Archive for the ‘denoising’ Category

Sony EX3 Noise & Bits-Resolution & Green-Screen

Sunday, November 4th, 2012

It has been said ( I believe by Alister Chapman ) that there are only marginal benefits from recording XDCAM-EX to more than 8 bits, due to the relatively high noise of this camera, as compared to more typical broadcast cameras.

In my experience, while it was a wonderful step-up from my Z1, certainly it’s recordings are noisier than I’d like, leading me to pretty-process certain footage (using Neat Video denoising plugin to my NLE).  And as a recent project with reasonably well-lit green-screen illustrated, it’s noise in shadows can be a particularly nuisance (much time in post experimenting to work around this).

So I wondered:

  • Even if marginal, to what extent is 10-bit beneficial to EX3 recording?
  • For the EX3, when recording 10-bit, it is also 4:2:2, surely a benefit to chroma keying and resizing (reframing, stabilising/deshaking/tracking).
  • Could the benefit depend on editing workflow?  For example:
    • What if subsequently de-noising (like I mentioned)?
    • Some NLE’s do bits-dithering, hiding the quantisation/banding that would otherwise be apparent from having only 8 bits.

I need to do my own experiments, but for now, here (below) are some results from web-searching…


Effects-Order: Denoise before Deshake

Thursday, November 1st, 2012

This is my impression, from the expressed views of others:

  • If you have e.g. 60i or 50i then do any stabilization first, so it gets maximum temporal information, prior to any deinterlacing e.g. to corresponding 30p or 25p.  Presumably if double-deinterlacing e.g. to 60p or 50p then this is immaterial.
  • If you’re using noise reduction, always do that prior to stabilisation as it helps the algorithm to concentrate on wanted detail and not on random noise. But then if it’s Neat Video denoising then that works best with stable progressive material.


AviSynth and Motion-Estimation-Related Processing by QTGMC & MVtools 2

Thursday, January 5th, 2012

Looking for some user-friendly top-down explanation of sensible uses of AviSynth.

See Web-Research further below.

I expect to update this post. (more…)

Initial Cuda Experiences & Hopes

Friday, September 2nd, 2011

My systems have CUDA, though I have never knowingly made use of this.  Using GPU Caps (Capabilities) Viewer, that I discovered my computers’ GPUs definitely had CUDA capability:

  • MacBook Pro GPU: NVIDIA 9600M GT, has CUDA, 4 multiprocessors, each 1.25 GHz (shader-clock), CC (Compute Capability) of 1.1.
  • Mac Pro GPU: GeForce 8800 GT, has CUDA, 14 multiprocessors each of 1.5GHz (shader-clock), CC of 1.1 (again).

Sounds promising, but can any of my video apps use this CUDA?  And is it the “right kind” of CUDA, like does it come in various varieties?  What difference will it make to framerate and processing speed? And are there any negatives, e.g. GPU overheat crashes or video “tearing”  ? I’ll have to experiment to find out, but as a starting-point, here’s what I learnt from the web:

  • General knowledge & tips:
    • Quality
      • Some applications/effects are quality-limited in their design in order to avoid excessive (unpopular) processing times on single-CPU systems (lowest common denominator).
      • Some exploit multi-threading in the context of either multiple CPU cores and/or multiple GPU cores, either in terms of quality (the overall processing speed constraint having been reduced).
      • Alternatively some go purely for speed, sometimes even at the expense of reduced quality.
    • Speed
      • Depends on the machine.  For example a fast GPU on a slow machine may be bottlenecked by transfer speeds.
    • GPU Driver Version
      • Update to the latest (having backed-up beforehand, just in case etc.).
        • On my Mac Pro, one of the CUDA-enabled applications (Neat Video, further below) refused it, complaining: “CUDA Driver is too old”.
  • Applications:
    • Sony Vegas (SV)
      • Only helps with SV version 10, and then only with the Sony encoder for H264 (does not help with the MainConcept H264 encoder).
      • Does not contribute to previewing etc.
      • In principle could help with plugins that are themselves designed for CUDA.
      • One such plugin is Neat Video version 3.
    • Neat Video
      • Available as a plugin for several NLEs.  Currently I have its version 2 for Sony Vegas and for VirtualDub, though I only really use the former.
      • Version 3 is designed to take advantage of CUDA.
      • Might as well put this on the Mac Pro, as that has vastly more processing resource and doesn’t tend to crash on overheat when heavily processing for extended periods (unlike the MacBook Pro…).
    • Sorenson Squeeze
      • The new Version 7 takes advantage of CUDA.
      • Adobe:
        • Version 7 comes with an export plugin for Adobe CS5.5
      • Avid
        • The one that comes bundled with Avid MV 5.5 is an earlier version (6).
        • It is possible to upgrade to version 7 independently of the Avid package, in which case:
          • It has an Export-Plugin for Avid
          • However Avid Support (including Forums) won’t support that version.