[FOSDEM] Embedded, Mobile and Automotive devroom @FOSDEM2021

[Luke Kenneth Casson Leighton]

---
crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68

On Mon, Dec 21, 2020 at 2:45 AM Alasdair G Kergon <agk at fosdem.org> wrote:
>
> On Mon, Dec 21, 2020 at 12:57:08AM +0000, Luke K C Leighton wrote:
> >      *there needs to be time allocated to this in the schedule*
>
> I hope there is and we will suggest some ways to do it (and do automated
> ffmpeg standardisation ourselves).

that may be challenging (one size may not fit all) if i can illustrate why.

attached ffmpeg_speedup.sh - you have to "invert" the number for the
speed of the video and of the audio (1/x) *sigh*.  this is useful if
someone makes a talk that's simply too long but there's not time to
redo it.  don't go overboard: 1.25% speedup is just about on the
limit.

another one reduces the framerate (-rf 8) which *massively* gets the
size of the upload down.  if there's just some slides with huge fonts
and no person walking around in it, setting "scale=640:-1" and "-r 2"
will get even a 1 hour video down to under 40 MB which, given that
some people are doing font sizes of 80px then naively recording
1080p60 and ending up with a 2GB file, this is a huuuge reduction.

"-b:v 1600k" drops the mpeg quality, you do start to get artefacts
over frame-changes that take a while to "recover" if you go down to
say "-b:v 800k", however, again: if the size is only 640 wide nobody's
going to notice.

do note that the output format *changes* depending on the extension
name (!).  you get *different* CODECs engaged if you start from .mp4
and target .avi, than if you start from .mp4 and target .mp4.
likewise with mkv.  sigh.

i have had best results with setting the destination to ".avi".


> I'll be surprised if they make it onto youtube any time soon

individuals could do it (if they're not limited, had an account for a
while).  devroom organisers asking them, "this needs converting, can
you upload it to youtube, we can grab it from there" is dead simple.
if they don't have an account, then, well, *shrug*.

> us.  (We used to have a large upload limit previously but they removed
> it presumably because we only do large uploads once a year, and all our
> attempts to obtain reinstatement fell on deaf ears.)

sigh.  presumably the spike was too high, they may not be able to cope
with the transient load.  and can't be bothered.  by chance did you
ask them, "would you like to sponsor FOSDEM?"

l.
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