Bump version to 2.1

In forward mode, the dummy byte must be written immediately after the
first accept(), otherwise the client will wait indefinitely, causing a
deadlock (or a timeout).

Regression introduced by 8c650e53cd.

FAQ.md

@@ -159,6 +159,8 @@ In developer options, enable:
 > **USB debugging (Security settings)**  
 > _Allow granting permissions and simulating input via USB debugging_
 
+Rebooting the device is necessary once this option is set.
+
 [simulating input]: https://github.com/Genymobile/scrcpy/issues/70#issuecomment-373286323
 
 
@@ -168,12 +170,12 @@ The default text injection method is [limited to ASCII characters][text-input].
 A trick allows to also inject some [accented characters][accented-characters],
 but that's all. See [#37].
 
-Since scrcpy v1.20, it is possible to simulate a [physical keyboard][hid] (HID).
+It is also possible to simulate a [physical keyboard][hid] (HID).
 
 [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
-[hid]: README.md#physical-keyboard-simulation-hid
+[hid]: doc/hid-otg.md
 
 
 ## Client issues
@@ -229,4 +231,4 @@ Translations of this FAQ in other languages are available in the [wiki].
 
 [wiki]: https://github.com/Genymobile/scrcpy/wiki
 
-Only this README file is guaranteed to be up-to-date.
+Only this FAQ file is guaranteed to be up-to-date.

README.md

@@ -30,7 +30,7 @@ Its features include:
  - mirroring with [Android device screen off](doc/device.md#turn-screen-off)
  - [copy-paste](doc/control.md#copy-paste) in both directions
  - [configurable quality](doc/video.md)
- - Android device [as a webcam (V4L2)](doc/v4l2.md) (Linux-only)
+ - Android device screen [as a webcam (V4L2)](doc/v4l2.md) (Linux-only)
  - [physical keyboard/mouse simulation (HID)](doc/hid-otg.md)
  - [OTG mode](doc/hid-otg.md#otg)
  - and more…
@@ -39,7 +39,7 @@ Its features include:
 
 The Android device requires at least API 21 (Android 5.0).
 
-[Audio forwarding](doc/audio.md) is supported from API 30 (Android 11).
+[Audio forwarding](doc/audio.md) is supported for API >= 30 (Android 11+).
 
 Make sure you [enabled USB debugging][enable-adb] on your device(s).
 
@@ -47,10 +47,14 @@ Make sure you [enabled USB debugging][enable-adb] on your device(s).
 
 On some devices, you also need to enable [an additional option][control] `USB
 debugging (Security Settings)` (this is an item different from `USB debugging`)
-to control it using a keyboard and mouse.
+to control it using a keyboard and mouse. Rebooting the device is necessary once
+this option is set.
 
 [control]: https://github.com/Genymobile/scrcpy/issues/70#issuecomment-373286323
 
+Note that USB debugging is not required to run scrcpy in [OTG
+mode](doc/hid-otg.md#otg).
+
 
 ## Get the app
 

app/prebuilt-deps/prepare-adb.sh

@@ -6,10 +6,10 @@ cd "$DIR"
 mkdir -p "$PREBUILT_DATA_DIR"
 cd "$PREBUILT_DATA_DIR"
 
-DEP_DIR=platform-tools-34.0.1
+DEP_DIR=platform-tools-34.0.3
 
-FILENAME=platform-tools_r34.0.1-windows.zip
-SHA256SUM=5dd9c2be744c224fa3a7cbe30ba02d2cb378c763bd0f797a7e47e9f3156a5daa
+FILENAME=platform-tools_r34.0.3-windows.zip
+SHA256SUM=fce992e93eb786fc9f47df93d83a7b912c46742d45c39d712c02e06d05b72e2b
 
 if [[ -d "$DEP_DIR" ]]
 then

app/scrcpy-windows.rc

@@ -13,7 +13,7 @@ BEGIN
       VALUE "LegalCopyright", "Romain Vimont, Genymobile"
       VALUE "OriginalFilename", "scrcpy.exe"
       VALUE "ProductName", "scrcpy"
-      VALUE "ProductVersion", "2.0"
+      VALUE "ProductVersion", "2.1"
     END
   END
   BLOCK "VarFileInfo"

app/scrcpy.1

@@ -21,7 +21,7 @@ Make scrcpy window always on top (above other windows).
 
 .TP
 .BI "\-\-audio\-bit\-rate " value
-Encode the audio at the given bit\-rate, expressed in bits/s. Unit suffixes are supported: '\fBK\fR' (x1000) and '\fBM\fR' (x1000000).
+Encode the audio at the given bit rate, expressed in bits/s. Unit suffixes are supported: '\fBK\fR' (x1000) and '\fBM\fR' (x1000000).
 
 Default is 128K (128000).
 
@@ -71,7 +71,7 @@ Default is 5.
 
 .TP
 .BI "\-b, \-\-video\-bit\-rate " value
-Encode the video at the given bit\-rate, expressed in bits/s. Unit suffixes are supported: '\fBK\fR' (x1000) and '\fBM\fR' (x1000000).
+Encode the video at the given bit rate, expressed in bits/s. Unit suffixes are supported: '\fBK\fR' (x1000) and '\fBM\fR' (x1000000).
 
