Prosumer and professional cameras: High video quality, but a connectivity vulnerability

As I’ve recently mentioned a few times, I’m ramping up my understanding and skill set on a couple of Blackmagic Design Pocket Cinema Cameras (BMPCCs), both 6K in maximum captured resolution: a first-generation model based on the BMPCC 4K and using Canon LP-E6 batteries:

and the second-generation successor with a redesigned body derived from the original BMPCC 6K Pro. It uses higher-capacity Sony NP-F570 batteries, has an integrated touchscreen LCD that’s position-adjustable, and is compatible with an optional electronic viewfinder (which I also own):

I’m really enjoying playing with them both so far, steep learning curve aside, but as I use them, I can’t shake the feeling that I’ve got ticking time bombs in my hands. As I’ve mentioned also recently, cameras like these are commonly used in conjunction with external “field” monitors, whether wirelessly- or (for purposes of this writeup’s topic) wired-connected to the camera:

And as I’ve also recently mentioned, it’s common to power cameras like these from a beefy external battery pack such as this 155 Wh one from SmallRig:

or a smaller-capacity sibling that’s airplane-travel amenable:

Such supplemental power sources commonly offer multiple outputs, either directly or via a battery plate intermediary:

enabling you to fuel not only the camera but also the field monitor, a nearby illumination source, a standalone microphone preamp, an external high-performance SSD or hard drive, and the like. Therein lies the crux of the issue I’m alluding to. Check out, to start, this Reddit thread.

The gist of the issue, I’ve gathered (reader insights are also welcomed), is that if you “hot-socket” either the camera or the display (and either the particular device’s power or the common HDMI connection) while the other device is already powered up, there’s a finite chance that the power supply circuit loop (specifically the startup spike) will route through the HDMI connection instead, frying the HDMI transceiver inside the camera and/or display (and maybe other circuitry as well). The issue seems to be most common, but not exclusively the case, when both the camera and display are fed by the same power source, albeit not leveraging a common ground, and when they’re running on different supply voltages.

I ran the situation by my technical contact at Blackmagic after stumbling across it online, and here’s what he had to say:

Our general recommendation is to…

Power down all the devices used if they have internal or built-in batteries
Connect the external power sources to all devices
Connect the HDMI/SDI cable between the devices
Power on the devices

Sounds reasonable at first glance, doesn’t it? But what if you’re a professional with clients that pay by the hour and want to keep their costs at a minimum, and you want to keep them happy, or you’re juggling multiple clients in a day? Or if you’re just an imperfectly multitasking prosumer (aka power user) like me? In the rush of the moment, you might forget to power the camera off before plugging in a field monitor, for example. And then…zap.

My initial brainstorm on a solution was to switch from conventional copper-based HDMI cables to optical ones. Two problems with this idea, though: they tend to be bulkier than their conventional counterparts, which is particularly problematic with the short cable runs used with cameras as well as a general desire for svelteness, both again exemplified by SmallRig products:

The other issue, of course, is that optical HDMI cables aren’t completely optical. Quoting from a CableMatters blog post on the topic:

A standard HDMI cable is made up of several twisted pairs of copper wiring, insulated and protected with shielding and silicon wraps. A fiber optic HDMI cable, on the other hand, does away with the central twisted copper pair, but still retains some [copper strands]. At its core are four glass filaments which are encased in a protective coating. Those glass strands transmit the data as pulses of light, instead of electricity. Surrounding those glass fibers are seven to nine twisted copper pairs that handle the power supply for the cable, one for Consumer Electronics Control (CEC), two for sound return (ARC and eARC), and one set for a Display Data Channel (DDC) signal.

My Blackmagic contact also wisely made the following observations, by the way:

It may not be fair to say that Blackmagic Pocket Cinema Cameras are especially susceptible to issues that could affect any camera. Any camera used in the same situation would be affected equally. (Hence the references to Arri camera white papers in the sources you quoted)

He’s spot-on. This isn’t a Blackmagic-specific issue. Nor is it a HDMI-specific issue, hence my earlier allusion to SDI (the Serial Data Interface), which also comes in copper and fiber variants. Here’s a Wikipedia excerpt, for those not already familiar with the term (and the technology).

