Handle down/up actions for BACK or POWER ON

Pressing right-click generates either BACK or POWER ON, depending on the
current screen state.

Forward DOWN and UP events separately to the device, to generate key
events accordingly.

Ref #1062 <https://github.com/Genymobile/scrcpy/issues/1062>

DEVELOP.md

@@ -189,7 +189,7 @@ The client uses 4 threads:
    recording,
  - the **controller** thread, sending _control messages_ to the server,
  - the **receiver** thread (managed by the controller), receiving _device
-   messages_ from the server.
+   messages_ from the client.
 
 In addition, another thread can be started if necessary to handle APK
 installation or file push requests (via drag&drop on the main window) or to
@@ -214,7 +214,7 @@ When a new decoded frame is available, the decoder _swaps_ the decoding and
 rendering frame (with proper synchronization). Thus, it immediatly starts
 to decode a new frame while the main thread renders the last one.
 
-If a [recorder] is present (i.e. `--record` is enabled), then it muxes the raw
+If a [recorder] is present (i.e. `--record` is enabled), then its muxes the raw
 H.264 packet to the output video file.
 
 [stream]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/stream.h

FAQ.md

@@ -3,102 +3,19 @@
 Here are the common reported problems and their status.
 
 
-## `adb` issues
+### On Windows, my device is not detected
 
-`scrcpy` execute `adb` commands to initialize the connection with the device. If
-`adb` fails, then scrcpy will not work.
+The most common is your device not being detected by `adb`, or is unauthorized.
+Check everything is ok by calling:
 
-In that case, it will print this error:
+    adb devices
 
->     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).
+Windows may need some [drivers] to detect your device.
 
 [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
+### 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:
@@ -112,25 +29,18 @@ In developer options, enable:
 ### Mouse clicks at wrong location
 
 On MacOS, with HiDPI support and multiple screens, input location are wrongly
-scaled. See [#15].
+scaled. See [issue 15].
 
-[#15]: https://github.com/Genymobile/scrcpy/issues/15
+[issue 15]: https://github.com/Genymobile/scrcpy/issues/15
 
-Open _scrcpy_ directly on the monitor you use it.
+A workaround is to build with HiDPI support disabled:
 
+```bash
+meson x --buildtype release -Dhidpi_support=false
+```
 
-### Special characters do not work
+However, the video will be displayed at lower resolution.
 
-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
 
@@ -141,11 +51,6 @@ 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
 
@@ -156,29 +61,19 @@ As a workaround, [disable "Block compositing"][kwin].
 [kwin]: https://github.com/Genymobile/scrcpy/issues/114#issuecomment-378778613
 
 
-## Crashes
-
-### Exception
+### 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$CodecException: Error 0xfffffc0e
-> ...
-> Exit due to uncaughtException in main thread:
-> ERROR: Could not open video stream
-> INFO: Initial texture: 1080x2336
-> ```
-
-or
-
-> ```
-> ERROR: Exception on thread Thread[main,5,main]
-> java.lang.IllegalStateException
->         at android.media.MediaCodec.native_dequeueOutputBuffer(Native Method)
-> ```
+```
+ERROR: Exception on thread Thread[main,5,main]
+android.media.MediaCodec$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:
 

LICENSE

@@ -188,7 +188,7 @@
       identification within third-party archives.
 
    Copyright (C) 2018 Genymobile
-   Copyright (C) 2018-2020 Romain Vimont
+   Copyright (C) 2018-2019 Romain Vimont
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

README.ko.md

@@ -475,7 +475,7 @@ _²화면이 꺼진 상태에서 우클릭 시 다시 켜지며, 그 외의 상
 ## 라이선스
 
     Copyright (C) 2018 Genymobile
-    Copyright (C) 2018-2020 Romain Vimont
+    Copyright (C) 2018-2019 Romain Vimont
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.

README.md

@@ -37,11 +37,8 @@ control it using keyboard and mouse.
 
 ### Linux
 
-In Debian (_testing_ and _sid_ for now):
-
-```
-apt install scrcpy
-```
+On Linux, you typically need to [build the app manually][BUILD]. Don't worry,
+it's not that hard.
 
 A [Snap] package is available: [`scrcpy`][snap-link].
 
@@ -59,39 +56,20 @@ For Gentoo, an [Ebuild] is available: [`scrcpy/`][ebuild-link].
 [Ebuild]: https://wiki.gentoo.org/wiki/Ebuild
 [ebuild-link]: https://github.com/maggu2810/maggu2810-overlay/tree/master/app-mobilephone/scrcpy
 
-You could also [build the app manually][BUILD] (don't worry, it's not that
-hard).
-
-
 
 ### Windows
 
-For Windows, for simplicity, a prebuilt archive with all the dependencies
-(including `adb`) is available:
+For Windows, for simplicity, prebuilt archives with all the dependencies
+(including `adb`) are available:
 
+ - [`scrcpy-win32-v1.12.1.zip`][direct-win32]  
+   _(SHA-256: 0f4b3b063536b50a2df05dc42c760f9cc0093a9a26dbdf02d8232c74dab43480)_
  - [`scrcpy-win64-v1.12.1.zip`][direct-win64]  
    _(SHA-256: 57d34b6d16cfd9fe169bc37c4df58ebd256d05c1ea3febc63d9cb0a027ab47c9)_
 
+[direct-win32]: https://github.com/Genymobile/scrcpy/releases/download/v1.12.1/scrcpy-win32-v1.12.1.zip
 [direct-win64]: https://github.com/Genymobile/scrcpy/releases/download/v1.12.1/scrcpy-win64-v1.12.1.zip
 
-It is also available in [Chocolatey]:
-
-[Chocolatey]: https://chocolatey.org/
-
-```bash
-choco install scrcpy
-choco install adb    # if you don't have it yet
-```
-
-And in [Scoop]:
-
-```bash
-scoop install scrcpy
-scoop install adb    # if you don't have it yet
-```
-
-[Scoop]: https://scoop.sh
-
 You can also [build the app manually][BUILD].
 
 
@@ -159,12 +137,14 @@ scrcpy -b 2M  # short version
 
 #### Limit frame rate
 
-On devices with Android >= 10, the capture frame rate can be limited:
+The capture frame rate can be limited:
 
 ```bash
 scrcpy --max-fps 15
 ```
 
+This is officially supported since Android 10, but may work on earlier versions.
+
 #### Crop
 
