Friday, February 19, 2016

Free Tektronix UHD/4k info posters

Get 'em here & here!

Sunday, February 14, 2016

The Engineer's Bench podcast - "Top Tips; Audio"

Hugh and Phil talk about some tips and get-out-of-gaol-free cards with respect to broadcast audio.
Go to the website for a PDF of the notes.

Find it on iTunes, vanilla RSS, YouTube or the show notes website.

Thursday, February 11, 2016

Shooting & editing HDR via Avid using CLog gamma

We've got BVE2016 coming up and one of the things Root6 will be showing is an HDR workflow via Media Composer using Canon monitors.
HDR is still a bit of a crap-shoot as far as standardisation is concerned with the BBC/NHK system, Dolby Vision, Sony's SLog3 and Canon's camera-native CLog. The principle of using an alternate gamma so that you concentrate the bit-depth where you want the extra range is well established;

The hope is that all of these manufacturers will coalesce around ST.2084 which (amongst other things) defines how you handle the specular highlights; those very bright parts of the picture which give a real addition to the look of the pictures. These are typically defined to be >500 Cd/m2 which is MUCH brighter than broadcast white! The idea is that the last bit of dynamic range (10th bit - all values above 512) represent the highlights and everything up to 50% is akin to the usual video dynamic range. You calibrate the monitor such that 50% is set at 100Cd/m2 and just hope that the colourimetry of the highlights tracks RGB-wise!

So - Root6's own Dave Skeggs and I set off around Soho and London Bridge to capture some night time and daytime footage. We were using a Canon C300 mk.2 set to UHD (3840 x 2160) at 25P (no interlaced fields at UHD and no high framerates at that resolution unfortunately). We set the colour space to an optimistic Rec.2020 and gamma to Clog. In that mode the camera shoots 410mBit/s XAVC codec MXF files.
We've been using Media Composer v 8.5 on an HP Z840 workstation & the new Avid/BlackMagic DNXio video hardware; we had to update the firmware to get it to generate quad-link SDi. Although HDMI works it is nobbled down to eight-bit and so would not be suitable for this test. I would put a link to the video but none of the video sharing sites support HDR and neither does the screen of your tablet/laptop/TV! I took all the monitor photos with my Fuji bridge-camera in a very bright office; you'll have to take my word for it!

Notice the headlights of the taxi - you can see details inside the light!

exactly the same frame; notice the dark details in the trees against the night-sky.

 Of course on Media Composer's GUI display you get the CLog gamma rendered as if it was Rec.709 and so it looks very washed out and lacking in detail

You can have Avid flatten the gamma of source clips so that it looks OK on the GUI - that doesn't affect sequences that the clip mas been used in.

Quite a large range of alternate gamma and colour spaces

 It shows up in the bin-view which is useful

So now clicking the source window and setting the monitor to regular HD gamma (BT. 1886 fact fans) shows you what the same material shot on a "regular" camera would look like; very little detail in the blacks and none in the whites.
 Root6's own DOP; Dave "is that in focus?" Skeggs

I'd forgotten how limited a normal video-camera's dynamic range was. The Canon monitors top out the specular highlights at 400Cd/m2 which is somewhat less than a Sony BVM-X300 (1,000 Cd/m2!) but for €10k less than the Sony (and losing only a stop-and-a-half of specular highlights) the Canon 30" UHD/4k IPS panel represents superb value. I was a bit disappointed that the camera tops out at 29.97P at >2k resolution so I couldn't see how nice fluid video motion looked at high res; everything has a jerky film-look to it.
Steve Shaw at Light Illusion has a very good article exploring some of the fundamentals of HDR.

Tuesday, February 09, 2016

They broke multicast PING in El Capitan (well, kinda!)

I've written in the past about how much I rely on the multicast PING for getting the basic network settings out of a piece of equipment (that's has come back from a customer in some unknown state). Imagine my horror when I discovered they've broken it in OS-X v 10.11 El Capitan.

 So, here's the setup, piece of gear connected directly via an Ethernet interface to my laptop (with a hard-set IP address). Ordinarily using;


would force the equipment to respond with it's IP address. Then it's easy to change your laptop's IP to be on the same subnet and you're in (like Flynn). No worries that the computer and equipment are on different subnets, multicast PING forces it to respond.
It appears I'm not the only one to notice this. See here on Apple's support site.

So here's the answer; you can see the effect "No route to host", then I attach to a pocket-router with only the Amulet box on it and by attaching to it over WiFi (it's a router, no need to worry about "wrong" IP subnets) I can PING and determine the Amulet is on

I can only assume that by now having an ARP table in the way (the pocket-router) we have a source of H/W address to IP conversion. When there was just a cable between the devices and hard-set IP addresses multicast relies on the second device to answer the broadcast PING with it's H/W address in the return packet. I can only assume that OS-X 10.11 ignores that and instead does an ARP equiry of the router to match the H/W and IP addresses?

It's not a big deal as I do carry one of those little pocket routers in my rucksack as they are supper useful for lots of things;
  • Isolating yourself from an (untrusted) client's network
  • Isolating an untrusted machine from your network whilst working on it
  • Making wired-only demo equipment wireless to aid in customer demos
  • A source of IP addresses when lashing up an ad-hoc network.

Monday, February 08, 2016

Blackmagic iOS app works with Barnfind!

Super-impressed with how open Barnfind are over other manufacturers. I wrote before about how they work with Blackmagic control panels, but today for a demo I pointed the BM app at the BF chassis and it's all good.