9 Replies Latest reply on Mar 27, 2012 1:45 PM by Timothy S. Kang

    How can I properly export video w/ bars to Rec709 (16-235 in 8-bit) from Premiere's RGB (0-255)?

    Timothy S. Kang

      I have hit some real frustrations in working with Premiere to meet broadcast Rec709 standards for DVD & Blu-Ray. Avid Symphony works in a Rec709 space and clearly operates with its video signal from 16-235 (which matches IRE 7.5 to 100), but Premiere doesn't seem to have this understanding in its programming and engineering. Here are my issues:

       

      1) I can't manually enter in the digital values in the RGB Curve tool's points. Why would Premiere's engineers lock this basic feature out? It's in Photoshop.

      2) I can't properly export Premiere's color bars. In order to export to Rec709 standards, to get around issue #1, I hack into the RGB Curves preset XML file to lift the Master Curve's point 1 from 0 to 16 and set the final white point from 255 to 235. If I use Premiere's bars, on the waveform, I can see the sub-black values, but when I lift the blacks with the curves preset, it clips all sub-black values upon export. WHY?! To get around this problem, I import bars generated by a camera (for example, by a Sony EX-350, i.e. XDCAM footage). All of this wouldn't be an issue if there were an export function that specifies exporting to rec709's 16-235 values instead of 0-255, as Avid does.

      3) Particularly, the Waveform scope lies to me. The 7.5 IRE setup button does NOTHING for me, it's just a preview option that causes more confusion than clarity. Does Premiere map 0 out of 0-255 as 0 IRE or 7.5 IRE? I think it does the former and just uses that setup button to make you think that it's at 7.5. so if you do set it to 7.5, how then do you export it to match that option? Also, why can't the waveform scope have multiple options for the units - not just IRE, but also digital values (8-bit, 10-bit, linearized, etc.)?!

      4) Speaking of importing the bars and footage. To continue the example of the Sony EX-350 - it imports the bars automatically by putting the black values at 0 IRE, not 7.5 IRE.

       

      If Adobe wants industry professionals to take Premiere seriously, it needs to open up these options and clearly present what happens to tonal values in the image. It's very frustrating to figure out all of these problems and create cockamamy work-arounds.

      http://www.avsforum.com/avs-vb/showthread.php?t=1090642

      http://www.glennchan.info/articles/technical/setup/75IREsetup.html

        • 1. Re: How can I properly export video w/ bars to Rec709 (16-235 in 8-bit) from Premiere's RGB (0-255)?
          SteveHoeg Adobe Employee

          Hey Tim - Premiere Pro can process natively in Rec709 with signal from 16-235 you do not need special adjustments. Curves are the wrong tool for numeric adjustments, try Levels or RGB Corrector. Sub black values are not necessarily clamped on export.  --sh

          • 2. Re: How can I properly export video w/ bars to Rec709 (16-235 in 8-bit) from Premiere's RGB (0-255)?
            Jim_Simon Level 8

            it imports the bars automatically by putting the black values at 0 IRE, not 7.5 IRE.

             

            You sure the bars are recorded at 7.5 IRE?  Setup hasn't been used (or at least, it's been advised against) in DV for a long while now.  I don't see why that old analog issue would return in the wholly digital ATSC standard.

            • 3. Re: How can I properly export video w/ bars to Rec709 (16-235 in 8-bit) from Premiere's RGB (0-255)?
              jojejo Level 2

              Hi,

              I have the same problems. I often wondering if premiere is working in RGB 0-255. I find no answer in any help file.  Why can't I export a QT  with exact Rec 709 levels. If I import this QT into Avid, black is neither 0 nor 16, it is somthing in between. And when I import, why can't I choose if the footage is in RGB (from AE) or in Rec709(Avid export)???

              • 4. Re: How can I properly export video w/ bars to Rec709 (16-235 in 8-bit) from Premiere's RGB (0-255)?
                Jim Curtis Level 3

                There is a setting in the Avid Import menu to accept an RGB source.  That's the simplest answer.  Works great.  Almost all animation and stills that working editors import into Avid are RGB.  Any experienced editor should be able to tell instantly whether she chose the wrong import settings.

                 

                Steve gave another answer:  If you must have 601, nest your Pr Sequence and put a Levels filter on it using 16 and 235 for input values.  Then export.

                • 5. Re: How can I properly export video w/ bars to Rec709 (16-235 in 8-bit) from Premiere's RGB (0-255)?
                  jojejo Level 2

                  Hi Jim,

                  maybe my english skills are not that good. When I wrote "to choose between RGB and 709 import", I mean exactly the way I can do it in the Avid import settings.

                  • 6. Re: How can I properly export video w/ bars to Rec709 (16-235 in 8-bit) from Premiere's RGB (0-255)?
                    Jim Curtis Level 3

                    Sorry, jojejo, but I'm not sure what you're asking. 

                     

                    Have you tried importing into your Avids using the RGB setting on the import dialog?  If you can do that, you don't have to worry about converting to 601 in Pr.

