Case 2.0

Case 2.0
Rework of the Lecture Room Cases
Bix, jtbx, Kunsi, Thorti, ...
in progress

The c3voc currently has six lecture room cases which contain everything that's needed to stream and record lectures in some kind of venue. The venue only has to provide a projector and some kind of speakers besides power and internet access.

As the requirements have changed over the years, all the stuff we carry for every eventuality does only barely fit into the road case and the two additional boxes we but on top. As one of the boxes is wider than the others, they tend to break during shipping. Another pain point of the current setup is the vast amount of items (about 240). We need to be prepared for different ways to connect our setup to the lecture hall (PA and projector), but most of the items are always connected in the same way.

High-level goals of the project are:

  • Optimize buildup and tear-down time by reducing the number of indivdiual items
    • Items should be grouped into modules in which the devices are pre-connected
    • This reduces wear and tear on connectors, the chance to loose things and the amount of items to track
  • The focus should be on the “small” events like FrOSCon, MRMCD, Jugend Hackt and even GPN
    • Those use “standard” setups with 1-2 cameras and no fancy setup on the stage
    • These events usually have too little experience VOC people available
  • Big events like Congress and Camp are special, so don't optimize for that!

The main purpose of the VOC case is to provide a video stream and recording of lectures:

  • Inputs:
    • Slides and speaker laptop audio (stereo)
    • 1-3 cameras
    • 3-4 microphones for native language
    • (optional) 1 translation track (mono)
    • (optional) additional video sources on stage
    • (Infobeamer)
  • Outputs:
    • Finished video signal on disk and stream
    • Signal for the projector (slides/ Infobeamer/ additional camera)
    • Audio-mix for the hall (native audio)

So the recommended signal flow looks like this: projects:case2-hall-cabling.png

Additional requirements include:

  • It shall be possible to “inject” public LAN or VOC-VLAN on any box, which has a network switch
  • Use patch panels where possible to reduce the risk of broken connectors on the devices themselves
  • Group items by their place in the hall

With the usual setup and the cabling plan in mind, there are a some basic building blocks:

  • Lectern Module: Everything usually setup on stage
    • Inputs from speakers
    • Output to the hall
  • FOH Module:
    • Audio mixer
    • Connections for mixer laptop and telephone/ intercom
    • Connections for one camera
  • Encoder Module:
    • Can either be placed on stage or at FOH

Additional crates are needed to store:

  • Everything belonging to the camera
  • Microphones
  • Everything for the FOH workplace (mixer laptop, etc.)
  • Random special adapters


  • The following lists does not include ethernet ports for a possible ethernet-based intercom!
  • Should be be prepared for SMPTE 2110 (10G switches (at least some ports), PTP)?

This module will be placed at the stage near the lectern and contains the interface to “slide” input(s) as well as the connection to the hall's infrastructure (projector and speakers).


  • Switch “slides” signal between speaker laptop, Infobeamer and additional sources
    • Output HDMI at 1080p50 for projector
    • Output SDI (and HDMI) at 1080p25 for recording
  • Convert asymmetric stereo audio input to symmetric signal
  • Output symmetric signal to hall PA
  • (Network for all devices in this module + “uplink” + debugging ports)


  • Devices:
    • ATEM Mini (buttons shall be accessible)
    • Network switch (8 ports, no PoE required)
      • 2 ports trunk for module interconnect
      • 2 ports internal for Infobeamer and ATEM Mini
      • 2 ports public LAN (1 “input”, 1 for speaker laptop/ debugging)
      • 2 ports VOC LAN (1 “input”, 1 for debugging)
    • Stereo DI Box
    • HDMI Splitter
    • BMD Up Down Cross
    • Infobeamer Pi
    • (passive adapter from Ethercon to 2x XLR in + 2x XLR out)
    • Common power supplies for the deviced (probably 12V and 5V)
  • I/O-Panel (11 ports, all at the front side)
    • 2x Cinch for speaker laptop
    • 3x HDMI in to ATEM Mini
    • 1x HDMI out to projector
    • 1x SDI out to encoder (from BMD Up Down Cross)
    • 1x HDMI out (other output from BMD Up Down Cross)
    • 2x XLR out to projector
    • 1x Ethercon for module audio interconnect
    • 1x PowerCON in
    • 1x PowerCON out
    • (network ports are used directly on the network switch)
  • Internal connections:
    • TODO
  • Additionally:
    • Meshbag with speaker adapters (all to HDMI socket): USB-C, USB-C multiport, DisplayPort, Mini-DP, mini-HDMI, micro-HDMI, VGA, DVI
    • HDMI Cable 2m
    • 3.5mm-Jack to 2x Cinch 2m
    • (Cables to hall are listed separately)

