C100: The effects of Noise on recording to ProRes

MattDavis

MattDavis

Well-known member
I happened to be checking out the new software for my Pix220 external 4:2:2 recorder - no joy, still doesn't see C100 timecode.

What I did find by accident is a 'worst case scenario' of the C100's... ahem... 'textured' (not noisy?) image giving the compressor a really hard time. Darkish areas of flat tone make for boiling noise, and whilst we're all great fans of the internal AVCHD codec, the ProRes 422 'should' be better. It wasn't - it was horrible:

noiseandprores-crop.jpg


This still doesn't really tell the full story, so I put it on Vimeo:


And even Vimeo doesn't seem to do it justice - hopefully the downloadable master file (I uploaded ProRes) will unlock the true horrors within. That's with 0dB gain, f11, 1/50th. Maybe there's a bit more in the 4444 version. I'm not sure if I'd go that extra step unless doing packshots, special chromakey etc. I've also uploaded the master ProRes version here.

Sorry about the composition and style. This wasn't a posed shot. I was testing timecode, so I didn't even bother to focus the camera, just getting an image...

The Skinny: Use ProRes HQ! It's not just for chromakey! In this (not representative) case, I'd prefer the AVCHD files over the standard ProRes 422 record, 145 Mbits per second just isn't man enough to deal with the noise in shadows.
 
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Hi Matt.

What persuaded you to go for the more pricey Pix 220, over products like the Ninja/Shuttle etc?

Have you found a way of mounting it on your C100, without it all feeling like a "Christmas Tree"? Centre of Gravity/Weight Balance etc?

Thanks,

Ben.
 
LOL!

Well, the Pix was originally for the FS100. The Pix had many things going for it: a better screen compared to the Ninja 1, a more studley build quality, a good reliability track record...

But the Number 1 feature was its Mic Pre-amps and XLR inputs. Superb audio, brilliant limiter. Knocked the FS100 audio into a cocked hat:


On the FS100 MegaRig, it kinda worked well, being the counterweight at the back (it did the TimeCode Start/Stop thing reliably).

But now I am a C100 user, and the two will sort of work, but not slickly. Apparently support for TC on HDMI in the C100 mode is coming.

I like the big buttons and tank like feel of the pix but that precluded it from sitting on the camera. I have toyed with selling it and getting something like a Samurai Blade, but I've not needed 4:2:2 in run & gun situations, just for chromakey, packshots and VIP work (where failure is not an option).

I used to feel it was okay as a comfort monitor, but I've since invested in a SmallHD AC7 as a proper lined-up high resolution 'decent focus' monitor for these situations.

Hyperdeck Shuttle? I don't want to work blind, I need options other than Uncompressed and ProRes4444, and need more power options that don't need huge amounts of rigging. Shrug.
 
Did you really think attaching a recorder would give you cleaner noise? There is no noise reduction being applied to the feed out of the HDMI "Uncompressed" to the recorder. It's software in camera doing that to the AVCHD. Now you need software to do that to the Prores. The more "uncompressed" Prores you use, the higher the noise will be.
 
If you want to see noise than put the black cover to the lens and record various ISO levels. Apply some strange gain in your sw to these black clips and you will see a sequence of eleven frames where every third frame is different from two others and the first frame of this group is different from all others (if you record in a PAL framerate). It is the internal AVCHD record.

After a final export to H264 (from editing sw) you can see some differences on dark faces, it depends on the type of compression and type of codec (manufacturer). Some makes noise more visible, some others less visible. If you record source clips eternally (with Ninja and I-frame only type of compression) you will see noise with less differences in this eleven frame group of pictures. For me it is better source than avchd clips.
 
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