 Default is 8M (8000000).
 

app/src/cli.c

@@ -124,7 +124,7 @@ static const struct sc_option options[] = {
         .longopt_id = OPT_AUDIO_BIT_RATE,
         .longopt = "audio-bit-rate",
         .argdesc = "value",
-        .text = "Encode the audio at the given bit-rate, expressed in bits/s. "
+        .text = "Encode the audio at the given bit rate, expressed in bits/s. "
                 "Unit suffixes are supported: 'K' (x1000) and 'M' (x1000000).\n"
                 "Default is 128K (128000).",
     },
@@ -185,7 +185,7 @@ static const struct sc_option options[] = {
         .shortopt = 'b',
         .longopt = "video-bit-rate",
         .argdesc = "value",
-        .text = "Encode the video at the given bit-rate, expressed in bits/s. "
+        .text = "Encode the video at the given bit rate, expressed in bits/s. "
                 "Unit suffixes are supported: 'K' (x1000) and 'M' (x1000000).\n"
                 "Default is 8M (8000000).",
     },

app/src/server.c

@@ -533,8 +533,8 @@ sc_server_connect_to(struct sc_server *server, struct sc_server_info *info) {
                 if (audio_socket == SC_SOCKET_NONE) {
                     goto fail;
                 }
-                bool ok = net_connect_intr(&server->intr, audio_socket, tunnel_host,
-                                           tunnel_port);
+                bool ok = net_connect_intr(&server->intr, audio_socket,
+                                           tunnel_host, tunnel_port);
                 if (!ok) {
                     goto fail;
                 }

doc/audio.md

@@ -71,6 +71,13 @@ scrcpy --audio-codec=aac
 scrcpy --audio-codec=raw
 ```
 
+In particular, if you get the following error:
+
+> Failed to initialize audio/opus, error 0xfffffffe
+
+then your device has no Opus encoder: try `scrcpy --audio-codec=aac`.
+
+
 Several encoders may be available on the device. They can be listed by:
 
 ```bash
@@ -91,7 +98,7 @@ check `--audio-codec-options` in the manpage or in `scrcpy --help`.
 