Serial digital interface (SDI) is a family of digital video interfaces first standardized by SMPTE (The Society of Motion Picture and Television Engineers) in 1989…These standards are used for transmission of uncompressed, unencrypted digital video signals (optionally including embedded audio and time code) within television facilities; they can also be used for packetized data. SDI is used to connect together different pieces of equipment such as recorders, monitors, PCs and vision mixers.

In fact, a thorough and otherwise excellent white paper on the big-picture topic, which I commend to your attention, showcases SDI (vs HDMI) and Arri cameras (vs Blackmagic ones).

To wit, and exemplifying my longstanding theory that it’s possible to find and buy pretty much anything (legal, at least) on eBay, I recently stumbled across (and of course acted on and purchased, for less than $40 total including tax and shipping) a posting for the battery-acid-damaged motherboard of a Blackmagic Production Camera 4K, which dates from 2014. Here are some stock images of the camera standalone:

Rigged out:

And in action:

Now for our mini-teardown patient. I’ll start out with a side view, as usual accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for size comparison purposes:

Compare this to the earlier stock shot of the camera and you’ll quickly realize that the penny’s location corresponds to the top edge of the camera in its operating orientation. Right-to-left (or, if you prefer, top-to-bottom), the connections are (copy-and-pasting from the user manual, with additional editorializing by yours truly in brackets):

LANC [the Sony-championed Logic Application Control Bus System or Local Application Control Bus System] REMOTE: The 2.5mm stereo jack for LANC remote control supports record start and stop, and iris and focus control on [Canon] EF [lens] mount models.
HEADPHONES: 3.5 mm [1/8”] stereo headphone jack connection.
AUDIO IN: 2 x 1/4 inch [6.35 mm] balanced TRS phono jacks for mic or line level audio.
SDI OUT: SDI output for connecting to a switcher [field monitor] or to DaVinci Resolve via capture device for live grading.
THUNDERBOLT CONNECTION: Blackmagic Cinema Camera outputs 10-bit uncompressed 1080p HD. Production Camera 4K also outputs compressed Ultra HD 4K. Use the Thunderbolt connection for HD UltraScope waveform monitoring and streaming video to a Thunderbolt compatible computer.
POWER: 12 – 30V power input for power supply and battery charging.

Now for an overview shot of the front of the main system PCB I bought:

After taking this first set of photos, I realized that I’d oriented the PCB 180° from how it would be when installed in the camera in its operating orientation (remember, the power input is at the bottom). This explains why the U.S. penny is upside-down in the pictures; I re-rotated the images in more intuitive-to-you orientations before saving them!

Speaking of which, above and to the right of the U.S. penny is the battery acid damage I mentioned earlier; it would make sense to have the battery nearby the power input, after all. One unique thing about this camera versus all the ones I own is that the battery is embedded, not user removable (I wonder how much Blackmagic charged as a service fee to replace it after heavy use had led to the demise of the original?).

Another thing to keep in mind is that the not-shown image sensor is in front of this side of the PCB. Here’s another stock image which shows (among other things) the Super 35-sized image sensor peeking through the lens mount hole:

My guess would be that the long vertical connector on the left side of the PCB, to the right of the grey square thing I’ll get to shortly, mates to a daughter card containing the image sensor.

I bet that many of you had the same thought I did when I first reviewed this side of the PCB…holy cow, look at all those chips! Right? Let’s zoom in a bit for a closer inspection:

This is the left half. Again, note the vertical connector and the mysterious grey square to the left of it (keep holding that thought; I promise I’ll do a reveal shortly!). Both above and below it are Samsung K4B4G1646B-HCK0 4 Gbit (256Mbit x16) DDR3 SDRAMS, four total, for 2 GBytes of total system RAM. I’m betting that, among other things, the RAM array temporarily holds each video frame’s data streamed off the global shutter image sensor (FYI I plan to publish an in-depth tutorial on global vs rolling shutter sensors, along with other differentiators, in EDN soon!) for in-camera processing purposes prior to SSD storage.

And here’s the right half:

Wow, look at all that acid damage! I’m guessing the battery either leaked due to old age or exploded due to excessive applied charging voltage. Other theories, readers?

I realize I’ve so far skipped over a bunch of potentially interesting ICs. And have I mentioned that mysterious grey square yet? Let’s return to the left side, this time zoomed in even more (and ditching the penny) and dividing the full sequence into thirds. That grey patch is thermal tape, and it peeled right off the IC below it (here’s its adhesive underside):

Exposing to view…a FPGA!

