scrcpy/doc/v4l2.md
2023-11-28 08:32:28 +01:00

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# Video4Linux
On Linux, it is possible to send the video stream to a [v4l2] loopback device,
so that the Android device can be opened like a webcam by any v4l2-capable tool.
[v4l2]: https://en.wikipedia.org/wiki/Video4Linux
The module `v4l2loopback` must be installed:
```bash
sudo apt install v4l2loopback-dkms
```
To create a v4l2 device:
```bash
sudo modprobe v4l2loopback
```
This will create a new video device in `/dev/videoN`, where `N` is an integer
(more [options](https://github.com/umlaeute/v4l2loopback#options) are available
to create several devices or devices with specific IDs).
If you encounter problems detecting your device with Chrome/WebRTC, you can try
`exclusive_caps` mode:
```
sudo modprobe v4l2loopback exclusive_caps=1
```
To list the enabled devices:
```bash
# requires v4l-utils package
v4l2-ctl --list-devices
# simple but might be sufficient
ls /dev/video*
```
To start `scrcpy` using a v4l2 sink:
```bash
scrcpy --v4l2-sink=/dev/videoN
scrcpy --v4l2-sink=/dev/videoN --no-video-playback # disable playback window
```
(replace `N` with the device ID, check with `ls /dev/video*`)
Once enabled, you can open your video stream with a v4l2-capable tool:
```bash
ffplay -i /dev/videoN
vlc v4l2:///dev/videoN # VLC might add some buffering delay
```
For example, you could capture the video within [OBS] or within your video
conference tool.
[OBS]: https://obsproject.com/
## Buffering
By default, there is no video buffering, to get the lowest possible latency.
As for the [video display](video.md#buffering), it is possible to add
buffering to delay the v4l2 stream:
```bash
scrcpy --v4l2-buffer=300 # add 300ms buffering for v4l2 sink
```