 ## Bit rate
 
-The default video bit-rate is 128Kbps. To change it:
+The default audio bit rate is 128Kbps. To change it:
 
 ```bash
 scrcpy --audio-bit-rate=64K

doc/develop.md

@@ -9,16 +9,52 @@ This application is composed of two parts:
 The client is responsible to push the server to the device and start its
 execution.
 
-Once the client and the server are connected to each other, the server initially
-sends device information (name and initial screen dimensions), then starts to
-send a raw H.264 video stream of the device screen. The client decodes the video
-frames, and display them as soon as possible, without buffering, to minimize
-latency. The client is not aware of the device rotation (which is handled by the
-server), it just knows the dimensions of the video frames.
+The client and the server establish communication using separate sockets for
+video, audio and controls. Any of them may be disabled (but not all), so
+there are 1, 2 or 3 socket(s).
 
-The client captures relevant keyboard and mouse events, that it transmits to the
-server, which injects them to the device.
+The server initially sends the device name on the first socket (it is used for
+the scrcpy window title), then each socket is used for its own purpose. All
+reads and writes are performed from a dedicated thread for each socket, both on
+the client and on the server.
 
+If video is enabled, then the server sends a raw video stream (H.264 by default)
+of the device screen, with some additional headers for each packet. The client
+decodes the video frames, and displays them as soon as possible, without
+buffering (unless `--display-buffer=delay` is specified) to minimize latency.
+The client is not aware of the device rotation (which is handled by the server),
+it just knows the dimensions of the video frames it receives.
+
+Similarly, if audio is enabled, then the server sends a raw audio stream (OPUS
+by default) of the device audio output (or the microphone if
+`--audio-source=mic` is specified), with some additional headers for each
+packet. The client decodes the stream, attempts to keep a minimal latency by
+maintaining an average buffering. The [blog post][scrcpy2] of the scrcpy v2.0
+release gives more details about the audio feature.
+
+If control is enabled, then the client captures relevant keyboard and mouse
+events, that it transmits to the server, which injects them to the device. This
+is the only socket which is used in both direction: input events are sent from
+the client to the device, and when the device clipboard changes, the new content
+is sent from the device to the client to support seamless copy-paste.
+
+[scrcpy2]: https://blog.rom1v.com/2023/03/scrcpy-2-0-with-audio/
+
+Note that the client-server roles are expressed at the application level:
+
+ - the server _serves_ video and audio streams, and handle requests from the
+   client,
+ - the client _controls_ the device through the server.
+
+However, by default (when `--force-adb-forward` is not set), the roles are
+reversed at the network level:
+
+ - the client opens a server socket and listen on a port before starting the
+   server,
+ - the server connects to the client.
+
+This role inversion guarantees that the connection will not fail due to race
+conditions without polling.
 
 
 ## Server
@@ -32,15 +68,14 @@ The server is a Java application (with a [`public static void main(String...
 args)`][main] method), compiled against the Android framework, and executed as
 `shell` on the Android device.
 
-[main]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/server/src/main/java/com/genymobile/scrcpy/Server.java#L123
+[main]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/Server.java#L193
 
 To run such a Java application, the classes must be [_dexed_][dex] (typically,
 to `classes.dex`). If `my.package.MainClass` is the main class, compiled to
 `classes.dex`, pushed to the device in `/data/local/tmp`, then it can be run
 with:
 
-    adb shell CLASSPATH=/data/local/tmp/classes.dex \
-        app_process / my.package.MainClass
+    adb shell CLASSPATH=/data/local/tmp/classes.dex app_process / my.package.MainClass
 
 _The path `/data/local/tmp` is a good candidate to push the server, since it's
 readable and writable by `shell`, but not world-writable, so a malicious
@@ -49,7 +84,7 @@ application may not replace the server just before the client executes it._
 Instead of a raw _dex_ file, `app_process` accepts a _jar_ containing
 `classes.dex` (e.g. an [APK]). For simplicity, and to benefit from the gradle
 build system, the server is built to an (unsigned) APK (renamed to
-`scrcpy-server`).
+`scrcpy-server.jar`).
 
 [dex]: https://en.wikipedia.org/wiki/Dalvik_(software)
 [apk]: https://en.wikipedia.org/wiki/Android_application_package
@@ -65,42 +100,77 @@ They can be called using reflection though. The communication with hidden
 components is provided by [_wrappers_ classes][wrappers] and [aidl].
 
 [hidden]: https://stackoverflow.com/a/31908373/1987178
-[wrappers]: https://github.com/Genymobile/scrcpy/tree/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/server/src/main/java/com/genymobile/scrcpy/wrappers
-[aidl]: https://github.com/Genymobile/scrcpy/tree/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/server/src/main/aidl/android/view
+[wrappers]: https://github.com/Genymobile/scrcpy/tree/master/server/src/main/java/com/genymobile/scrcpy/wrappers
+[aidl]: https://github.com/Genymobile/scrcpy/tree/master/server/src/main/aidl
 
 
-### Threading
 
-The server uses 3 threads:
+### Execution
 
- - the **main** thread, encoding and streaming the video to the client;
- - the **controller** thread, listening for _control messages_ (typically,
-   keyboard and mouse events) from the client;
- - the **receiver** thread (managed by the controller), sending _device messages_
-   to the clients (currently, it is only used to send the device clipboard
-   content).
+The server is started by the client basically by executing the following
+commands:
 
-Since the video encoding is typically hardware, there would be no benefit in
-encoding and streaming in two different threads.
+```bash
+adb push scrcpy-server /data/local/tmp/scrcpy-server.jar
+adb forward tcp:27183 localabstract:scrcpy
+adb shell CLASSPATH=/data/local/tmp/scrcpy-server.jar app_process / com.genymobile.scrcpy.Server 2.1
+```
+
+The first argument (`2.1` in the example) is the client scrcpy version. The
+server fails if the client and the server do not have the exact same version.
+The protocol between the client and the server may change from version to
+version (see [protocol](#protocol) below), and there is no backward or forward
+compatibility (there is no point to use different client and server versions).
+This check allows to detect misconfiguration (running an older or newer server
+by mistake).
+
+It is followed by any number of arguments, in the form of `key=value` pairs.
+Their order is irrelevant. The possible keys and associated value types can be
+found in the [server][server-options] and [client][client-options] code.
+
+[server-options]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/Options.java#L181
+[client-options]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/app/src/server.c#L226
+
+For example, if we execute `scrcpy -m1920 --no-audio`, then the server
+execution will look like this:
+
+```bash
+# scid is a random number to identify different clients running on the same device
+adb shell CLASSPATH=/data/local/tmp/scrcpy-server.jar app_process / com.genymobile.scrcpy.Server 2.1 scid=12345678 log_level=info audio=false max_size=1920
+```
+
+### Components
+
+When executed, its [`main()`][main] method is executed (on the "main" thread).
+It parses the arguments, establishes the connection with the client and starts
+the other "components":
+ - the **video** streamer: it captures the video screen and send encoded video
+   packets on the _video_ socket (from the _video_ thread).
+ - the **audio** streamer: it uses several threads to capture raw packets,
+   submits them to encoding and retrieve encoded packets, which it sends on the
+   _audio_ socket.
+ - the **controller**: it receives _control messages_ (typically input events)
+   on the _control_ socket from one thread, and sends _device messages_ (e.g. to
+   transmit the device clipboard content to the client) on the same _control