 The device screen may be cropped to mirror only part of the screen.
@@ -236,13 +216,6 @@ scrcpy --serial 0123456789abcdef
 scrcpy -s 0123456789abcdef  # short version
 ```
 
-If the device is connected over TCP/IP:
-
-```bash
-scrcpy --serial 192.168.0.1:5555
-scrcpy -s 192.168.0.1:5555  # short version
-```
-
 You can start several instances of _scrcpy_ for several devices.
 
 #### SSH tunnel
@@ -518,7 +491,7 @@ Read the [developers page].
 ## Licence
 
     Copyright (C) 2018 Genymobile
-    Copyright (C) 2018-2020 Romain Vimont
+    Copyright (C) 2018-2019 Romain Vimont
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.

app/meson.build

@@ -76,11 +76,9 @@ cc = meson.get_compiler('c')
 
 if host_machine.system() == 'windows'
     src += [ 'src/sys/win/command.c' ]
-    src += [ 'src/sys/win/net.c' ]
     dependencies += cc.find_library('ws2_32')
 else
     src += [ 'src/sys/unix/command.c' ]
-    src += [ 'src/sys/unix/net.c' ]
 endif
 
 conf = configuration_data()

app/scrcpy.1

@@ -43,7 +43,7 @@ Print this help.
 
 .TP
 .BI "\-\-max\-fps " value
-Limit the framerate of screen capture (only supported on devices with Android >= 10).
+Limit the framerate of screen capture (officially supported since Android 10, but may work on earlier versions).
 
 .TP
 .BI "\-m, \-\-max\-size " value
@@ -261,7 +261,7 @@ Copyright \(co 2018 Genymobile
 Genymobile
 .UE
 
-Copyright \(co 2018\-2020
+Copyright \(co 2018\-2019
 .MT rom@rom1v.com
 Romain Vimont
 .ME

app/src/cli.c

@@ -42,8 +42,8 @@ scrcpy_print_usage(const char *arg0) {
         "        Print this help.\n"
         "\n"
         "    --max-fps value\n"
-        "        Limit the frame rate of screen capture (only supported on\n"
-        "        devices with Android >= 10).\n"
+        "        Limit the frame rate of screen capture (officially supported\n"
+        "        since Android 10, but may work on earlier versions).\n"
         "\n"
         "    -m, --max-size value\n"
         "        Limit both the width and height of the video to value. The\n"

app/src/command.c

@@ -4,9 +4,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <unistd.h>
 
 #include "config.h"
 #include "common.h"
@@ -205,14 +202,3 @@ process_check_success(process_t proc, const char *name) {
     }
     return true;
 }
-
-bool
-is_regular_file(const char *path) {
-    struct stat path_stat;
-    int r = stat(path, &path_stat);
-    if (r) {
-        perror("stat");
-        return false;
-    }
-    return S_ISREG(path_stat.st_mode);
-}

app/src/control_msg.c

@@ -75,6 +75,8 @@ control_msg_serialize(const struct control_msg *msg, unsigned char *buf) {
             buf[1] = msg->set_screen_power_mode.mode;
             return 2;
         case CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON:
+            buf[1] = msg->back_or_screen_on.action;
+            return 2;
         case CONTROL_MSG_TYPE_EXPAND_NOTIFICATION_PANEL:
         case CONTROL_MSG_TYPE_COLLAPSE_NOTIFICATION_PANEL:
         case CONTROL_MSG_TYPE_GET_CLIPBOARD:

app/src/control_msg.h

@@ -66,6 +66,9 @@ struct control_msg {
         struct {
             enum screen_power_mode mode;
         } set_screen_power_mode;
+        struct {
+            enum android_keyevent_action action;
+        } back_or_screen_on;
     };
 };
 

app/src/input_manager.c

@@ -99,9 +99,14 @@ action_menu(struct controller *controller, int actions) {
 
 // turn the screen on if it was off, press BACK otherwise
 static void
-press_back_or_turn_screen_on(struct controller *controller) {
+press_back_or_turn_screen_on(struct controller *controller, int action) {
+    assert(action == ACTION_DOWN || action == ACTION_UP);
+
     struct control_msg msg;
     msg.type = CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON;
+    msg.back_or_screen_on.action = action == ACTION_DOWN
+                                 ? AKEY_EVENT_ACTION_DOWN
+                                 : AKEY_EVENT_ACTION_UP;
 
     if (!controller_push_msg(controller, &msg)) {
         LOGW("Could not request 'press back or turn screen on'");
@@ -521,31 +526,36 @@ input_manager_process_mouse_button(struct input_manager *im,
         // simulated from touch events, so it's a duplicate
         return;
     }
-    if (event->type == SDL_MOUSEBUTTONDOWN) {
-        if (control && event->button == SDL_BUTTON_RIGHT) {
-            press_back_or_turn_screen_on(im->controller);
+
+    // double-click on black borders resize to fit the device screen
+    if (event->type == SDL_MOUSEBUTTONDOWN
+            && event->button == SDL_BUTTON_LEFT
+            && event->clicks == 2) {
+        bool outside = is_outside_device_screen(im, event->x, event->y);
+        if (outside) {
+            screen_resize_to_fit(im->screen);
             return;
         }
-        if (control && event->button == SDL_BUTTON_MIDDLE) {
-            action_home(im->controller, ACTION_DOWN | ACTION_UP);
-            return;
-        }
-        // double-click on black borders resize to fit the device screen
-        if (event->button == SDL_BUTTON_LEFT && event->clicks == 2) {
-            bool outside =
-                is_outside_device_screen(im, event->x, event->y);
-            if (outside) {
-                screen_resize_to_fit(im->screen);
-                return;
-            }
-        }
-        // otherwise, send the click event to the device
     }
 
     if (!control) {
         return;
     }
 
+    if (event->button == SDL_BUTTON_MIDDLE) {
+        int action = event->type == SDL_MOUSEBUTTONDOWN ? ACTION_DOWN
+                                                        : ACTION_UP;
+        action_home(im->controller, action);
+        return;
+    }
+
+    if (event->button == SDL_BUTTON_RIGHT) {
+        int action = event->type == SDL_MOUSEBUTTONDOWN ? ACTION_DOWN
+                                                        : ACTION_UP;
+        press_back_or_turn_screen_on(im->controller, action);
+        return;
+    }
+
     struct control_msg msg;
     if (convert_mouse_button(event, im->screen, &msg)) {
         if (!controller_push_msg(im->controller, &msg)) {

app/src/server.c

@@ -6,11 +6,13 @@
 #include <libgen.h>
 #include <stdio.h>
 #include <SDL2/SDL_timer.h>
+#include <SDL2/SDL_platform.h>
 
 #include "config.h"
 #include "command.h"
 #include "util/log.h"
 #include "util/net.h"
+#include "util/str_util.h"
 
 #define SOCKET_NAME "scrcpy"
 #define SERVER_FILENAME "scrcpy-server"
@@ -18,20 +20,39 @@
 #define DEFAULT_SERVER_PATH PREFIX "/share/scrcpy/" SERVER_FILENAME
 #define DEVICE_SERVER_PATH "/data/local/tmp/scrcpy-server.jar"
 
-static const char *
+static char *
 get_server_path(void) {
+#ifdef __WINDOWS__
+    const wchar_t *server_path_env = _wgetenv(L"SCRCPY_SERVER_PATH");
+#else
     const char *server_path_env = getenv("SCRCPY_SERVER_PATH");
+#endif
     if (server_path_env) {
-        LOGD("Using SCRCPY_SERVER_PATH: %s", server_path_env);
         // if the envvar is set, use it
-        return server_path_env;
+#ifdef __WINDOWS__
+        char *server_path = utf8_from_wide_char(server_path_env);
+#else
+        char *server_path = SDL_strdup(server_path_env);
+#endif
+        if (!server_path) {
+            LOGE("Could not allocate memory");
+            return NULL;
+        }
+        LOGD("Using SCRCPY_SERVER_PATH: %s", server_path);
+        return server_path;
     }
 
 #ifndef PORTABLE
     LOGD("Using server: " DEFAULT_SERVER_PATH);
+    char *server_path = SDL_strdup(DEFAULT_SERVER_PATH);
+    if (!server_path) {
+        LOGE("Could not allocate memory");
+        return NULL;
+    }
     // the absolute path is hardcoded
-    return DEFAULT_SERVER_PATH;
+    return server_path;
 #else
+
     // use scrcpy-server in the same directory as the executable
     char *executable_path = get_executable_path();
     if (!executable_path) {
@@ -67,12 +88,17 @@ get_server_path(void) {
 
 static bool
 push_server(const char *serial) {
-    const char *server_path = get_server_path();
+    char *server_path = get_server_path();
+    if (!server_path) {
+        return false;
+    }
     if (!is_regular_file(server_path)) {
         LOGE("'%s' does not exist or is not a regular file\n", server_path);
+        SDL_free(server_path);
         return false;
     }
     process_t process = adb_push(serial, server_path, DEVICE_SERVER_PATH);
+    SDL_free(server_path);
     return process_check_success(process, "adb push");
 }
 

app/src/sys/unix/command.c

@@ -15,6 +15,7 @@
 #include <signal.h>
 #include <stdlib.h>
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <sys/wait.h>
 #include <unistd.h>
 
@@ -127,3 +128,14 @@ get_executable_path(void) {
     return NULL;
 #endif
 }
+
+bool
+is_regular_file(const char *path) {
+    struct stat path_stat;
+
+    if (stat(path, &path_stat)) {
+        perror("stat");
+        return false;
+    }
+    return S_ISREG(path_stat.st_mode);
+}

app/src/sys/unix/net.c

@@ -1,21 +0,0 @@
-#include "util/net.h"
-
-#include <unistd.h>
-
-#include "config.h"
-
-bool
-net_init(void) {
-    // do nothing
-    return true;
-}
-
-void
-net_cleanup(void) {
-    // do nothing
-}
-
-bool
-net_close(socket_t socket) {
-    return !close(socket);
-}

app/src/sys/win/command.c

@@ -4,6 +4,8 @@
 #include "util/log.h"
 #include "util/str_util.h"
 
+#include <sys/stat.h>
+
 static int
 build_cmd(char *cmd, size_t len, const char *const argv[]) {
     // Windows command-line parsing is WTF:
@@ -90,3 +92,22 @@ get_executable_path(void) {
     buf[len] = '\0';
     return utf8_from_wide_char(buf);
 }
+
+bool
+is_regular_file(const char *path) {
+    wchar_t *wide_path = utf8_to_wide_char(path);
+    if (!wide_path) {
+        LOGC("Could not allocate wide char string");
+        return false;
+    }
+
+    struct _stat path_stat;
+    int r = _wstat(wide_path, &path_stat);
+    SDL_free(wide_path);
+
+    if (r) {
+        perror("stat");
+        return false;
+    }
+    return S_ISREG(path_stat.st_mode);
+}

app/src/sys/win/net.c

@@ -1,25 +0,0 @@
-#include "util/net.h"
-
-#include "config.h"
-#include "util/log.h"
-
-bool
-net_init(void) {
-    WSADATA wsa;
-    int res = WSAStartup(MAKEWORD(2, 2), &wsa) < 0;
-    if (res < 0) {
-        LOGC("WSAStartup failed with error %d", res);
-        return false;
-    }
-    return true;
-}
-
-void
-net_cleanup(void) {
-    WSACleanup();
-}
-
-bool
-net_close(socket_t socket) {
-    return !closesocket(socket);
-}

app/src/util/net.c

@@ -1,6 +1,7 @@
 #include "net.h"
 
 #include <stdio.h>
+#include <SDL2/SDL_platform.h>
 
 #include "config.h"
 #include "log.h"
@@ -115,3 +116,32 @@ bool
 net_shutdown(socket_t socket, int how) {
     return !shutdown(socket, how);
 }
+
+bool
+net_init(void) {
+#ifdef __WINDOWS__
+    WSADATA wsa;
+    int res = WSAStartup(MAKEWORD(2, 2), &wsa) < 0;
+    if (res < 0) {
+        LOGC("WSAStartup failed with error %d", res);
+        return false;
+    }
+#endif
+    return true;
+}
+
+void
+net_cleanup(void) {
+#ifdef __WINDOWS__
+    WSACleanup();
+#endif
+}
+
+bool
