This week, some of the
DebConf Video Team
met in Herefordshire (UK) for
a
sprint. We didn't have
a sprint in 2024, and it was sorely needed, now.
At the sprint we made good progress towards using Voctomix 2 more
reliably, and made plans for our future hardware needs.
Attendees
- Chris Boot (host)
- Stefano Rivera
- Kyle Robbertze
- Carl Karsten
- Nicolas Dandrimont
Voctomix 2
DebConf 25 was the first event that
the team used
Voctomix version 2.
Testing it during DebCamp 25 (the week before DebConf), it seemed to
work reliably. But during the event, we hit repeated
audio dropout
issues, that affected about
18 of our recordings (and live streams).
We had attempted to use Voctomix 2 at DebConf 24, and quickly rolled
back to version 1, on day 1 of the conference, when we hit similar
issues. We thought these issues would be resolved for DebConf 25, by
using more powerful (newer) mixing machines.
Trying to get to the bottom of these issues was the main focus of the
sprint. Nicolas brought 2 of Debian's cameras and the Framework laptop
that we'd used at the conference, so we could reproduce the problem.
It didn't take long to reproduce, in fact, we spent most of the week
trying any configuration changes we could think of to avoid it.
The issue we've been seeing feels like a gstreamer bug, rather than
something voctomix is doing incorrectly. If anything, configuration
changes are avoiding hitting it.
Finally, on the last night of the sprint, we managed to run voctomix all
night without the problem appearing. But... that isn't enough to feel
confident that the issue is avoided. More testing will be required.
Detecting audio breakage
Kyle worked on a way to report the audio quality in our Prometheus
exporter, so we can automatically detect this kind of audio breakage.
This was implemented in
helios our audio
level monitor, and lead to some related code refactoring.
Framework Laptops
Historically, the video team has relied on borrowed and rented computer
hardware at conferences for our (software) video mixing, streaming,
storage and encoding. Many years ago, we'd even typically have a local
Debian mirror and upload queue on site.
Our video mixing machines had to be desktop size computers with 2
Blackmagic Declink Mini
Recorder PCI-e
cards installed in them, to capture video from our cameras.
Now that we reliably have more Internet bandwidth than we really need,
at our conference venues, we can rely on offsite cloud servers. We only
need the video capture and mixing machines on site.
Blackmagic also has
UltraStudio
Recorder
thunderbolt capture boxes that we can use with a laptop.
The project bought a couple of these and a
Framework 13
AMD laptop to test at DebConf 25.
We used it in production at DebConf, in the "Petit Amphi" room, where it
seemed to work fairly well. It was very picky about thunderbolt cable
and port combinations, refusing to even boot when they were connected.
Since then, Framework firmware has fixed these issues, and in our
testing at the sprint, it worked almost perfectly. (One of the capture boxes
got into a broken
state,
and had to be unplugged and re-connected to fix it.)
We think these are the best option for the future, and plan to ask the
project to buy some more of them.
HDCP
Apple Silicon devices seem to like to HDCP-encrypt their HDMI output
whenever possible. This causes our HDMI capture hardware to display an
"Encrypted" error, rather than any useful image.
Chris experimented with a few different devices to strip HDCP from HDMI
video, at least 2 of them worked.
Spring Cleaning
Kyle dug through the open issues in our
Salsa
repositories and cleaned
up some issues.
DebConf 25 Video Encoding
The core video team at DebConf 25 was a little under-staffed,
significantly overlapping with core conference organization, which
took priority.
That, combined with the Voctomix 2 audio dropout issues we'd hit, meant
that there was quite a bit of work left to be done to get the conference
videos properly encoded and released.
We found that the encodings had been done at the wrong resolution, which
forced a re-encode of all videos. In the process, we reviewed videos for
audio issues and
made a list of the
ones
that need more work. We ran out of time and this work isn't done,
yet.
DebConf 26 Preparation
Kyle reviewed floorplans and photographs of the proposed
DebConf
26 talk venues, and build up a
list of A/V kit
that we'll need to hire.
Carl's Video Box
Carl uses much of the same stack as the video team,
for many other
events in the US. He has
experimenting with
using a
Dell 7212 tablet in an all-in-one laser-cut box.
Carl demonstrated this box, which could perfect for small miniDebConfs,
at the sprint. Using voctomix 2 on the box requires some work, because
it doesn't use Blackmagic cards for video capture.
gst-fallbacksrc
Carl's box's needs lead to looking at
gstfallbacksrc.