                    • 7. Re: How can I properly export video w/ bars to Rec709 (16-235 in 8-bit) from Premiere's RGB (0-255)?
                      Timothy S. Kang Level 1

                      Steve,

                       

                      Thanks for your reply! However, I hope you don't take my response the wrong way, but, with no meaning of disrespect to you personally, the notion that curves are the wrong tool for numeric adjustments extremely infuriates me and displays a real lack of understanding of why a colorist or cinematographer such as myself would want to use curves in the first place.

                       

                      First, any LUT generation program or coloring program, such as Apple Color, gives complete access to numerical control to give precise, repeatable changes that you cannot get with the drag of a mouse. Photoshop, Avid Symphony, etc. all have curves tools with the ability to manually enter points.

                       

                      Second, on a user level, there should be no wrong tool for numeric adjustments, especially curves - they are the most precise means to obtain a specific contrast response. Levels or RGB corrector will only give gamma, pedestal, and gain operations, but curves gives every possible shape of a contrast response in between. If I wanted to create a very specific S-curve, I must use the curves tool to do so.

                       

                      Third, the question at hand is not Premiere Pro's ability to process natively in Rec709 with signal from 16-235 - Premiere's native ability to process all types of video input is the sole reason why I've switched to it as a platform. 'Sub-black values are not necessarily clamped'?! How then can I export a TIFF, for example, of Premiere's bars, with the sub-black values left intact? How do I even access these sub-black values, when all footage clips below 0 IRE? The primary question is, how does Premiere handle and export these IRE values with respect to digital values, whether they are 8-bit, 10-bit, 12-bit, etc.?

                       

                      Adobe's video workflow lacks a concise, cohesive FAQ or explanation of its numerical signal chain. At least, I have missed it and can't find it anywhere. If I want to properly color grade footage with a proper final output in mind, I need to know my end goals to take the proper intermediary steps.

                      SteveHoeg wrote:

                       

                      Hey Tim - Premiere Pro can process natively in Rec709 with signal from 16-235 you do not need special adjustments. Curves are the wrong tool for numeric adjustments, try Levels or RGB Corrector. Sub black values are not necessarily clamped on export.  --sh

                      • 8. Re: How can I properly export video w/ bars to Rec709 (16-235 in 8-bit) from Premiere's RGB (0-255)?
                        Timothy S. Kang Level 1

                        Hey Jim!

                        Jim Simon wrote:

                          You sure the bars are recorded at 7.5 IRE?  Setup hasn't been used (or at least, it's been advised against) in DV for a long while now.  I don't see why that old analog issue would return in the wholly digital ATSC standard.

                         

                        It's not DV, it's a solid state recording ENG-type camera. I made a mistake about the middle pluge bar being placed at 7.5 IRE - the actual waveform monitor (not Premiere or software) reads 0 IRE and goes negative. This is a distracting point, I apologize; the main point is that bars are still used to ensure the ability to calibrate displays for proper viewing of material, and in the 8-bit digital file, 0 IRE black is placed at 16, 100 IRE white is placed at 235, 109 IRE white placed at 255. Premiere makes it impossible for me to get this correct normally with exported files because I have no idea what it's doing with its digital values - it gives me no readout and there is a disconnect between what I see on its waveform and the file that it exports. I have to do exports using levels instead of something that should be a normal option.

                        • 9. Re: How can I properly export video w/ bars to Rec709 (16-235 in 8-bit) from Premiere's RGB (0-255)?
                          Timothy S. Kang Level 1

                          Jim Curtis wrote:

                           

                          There is a setting in the Avid Import menu to accept an RGB source.  That's the simplest answer.  Works great.  Almost all animation and stills that working editors import into Avid are RGB.  Any experienced editor should be able to tell instantly whether she chose the wrong import settings.

                           

                          Steve gave another answer:  If you must have 601, nest your Pr Sequence and put a Levels filter on it using 16 and 235 for input values.  Then export.

                           

                          As far as I understand it, on a numerical basis, Avid works with all footage by setting 16 to black and 235 to white. upon import, the rec709 option reads file as is, while the RGB option remaps file values between 0-255 into 16-235. Premiere, on the other hand, is a mystery to me. I have no clear idea how the IRE values in the waveform correspond to the digital values, because i've seen enough conflicting information to completely confuse me. Normally, Adobe bars are at 0, and upon export sub black values are clipped off, but I can see sub-black values in the waveform.

                           

                          Steve's answer is what I exactly do: to be safe, I nest the timeline using curves or levels to lift my footage black point to 16 (which reads as 7.5 in premiere). By the way, with his solution, 16 and 235 should be the output values, not the input values. Setting them to input will clip the signal.

                           

                          Namely, it's not just 601, it's 601/709. They both live in between 16-235. see http://en.wikipedia.org/wiki/Rec._709

                           

                          However, this is all a hack of a solution. I'm frustrated that this has to be done instead of being a native issue with Premiere; it seems esoteric to me but it honestly is very foundational and basic, especially for professionals such as myself.