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CCRMA Seminar Room

The CCRMA Seminar Room (Knoll 315) is a small room with a large conference table, ideal for small classes and meetings or short projects requiring lots of surface area.

Contents

Photo of the Seminar Room showing the conference table, chairs, Linux machine, cookie jar, audio mixer, document camera, and Kramer rack.

In this room you should see:

Audiovisual Selection

Use the Kramer system to plug in and choose one video source.

Use the mixer to mix the audio (including stereo from the selected HDMI source).

The Kramer VP-551x HDMI switcher and some of its input sockets.

Audio System

We now hear the mix of a few audio sources via a K-Mix Blue digital mixer:

(Microphones)
The first two mixer channels are currently reserved for future microphone inputs, or live signals from the Stage.
HDMI
Whatever stereo audio the selected HDMI source may contain.
Linux/Tascam
Stereo sound, in analog, from the Tascam 2x2 audio interface connected via the KVM to Linux, Mac Pro, or Laptop (affected by the Tascam’s LINE OUT 1-2 and MONITOR BALANCE volume knobs)
Analog
From the dangling stereo audio cable with a 1/8 inch (aka 3.5mm) TRS unbalanced analog stereo connector, meant to plug into the headphone jack of a laptop, phone, etc.).

Operating the K-Mix

We use only a fraction of the capabilities of the K-Mix; this diagram shows which parts of the user interface we do and don’t use in the Seminar Room:

Labeled K-Mix front panel. We ignore most of the interface’s buttons. The power switch and A/Main buttons should be lit. The lower-left VU button toggles whether the visual metering for the 8 channels and overall mix will show the virtual fader levels (how much each track is turned up in the mix) versus being VU meters that display in real time the changing volume of the source material.

Each of the mixer’s 9 faders is touch-sensitive; just rub your finger up and down to control volume.

Channel trims have been adjusted so that a computer’s 0 dB just barely doesn’t clip and is approximately identical in loudness when switching between HDMI and headphone jack (at least on one particular laptop).

The HDMI, Linux, and Analog inputs are “paired into stereo channels”; adjusting either (left or right) volume will always control both equally.

Each fader is also a 12-segment LED display. The VU button in the lower left corner toggles between the two modes of what these meters display:

We recommend VU on, because it lets you see visually which mixer channels correspond to the sound you’re currently hearing, so you know which faders will adjust the volume.

K-Mix in VU mode: note the lit blue VU button in the lower left and that all the meters are displaying zero (showing that all mixer inputs are currently silent)
K-Mix not in VU mode: note the unlit VU button in the lower left. We see from the meters that the HDMI, Linux, and Analog inputs are at 0dB (barely “touching” the red) and that the Overall output volume is a bit lower.

Hybrid Meeting Camera System

A Kandao Meeting Ultra Standard 4K 360° camera (manufacturer’s page) sits in the middle of the table (from where it can focus on the faces of the people sitting around the table).

It’s running Android OS including the Android implementations of Zoom and Google Meet.

Typically you would run Zoom on the Kandao itself, being seen and heard by the Kandao’s camera(s) and mic(s), seeing (and operating) Zoom on the (touch)screens connected to the Kandao box. For Zoom purposes it’s acutally better not to use the projector, so that the local participants look at the touchscreens and hence towards the camera.

There’s a labeled power on/off pushbutton on top of the unit as well as a rubber privacy cover that physically blocks the camera lenses.

The Box

A custom wooden box holds the camera (on top), three touchscreens (on three sides), lots of hidden wiring (inside), and a bunch of I/O (on the fourth side, facing the projection screen):

“inputs” “outputs”
(Kando’s 2nd out is open)
(cable hole) Touchscreen mirror
Laptop thru Laptop thru
Kandao in (ethernet)
Upper Left
Hole for cables passing between Kandao and Box interior
Upper Right
HDMI socket outputting another mirror of the video that is mirrored to the three touchscreens
Middle Left
HDMI socket accepting a signal from a laptop on the table
Middle Right
HDMI socket outputting that signal from a laptop on the table
Bottom Left
HDMI socket accepting a “screen share” signal going into the Kandao
Bottom Right
Ethernet socket

Recipes for a Hybrid Meeting

Have the Zoom link (like one you made by logging into https://stanford.zoom.us)

Start the meeting

If somebody not in the Seminar Room shares their screen over Zoom, you’ll see that on the three monitors attached to the Kandao, with Zoom’s choices of whether to also see the speaker or gallery view. (Try “clicking” on the picture-in-picture camera images if you want to toggle those bigger and the screen share smaller, like if you can see the same screen share content on the projection screen.)

For somebody in the Seminar Room to screen share, there are many options:

  1. Get your laptop in the same Zoom meeting (but no sound I/O) and Zoom-screen-share from there.

  2. You can plug your laptop’s HDMI output into the Kandao’s HDMI input, then from the Kandao’s Zoom you can “share screen” which will give you the option of sharing the video from “external HDMI”.

  3. Also the Kandao can take wireless video input from your laptop and screen share that.

By default the Kandao will act like a Zoom client connected to a single display screen, so that screen sharing will take over the display, and you have to switch between that and seeing the remote participants’ cameras. You might instead want to see the screen-shared video on the big projection screen, but set the Kandao to keep the Zoom gallery view on the touchscreens (so you can see the presentation and/or the remote participants in a natural way). Again there are options:

  1. If the screen share is from a laptop in the room, that laptop could also go straight into the projector via HDMI.

  2. If another laptop is available in the room, then it could get on the Zoom with no audio connected, with its HDMI connected to the projector, set as the screen share projection client.

  3. You can plug the Kandao’s second HDMI output into the projector and try to figure out how to arrange the screen share and gallery view on the two displays. (External mouse might make this easier.)

In any case, the Kandao camera can “see” the projection screen and may “choose” some of the faces there along with any actual humans seated around the table.

Also there could be flicker or annoying pulsating color patterns in the Kandao camera’s view of the projection screen.


This page of CCRMA documentation last committed on Tue Sep 10 13:35:53 2024 -0700 by Matthew James Wright. Stanford has a page for Digital Accessibility.