scrcpy/FAQ.md
Romain Vimont 43d3dcbd97 Document Windows command line usage
PR #1973 <https://github.com/Genymobile/scrcpy/pull/1973>

Reviewed-by: Yu-Chen Lin <npes87184@gmail.com>
2020-12-22 01:44:55 +01:00

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# Frequently Asked Questions
Here are the common reported problems and their status.
## `adb` issues
`scrcpy` execute `adb` commands to initialize the connection with the device. If
`adb` fails, then scrcpy will not work.
In that case, it will print this error:
> 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
> adb: error: failed to get feature set: no devices/emulators found
If your device is not detected, you may need some [drivers] (on Windows).
[drivers]: https://developer.android.com/studio/run/oem-usb.html
### 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:
> **USB debugging (Security settings)**
> _Allow granting permissions and simulating input via USB debugging_
[simulating input]: https://github.com/Genymobile/scrcpy/issues/70#issuecomment-373286323
### Mouse clicks at wrong location
On MacOS, with HiDPI support and multiple screens, input location are wrongly
scaled. See [#15].
[#15]: https://github.com/Genymobile/scrcpy/issues/15
Open _scrcpy_ directly on the monitor you use it.
### 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
If the definition of your client window is smaller than that of your device
screen, then you might get poor quality, especially visible on text (see [#40]).
[#40]: https://github.com/Genymobile/scrcpy/issues/40
To improve downscaling quality, trilinear filtering is enabled automatically
if the renderer is OpenGL and if it supports mipmapping.
On Windows, you might want to force OpenGL:
```
scrcpy --render-driver=opengl
```
You may also 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.
As a workaround, [disable "Block compositing"][kwin].
[kwin]: https://github.com/Genymobile/scrcpy/issues/114#issuecomment-378778613
## 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
> ```
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:
```
scrcpy -m 1920
scrcpy -m 1024
scrcpy -m 800
```
## Command line on Windows
Some Windows users are not familiar with the command line. Here is how to open a
terminal and run `scrcpy` with arguments:
1. Press <kbd>Windows</kbd>+<kbd>r</kbd>, this opens a dialog box.
2. Type `cmd` and press <kbd>Enter</kbd>, this opens a terminal.
3. Go to your _scrcpy_ directory, by typing (adapt the path):
```bat
cd C:\Users\user\Downloads\scrcpy-win64-xxx
```
and press <kbd>Enter</kbd>
4. Type your command. For example:
```bat
scrcpy --record file.mkv
```
If you plan to always use the same arguments, create a file `myscrcpy.bat`
(enable [show file extensions] to avoid confusion) in the `scrcpy` directory,
containing your command. For example:
```bat
scrcpy --prefer-text --turn-screen-off --stay-awake
```
Then just double-click on that file.
[show file extensions]: https://www.howtogeek.com/205086/beginner-how-to-make-windows-show-file-extensions/