To be discussed:

  • Feed 3.5 mm audio jack to ATEM Mini and de-embed audio from SDI at encoder?
    • Would remove the need for a DI box
    • Would enable using HDMI audio (as it's done by default on many laptops)

Shopping List

This module will be placed at the FOH and includes the audio mixer and microphone receivers as well as additional infrastructure needed at the mixer's position.


  • Provide at least 3-4 audio mixes (from sources listed bewlo)
    • Native for recording (just more compression than hall)
    • Native for hall (might need additional output EQ)
    • n-1 mix to remote speaker(s)
    • translation
  • Have audio inputs for:
    • 3-4 wireless microphones
      • 2 handheld microphones and at least 2 beltpacks (one receiver could have 2 transmitter to use whatever is needed more)
      • max. 4 antennas (use antenna combiner, if necessary)
      • Frequency band shall be usable in EU and not be the 800 MHz band already used by the c3voc
    • Stereo-input for “slides” audio
    • (Stereo-)input for remote speaker(s)
    • Mono-input for translation
  • Provide VPN access to VOC-equipment in the hall
  • Provide enough network ports for all device on this module, the encoder, tally lights, mixer laptop and a SIP phone


  • Devices:
    • Audio mixer Allen&Heath CQ-12
    • Router (Hardware TBD)
    • Network switch (14 ports, 4 with PoE)
      • 2 ports trunk for module interconnect
      • 1 port internal for router (VLAN trunk)
      • 1 port internal for audio mixer
      • 2 ports for encoder PC and mixer laptop
      • 3 PoE ports for tally lights
      • 1 PoE port for SIP phone
      • 2 ports public LAN (1 “input”, 1 for debugging)
      • 2 ports VOC LAN (1 “input”, 1 for debugging)
    • “Rack-mounted” battery charger for wireless microphones (depends on microphone model!)
  • I/O-Panel top-side (TODO ports)
    • 2-4 BNC-connectors for receiver antennas
    • (if not well accessible: Headphone jack from audio- mixer)
    • (if not well accessible: USB port of audio- mixer)
  • I/O-Panel front-side (8 ports)
    • 2x XLR with recording mix
    • 2x XLR with n-1 mix
    • 1x XLR with translation mix
    • 1x Ethercon for module audio interconnect
    • 1x PowerCON in
    • 1x PowerCON out
    • (network ports are used directly on the network switch?)
  • 2x CEE 7/3 (Schuko) sockets externally accessible (for mixer laptop, camera)
  • Internal connections:
    • TODO

Shopping List

The encoder can either be placed at the FOH or at the stage and is therfore contained in a separate module.


  • Contain the encoder PC in a portable enclosure
  • Provide a patch-panel for all inputs, so that the connectors on the decklink card are protected against excessive mechanical force


  • Devices:
    • Encoder PC with 4 SDI inputs and 1 HDMI output for local playout
  • I/O-Panel front-side (8 ports)
    • 4x SDI
    • 1x HDMI socket
    • 1x Ethernet
    • 1x PowerCON in
    • 1x PowerCON out
  • Internal connections:
    • 4x SDI patch
    • 1x HDMI patch
    • 1x Ethernet patch
    • 1x power patch

Shopping List

To reduce the weight of the FOH/ Audio module, the microhones are stored in a separate crate.

  • Enough space and foam cutouts for:
    • 2 handheld microphones
    • 2 beltbacks
    • 2 headsets
    • 1 Lavalier (TODO: really?)
    • TODO: Batteries?
  • TODO: Monitoring Headphones (DT770)

Shopping List

This crate shall contain all devices usually attached to the camera or tripod. Every item shall have a fixed place, e.g. in a foam cutout.

