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Grading MTS vs. ProRes converted files on OS X: is there a concensus?
  • I just started grading my footage with Premiere CS6 after using Final Cut Pro for a long time. I had been converting all my files to ProRes using 5D to RGB, which was the original recommendation of Andrew Reid on EOSHD. Then more recently he said it wasn't necessary to do that anymore because there's a fix in Premiere where you increase input and output levels to 15 and 235 respectively http://www.eoshd.com/content/8612/mac-avchd-gamma-issues-the-fix

    In an AVCHD timeline in Premiere Pro CS6, I imported two clips, one the original MTS and the other a converted ProRes of that clip. But the result was not fixed by only 15 and 235 input/output adjustment, it required something closer to 40 and 215. And that did not mean that the result was the same, there was still more blue in the highlights and shadows in the MTS vs. the ProRes. Further adjustment would be needed, but the ProRes conversion was more balanced.

    This was just my first test, and I'm no expert in this, but it seems like conversion to ProRes still makes sense. What are other people's take on this?

    Screen Shot 2013-06-19 at 10.41.04 AM.png
    1920 x 1200 - 2M
  • 14 Replies sorted by
  • I still convert all my files to ProRes 4:4:4 Rec .709 with 5dtorgb... This is time consuming since I dont have the batch version but it works awesome and I have excellent results with color grading... Mts files are just so damn unwieldy IMO.

  • MTS files are more taxing on the system, plus the need to add the 3-way color correction filter. On the other hand, Premiere Pro with CUDA or even software acceleration can play the files fine that way and still allow for another filter or two, and I hadn't even installed the quadro 4000 card I just received. It would save a lot of disk space not to convert to ProRes.

    If I did decide to use the MTS files, I would need to make presets for each mode and hack, to balance the differences in color balance. Even if the color had been balanced as well as the ProRes conversion, I'd still have needed to make further tweaks because after adjusting the input and output settings, the highlights and shadows become more compressed. It would be necessary to make some changes in the range settings for highlights and shadows.

  • For highest quality, it's still best to transcode. But for fast turnaround, I'm a big fan of working native in Premiere.

  • Still one BIG question: Is the 0-255/16-235 flaw camera/model dependend? Maybe Quicktime reads AVCHD´s latitue/dynamic range correct from GH3/G6, but misinterprets it from a GH2? So everybody cries "more latitude" without reason?

  • @Alienhead

    First of all, the 7.5 IRE setup shouldn't be checked on your waveform monitors. That's for standard definition only.

    Andrew Reid, whose post you cite, appears to be confused (or maybe he just confused me). If a camera records superwhites, it doesn't matter whether you're working in QT or not -- what he describes is not a "bug". You just need to lower input levels to get your highlights at or below 100 IRE, to recapture that highlight detail after its mapped to RGB by the NLE. This can be done in PPro with the Fast or 3-way color corrector, using the input slider. If 5D to RGB is doing that for you, it's probably something to worry about, rather than celebrate.

    Also bear in mind the PPro processes most of its fx in 32-bit, regardless of the format of the source footage. So what exactly is the advantage of transcoding?

  • @jrd

    The advantage of transcoding is a)ProRes files are less compressed and therefore less taxing on the graphics processing, and b)If I don't transcode then I'll have to add a custom 3-way color correction setting for each mode and hack that I use. Because once I've reduced the output AND the input (in this case by not 15 units but more like 40!) the result is that the highlights and shadows are more compressed together than the ProRes transcode from 5DtoRGB, and the color levels are farther out of whack / less balanced. to change that, I would have to tweak the range of what is considered shadow and highlights, to expand it and change the midtones range to encompass less range, to get the same effect.

    As long as I can get consistent results within one hack/mode setting even with these adjustments, it's not worth transcoding. Probably that's the case, but if it turns out I've got to made different tweaks for every single shot even before the other grading I want to do, it may be more extra effort than I want to put in.

    I'd be doing more tests right now, but I just bought a faulty used Quadro 4000 graphics card that quickly burned out, taking some of my RAM with it.

  • @No_SuRReNDeR in the 5DtoRGB mac free version there are 2 options for batching

    the trick for using directly MTS/mts files is to rename them with a .MOV extension, there are plenty of free renaming tools at hand, I'll leave here the script case you want to use it, more convenient ;)

    all good

  • Today I got the chance to run the same clip with the 709/Broadcast setting instead of the 601/Full setting that I had been using (per the recommendation of EOSHD.com), and I made an interesting discovery. That very same MTS file, converted to ProRes with the 709/Broadcast setting, ended up looking almost identical to the original, unconverted MTS file! Actually, the scopes showed that the ProRes was slightly more compressed in the highlights and shadows, which I take to mean is a worse result than the original MTS/AVCHD.

    What this tells me is that the 709/Broadcast setting, whatever people's logic for using that setting, should not be used. With those settings, then definitely there is no point in using 5DtoRGB if you are going to bring the files into Premiere. The 601/Full setting, on the other hand, results in a ProRes file that has better color balance and reasonable luma levels, and is therefore more easily color graded from the start.

    The question still remains whether it's necessary to convert even with the 601/Full setting, but for the reasons I outlined earlier, there are good reasons to do it. I encourage everyone to try this test out and tell me what conclusion you come to.

  • This has been discussed over and over again on another thread. Not sure why V let another thread run on about it but the reason you don't use full is because the camera doesn't shoot full. It shoots broadcast. What you are doing by changing it to full is making up dynamic range that's not really there and baking it into your footage. Why do I say this? Because guys that know a hell of a lot more than me and been in this game for a long time, some as colorists, tested this theory for a few months. You are making up information that's not really there, introducing noise that's not there and a slew of other stuff. If you want to do this, go ahead but it's not the correct thing to do with the footage. But to each his own.

  • Ok, well I was pretty explicit that I'm not an expert in color grading, just making an observation based on scopes. I did some searching earlier on this forum and didn't see it, but I think I found the original topic from 2 years ago. But if it's the case that 601 is just adding noise, then I'm not going to bother with 5DtoRGB anymore. Premiere seems to do a pretty good job of handling AVCHD files.

  • Nope, the post was still active a few months ago. Their were advantages to transcoding instead of native though. Search for it again. It will be worth it.

  • @maxr, does this script run with the latest version od 5DtoRGB Lite? (1.5.14 I guess) Found no working scripts for versions later than 1.5.3b...

  • @Frame the truth is I never had much of a use for 5DtoRGB. before I changed from FC 7 to premiere I just rewrapped the mts and very occasionally used 5DtoRGB. in my heterodoxy of unscientific tests I found there was a noticeable improvement visible to the naked eye, especially fine details, highlights, fringing, gradients and colour accuracy. but this was long ago and basically the time spent didn't seem to worth it.
    so can't tell if latest lite version can run the script, mine still is 1.5.3b

    gashô

  • @jrd

    You just need to lower input levels to get your highlights at or below 100 IRE, to recapture that highlight detail after its mapped to RGB by the NLE. This can be done in PPro with the Fast or 3-way color corrector, using the input slider. If 5D to RGB is doing that for you, it's probably something to worry about, rather than celebrate.

    Just FYI...: in 5DtoRGB you can choose to transcode the full range of luminance levels contained in the source file or you can choose to utilze only the range of broadcast-safe luminance levels of the source file and remap these into fullswing on export. So there's nothing to worry about ;-)