+   socket_ from another thread. Thus, the _control_ socket is used in both
+   directions (contrary to the _video_ and _audio_ sockets).
 
 
 ### Screen video encoding
 
 The encoding is managed by [`ScreenEncoder`].
 
-The video is encoded using the [`MediaCodec`] API. The codec takes its input
-from a [surface] associated to the display, and writes the resulting H.264
-stream to the provided output stream (the socket connected to the client).
+The video is encoded using the [`MediaCodec`] API. The codec encodes the content
+of a `Surface` associated to the display, and writes the encoding packets to the
+client (on the _video_ socket).
 
-[`ScreenEncoder`]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java
+[`ScreenEncoder`]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java
 [`MediaCodec`]: https://developer.android.com/reference/android/media/MediaCodec.html
-[surface]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java#L68-L69
 
-On device [rotation], the codec, surface and display are reinitialized, and a
-new video stream is produced.
+On device rotation (or folding), the encoding session is [reset] and restarted.
 
-New frames are produced only when changes occur on the surface. This is good
-because it avoids to send unnecessary frames, but there are drawbacks:
+New frames are produced only when changes occur on the surface. This avoids to
+send unnecessary frames, but by default there might be drawbacks:
 
  - it does not send any frame on start if the device screen does not change,
  - after fast motion changes, the last frame may have poor quality.
@@ -108,11 +178,24 @@ because it avoids to send unnecessary frames, but there are drawbacks:
 Both problems are [solved][repeat] by the flag
 [`KEY_REPEAT_PREVIOUS_FRAME_AFTER`][repeat-flag].
 
+[reset]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java#L179
 [rotation]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java#L90
-[repeat]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java#L147-L148
+[repeat]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java#L246-L247
 [repeat-flag]: https://developer.android.com/reference/android/media/MediaFormat.html#KEY_REPEAT_PREVIOUS_FRAME_AFTER
 
 
+### Audio encoding
+
+Similarly, the audio is [captured] using an [`AudioRecord`], and [encoded] using
+the [`MediaCodec`] asynchronous API.
+
+More details are available on the [blog post][scrcpy2] introducing the audio feature.
+
+[captured]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/AudioCapture.java
+[encoded]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/AudioEncoder.java
+[`AudioRecord`]: https://developer.android.com/reference/android/media/AudioRecord
+
+
 ### Input events injection
 
 _Control messages_ are received from the client by the [`Controller`] (run in a
@@ -124,13 +207,13 @@ separate thread). There are several types of input events:
  - other commands (e.g. to switch the screen on or to copy the clipboard).
 
 Some of them need to inject input events to the system. To do so, they use the
-_hidden_ method [`InputManager.injectInputEvent`] (exposed by our
+_hidden_ method [`InputManager.injectInputEvent()`] (exposed by the
 [`InputManager` wrapper][inject-wrapper]).
 
-[`Controller`]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/server/src/main/java/com/genymobile/scrcpy/Controller.java#L81
+[`Controller`]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/Controller.java
 [`KeyEvent`]: https://developer.android.com/reference/android/view/KeyEvent.html
 [`MotionEvent`]: https://developer.android.com/reference/android/view/MotionEvent.html
-[`InputManager.injectInputEvent`]: https://android.googlesource.com/platform/frameworks/base/+/oreo-release/core/java/android/hardware/input/InputManager.java#857
+[`InputManager.injectInputEvent()`]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/wrappers/InputManager.java#L34
 [inject-wrapper]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/server/src/main/java/com/genymobile/scrcpy/wrappers/InputManager.java#L27
 
 
@@ -140,126 +223,222 @@ _hidden_ method [`InputManager.injectInputEvent`] (exposed by our
 The client relies on [SDL], which provides cross-platform API for UI, input
 events, threading, etc.
 
-The video stream is decoded by [libav] (FFmpeg).
+The video and audio streams are decoded by [FFmpeg].
 
 [SDL]: https://www.libsdl.org
-[libav]: https://www.libav.org/
+[ffmpeg]: https://ffmpeg.org/
+
 
 ### Initialization
 
-On startup, in addition to _libav_ and _SDL_ initialization, the client must
-push and start the server on the device, and open two sockets (one for the video
-stream, one for control) so that they may communicate.
+The client parses the command line arguments, then [runs one of two code
+paths][run]:
+ - scrcpy in "normal" mode ([`scrcpy.c`])
+ - scrcpy in [OTG mode](hid-otg.md) ([`scrcpy_otg.c`])
 
-Note that the client-server roles are expressed at the application level:
+[run]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/app/src/main.c#L81-L82
+[`scrcpy.c`]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/app/src/scrcpy.c#L292-L293
+[`scrcpy_otg.c`]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/app/src/usb/scrcpy_otg.c#L51-L52
 
- - the server _serves_ video stream and handle requests from the client,
- - the client _controls_ the device through the server.
+In the remaining of this document, we assume that the "normal" mode is used
+(read the code for the OTG mode).
 
-However, the roles are reversed at the network level:
-
- - the client opens a server socket and listen on a port before starting the
-   server,
- - the server connects to the client.
-
-This role inversion guarantees that the connection will not fail due to race
-conditions, and avoids polling.
-
-_(Note that over TCP/IP, the roles are not reversed, due to a bug in `adb
-reverse`. See commit [1038bad] and [issue #5].)_
-
-Once the server is connected, it sends the device information (name and initial
-screen dimensions). Thus, the client may init the window and renderer, before
-the first frame is available.
-
-To minimize startup time, SDL initialization is performed while listening for
-the connection from the server (see commit [90a46b4]).
-
-[1038bad]: https://github.com/Genymobile/scrcpy/commit/1038bad3850f18717a048a4d5c0f8110e54ee172
-[issue #5]: https://github.com/Genymobile/scrcpy/issues/5
-[90a46b4]: https://github.com/Genymobile/scrcpy/commit/90a46b4c45637d083e877020d85ade52a9a5fa8e
+On startup, the client:
+ - opens the _video_, _audio_ and _control_ sockets;
+ - pushes and starts the server on the device;
+ - initializes its components (demuxers, decoders, recorder…).
 
 
-### Threading
+### Video and audio streams
 
-The client uses 4 threads:
-
- - the **main** thread, executing the SDL event loop,
- - the **stream** thread, receiving the video and used for decoding and
-   recording,
- - the **controller** thread, sending _control messages_ to the server,
- - the **receiver** thread (managed by the controller), receiving _device
-   messages_ from the server.
-
-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
-print the framerate regularly in the console.
-
-
-
-### Stream
-
-The video [stream] is received from the socket (connected to the server on the
-device) in a separate thread.
-
-If a [decoder] is present (i.e. `--no-display` is not set), then it uses _libav_
-to decode the H.264 stream from the socket, and notifies the main thread when a
-new frame is available.
-
-There are two [frames][video_buffer] simultaneously in memory:
- - the **decoding** frame, written by the decoder from the decoder thread,
- - the **rendering** frame, rendered in a texture from the main thread.
-
-When a new decoded frame is available, the decoder _swaps_ the decoding and
-rendering frame (with proper synchronization). Thus, it immediately 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
-H.264 packet to the output video file.
-
-[stream]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/stream.h
-[decoder]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/decoder.h
-[video_buffer]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/video_buffer.h
-[recorder]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/recorder.h
+Depending on the arguments passed to `scrcpy`, several components may be used.
+Here is an overview of the video and audio components:
 