Goals/ Design

  • Devices:
    • Camcorder (TODO: Model) with:
      • power supply
      • battery and battery charger
    • Preview monitor with:
      • Power supply
      • Magic arm
      • HDMI cable 1m
    • At least 1 tally light
    • 4 SD cards
    • 3-port power strip?
    • (optionally: Intercom-beltpack with headset)
  • Containment: Top-loaded box/ crate

Camera requirements:

  • SDI output 1080p25
  • HDMI output usable at the same time as SDI
  • Zoom range of 15-25x (current Panasonic camcorders: 22x 3,9-86mm (28-616mm KB) at f1.6-3.2)
  • Motorized zoom
  • 2x SD card slots
  • 2x XLR inputs (full size!)

Shopping List

It does not make sense to put all items needed at the FOH inside the FOH module. So the mixer laptop, etc. shall be in a separate box.

Goals/ Design

  • Devices:
    • Mixer laptop
    • Power supply for mixer laptop
    • Computer mouse
    • 1x Ethernet 3m (for mixer laptop)
    • (optionally: Intercom-station with headset)

Shopping List

We need several cables to connect the different modules and the camera, which weren't already placed in a module/ box. Each cable type shall have a separate box or compartment and all cables shall be marked with their length.

  • Cables sorted by place
    • lectern module ↔ FOH
      • 2x ethernet
      • 1x SDI
      • length: 20m + 10m
    • lectern module ↔ hall
      • 2x XLR
      • (fallback to mini jack or cinch via DI box is listed in special adapters)
      • 1x HDMI
      • length: 5m (10m XLR will be in additional cables)
    • lectern module ↔ speaker laptop
      • (already listed at lectern module)
    • FOH ↔ camera
      • 1x SDI
      • 2x XLR
      • 1x Ethernet (Tally)
      • length: 5m
    • for remote
      • 2-4x XLR
      • 1x HDMI (from preview monitor)
      • length: 5m
    • power for everything
      • Schuko to Powercon (Lectern, Audio, Encoder)
        • 3x 2m
        • 3x 10m
      • 1x Powercon blau auf grau (to daisy-chain mixer to the audio module)
      • 1x 10m Schuko-Verlängerung
      • 1x Steckdosenleiste 3-er (Kamera), TBD mit Powercon oder Schuko?
    • ethernet misc
      • 1x uplink
      • 1x to Mixer-Laptop
      • 1x to phone
      • 1x for debugging/ spare
      • length: 3m
    • SDI misc
      • 5m e.g. to connect lectern to encoder if placed at stage
    • XLR misc
      • 2x XLR 20m zusätzlich
      • 2x XLR 10m zusätzlich
  • (sorted by type and length)
    • SDI
      • 1x 20m
      • 1x 10m
      • 2x 5m
    • XLR
      • 2x 20m
      • 2x 10m
      • 4-6x 5m
    • HDMI
      • 2x 5m
    • Ethernet
      • 2x 20m
      • 2x 10m
      • 1x 5m
      • 4x 3m
  • Containment: TODO

To Be Sorted

Additional items in need for a fixed place are:

  • Winkekatze
  • 3 rolls for gaffer's Tape (black, white, yellow/black striped)
  • SD card reader
  • Intercom (if not placed elsewhere)
  • “Kabelbindertüte” + Pens
  • Spare batteries?
  • Additional network switch?
  • Minion + power supply
  • DI-Box passive
  • DI-Box stereo active (e.g. to connect to hall via 3.5 mm jack or Cinch)
  • 2m 2x Cinch to 3.5 mm jack cable
  • 2m 2x Cinch to 2x Cinch cable
  • Remaining stuff from “Meshbag Audio kurz”
  • Stuff from “Meshbag Audio/ BNC Adapter”
  • Remote speaker setup (audio interface, HDMI grabber)?
  • Tally 2+3 (if not in camera box)
  • Presentation clicker?

This section contains information why certain aspects of the setup are defined as described above.

