Improve FAQ

FAQ.md

@@ -1,10 +1,5 @@
 # Frequently Asked Questions
 
-## Common issues
-
-The application is very young, it is not unlikely that you encounter problems
-with it.
-
 Here are the common reported problems and their status.
 
 
@@ -20,9 +15,13 @@ Windows may need some [drivers] to detect your device.
 [drivers]: https://developer.android.com/studio/run/oem-usb.html
 
 
-### Mouse clicks do not work
+### I can only mirror, I cannot interact with the device
 
 On some devices, you may need to enable an option to allow [simulating input].
+In developer options, enable:
+
+> **USB debugging (Security settings)**  
+> _Allow granting permissions and simulating input via USB debugging_
 
 [simulating input]: https://github.com/Genymobile/scrcpy/issues/70#issuecomment-373286323
 
@@ -43,6 +42,16 @@ meson x --buildtype release -Dhidpi_support=false
 However, the video will be displayed at lower resolution.
 
 
+### The quality is low on HiDPI display
+
+On Windows, you may need to configure the [scaling behavior].
+
+> `scrcpy.exe` > Properties > Compatibility > Change high DPI settings >
+> Override high DPI scaling behavior > Scaling performed by: _Application_.
+
+[scaling behavior]: https://github.com/Genymobile/scrcpy/issues/40#issuecomment-424466723
+
+
 ### KWin compositor crashes
 
 On Plasma Desktop, compositor is disabled while _scrcpy_ is running.
@@ -50,3 +59,26 @@ On Plasma Desktop, compositor is disabled while _scrcpy_ is running.
 As a workaround, [disable "Block compositing"][kwin].
 
 [kwin]: https://github.com/Genymobile/scrcpy/issues/114#issuecomment-378778613
+
+
+### I get an error "Could not open video stream"
+
+There may be many reasons. One common cause is that the hardware encoder of your
+device is not able to encode at the given definition:
+
+```
+ERROR: Exception on thread Thread[main,5,main]
+android.media.MediaCodec$CodecException: Error 0xfffffc0e
+...
+Exit due to uncaughtException in main thread:
+ERROR: Could not open video stream
+INFO: Initial texture: 1080x2336
+```
+
+Just try with a lower definition:
+
+```
+scrcpy -m 1920
+scrcpy -m 1024
+scrcpy -m 800
+```