 ```
-                                   +----------+      +----------+
-                              ---> | decoder  | ---> |  screen  |
-             +---------+     /     +----------+      +----------+
- socket ---> | stream  | ----
-             +---------+     \     +----------+
-                              ---> | recorder |
-                                   +----------+
+                                                 V4L2 sink
+                                               /
+                                       decoder
+                                     /         \
+        VIDEO -------------> demuxer             display
+                                     \
+                                       recorder
+                                     /
+        AUDIO -------------> demuxer
+                                     \
+                                       decoder --- audio player
 ```
 
+The _demuxer_ is responsible to extract video and audio packets (read some
+header, split the video stream into packets at correct boundaries, etc.).
+
+The demuxed packets may be sent to a _decoder_ (one per stream, to produce
+frames) and to a recorder (receiving both video and audio stream to record a
+single file). The packets are encoded on the device (by `MediaCodec`), but when
+recording, they are _muxed_ (asynchronously) into a container (MKV or MP4) on
+the client side.
+
+Video frames are sent to the screen/display to be rendered in the scrcpy window.
+They may also be sent to a [V4L2 sink](v4l2.md).
+
+Audio "frames" (an array of decoded samples) are sent to the audio player.
+
+
 ### Controller
 
-The [controller] is responsible to send _control messages_ to the device. It
+The _controller_ is responsible to send _control messages_ to the device. It
 runs in a separate thread, to avoid I/O on the main thread.
 
-On SDL event, received on the main thread, the [input manager][inputmanager]
-creates appropriate [_control messages_][controlmsg]. It is responsible to
-convert SDL events to Android events (using [convert]). It pushes the _control
-messages_ to a queue hold by the controller. On its own thread, the controller
-takes messages from the queue, that it serializes and sends to the client.
-
-[controller]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/controller.h
-[controlmsg]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/control_msg.h
-[inputmanager]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/input_manager.h
-[convert]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/convert.h
+On SDL event, received on the main thread, the _input manager_ creates
+appropriate _control messages_. It is responsible to convert SDL events to
+Android events. It then pushes the _control messages_ to a queue hold by the
+controller. On its own thread, the controller takes messages from the queue,
+that it serializes and sends to the client.
 
 
-### UI and event loop
+## Protocol
 
-Initialization, input events and rendering are all [managed][scrcpy] in the main
-thread.
+The protocol between the client and the server must be considered _internal_: it
+may (and will) change at any time for any reason. Everything may change (the
+number of sockets, the order in which the sockets must be opened, the data
+format on the wire…) from version to version. A client must always be run with a
+matching server version.
 
-Events are handled in the [event loop], which either updates the [screen] or
-delegates to the [input manager][inputmanager].
+This section documents the current protocol in scrcpy v2.1.
 
-[scrcpy]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/scrcpy.c
-[event loop]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/scrcpy.c#L201
-[screen]: https://github.com/Genymobile/scrcpy/blob/ffe0417228fb78ab45b7ee4e202fc06fc8875bf3/app/src/screen.h
+### Connection
+
+Firstly, the client sets up an adb tunnel:
+
+```bash
+# By default, a reverse redirection: the computer listens, the device connects
+adb reverse localabstract:scrcpy_<SCID> tcp:27183
+
+# As a fallback (or if --force-adb forward is set), a forward redirection:
+# the device listens, the computer connects
+adb forward tcp:27183 localabstract:scrcpy_<SCID>
+```
+
+(`<SCID>` is a 31-bit random number, so that it does not fail when several
+scrcpy instances start "at the same time" for the same device.)
+
+Then, up to 3 sockets are opened, in that order:
+ - a _video_ socket
+ - an _audio_ socket
+ - a _control_ socket
+
+Each one may be disabled (respectively by `--no-video`, `--no-audio` and
+`--no-control`, directly or indirectly). For example, if `--no-audio` is set,
+then the _video_ socket is opened first, then the _control_ socket.
+
+On the _first_ socket opened (whichever it is), if the tunnel is _forward_, then
+a [dummy byte] is sent from the device to the client. This allows to detect a
+connection error (the client connection does not fail as long as there is an adb
+forward redirection, even if nothing is listening on the device side).
+
+Still on this _first_ socket, the device sends some [metadata][device meta] to
+the client (currently only the device name, used as the window title, but there
+might be other fields in the future).
+
+[dummy byte]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/DesktopConnection.java#L93
+[device meta]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/DesktopConnection.java#L151
+
+You can read the [client][client-connection] and [server][server-connection]
+code for more details.
+
+[client-connection]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/app/src/server.c#L465-L466
+[server-connection]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/DesktopConnection.java#L63
+
+Then each socket is used for its intended purpose.
+