Specifically, it’s a Xilinx (now AMD) Kintex 7 XC7K160T. I’d long suspected Blackmagic based its cameras on programmable logic vs an ASIC-based SoC, considering their:

Modest production volumes versus consumer camcorders
High-performance requirements
High functionality, therefore high connectivity requirements, and
Fairly short operating time between battery charges, inferring high power consumption.

The only thing that surprised me was that Blackmagic had gone with a classic FPGA versus one with an embedded “hard” CPU core, such as Xilinx-now-AMD’s Arm-based Zynq-7000 family. That said, I’d be willing to bet that there’s still a MicroBlaze “soft” CPU core implemented inside.

Other ICs of note in this view include, at the bottom left corner, a Cypress Semiconductor (now Infineon) CY7C68013A USB 2.0 controller, to the right of and below a mini-USB connector which is exposed to the outside world via the SSD compartment and finds use for firmware updates:

In the lower right corner is the firmware chip, a Spansion (also now Infineon) S25FL256S 256 Mbit flash memory with a SPI interface. And along the right side, to the right of that long tall connector I’ve already mentioned, is another Cypress (now Infineon) chip, the CY24293 dual-output PCI Express clock generator. I’m guessing that’s a PCIe 1.0 connector, then?

Now for the middle segment:

Interesting (at least to me) components here that I haven’t already mentioned include the diminutive coin cell battery in the upper left, surrounded on three sides by LM3100 voltage regulators (I “think” originally from National Semiconductor, now owned by Texas Instruments…there are at least four more LM3100s, along with two LM3102s, that I can count in various locales on the board). Power generation and regulation is obviously a key focus of this segment of the circuitry. That all said, toward the center is another Xilinx-now-AMD programmable logic chip, this one a XC9572XL CPLD. Also note the four conductor strips at top, jointly labeled JT3 (and I’m guessing used for testing).

Finally, the right side:

Connectivity dominates the landscape here, along with acid damage (it gets uglier the closer you get to it, doesn’t it?). Note the speaker and microphone connectors at top. And toward the middle, alongside the dual balanced audio input plugs, are two Texas Instruments TLV320AIC3101 low-power stereo audio codecs; in-between them is a National Semiconductor-now-Texas Instruments L49743 audio op amp.

Last, but not least, let’s look at the other side of the PCB:

It’s comparatively unremarkable, from an IC standpoint compared to the other side, and aside from the oddly unpopulated J14 and U19 sites at the top. What it lacks in chip excitement (unless you’re into surface-mount passives, I guess), it compensates with connector curiosity.

On the left side (I’d oriented the PCB correctly straightaway this time, therefore the non-upside-down Abraham Lincoln on the penny):

there’s first a flex PCB connector up top (J12). In the middle is, I believe, the 2.5” SATA connector for the SSD. And on the bottom edge are, left to right, the connectors for the battery, the cable that runs to the electrical connectors on the lens mount (I’m guessing here based on the “EF POGO” phrase) and a Peltier cooler. Here’s a Wikipedia excerpt on the latter, for those not already familiar with the concept:

Thermoelectric cooling uses the Peltier effect to create a heat flux at the junction of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermoelectric cooler (TEC) and occasionally a thermoelectric battery.

Also note the two four-pad conductor clusters, one at the top and the other, although this time (versus the earlier mentioned JT3) unlabeled and on only one side of the board. And what’s under that tape? Glad you asked:

And now for the other (right) side:

Oodles o’passives under the FPGA, as previously noted, plus a few more connectors that I haven’t already mentioned. On the top edge are ones for the back panel touchscreen and the up-front record button, while along the bottom edge (again, left to right) are ones for the additional (back panel, this time) interface buttons and a fan. Yes, this camera contains both a Peltier cooler and a fan!

That’s “all” I’ve got for you today. I welcome any reader thoughts on the upfront HDMI/SDI connectivity issue, along with anything from the subsequent mini-teardown, in the comments!

—Brian Dipert is the Editor-in-Chief of the Edge AI and Vision Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company’s online newsletter.

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Prosumer and professional cameras: High video quality, but a connectivity vulnerability

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