This should let Voctomix 2 survive cameras (or network sources) going
away for a moment.
Matthias Geiger
packaged it for us,
and it's now in Debian NEW. Thanks!
voctomix-outcasts
Carl cut a release of
voctomix-outcasts and
Stefano uploaded it to unstable.
Ansible Configuration
The videoteam's stack is deployed with Ansible, and almost everything we
do involves work on this stack. Carl upstreamed some of his features to
us, and we updated our voctomix2 configuration to
take
advantage
of our experiments at the sprint.
Miscellaneous Voctomix contributions
We fixed a couple of
minor
bugs in voctomix.
More Nageru experimentation
In 2023, we tried to configure
Nageru
(another live video mixer) for the video team's needs. Like voctomix
it needs some configuration and scaffolding to adapt it to your needs.
Practically, this means writing a "theme" in Lua that controls the
mixer.
The team still has a preference for Voctomix (as we're all very familiar
with it), but would like to have Nageru available as an option when we
need it. We
fixed
some minor issues in our theme, enough to get it running again, on the
Framework laptop. Much more work is needed to really make it a useable
option.
Thank you
Thanks to the Debian project for funding the costs of the sprint, and
Chris Boot's extended family for providing us with a no-cost sprint
venue.
Thanks to
c3voc for developing and maintaining
voctomix, and helping us to debug issues in it.
Thank you to everyone in the videoteam who attended or helped out
remotely! And to employers who let us work on Debian on company time.
We'll likely need to keep working on our stack remotely, in the leadup
to DebConf 26, and/or have another sprint before then.
It occurred to me recently that one of the attractions of vinyl, or more
generally physical media, could be that it's inert, safe: the music is a
groove cut into some plastic. That's it. The record can't do anything
unexpected to you
DC25 network usage graphs. 
Flow diagrams. 
Streaming bandwidth graph. 
Another (again somewhat minor) maintenance release of the 
This was the first year I attended 
Hi, I m Melissa Wen from Igalia. As we already started sharing kernel recipes
and even more is coming in the next three days, in this presentation I ll talk
about kworkflow: a cookbook to mix & match kernel recipes end-to-end.
This is my first time attending Kernel Recipes, so lemme introduce myself
briefly.
And what s this cookbook called kworkflow?
Kworkflow is a tool created by 
It s mostly done by volunteers, kernel developers using their spare time. Its
features cover real use cases according to kernel developer needs.
Basically it s mixing and matching the daily life of a typical kernel developer
with kernel workflow recipes with some secret sauces.
So, it s time to start the first recipe: A good GPU driver for my AMD laptop.
Before starting any recipe we need to check the necessary ingredients and
tools. So, let s check what you have at home.
With kworkflow, you can use:
Now, with all ingredients and tools selected and well portioned, follow the
right steps to prepare your custom kernel!
First step: Mix ingredients with 
After compiling the custom kernel, we want to install it in the target machine.
Check the name of the custom kernel built: 
Oh no! That custom kernel isn t tasting good. Don t worry, as in many recipes
preparations, we can search on the internet to find suggestions on how to make
it tasteful, alternative ingredients and other flavours according to your
taste.
With 
As in all recipes, we need ingredients and tools, but with kworkflow you can
get everything set as when changing scenarios in a TV show. We can use kw env
to change to a different environment with all kw and kernel configuration set
and also with the latest compiled kernel cached.
I was preparing the first recipe for a x86 AMD laptop and with 
If you didn t plan for this recipe in advance, don t worry. You can create a
new environment with 
And you can use 
Let s show you how easy is to build, install and test a custom kernel for Steam
Deck with Kworkflow. It s a live demo, but I also recorded it because I know
the risks I m exposed to and something can go very wrong just because of
reasons :)
As I started the demo in the kw environment for Raspberry Pi 4, I first moved
to another environment previously used for Steam Deck. In this STEAMDECK
environment, the mainline kernel was already compiled and cached, and all
settings for accessing the target machine, compiling and installing a custom
kernel were retrieved automatically.
My live demo followed these steps:
Quiete some things made progress last month: We put out
Playing Clair Obscur Expedition 33. I didn't think I would try again and again to beat a boss I cannot beat for multiple days. But here I am.
