Improve FAQ

FAQ.md

@@ -3,19 +3,102 @@
 Here are the common reported problems and their status.
 
 
-### On Windows, my device is not detected
+## `adb` issues
 
-The most common is your device not being detected by `adb`, or is unauthorized.
-Check everything is ok by calling:
+`scrcpy` execute `adb` commands to initialize the connection with the device. If
+`adb` fails, then scrcpy will not work.
 
-    adb devices
+In that case, it will print this error:
 
-Windows may need some [drivers] to detect your device.
+>     ERROR: "adb push" returned with value 1
+
+This is typically not a bug in _scrcpy_, but a problem in your environment.
+
+To find out the cause, execute:
+
+```bash
+adb devices
+```
+
+### `adb` not found
+
+You need `adb` accessible from your `PATH`.
+
+On Windows, the current directory is in your `PATH`, and `adb.exe` is included
+in the release, so it should work out-of-the-box.
+
+
+### Device unauthorized
+
+Check [stackoverflow][device-unauthorized].
+
+[device-unauthorized]: https://stackoverflow.com/questions/23081263/adb-android-device-unauthorized
+
+
+### Device not detected
+
+If your device is not detected, you may need some [drivers] (on Windows).
 
 [drivers]: https://developer.android.com/studio/run/oem-usb.html
 
 
-### I can only mirror, I cannot interact with the device
+### Several devices connected
+
+If several devices are connected, you will encounter this error:
+
+>     adb: error: failed to get feature set: more than one device/emulator
+
+the identifier of the device you want to mirror must be provided:
+
+```bash
+scrcpy -s 01234567890abcdef
+```
+
+Note that if your device is connected over TCP/IP, you'll get this message:
+
+>     adb: error: more than one device/emulator
+>     ERROR: "adb reverse" returned with value 1
+>     WARN: 'adb reverse' failed, fallback to 'adb forward'
+
+This is expected (due to a bug on old Android versions, see [#5]), but in that
+case, scrcpy fallbacks to a different method, which should work.
+
+[#5]: https://github.com/Genymobile/scrcpy/issues/5
+
+
+### Conflicts between adb versions
+
+>     adb server version (41) doesn't match this client (39); killing...
+
+This error occurs when you use several `adb` versions simultaneously. You must
+find the program using a different `adb` version, and use the same `adb` version
+everywhere.
+
+You could overwrite the `adb` binary in the other program, or ask _scrcpy_ to
+use a specific `adb` binary, by setting the `ADB` environment variable:
+
+```bash
+set ADB=/path/to/your/adb
+scrcpy
+```
+
+
+### Device disconnected
+
+If _scrcpy_ stops itself with the warning "Device disconnected", then the
+`adb` connection has been closed.
+
+Try with another USB cable or plug it into another USB port. See [#281] and
+[#283].
+
+[#281]: https://github.com/Genymobile/scrcpy/issues/281
+[#283]: https://github.com/Genymobile/scrcpy/issues/283
+
+
+
+## Control issues
+
+### Mouse and keyboard do not work
 
 On some devices, you may need to enable an option to allow [simulating input].
 In developer options, enable:
@@ -29,19 +112,26 @@ In developer options, enable:
 ### Mouse clicks at wrong location
 
 On MacOS, with HiDPI support and multiple screens, input location are wrongly
-scaled. See [issue 15].
+scaled. See [#15].
 
-[issue 15]: https://github.com/Genymobile/scrcpy/issues/15
+[#15]: https://github.com/Genymobile/scrcpy/issues/15
 
-A workaround is to build with HiDPI support disabled:
+Open _scrcpy_ directly on the monitor you use it.
 
-```bash
-meson x --buildtype release -Dhidpi_support=false
-```
 
-However, the video will be displayed at lower resolution.
+### Special characters do not work
+
+Injecting text input is [limited to ASCII characters][text-input]. A trick
+allows to also inject some [accented characters][accented-characters], but
+that's all. See [#37].
+
+[text-input]: https://github.com/Genymobile/scrcpy/issues?q=is%3Aopen+is%3Aissue+label%3Aunicode
+[accented-characters]: https://blog.rom1v.com/2018/03/introducing-scrcpy/#handle-accented-characters
+[#37]: https://github.com/Genymobile/scrcpy/issues/37
 
 
+## Client issues
+
 ### The quality is low on HiDPI display
 
 On Windows, you may need to configure the [scaling behavior].
@@ -51,6 +141,11 @@ On Windows, you may need to configure the [scaling behavior].
 
 [scaling behavior]: https://github.com/Genymobile/scrcpy/issues/40#issuecomment-424466723
 
+If your computer definition is far smaller than your screen, then you'll get
+poor quality. See [#40].
+
+[#40]: https://github.com/Genymobile/scrcpy/issues/40
+
 
 ### KWin compositor crashes
 
@@ -61,19 +156,29 @@ 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"
+## Crashes
+
+### Exception
 
 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$CodecException: Error 0xfffffc0e
-...
-Exit due to uncaughtException in main thread:
-ERROR: Could not open video stream
-INFO: Initial texture: 1080x2336
-```
+> ```
+> ERROR: Exception on thread Thread[main,5,main]
+> android.media.MediaCodec$CodecException: Error 0xfffffc0e
+> ...
+> Exit due to uncaughtException in main thread:
+> ERROR: Could not open video stream
+> INFO: Initial texture: 1080x2336
+> ```
+
+or
+
+> ```
+> ERROR: Exception on thread Thread[main,5,main]
+> java.lang.IllegalStateException
+>         at android.media.MediaCodec.native_dequeueOutputBuffer(Native Method)
+> ```
 
 Just try with a lower definition: