brmlab

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====== brmlab talks.md ======
[[event:talk_imageviewers|Back to the event page ⇐]]
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***
# Venue overview
There are several variously poor options for presenting, which you can feel free to improve yourself:
- You can stand near the couch if you want to be seen.
- You can sit or stand on the northern/door side if you needn't be seen on a camera.

It's theoretically possible to hang a camera from the metal structure near the ceiling if you don't want to put the camera on a tripod (contact prdak who thought of using a selfie stick). Note that there are cables hanging down from the projector, attached to said structure.

![[brmlab talks venue.svg]]

## Example talk setup
- On 26. 3. 2026, a mostly successful setup has been as follows, using a lot of personal equipment:

![[brmlab talks 20260326 setup.svg]]

- MacBook Pro with OBS Studio
	- Virtual Camera → Streamed over meet.jit.si running in Firefox
	- Recording the projector screen, with Keynote.app presenting in a fullscreen window.
- iPhone → Remote control over Wi-Fi with Keynote.app
- Nikon D7500 on a tripod, roughly 1.9m high
	- Captured with an HDMI grabber (~150 Kč on AliExpress)
	- Internal batteries may provide enough runtime, but a fake battery has been used (~325 Kč on AliExpress).
- RØDE wireless microphone set

***
# Venue equipment survey
## Projector
- Native resolution: 1920×1200, switchable with its remote control
- The resolution defines the correct aspect ratio for the presentation.
- It has a rather long HDMI cable attached, and perhaps DVI.
## Laptop
- There is a Linux laptop with OBS that may be used to stream and record, ROT13 login password oezoez.
## Sound output
- You can connect the mixer with a 3.5mm jack and get loudspeakers, such as to make Internet audience be heard, if you want to have that option. Beware that merely being connected to the projector over any cable will probably make your audio ground noisy.
## Sound input
- There should be a wired microphone, if you have something to connect it to, over 3.5mm jack. You could be able to find a 6.3mm jack adapter as well.

***
# Personal equipment survey
This list can easily become out of date or irrelevant:

- **pe**: Nikon D7500, Insta360 One RS 1-inch, Logitech C922, MBP M1 Pro, SoundBlaster X-Fi HD
- **fyzikar:** RØDE wireless microphone set
- **prdak/sladidlostevia/FBMeta:** GoPro HERO3+, some kind of a static microphone
## Nikon D7500
- **Positives:**
	- Excellent optics, adjustable zoom, adjustable colour balance.
	- With a Sigma 18-50 lens, there is no apparent barrel distortion at the desired zoom level (something around 35mm APS-C/half-frame).
- **Negatives**:
	- It's heavy and a bit inconvenient to set up.
- The camera can be used in multiple modes:
	- The only _reasonable_ way of recording is to use an HDMI grabber, which acts as a webcam.
	- The native webcam mode (use the official Windows and Mac "Webcam Utility") is limited to 1024x768 at 10-15 FPS. This looks very choppy, and it's a bit awkward to configure the _necessary_ crop in OBS.
	- Standalone use is limited to 30 minutes of recording. Half an hour of 4K@30 also takes about 26 gigabytes, which is needlessly large.
- It lasts quite long on batteries, but it's still safer to use a fake battery adapter and run it from a powerbank.
## Insta360 ONE RS 1-inch
- **Positives:** 1920x1080 webcam (otherwise 5K video), high framerate, huge DOF.
- **Negatives:** heavy barrel distortion + huge FOV = requires some crop.
- Might last about an hour standalone, now likely much less.
- Colour balance is automatic, a bit yellow-happy.
## GoPro HERO3
- Similar but overall slightly worse than the Insta360.
## Logitech C922 webcam
- **Positives:** 1920x1080, high framerate, huge DOF, appropriate zoom.
- **Negatives:** very noisy: image quality is generally trash.
- Colour balance is automatic.
## RØDE microphone
- This works beautifully as a USB C sound card, and attaches to T/shirts easily.
- It may need switching to a merged output channel by holding both buttons on the receiver, otherwise each transmitter can send a separate channel, if ever needed.
- Normally it has a somewhat poor gain (lower volume). Keep that in mind when mixing.
- It also captures some of the background, so the audience isn't lost completely.

***
# Presenting
## Lighting
- Colour temperature estimated at 4000K (fluorescent), we can measure it precisely if necessary. In any case, projectors are normally 6500K, so there's always a mismatch.
- You can turn on all lights, and/or just the lights in the half of the room further from the projector.
- It is mostly reasonable to have all lights on for the purpose of being personally visible on record. Visibility of the projected image becomes somewhat reduced, but it's alright for text.
## Clicker
- iPhone: If you present using a Mac and Keynote.app, it's best to use the respective iPhone app, which gives you full control over the presentation, including speaker notes, over Wi-Fi.
- Android: download BT Remote from the Play Store, which acts as a Bluetooth mouse, and you can use it to switch slides.
- Don't even think about AliExpress "TikTok remotes", those only work on with mobile phones.

***
# Recording
When not streaming, you can record all audio and video separately, then merge it afterwards in DaVinci Resolve or similar software.

Otherwise the software that everyone and their cat uses is OBS Studio, preinstalled on the brmlab laptop.

There are two suggested scene setups:
1. Just record the projector screen.
2. Also record yourself. Due to lighting limitations you should place yourself in a small window next to the slides, even if you record the projected slides.

Note that dis/connecting devices may screw up your OBS Studio configuration, forcing you to reconfigure everything at the venue.
## macOS example
- Add "macOS Screen Capture", set it to the extended display projector.
- Add "Video Capture Device", select the appropriate device.
- Since you'll be left with free space, it is a good idea to add the brmlab logo somewhere.

***
# Streaming
We should be able to set up our own restreaming, but the simplest option is to Start Virtual Camera in OBS and use this webcam in http://meet.jit.si. This public instance however crops the video to eliminate all blank space, so the viewers' browsers need to have the right aspect ratio.

***
# Video hosting
Historically video files were hosted by nat.brmlab.cz, but https://mirror.vpsfree.cz/videohrach/video/brm/ administered by Mrkva is what we have now; see https://brmlab.cz/video/start

santiago-oz suggests new.brmlab.cz (where brmlab.cz runs), but dzoe is not sure of disc space.

Wherever the actual video files are hosted, we should provide an interface to them with HTML video.
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