android: added ip webcam and follow ups

wiki/android/ip_webcam.md

@@ -0,0 +1,38 @@
+# IP Webcam
+
+[IP Webcam](https://play.google.com/store/apps/details?id=com.pas.webcam&hl=de&gl=US) is an App
+developed and published by Pavel Khlebovich for [Android](/wiki/android.md) systems.
+It enables a [smartphone](/wiki/smart_devices.md) to be used as [webcam](/wiki/webcams.md).
+
+## Setup
+
+On [Android](/wiki/android.md) IP Webcam is available on the
+[Google Play Store](/wiki/android.md#app-store) in a package called
+[IP Webcam](https://play.google.com/store/apps/details?id=com.pas.webcam&hl=de&gl=US).
+
+## Usage
+
+To initiate a connection between the [smartphone](/wiki/smart_devices.md) and the computer first
+start the app on the smartphone.
+Make sure to be connected to the same W-LAN as the computer or alternatively connect them with an
+USB-cable.
+After starting the application an IPv4 link be displayed.
+This link can be pasted into a [browser](/wiki/web_browser.md).
+There the video aswell as various settings will be available.
+An example link will look like the following.
+
+```txt
+http://192.168.178.66:8080
+```
+
+Additionally it can be piped into [OBS](/wiki/obs.md) to edit it or into
+[ffmpeg](/wiki/linux/ffmpeg.md) on [Linux](/wiki/linux.md) systems to create a virtual webcam
+device as explained in the
+[ffmpeg entry](/wiki/linux/ffmpeg.md#create-a-virtual-camera-using-an-ip-video-stream).
+The link used for applications like this will be the previously displayed IPv4 link aswell as an
+appended `/videofeed`.
+An example link will look like the following.
+
+```txt
+http://192.168.178.66:8080/videofeed
+```

wiki/linux/ffmpeg.md

@@ -63,3 +63,20 @@ Note that the bitrate for videos is split amongst a bitrate for video and a
 bitrate for audio.
 The target bitrate has to be equal to or greater than the sum of both video
 bitrate and audio bitrate.
+
+### Create a Virtual Camera Using an IP Video Stream
+
+The following section will create a virtual [webcam](/wiki/webcams.md) from an IP video stream like
+the one provided by [IP Webcam](/wiki/android/ip_webcam.md) [Android](/wiki/android.md) app.
+For this a free [V4L2](/wiki/linux/v4l2.md) video device will be needed.
+To information on how to create it navigate to the V4L2 entry and its sections on
+[permanent](/wiki/linux/v4l2.md#create-permanent-v4l2-devices) and
+[temporary creation of V4L2 video devices](/wiki/linux/v4l2.md#create-temporary-v4l2-devices).
+The following command will create a video device  using the pixel format planar YUV 4:2:0.
+In this example it is assumed that the IP link is `http://192.168.178.66:8080/videofeed` and the
+V4L2 video device that is not used but exists is `/dev/video8`.
+If any of those differs on a given system adjustments are needed.
+
+```sh
+ffmpeg -i http://192.168.178.66:8080/videofeed -f v4l2 -pix_fmt yuv420p /dev/video8
+```

wiki/linux/v4l2.md

@@ -13,11 +13,21 @@ The following section is based on a
 [v4l2loopback](https://github.com/umlaeute/v4l2loopback) is a utility to create
 a virtual video device.
 One use of it is in [OBS Virtual Camera](/wiki/obs.md#virtual-camera).
+
+### Setup
+
 To use v4l2loopback an according
 package needs to be installed.
 Some distributions have a package named `v4l2loopback-dkms` in the package
 manager, making the manual installation process unnecessary.
-Afterwards v4l2loopback can be manually started by running:
+
+### Usage
+
+This section focusses on various use-cases for the v4l2loopback software.
+
+### Create Temporary V4L2 Devices
+
+v4l2loopback can be manually started by running:
 
 ```sh
 modprobe v4l2loopback card_label='V4L2 Loopback' video_nr=7 exclusive_caps=1
@@ -28,6 +38,15 @@ modprobe v4l2loopback card_label='V4L2 Loopback' video_nr=7 exclusive_caps=1
 This can be changed according to the needs.
 It is important that the device is not already in use by another application.
 
+To create more than one device more labels or numbers can be appended.
+An example command with 2 V4L2 video devices will look like the following command.
+
+```sh
+modprobe v4l2loopback card_label='OBS Virtual Camera','IP Webcam' video_nr=7,8 exclusive_caps=1
+```
+
+### Create Permanent V4L2 Devices
+
 For an automatic start at boot via [SystemD](./systemd.md) a service can be
 created - as described in [the SystemD entry](./systemd.md#run-command-on-boot).
 For v4l2loopback create the file `/etc/systemd/system/v4l2loopback.service`
@@ -40,15 +59,15 @@ Description=V4L2 Loopback
 [Service]
 Type=simple
 RemainAfterExit=yes
-ExecStart=/bin/modprobe v4l2loopback card_label='V4L2 Loopback' video_nr=7 exclusive_caps=1
+ExecStart=/bin/modprobe v4l2loopback card_label='OBS Virtual Camera' video_nr=7 exclusive_caps=1
 ExecStop=/bin/rmmod v4l2loopback
 
 [Install]
 WantedBy=default.target
 ```
 
-Note the line starting with `ExecStart=/bin/` is the same line described above
-to change the device path.
+Note the line starting with `ExecStart=/bin/` is the same line described in the
+[above section](#create-temporary-v4l2-devices).
 Make sure to change it if needed.
 
 Afterwards enable the service to start at every boot process by running:

wiki/webcams.md

@@ -27,3 +27,5 @@ A [smartphone](/wiki/smart_devices.md) and its camera aswell as flashlight can b
 replacement for a webcam.
 For [Android](/wiki/android.md) smartphones this can be easily achieved by using
 [DroidCam](/wiki/android/droidcam.md).
+An alternative to DroidCam with a with decidedly better resolution is
+[IP Webcam](/wiki/android/ip_webcam.md).