+### Video and audio
+
+On the _video_ and _audio_ sockets, the device first sends some [codec
+metadata]:
+ - On the _video_ socket, 12 bytes:
+   - the codec id (`u32`) (H264, H265 or AV1)
+   - the initial video width (`u32`)
+   - the initial video height (`u32`)
+ - On the _audio_ socket, 4 bytes:
+   - the codec id (`u32`) (OPUS, AAC or RAW)
+
+[codec metadata]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/Streamer.java#L33-L51
+
+Then each packet produced by `MediaCodec` is sent, prefixed by a 12-byte [frame
+header]:
+ - config packet flag (`u1`)
+ - key frame flag (`u1`)
+ - PTS (`u62`)
+ - packet size (`u32`)
+
+Here is a schema describing the frame header:
+
+```
+    [. . . . . . . .|. . . .]. . . . . . . . . . . . . . . ...
+     <-------------> <-----> <-----------------------------...
+           PTS        packet        raw packet
+                       size
+     <--------------------->
+           frame header
+
+The most significant bits of the PTS are used for packet flags:
+
+     byte 7   byte 6   byte 5   byte 4   byte 3   byte 2   byte 1   byte 0
+    CK...... ........ ........ ........ ........ ........ ........ ........
+    ^^<------------------------------------------------------------------->
+    ||                                PTS
+    | `- key frame
+     `-- config packet
+```
+
+[frame header]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/Streamer.java#L83
+
+
+### Controls
+
+Controls messages are sent via a custom binary protocol.
+
+The only documentation for this protocol is the set of unit tests on both sides:
+ - `ControlMessage` (from client to device): [serialization](https://github.com/Genymobile/scrcpy/blob/master/app/tests/test_control_msg_serialize.c) | [deserialization](https://github.com/Genymobile/scrcpy/blob/master/server/src/test/java/com/genymobile/scrcpy/ControlMessageReaderTest.java)
+ - `DeviceMessage` (from device to client) [serialization](https://github.com/Genymobile/scrcpy/blob/master/server/src/test/java/com/genymobile/scrcpy/DeviceMessageWriterTest.java) | [deserialization](https://github.com/Genymobile/scrcpy/blob/master/app/tests/test_device_msg_deserialize.c)
+
+
+## Standalone server
+
+Although the server is designed to work for the scrcpy client, it can be used
+with any client which uses the same protocol.
+
+For simplicity, some [server-specific options] have been added to produce raw
+streams easily:
+ - `send_device_meta=false`: disable the device metata (in practice, the device
+   name) sent on the _first_ socket
+ - `send_frame_meta=false`: disable the 12-byte header for each packet
+ - `send_dummy_byte`: disable the dummy byte sent on forward connections
+ - `send_codec_meta`: disable the codec information (and initial device size for
+   video)
+ - `raw_stream`: disable all the above
+
+[server-specific options]: https://github.com/Genymobile/scrcpy/blob/a3cdf1a6b86ea22786e1f7d09b9c202feabc6949/server/src/main/java/com/genymobile/scrcpy/Options.java#L309-L329
+
+Concretely, here is how to expose a raw H.264 stream on a TCP socket:
+
+```bash
+adb push scrcpy-server-v2.1 /data/local/tmp/scrcpy-server-manual.jar
+adb forward tcp:1234 localabstract:scrcpy
+adb shell CLASSPATH=/data/local/tmp/scrcpy-server-manual.jar \
+    app_process / com.genymobile.scrcpy.Server 2.1 \
+    tunnel_forward=true audio=false control=false cleanup=false \
+    raw_stream=true max_size=1920
+```
+
+As soon as a client connects over TCP on port 1234, the device will start
+streaming the video. For example, VLC can play the video (although you will
+experience a very high latency, more details [here][vlc-0latency]):
+
+```
+vlc -Idummy --demux=h264 --network-caching=0 tcp://localhost:1234
+```
+
+[vlc-0latency]: https://code.videolan.org/rom1v/vlc/-/merge_requests/20
 
 
 ## Hack

doc/hid-otg.md

@@ -106,3 +106,7 @@ scrcpy --otg                             # keyboard and mouse
 
 Like `--hid-keyboard` and `--hid-mouse`, it only works if the device is
 connected over USB.
+
+## HID/OTG issues on Windows
+
+See [FAQ](/FAQ.md#hidotg-issues-on-windows).

doc/linux.md

@@ -9,12 +9,10 @@ Scrcpy is packaged in several distributions and package managers:
  - Debian/Ubuntu: `apt install scrcpy`
  - Arch Linux: `pacman -S scrcpy`
  - Fedora: `dnf copr enable zeno/scrcpy && dnf install scrcpy`
- - Gentoo: [ebuild][ebuild-link] file
+ - Gentoo: `emerge scrcpy`
  - Snap: `snap install scrcpy`
  - … (see [repology](https://repology.org/project/scrcpy/versions))
 
-[ebuild-link]: https://github.com/maggu2810/maggu2810-overlay/tree/master/app-mobilephone/scrcpy
-
 ### Latest version
 
 However, the packaged version is not always the latest release. To install the

doc/shortcuts.md

@@ -29,7 +29,7 @@ _<kbd>[Super]</kbd> is typically the <kbd>Windows</kbd> or <kbd>Cmd</kbd> key._
  | Resize window to 1:1 (pixel-perfect)        | <kbd>MOD</kbd>+<kbd>g</kbd>
  | Resize window to remove black borders       | <kbd>MOD</kbd>+<kbd>w</kbd> \| _Double-left-click¹_
  | Click on `HOME`                             | <kbd>MOD</kbd>+<kbd>h</kbd> \| _Middle-click_
- | Click on `BACK`                             | <kbd>MOD</kbd>+<kbd>b</kbd> \| _Right-click²_
+ | Click on `BACK`                             | <kbd>MOD</kbd>+<kbd>b</kbd> \| <kbd>MOD</kbd>+<kbd>Backspace</kbd> \| _Right-click²_
  | Click on `APP_SWITCH`                       | <kbd>MOD</kbd>+<kbd>s</kbd> \| _4th-click³_
  | Click on `MENU` (unlock screen)⁴            | <kbd>MOD</kbd>+<kbd>m</kbd>
  | Click on `VOLUME_UP`                        | <kbd>MOD</kbd>+<kbd>↑</kbd> _(up)_

doc/video.md

@@ -21,7 +21,7 @@ If encoding fails, scrcpy automatically tries again with a lower definition
 
 ## Bit rate
 
-The default video bit-rate is 8 Mbps. To change it:
+The default video bit rate is 8 Mbps. To change it:
 