+net_close(socket_t socket) {
+#ifdef __WINDOWS__
+    return !closesocket(socket);
+#else
+    return !close(socket);
+#endif
+}

app/tests/test_control_msg_serialize.c

@@ -140,14 +140,18 @@ static void test_serialize_inject_scroll_event(void) {
 static void test_serialize_back_or_screen_on(void) {
     struct control_msg msg = {
         .type = CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON,
+        .back_or_screen_on = {
+            .action = AKEY_EVENT_ACTION_UP,
+        },
     };
 
     unsigned char buf[CONTROL_MSG_SERIALIZED_MAX_SIZE];
     int size = control_msg_serialize(&msg, buf);
-    assert(size == 1);
+    assert(size == 2);
 
     const unsigned char expected[] = {
         CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON,
+        AKEY_EVENT_ACTION_UP,
     };
     assert(!memcmp(buf, expected, sizeof(expected)));
 }

server/src/main/java/com/genymobile/scrcpy/ControlMessage.java

@@ -85,6 +85,13 @@ public final class ControlMessage {
         return msg;
     }
 
+    public static ControlMessage createBackOrScreenOn(int action) {
+        ControlMessage msg = new ControlMessage();
+        msg.type = TYPE_BACK_OR_SCREEN_ON;
+        msg.action = action;
+        return msg;
+    }
+
     public static ControlMessage createEmpty(int type) {
         ControlMessage msg = new ControlMessage();
         msg.type = type;

server/src/main/java/com/genymobile/scrcpy/ControlMessageReader.java

@@ -13,6 +13,7 @@ public class ControlMessageReader {
     private static final int INJECT_TOUCH_EVENT_PAYLOAD_LENGTH = 21;
     private static final int INJECT_SCROLL_EVENT_PAYLOAD_LENGTH = 20;
     private static final int SET_SCREEN_POWER_MODE_PAYLOAD_LENGTH = 1;
+    private static final int BACK_OR_SCREEN_ON_PAYLOAD_LENGTH = 1;
 
     public static final int TEXT_MAX_LENGTH = 300;
     public static final int CLIPBOARD_TEXT_MAX_LENGTH = 4093;
@@ -73,6 +74,8 @@ public class ControlMessageReader {
                 msg = parseSetScreenPowerMode();
                 break;
             case ControlMessage.TYPE_BACK_OR_SCREEN_ON:
+                msg = parseBackOrScreenOn();
+                break;
             case ControlMessage.TYPE_EXPAND_NOTIFICATION_PANEL:
             case ControlMessage.TYPE_COLLAPSE_NOTIFICATION_PANEL:
             case ControlMessage.TYPE_GET_CLIPBOARD:
@@ -164,6 +167,14 @@ public class ControlMessageReader {
         return ControlMessage.createSetScreenPowerMode(mode);
     }
 
+    private ControlMessage parseBackOrScreenOn() {
+        if (buffer.remaining() < BACK_OR_SCREEN_ON_PAYLOAD_LENGTH) {
+            return null;
+        }
+        int action = toUnsigned(buffer.get());
+        return ControlMessage.createBackOrScreenOn(action);
+    }
+
     private static Position readPosition(ByteBuffer buffer) {
         int x = buffer.getInt();
         int y = buffer.getInt();

server/src/main/java/com/genymobile/scrcpy/Controller.java

@@ -26,6 +26,9 @@ public class Controller {
     private final MotionEvent.PointerProperties[] pointerProperties = new MotionEvent.PointerProperties[PointersState.MAX_POINTERS];
     private final MotionEvent.PointerCoords[] pointerCoords = new MotionEvent.PointerCoords[PointersState.MAX_POINTERS];
 
+    private boolean backPressed;
+    private boolean powerPressed;
+
     public Controller(Device device, DesktopConnection connection) {
         this.device = device;
         this.connection = connection;
@@ -88,7 +91,7 @@ public class Controller {
                 injectScroll(msg.getPosition(), msg.getHScroll(), msg.getVScroll());
                 break;
             case ControlMessage.TYPE_BACK_OR_SCREEN_ON:
