would input scale LUTs differently. I experienced that on Panasonic Varicam 35 using the Panny Vlog to Rec 709 LUT. I don't know why there isn't some visible way to see these aspects of under the hood level scaling before and after LUTs or color adapters.
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Re: [Avid-L2] Quicklimes with wrong levels flags.
Not on that system right now, but let me see if I can come up with a couple short files to send you in a day or two.
Not sure if QT Pro would do it. I'll give that a shot as well.
Dave
> On Mar 17, 2023, at 3:52 AM, bouke <bouke@editb.nl> wrote:
>
> QTchange can't do this right now.
> Was QT pro able to do this in the old days?
>
> If i have the same file twice, but with only this flag changed, I know where to look for.
>
> Bouke
>
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Not sure if QT Pro would do it. I'll give that a shot as well.
Dave
> On Mar 17, 2023, at 3:52 AM, bouke <bouke@editb.nl> wrote:
>
> QTchange can't do this right now.
> Was QT pro able to do this in the old days?
>
> If i have the same file twice, but with only this flag changed, I know where to look for.
>
> Bouke
>
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Re: [Avid-L2] Quicklimes with wrong levels flags.
Hi John,
The problem with checking that box is that it actually scales the levels, which is exactly what I don't want to do. Then, while I may have a file flagged as Full Range, it has actually had it's already correct levels expanded to be wrong.
Thanks,
Dave Hogan
On Mar 17, 2023, at 2:11 AM, John Moore <bigfish@pacbell.net> wrote:I don't recall what is or isn't available on that version of Avid but when exporting from Avid can't you check scale legal to full range or did they call it RGB back on that version, before they changed the nomenclature in Avid to more accurately reflect current terminology for legal vs. full scale? I've always battled whether Avid actually scales the video essence or just sets a flag depending on that choice. I've assumed over the years that it might depend on the codec being exported and the eccentricities that dnx media flagged levels as opposed to other codecs. I've always wanted to have some swiss army software that plays the video essence of a file directly out to my scope without any luts or embedded metadata influencing things. BM Express supposedly does this but I've never been sure and the codecs it is compatible with have always seemed limited and usually not the files I'm trying to check.
Re: [Avid-L2] Export to XDCAM, all Avid tracks to Ch1 and Ch2?
Well, Trevor, you called it correctly. Did not work as we hoped,
but rather as Trevor explained.
Thanks all for your input -- looks like we'll be doing the mix downs.
Tim Selander
On 2023.03.10 19:10, TrevorA wrote:
> Direct out routing only works on the baseband output - file
> 'direct out' exports are always track for track.
>
> We do immersive with a mix of timeline tracks routed to 16
> channels but, to deliver a file, have to do a multi-mixdown and
> export the resulting sequence as direct out. (Oftentimes it's
> quicker to play out to EVS, plus we get to QC the segment.)
>
> There is a FR for exports 'as monitored' that I heard was on the
> Avid radar....
>
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but rather as Trevor explained.
Thanks all for your input -- looks like we'll be doing the mix downs.
Tim Selander
On 2023.03.10 19:10, TrevorA wrote:
> Direct out routing only works on the baseband output - file
> 'direct out' exports are always track for track.
>
> We do immersive with a mix of timeline tracks routed to 16
> channels but, to deliver a file, have to do a multi-mixdown and
> export the resulting sequence as direct out. (Oftentimes it's
> quicker to play out to EVS, plus we get to QC the segment.)
>
> There is a FR for exports 'as monitored' that I heard was on the
> Avid radar....
>
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Re: [Avid-L2] Quicklimes with wrong levels flags.
QTchange can't do this right now.
Was QT pro able to do this in the old days?
If i have the same file twice, but with only this flag changed, I know where to look for.
Bouke
> On 17 Mar 2023, at 05:35, Dave Hogan via groups.io <mactvman=yahoo.com@groups.io> wrote:
>
> I have a client I am consulting with, who is stuck on an older version of Media Composer for infrastructure reasons. It is v8.8.5 on Mac.
>
> Problem is when they receive raw camera files, without any transforms and send them as any flavor of ProRes or DNx the files have the automatic assignment of "Video Levels" (a.k.a headroom).
>
> Currently, the only way I can get files out of that version of Media Composer without an automatic video levels flag is to make DPX frames, which is slow and huge.
>
> Would like to be able to take a mix down output to QuickTime or MXF wrapper, and switch the flag to full range.
>
> The point is, that the file being exported is actually full range, some flavor of Log, usually.