 ```bash
 scrcpy --video-bit-rate=2M

doc/windows.md

@@ -15,7 +15,13 @@ Download the [latest release]:
 
 and extract it.
 
-Alternatively, you could install it from packages manager, like [Chocolatey]:
+Alternatively, you could install it from packages manager, like [Winget]:
+
+```bash
+winget install scrcpy
+```
+
+or [Chocolatey]:
 
 ```bash
 choco install scrcpy
@@ -30,6 +36,7 @@ scoop install scrcpy
 scoop install adb    # if you don't have it yet
 ```
 
+[Winget]: https://github.com/microsoft/winget-cli
 [Chocolatey]: https://chocolatey.org/
 [Scoop]: https://scoop.sh
 

meson.build

@@ -1,5 +1,5 @@
 project('scrcpy', 'c',
-        version: '2.0',
+        version: '2.1',
         meson_version: '>= 0.48',
         default_options: [
             'c_std=c11',

release.mk

@@ -98,9 +98,9 @@ dist-win32: build-server build-win32
 	cp app/prebuilt-deps/data/ffmpeg-6.0-scrcpy-4/win32/bin/avcodec-60.dll "$(DIST)/$(WIN32_TARGET_DIR)/"
 	cp app/prebuilt-deps/data/ffmpeg-6.0-scrcpy-4/win32/bin/avformat-60.dll "$(DIST)/$(WIN32_TARGET_DIR)/"
 	cp app/prebuilt-deps/data/ffmpeg-6.0-scrcpy-4/win32/bin/swresample-4.dll "$(DIST)/$(WIN32_TARGET_DIR)/"
-	cp app/prebuilt-deps/data/platform-tools-34.0.1/adb.exe "$(DIST)/$(WIN32_TARGET_DIR)/"
-	cp app/prebuilt-deps/data/platform-tools-34.0.1/AdbWinApi.dll "$(DIST)/$(WIN32_TARGET_DIR)/"
-	cp app/prebuilt-deps/data/platform-tools-34.0.1/AdbWinUsbApi.dll "$(DIST)/$(WIN32_TARGET_DIR)/"
+	cp app/prebuilt-deps/data/platform-tools-34.0.3/adb.exe "$(DIST)/$(WIN32_TARGET_DIR)/"
+	cp app/prebuilt-deps/data/platform-tools-34.0.3/AdbWinApi.dll "$(DIST)/$(WIN32_TARGET_DIR)/"
+	cp app/prebuilt-deps/data/platform-tools-34.0.3/AdbWinUsbApi.dll "$(DIST)/$(WIN32_TARGET_DIR)/"
 	cp app/prebuilt-deps/data/SDL2-2.28.0/i686-w64-mingw32/bin/SDL2.dll "$(DIST)/$(WIN32_TARGET_DIR)/"
 	cp app/prebuilt-deps/data/libusb-1.0.26/libusb-MinGW-Win32/bin/msys-usb-1.0.dll "$(DIST)/$(WIN32_TARGET_DIR)/"
 
@@ -116,9 +116,9 @@ dist-win64: build-server build-win64
 	cp app/prebuilt-deps/data/ffmpeg-6.0-scrcpy-4/win64/bin/avcodec-60.dll "$(DIST)/$(WIN64_TARGET_DIR)/"
 	cp app/prebuilt-deps/data/ffmpeg-6.0-scrcpy-4/win64/bin/avformat-60.dll "$(DIST)/$(WIN64_TARGET_DIR)/"
 	cp app/prebuilt-deps/data/ffmpeg-6.0-scrcpy-4/win64/bin/swresample-4.dll "$(DIST)/$(WIN64_TARGET_DIR)/"
-	cp app/prebuilt-deps/data/platform-tools-34.0.1/adb.exe "$(DIST)/$(WIN64_TARGET_DIR)/"
-	cp app/prebuilt-deps/data/platform-tools-34.0.1/AdbWinApi.dll "$(DIST)/$(WIN64_TARGET_DIR)/"
-	cp app/prebuilt-deps/data/platform-tools-34.0.1/AdbWinUsbApi.dll "$(DIST)/$(WIN64_TARGET_DIR)/"
+	cp app/prebuilt-deps/data/platform-tools-34.0.3/adb.exe "$(DIST)/$(WIN64_TARGET_DIR)/"
+	cp app/prebuilt-deps/data/platform-tools-34.0.3/AdbWinApi.dll "$(DIST)/$(WIN64_TARGET_DIR)/"
+	cp app/prebuilt-deps/data/platform-tools-34.0.3/AdbWinUsbApi.dll "$(DIST)/$(WIN64_TARGET_DIR)/"
 	cp app/prebuilt-deps/data/SDL2-2.28.0/x86_64-w64-mingw32/bin/SDL2.dll "$(DIST)/$(WIN64_TARGET_DIR)/"
 	cp app/prebuilt-deps/data/libusb-1.0.26/libusb-MinGW-x64/bin/msys-usb-1.0.dll "$(DIST)/$(WIN64_TARGET_DIR)/"
 

server/build.gradle

@@ -7,8 +7,8 @@ android {
         applicationId "com.genymobile.scrcpy"
         minSdkVersion 21
         targetSdkVersion 33
-        versionCode 20000
-        versionName "2.0"
+        versionCode 20100
+        versionName "2.1"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
     buildTypes {

