On 2021-04-09 02:05, The Natural Philosopher wrote:
> On 09/04/2021 09:46, F. W. wrote:
>> I was asked if I can record a C-Programming-Course on Video for a small
>> amount of people. Maybe the Video will later be published on Vimeo or
>> Youtube. I need a relative good quality therefore.
>>
>> I would not like to be in picture. I think it is okay to write a program
>> on screen while explaining what I do. I prefer my Raspberry Pi 400
>> programming in C for the clarity of Linux-API and the natural
>> relationship between C and Unix.
>>
>> Is there a hardware that can do this? KAZAM & Co seem not to work
>> properly. What do professionals do?
>>
>> FW
>>
> Oddly enough raspberry pi aside, I would also like to do this for the
> purposes of teaching a friend how to use a bit of quite complex software...
>
> its done on You tube all the time
>
> Record what you are doing and then record a voice over explaining it...
>

VLC actually has the ability to do this.  In short, you do X11 capture
on the RPi, while recording the voice over.  Later you can use ffmpeg or
mencoder or something similar to combine the audio and video and do a
sound sync.

to make raw V4L video capture from the X11 display:

cvlc --no-sout-display --sout-video --sout file://./screencap.temp.raw \
     --screen-left=0 --screen-top=0 --screen-width=800 \
     --screen-height=480 \
     --screen-fps=25.000000 --live-caching=300 screen://

typically you need to post-crunch the video with something like
'mencoder' or it won't play

mencoder -idx -o ./screencap.mp4 -ovc x264 -demuxer rawvideo -rawvideo
format=bgra:w=800:h=480:size=3456000 -sb 300 screencap.temp.raw

(you may have to experiment with the numbers for w, h, and size, as well
as the '-sb' value - these were derived from the settings I use for a
larger screen resolution)

hope this helps.


--
(aka 'Bombastic Bob' in case you wondered)

'Feeling with my fingers, and thinking with my brain' - me

'your story is so touching, but it sounds just like a lie'
"Straighten up and fly right"

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