This is a list of the hardware we use. You do not need to replicate it perfectly, but it might give you some inspiration. Here you can see Diagrams of typical rooms setups used by the video team.
The cameras we use are Sony PXW-X70. We decided to buy this model for its performance in low-light due to its large sensor and the good zoom lens they have. They are also small and lightweight, which is a plus for shipping them around the globe.
We decided to buy the 4k firmware unlock they have to further future proof them.
If you want to use a different camera, you may use either:
- A camera with HDMI or SDI output (typically from a higher-end camera) via a SDI capture card.
- A webcam via USB.
Some other nice-to-have features of the camera include:
- The camera should be able to do 720p (we don’t do 1080p because it would require other changes to the infrastructure).
- SDI output: SDI cables are easier to run over long distances compared to HDMI. (USB is much more limited here).
- 2 XLR inputs for capturing audio from mixer together with video and outputting them to live mixing Computer.
- The output needs to be clean (without the camera UI on it).
- It needs to run for a long time without overheating.
Computers for live mixing¶
Each room needs a computer for live mixing. We typically refer to this machine as the voctomix PC, named after the live mixing software we are using.
With three inputs (two cameras and the presenter’s screen capture), Voctomix needs a fairly powerful CPU to run properly. We highly recommend using machines with Intel i7 CPUs from 2015 or later.
Using less powerful CPUs results dropped frames and audio synchronisation issues.
The live mixing machine includes the following hardware:
- 2 x SDI capture card
- 1 x >= 4 port gigabit Ethernet switch One port for the voctomix PC, one for the uplink, one for the opsis PC (speaker laptop output capture) and one spare for debugging purposes (or for the speaker, if wifi gets flaky) Having more than one spare port is useful.
- 2 x Serial adapters for tally-lights
- Assorted cabling
Tally lights are little LEDs that are taped on the cameras and light up when the camera is the active camera being recorded. It gives feedback to the camera operator and this greatly improves the quality of the recording.
We use serial to Ethernet adapters and run Ethernet cables along the SDI cables to the cameras.
We normally rent most of the audio gear we need for DebConfs, since we do not have enough audio kits for three rooms.
A typical room setup will use:
- 2 x headset mic for presenters. Headset mics provide good quality sound, while still being easy to put on presenters and ensures a constant distance between the presenter’s mouth and the mic
- 2 x handheld cordless mic for questions from audience
- 2 x ambient omni-directional condenser mics for room noise. These only get sent to the camera feed, as they allow any questions asked without a mic to be heard on camera
- 2 x mic stand for the ambient mics
- 1 x stereo DI Box for capturing the presenter laptop sound
- 1 x mixer (8 channels XLR in, aux and mains out). The aux out gets sent to the house speakers and the mains to the main camera for recording and streaming
- 1 x audio snake with 8 inputs and 4 returns (not all of those are used, this just describes a configuration that’s actually available on the market) 6 of the 8 inputs are used for mixer inputs and thus get connected to the mixing desk (4 for radio mic receivers, 2 for DI Box left/right), returns can be used for connection to speakers (instead of direct connection from mixing desk), if the speakers are placed at the front of the room far away from the mixer.
- 2 x speakers (active or with amplifier) for sound reinforcement in the venue
- Assorted cabling to connect the various pieces of equipment
Laptop output capture¶
To capture the output of the speaker’s laptop, We use a Numato Opsis board running HDMI2USB. The USB output goes to our Opsis capture PC, whereas one of the HDMI outputs goes to the room’s projector.
We use the Opsis and the HDMI2USB firmware because it is an open source hardware and software project. It is developed by TimVideos and is used for a variety of different Linux related conferences. It provides a switching matrix for two HDMI inputs, an internal test page input, two HDMI outputs and the USB output.
You will need:
- 1 x Numato Opsis board (with power supply)
- 1 x Opsis capture PC (we use small Minnowboard Turbots in the Opsis’ case)
- Assorted cabling
Please consult the Opsis board page for more details on how to use the Opsis board.