server/build_without_gradle.sh

@@ -12,7 +12,7 @@
 set -e
 
 SCRCPY_DEBUG=false
-SCRCPY_VERSION_NAME=2.0
+SCRCPY_VERSION_NAME=2.1
 
 PLATFORM=${ANDROID_PLATFORM:-33}
 BUILD_TOOLS=${ANDROID_BUILD_TOOLS:-33.0.0}
@@ -48,6 +48,7 @@ cd "$SERVER_DIR/src/main/aidl"
 "$BUILD_TOOLS_DIR/aidl" -o"$GEN_DIR" android/view/IRotationWatcher.aidl
 "$BUILD_TOOLS_DIR/aidl" -o"$GEN_DIR" \
     android/content/IOnPrimaryClipChangedListener.aidl
+"$BUILD_TOOLS_DIR/aidl" -o"$GEN_DIR" android/view/IDisplayFoldListener.aidl
 
 echo "Compiling java sources..."
 cd ../java

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

@@ -64,8 +64,6 @@ public final class DesktopConnection implements Closeable {
             throws IOException {
         String socketName = getSocketName(scid);
 
-        LocalSocket firstSocket = null;
-
         LocalSocket videoSocket = null;
         LocalSocket audioSocket = null;
         LocalSocket controlSocket = null;
@@ -74,24 +72,28 @@ public final class DesktopConnection implements Closeable {
                 try (LocalServerSocket localServerSocket = new LocalServerSocket(socketName)) {
                     if (video) {
                         videoSocket = localServerSocket.accept();
-                        firstSocket = videoSocket;
+                        if (sendDummyByte) {
+                            // send one byte so the client may read() to detect a connection error
+                            videoSocket.getOutputStream().write(0);
+                            sendDummyByte = false;
+                        }
                     }
                     if (audio) {
                         audioSocket = localServerSocket.accept();
-                        if (firstSocket == null) {
-                            firstSocket = audioSocket;
+                        if (sendDummyByte) {
+                            // send one byte so the client may read() to detect a connection error
+                            audioSocket.getOutputStream().write(0);
+                            sendDummyByte = false;
                         }
                     }
                     if (control) {
                         controlSocket = localServerSocket.accept();
-                        if (firstSocket == null) {
-                            firstSocket = controlSocket;
+                        if (sendDummyByte) {
+                            // send one byte so the client may read() to detect a connection error
+                            controlSocket.getOutputStream().write(0);
+                            sendDummyByte = false;
                         }
                     }
-                    if (sendDummyByte) {
-                        // send one byte so the client may read() to detect a connection error
-                        firstSocket.getOutputStream().write(0);
-                    }
                 }
             } else {
                 if (video) {

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

@@ -99,25 +99,27 @@ public final class Device {
             }
         }, displayId);
 
-        ServiceManager.getWindowManager().registerDisplayFoldListener(new IDisplayFoldListener.Stub() {
-            @Override
-            public void onDisplayFoldChanged(int displayId, boolean folded) {
-                synchronized (Device.this) {
-                    DisplayInfo displayInfo = ServiceManager.getDisplayManager().getDisplayInfo(displayId);
-                    if (displayInfo == null) {
-                        Ln.e("Display " + displayId + " not found\n" + LogUtils.buildDisplayListMessage());
-                        return;
-                    }
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            ServiceManager.getWindowManager().registerDisplayFoldListener(new IDisplayFoldListener.Stub() {
+                @Override
+                public void onDisplayFoldChanged(int displayId, boolean folded) {
+                    synchronized (Device.this) {
+                        DisplayInfo displayInfo = ServiceManager.getDisplayManager().getDisplayInfo(displayId);
+                        if (displayInfo == null) {
+                            Ln.e("Display " + displayId + " not found\n" + LogUtils.buildDisplayListMessage());
+                            return;
+                        }
 
-                    screenInfo = ScreenInfo.computeScreenInfo(displayInfo.getRotation(), displayInfo.getSize(), options.getCrop(),
-                            options.getMaxSize(), options.getLockVideoOrientation());
-                    // notify
-                    if (foldListener != null) {
-                        foldListener.onFoldChanged(displayId, folded);
+                        screenInfo = ScreenInfo.computeScreenInfo(displayInfo.getRotation(), displayInfo.getSize(), options.getCrop(),
+                                options.getMaxSize(), options.getLockVideoOrientation());
+                        // notify
+                        if (foldListener != null) {
+                            foldListener.onFoldChanged(displayId, folded);
+                        }
                     }
                 }
-            }
-        });
+            });
+        }
 
         if (options.getControl() && options.getClipboardAutosync()) {
             // If control and autosync are enabled, synchronize Android clipboard to the computer automatically

server/src/main/java/com/genymobile/scrcpy/wrappers/WindowManager.java

@@ -2,6 +2,7 @@ package com.genymobile.scrcpy.wrappers;
 
 import com.genymobile.scrcpy.Ln;
 
+import android.annotation.TargetApi;
 import android.os.IInterface;
 import android.view.IRotationWatcher;
 import android.view.IDisplayFoldListener;
@@ -106,16 +107,17 @@ public final class WindowManager {
                 cls.getMethod("watchRotation", IRotationWatcher.class).invoke(manager, rotationWatcher);
             }
         } catch (Exception e) {
-            throw new AssertionError(e);
+            Ln.e("Could not register rotation watcher", e);
         }
     }
 
+    @TargetApi(29)
     public void registerDisplayFoldListener(IDisplayFoldListener foldListener) {
         try {
             Class<?> cls = manager.getClass();
             cls.getMethod("registerDisplayFoldListener", IDisplayFoldListener.class).invoke(manager, foldListener);
         } catch (Exception e) {
-            throw new AssertionError(e);
+            Ln.e("Could not register display fold listener", e);
         }
     }
 }