Project Eideticker/DeckLink Primer

For the first version of Project Eideticker, we are using a Blackmagic DeckLink HD Extreme 3D to capture video data. Here's a quick introduction to the card's capabilities and usage as they pertain to Eideticker.

Capabilities

There are two major limitations in all Blackmagic cards, DeckLink or otherwise:

• They can only capture output at broadcast standards. This means HDMI 720p and 1080p at standard refresh rates and a handful of other standards. The important part here is that the output must be at a standard resolution, e.g. 1280x720 or 1920x1080. Unlike many TVs, the cards will not crop or add border to output that is larger or smaller than the standard; it just won't capture at all.

• Capturing at 1080p50 and up can only be done at YUV 4:2:2, i.e., full 8-bit RGB is not possible. Supposedly capturing at 720p is possible with 10-bit RGB, but not 8-bit RGB, for reasons unknown (perhaps due to the fact that the 10-bit formats use their own codecs).

Unfortunately neither of these limitations were apparent in their marketing materials; we had to contact support to find out.

What this means: it's almost impossible to get a pixel-perfect capture of a device with this card. The only potentially perfect solution with this card would a device that outputs full RGB at 720p and does not do any scaling (e.g. exactly a 720-pixel high screen, a cropped/bordered output, or the ability to treat the HDMI output as the primary output so Firefox can render at exactly 720p).

How this impacts Project Eideticker is unknown but a function of exactly what analyses we want to perform.

Installation

The manual can be found at the card's support page (I don't want to post a link directly to the manual in case they issue a new version and the URL changes).

The card has a plethora of adapters for various types of video input. At the moment we only care about HDMI. The HDMI inputs are on a separate slot, connected to the card via HDMI cables. There is an input port and an output port. They aren't labelled, but the input port is the one closest to the ePCI connector (e.g. closer to the motherboard). The HDMI slot should be wired to match this. See the Connection Diagrams on the support page linked above.

The drivers are available at the support page under the not-entirely-obvious name "Desktop Video for Linux". The current version is 8.0.1. The archive contains debs, rpms, and tarballs for various distros. On Ubuntu, the drivers can be installed with dpkg -i and the appropriate (32-bit or 64-bit) deb filename. This will install the kernel module, the shared libraries, a configuration app, and a firmware-updater app. See the readme in the archive for more details on installation.

Before doing anything with the card, you'll need to run the configuration program BlackmagicControlPanel. This utility is mostly used to activate particular hardware inputs and outputs, since not all can be active at the same time. You'll need to select HDMI input, and, if you want to see output on a separate screen, HDMI output.

MediaExpress

There is also a GUI program in the DesktopVideo package called MediaExpress. It can be installed from a deb file in the same way. MediaExpress can be useful to discover the DeckLink's capabilities and supported modes.

To run it from Linux, just enter MediaExpress in a terminal. For best results it requires a 1920x1200-resolution monitor. It is still usable at lesser resolutions, although some of the UI will be cropped.