At first we wanted to include a second phone in each case, so that we can have a VOC office even when the “regie box” was not shipped to the event. But we identified some issues with this concept:

  • Telephones only provide a benefit, if somebody is near the office phone all the time
    • This is probably not the case on small events with only 1-2 lecture rooms and the VOC people will be around in the venue
    • An alternative would be to have some DECTs and an RFP in each case. But the handsets would need to arrive charged, somebody has to set it up, etc.
    • So this is a lot of effort for diminishing returns and on bigger events there'll be a POC and/or we can bring our office setup and have enough people to staff a helpdesk
  • Intercom will be much more useful even on small events
    • Better take the space for the phones to have some intercom
    • A wired intercom limited to each hall would be enough
  • Cables attached to the units are a hassle to store properly
    • So use PowerCon sockets on the units and store cables separately
  • PowerCON TRUE1 TOP vs “regular” Power CON (blue/grey)
    • The new TRUE1 TOP seems like the way to go, but the “output” sockets are too bit for standard D-type patchpanels
    • So use the “old” blue/grey PowerCON instead

See above for requirements (most notable a decent motorized zoom range).

  • Something like a BMD Studio Camera would remove the need for a preview monitor
  • But this would need a separate lens, which needs to be transported properly
    • BMD Studio Camera: Has MFT mount with limited choice of suitable lenses
    • BMD Ursa: Quite big, transport with lens attached is probably a bad idea → not suitable for “untrained” users
  • So we're at a camcorder again b/c:
    • Single unit
    • Easy to operate for new people
    • Can also be used handheld quite easily (as a camera on stage)
  • Decision: JVC GY-HC500E

Prosumer Cameras

There's basically just Sony, Panasonic and JVC. Sony only has camcorders with 1/3 inch sensor, which is not beneficial for low-light performance.

Broadcast Cameras

For compatison, here are some featurs of the Blackmagic Design cameras:

  • Blackmagic Studio Kamera 4k G2 (~1.400€ w/o VAT)
    • MFT-Mount
    • possible lenses (focus and zoom control supported)
      • MFT
        • Olympus 12–50 mm f/3,5–6,3 ED M. Zuiko EZ Micro 4/3 Objektiv
        • Panasonic Lumix G X Vario PZ 45–175 mm f/4,0–5,6 Zoomobjektiv mit O.I.S
        • Olympus 14–42 mm M.Zuiko f/3,5–5,6 Digital ED EZ Objektiv
        • Panasonic Lumix G X Vario PZ 14–42 mm f/3,5–5,6 Power-Objektiv mit O.I.S.
      • with EF adapter
        • Canon CN-E 18–80 mm T4.4 Compact-Servo
        • Canon CN-E 70–200 mm T4.4 Compact-Servo
        • Canon EF-S 18–135 mm f/3,5–5,6 IS USM mit Canon PZ-E1 Power-Zoom-Adapter
  • Blackmagic Design URSA Broadcast G2 + Fujinon XA20x8.5BRM-K3 (~6.100€ w/o VAT)
    • 20x Zoom f1.8-2.7 / 8.5-170mm
    • BxHxT 278 x 150 x 252mm body + 85 x 85 x 181mm lens
    • 12G SDI (Encoder) + 3G SDI (preview monitor)


  • Ideally a quad-channel receiver, dual-channel also fine
  • digital transmission

Comparisons based upon 4 channel receiver(s), 2 handsets and 1 headset and antenna splitter where necessary. Per brand similar hand/headset/capsule etc.

Sennheiser (prices are MSRP incl. VAT):

Sennheiser (NL) recommends EW-DX for our use case, mainly because of the large number of available channels within the various bands. Analogue was highly discouraged for the same reason. I (Bix) couldn't get a firm recommendation for frequency band from them, but in NL bands R1-9 (520-607.8MHz) and S2-10 (614-693MHz) were sold the most, in DE Q1-9 (470.2-550 MHz).


    • 10x XLR in (5 combo jacks) + 1x Stereo in
    • 2x XLR out (main mix) + 6x 6.3 mm jack out
    • auto mic mixer
    • 16×16 channel USB interface
    • no hardware faders/ “touchmix form-factor”
    • stereo-linking possible
    • EQ (GEQ or PEQ + feedback-assist) and dynamics on all outputs
    • 16x XLR in (4 combo jacks)
    • 8x XLR out (busses: 1 Stereo, 6 Mix, 2 FX, 2 Matrix)
    • 18×18 channel USB interface
    • 8+1 faders, 140 mm high/ thick, 320 mm wide, 455 mm deep
    • stereo-linking possible
    • EQ and dynamics on all busses
    • available with or without Dante
  • projects/case_2.0.txt
  • Last modified: 2023/11/22 00:52
  • by bix