Video with 10-Bit Channels

If I had a 10-bit video recording such as from the PIX 240, would I know what to do with it, in order to make full use of the 10-bit information?  This question is important, because it cannot be assumed that this is simply a case of inputting it into any arbitrary nonlinear editing system (NLE) – not all NLEs preserve the extra information – and even for those that do, the workflow and configuration must be set up appropriately.  And even having got that right, how can we verify all is working as expected?  Can the NLE’s own effects and waveform monitors etc. be trusted to preserve the extra bits?

Having discovered some sample 10-bit footage at http://www.sounddevices.com/products/pix240/sample_files/ (as reported at http://blog.davidesp.com/archives/570), I was prompted to do some experiments in a few NLEs.   I based the experiments on the following two DNxHD files, as recorded by a PIX 240, both 1920x1080p29.97 and around half a minute in duration.

  • dnxhd220mb_8_29.97.mov = 8-bit
  • dnxhd220mb_10_29.97.mov = 10-bit

The comparison was based on an area of sky at the top-left of frame (in each case), with its (limited) levels-range mapped to full video range, so as to make 8-bit quantization-banding appear.

Conclusions (as far as I can tell from experiments):

  • Adobe Premiere:
    • Propagates the 10-bit footage’s information, achieving better image quality than for the 8-bit footage.
      • However this only happens when correctly configured and then only for certain effects.
    • The Fast Color Corrector levels-mapping appears to introduce some kind of dithering.
      • Hence while the expected banding is visible for 8-bit footage, it is slightly “blurred” on the Waveform Monitor and the resulting image looks more ragged than banded.
      • Nevertheless, the 10-bit footage through this same process has no such banding at all, and resulting the image looks obviously better.
      • None of the cases at http://blogs.adobe.com/VideoRoad/2010/06/understanding_color_processing.html apply here since no blur effect was used.
    • The result of Fast Color Corrector levels-mapping on 10-bit footage result also looks slightly brighter than that on 8-bit footage – presumably a mapping-inconsistency in Premiere?
    • Some other non-obvious pitfalls exist when making such comparisons:
  • Sony Vegas 10
    • Ignores the extra information in the 10-bit footage, evem for Project Settings of 32-bit.
  • Avid Symphony 6
    • AMA appears to truncate to 8-bit, at least it seems so based on what appears in Avid’s Waveform monitor.
    • Import of the given DNxHD-220 to Avid-Import-DNxHD-220 appears to give same result.
    • I assume I am missing something here, some knowledge and/or step and/or monitoring method…

The configurations I used within each application:

  • Sony Vegas 10:
    • Project Properties
      • 1920x1080p29.97. Not automatically readable by Vegas from the DNxHD format.
      • Pixel Format: 32-bit floating point (video levels)
    • Waveform Monitor via: Video Scopes > Waveform
    • Sky-range mapped to full range via: Sony Levels FX
  • Adobe Premiere CS 5.5:
    • Computer had a non Mercury Engine compatible GPU hence software-only graphics / effects processing.
    • Waveform Monitor via: Reference Monitor > YC Waveform
    • Sky-range mapped to full range via: Fast Color Corrector > Input Levels
      • (Prior to that tried various “Levels” effects but they did not work properly in this context)
    • Sequence Setting: Maximum Bit Depth (else levels-resolution was truncated to 8-bit)
  • Avid Symphony (hence presumably also Media Composer) 6

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