-                pressBackOrTurnScreenOn();
+                pressBackOrTurnScreenOn(msg.getAction());
                 break;
             case ControlMessage.TYPE_EXPAND_NOTIFICATION_PANEL:
                 device.expandNotificationPanel();
@@ -223,8 +226,33 @@ public class Controller {
         return device.injectInputEvent(event, InputManager.INJECT_INPUT_EVENT_MODE_ASYNC);
     }
 
-    private boolean pressBackOrTurnScreenOn() {
-        int keycode = device.isScreenOn() ? KeyEvent.KEYCODE_BACK : KeyEvent.KEYCODE_POWER;
-        return injectKeycode(keycode);
+    private boolean pressBackOrTurnScreenOn(int action) {
+        int keycode = -1;
+        if (action == KeyEvent.ACTION_UP) {
+            // if BACK or POWER were pressed, this action is the corresponding release event (regardless of the screen state)
+            if (backPressed) {
+                keycode = KeyEvent.KEYCODE_BACK;
+                backPressed = false;
+            } else if (powerPressed) {
+                keycode = KeyEvent.KEYCODE_POWER;
+                powerPressed = false;
+            }
+        }
+
+        if (keycode == -1) {
+            keycode = device.isScreenOn() ? KeyEvent.KEYCODE_BACK : KeyEvent.KEYCODE_POWER;
+        }
+
+        if (action == KeyEvent.ACTION_DOWN) {
+            if (keycode == KeyEvent.KEYCODE_BACK) {
+                backPressed = true;
+                powerPressed = false;
+            } else {
+                backPressed = false;
+                powerPressed = true;
+            }
+        }
+
+        return injectKeyEvent(action, keycode, 0, 0);
     }
 }

server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java

@@ -19,6 +19,7 @@ public class ScreenEncoder implements Device.RotationListener {
 
     private static final int DEFAULT_I_FRAME_INTERVAL = 10; // seconds
     private static final int REPEAT_FRAME_DELAY_US = 100_000; // repeat after 100ms
+    private static final String KEY_MAX_FPS_TO_ENCODER = "max-fps-to-encoder";
 
     private static final int NO_PTS = -1;
 
@@ -150,11 +151,10 @@ public class ScreenEncoder implements Device.RotationListener {
         // display the very first frame, and recover from bad quality when no new frames
         format.setLong(MediaFormat.KEY_REPEAT_PREVIOUS_FRAME_AFTER, REPEAT_FRAME_DELAY_US); // µs
         if (maxFps > 0) {
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
-                format.setFloat(MediaFormat.KEY_MAX_FPS_TO_ENCODER, maxFps);
-            } else {
-                Ln.w("Max FPS is only supported since Android 10, the option has been ignored");
-            }
+            // The key existed privately before Android 10:
+            // <https://android.googlesource.com/platform/frameworks/base/+/625f0aad9f7a259b6881006ad8710adce57d1384%5E%21/>
+            // <https://github.com/Genymobile/scrcpy/issues/488#issuecomment-567321437>
+            format.setFloat(KEY_MAX_FPS_TO_ENCODER, maxFps);
         }
         return format;
     }

server/src/test/java/com/genymobile/scrcpy/ControlMessageReaderTest.java

@@ -145,6 +145,7 @@ public class ControlMessageReaderTest {
         ByteArrayOutputStream bos = new ByteArrayOutputStream();
         DataOutputStream dos = new DataOutputStream(bos);
         dos.writeByte(ControlMessage.TYPE_BACK_OR_SCREEN_ON);
+        dos.writeByte(KeyEvent.ACTION_UP);
 
         byte[] packet = bos.toByteArray();
 
@@ -152,6 +153,7 @@ public class ControlMessageReaderTest {
         ControlMessage event = reader.next();
 
         Assert.assertEquals(ControlMessage.TYPE_BACK_OR_SCREEN_ON, event.getType());
+        Assert.assertEquals(KeyEvent.ACTION_UP, event.getAction());
     }
 
     @Test