Discussion between Fitz Watson and Raffa

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09:45

Asuming both machines are connected in a network and the PC can reach the laptop's IP. Please follow these steps: On the laptop Install v4l-utils and ffmpeg by running: sudo apt install v4l-utils ffmpeg Install matroska media container like so: sudo apt install libmatroska6v5 Run the following ...

Raffa

@JohnDoe This means missing v4l2 format. Install it by running sudo apt install v4l-utils ffmpeg on both

@JohnDoe run sudo modprobe -r v4l2loopback then run ls /dev/video* and note the existing cameras like /dev/video0 /dev/video1 /dev/video2 ... etc then run sudo modprobe v4l2loopback exclusive_capse=1 and run again ls /dev/video* a new camera will be added like so /dev/video0 /dev/video1 /dev/video2 /dev/video3 use the new camera in the commands under test instead of /dev/video0

@JohnDoe Did you install v4l2loopback this way sudo apt install v4l2loopback-dkms v4l2loopback-utils?

@JohnDoe Try this from the PC instead nc Laptop_IP 9999 | mplayer - and if it works then it is most likely v4l2loopback is the cause. so reinstall it the right way or the package available for Ubuntu 18.0 is outdated, I tested it on Ubuntu 19.10 and it works flawlessly.

@JohnDoe Check the version with apt policy v4l2loopback-utils v4l2loopback-dkms. I tested it on version 0.12.2-1 of v4l2loopback

@JohnDoe Answer updated to minimize latency

@JohnDoe No problem. Please check the updated answer. There will be sound latency because no compression is used.

Fitz Watson

I'm getting pipe:: Invalid data found when processing inputKB sq= 0B f=0/0 when I run nc Laptop_IP 9999 | ffmpeg -i /dev/stdin -codec copy -f v4l2 /dev/video0

Raffa

@FitzWatson Yoy need to change Laptop_IP to the actual IP of the laptop which can be something like 192.168.1.116 for example. Use the GUI of network manager or run ip address in the terminal to find out what the actual laptop's IP is and use that instead.

Fitz Watson

I'm streaming from user A in laptop to user B in the same laptop. So I replaced it with localhost. Is that ok?

dedoimedo.com/computers/xephyr.html

I've followed this guide and am now trying to get webcam in the xephyr session

Raffa

@FitzWatson Yes localhost or 127.0.0.1 should work, but open a new terminal for that command and leave the first terminal open to keep ffmpeg -i /dev/video0 -codec copy -f matroska - | nc -l 9999 running . I have not looked at the link you provided though and do not know whether it is compatible or not.

Fitz Watson

09:45

I did this: 1) Opened new terminal and ran ffmpeg -i /dev/video0 -codec copy -f matroska - | nc -l 9999. Webcam led on. 2) Opened new terminal and ran nc 127.0.0.1 9999 | ffmpeg -i /dev/stdin -codec copy -f v4l2 /dev/video0. 3) This gave /dev/stdin: Invalid data found when processing input

Raffa

@FitzWatson Test it with nc 127.0.0.1 9999 | mplayer - in the second terminal instead and make sure the command in the first terminal is running and if it works then you need to work with the format and see what is best for your solution. This test should work if you have followed the instructions in the answer correctly.

Fitz Watson

This is the output of the mplayer command. pastebin.com/4eq4KjQs

If I add lirc=no in .mplayer/config, it changes to: pastebin.com/ukNEiemP

Raffa

I apologize I do not have much time on hand but have you tried vlc

nc 127.0.0.1 9999 | vlc -

or ffplay

nc 127.0.0.1 9999 | ffplay -

to rule out format issues

Yes, it looks like format issue

try vlc or ffplay

there is a reason I added those as extra test methods in my answer

not all formats are supported on all systems the same way

that is always what gives people hard time

formats support

any luck with vlc or ffplay?

Fitz Watson

10:01

Here's the ffplay output: pastebin.com/iRrNr5mY

Raffa

The command in the first terminal exits and the Camera LED goes off. you need to restart the command in the first terminal and make sure Camera LED is on each time before testing in the second terminal :)

Fitz Watson

the led was on in all the tests

Raffa

restart the comand and test with vlc again

Fitz Watson

-- logger module started --
main: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
mjpeg error: cannot peek
-- logger module stopped --

This is the vlc log file

Raffa

Ctrl+c in the first terminal then rerun the first command

Vlc output normal

but any video?

Fitz Watson

10:06

@Raffa Could you explain what this msg means?

Raffa

yes

there is another version of vlc

called headless vlc

o cvlc

Fitz Watson

I should use that?

Raffa

for running vlc with no configured display

that is just a general message when you run vlc from terminal it assumes that no display is connected or configured and prints an advice

you have a display

Fitz Watson

yes

it's a laptop

$ nc 127.0.0.1 9999 | cvlc -
VLC media player 3.0.12 Vetinari (revision 3.0.12-1-0-gd147bb5e7e)

This command doesn't exit

I waited 10 secs and then did Ctrl+C

Raffa

OK?

Fitz Watson

10:10

It didn't play anything either

should we first try streaming a mp4?

Raffa

I suggest you reboot your system and follow the instructions in the answer again and test from the second terminal with vlc first then ffplay them mplayer like in the answer

If that did not work I suggest you post anew question

I apologize again I have to go now.

Fitz Watson

Ok. Thanks for your assisstance

Raffa

I wish I could help more.

bye

Fitz Watson

Bye mate :)

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