>
> When the colorist receives the file, their system automatically does a Legal to full range shift, which throws off all the dailies levels they have for the raw files.
>
> I imagine QT change might have the needed tools, but it's not the highlight on videotoolshed these days, so I am asking here.
>
> 1) Can QT Change fix the flag without having to transcode the video stream?
>
> 2) Are there other apps that easily do this…not for coders, but for simple minded staffers.
>
> Thanks in advance,
>
> Dave Hogan
> Burbank, CA
>
>
>
>
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Was QT pro able to do this in the old days?
If i have the same file twice, but with only this flag changed, I know where to look for.
Bouke
> On 17 Mar 2023, at 05:35, Dave Hogan via groups.io <mactvman=yahoo.com@groups.io> wrote:
>
> I have a client I am consulting with, who is stuck on an older version of Media Composer for infrastructure reasons. It is v8.8.5 on Mac.
>
> Problem is when they receive raw camera files, without any transforms and send them as any flavor of ProRes or DNx the files have the automatic assignment of "Video Levels" (a.k.a headroom).
>
> Currently, the only way I can get files out of that version of Media Composer without an automatic video levels flag is to make DPX frames, which is slow and huge.
>
> Would like to be able to take a mix down output to QuickTime or MXF wrapper, and switch the flag to full range.
>
> The point is, that the file being exported is actually full range, some flavor of Log, usually.
>
> When the colorist receives the file, their system automatically does a Legal to full range shift, which throws off all the dailies levels they have for the raw files.
>
> I imagine QT change might have the needed tools, but it's not the highlight on videotoolshed these days, so I am asking here.
>
> 1) Can QT Change fix the flag without having to transcode the video stream?
>
> 2) Are there other apps that easily do this…not for coders, but for simple minded staffers.
>
> Thanks in advance,
>
> Dave Hogan
> Burbank, CA
>
>
>
>
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Re: [Avid-L2] Quicklimes with wrong levels flags.
I don't recall what is or isn't available on that version of Avid but when exporting from Avid can't you check scale legal to full range or did they call it RGB back on that version, before they changed the nomenclature in Avid to more accurately reflect current terminology for legal vs. full scale? I've always battled whether Avid actually scales the video essence or just sets a flag depending on that choice. I've assumed over the years that it might depend on the codec being exported and the eccentricities that dnx media flagged levels as opposed to other codecs. I've always wanted to have some swiss army software that plays the video essence of a file directly out to my scope without any luts or embedded metadata influencing things. BM Express supposedly does this but I've never been sure and the codecs it is compatible with have always seemed limited and usually not the files I'm trying to check.
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Thursday, March 16, 2023
[Avid-L2] Quicklimes with wrong levels flags.
I have a client I am consulting with, who is stuck on an older version of Media Composer for infrastructure reasons. It is v8.8.5 on Mac.
Problem is when they receive raw camera files, without any transforms and send them as any flavor of ProRes or DNx the files have the automatic assignment of "Video Levels" (a.k.a headroom).
Currently, the only way I can get files out of that version of Media Composer without an automatic video levels flag is to make DPX frames, which is slow and huge.
Would like to be able to take a mix down output to QuickTime or MXF wrapper, and switch the flag to full range.
The point is, that the file being exported is actually full range, some flavor of Log, usually.
When the colorist receives the file, their system automatically does a Legal to full range shift, which throws off all the dailies levels they have for the raw files.
I imagine QT change might have the needed tools, but it's not the highlight on videotoolshed these days, so I am asking here.
1) Can QT Change fix the flag without having to transcode the video stream?
2) Are there other apps that easily do this…not for coders, but for simple minded staffers.
Thanks in advance,
Dave Hogan
Burbank, CA
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Problem is when they receive raw camera files, without any transforms and send them as any flavor of ProRes or DNx the files have the automatic assignment of "Video Levels" (a.k.a headroom).
Currently, the only way I can get files out of that version of Media Composer without an automatic video levels flag is to make DPX frames, which is slow and huge.
Would like to be able to take a mix down output to QuickTime or MXF wrapper, and switch the flag to full range.
The point is, that the file being exported is actually full range, some flavor of Log, usually.
When the colorist receives the file, their system automatically does a Legal to full range shift, which throws off all the dailies levels they have for the raw files.
I imagine QT change might have the needed tools, but it's not the highlight on videotoolshed these days, so I am asking here.
1) Can QT Change fix the flag without having to transcode the video stream?
2) Are there other apps that easily do this…not for coders, but for simple minded staffers.
Thanks in advance,
Dave Hogan
Burbank, CA
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