Split workarounds to fix audio on some devices

There were several workarounds applied in a single method. Some of them
are specific to Meizu phones, but cause issues on other devices.

Split the method to be able to only fill the app context for audio
capture without applying the Meizu workarounds.

Fixes #3801 <https://github.com/Genymobile/scrcpy/issues/3801>

README.md

@@ -35,15 +35,15 @@ Its features include:
  - [OTG mode](doc/hid-otg.md#otg)
  - and more…
 
-## Requirements
+## Prerequisites
 
 The Android device requires at least API 21 (Android 5.0).
 
 [Audio forwarding](doc/audio.md) is supported from API 30 (Android 11).
 
-Make sure you [enabled adb debugging][enable-adb] on your device(s).
+Make sure you [enabled USB debugging][enable-adb] on your device(s).
 
-[enable-adb]: https://developer.android.com/studio/command-line/adb.html#Enabling
+[enable-adb]: https://developer.android.com/studio/debug/dev-options#enable
 
 On some devices, you also need to enable [an additional option][control] `USB
 debugging (Security Settings)` (this is an item different from `USB debugging`)
@@ -90,10 +90,11 @@ documented in the following pages:
 
 - [Introducing scrcpy][article-intro]
 - [Scrcpy now works wirelessly][article-tcpip]
+- [Scrcpy 2.0, with audio][article-scrcpy2]
 
 [article-intro]: https://blog.rom1v.com/2018/03/introducing-scrcpy/
 [article-tcpip]: https://www.genymotion.com/blog/open-source-project-scrcpy-now-works-wirelessly/
-
+[article-scrcpy2]: https://blog.rom1v.com/2023/03/scrcpy-2-0-with-audio/
 
 ## Contact
 

app/src/audio_player.c

@@ -287,7 +287,7 @@ sc_audio_player_frame_sink_push(struct sc_frame_sink *sink,
 
             float avg = sc_average_get(&ap->avg_buffering);
             int diff = ap->target_buffering - avg;
-            if (abs(diff) < ap->sample_rate / 1000) {
+            if (abs(diff) < (int) ap->sample_rate / 1000) {
                 // Do not compensate for less than 1ms, the error is just noise
                 diff = 0;
             } else if (diff < 0 && buffered_samples < ap->target_buffering) {

app/src/demuxer.c

@@ -1,6 +1,7 @@
 #include "demuxer.h"
 
 #include <assert.h>
+#include <libavutil/channel_layout.h>
 #include <libavutil/time.h>
 #include <unistd.h>
 

app/src/screen.c

@@ -816,7 +816,7 @@ sc_screen_handle_event(struct sc_screen *screen, SDL_Event *event) {
     bool relative_mode = sc_screen_is_relative_mode(screen);
 
     switch (event->type) {
-        case SC_EVENT_SCREEN_INIT_SIZE:
+        case SC_EVENT_SCREEN_INIT_SIZE: {
             // The initial size is passed via screen->frame_size
             bool ok = sc_screen_init_size(screen);
             if (!ok) {
@@ -824,6 +824,7 @@ sc_screen_handle_event(struct sc_screen *screen, SDL_Event *event) {
                 return false;
             }
             return true;
+        }
         case SC_EVENT_NEW_FRAME: {
             bool ok = sc_screen_update_frame(screen);
             if (!ok) {

app/src/v4l2_sink.c

@@ -210,6 +210,9 @@ sc_v4l2_sink_open(struct sc_v4l2_sink *vs, const AVCodecContext *ctx) {
         goto error_avformat_free_context;
     }
 
+    // The codec is from the v4l2 encoder, not from the decoder
+    ostream->codecpar->codec_id = encoder->id;
+
     int ret = avio_open(&vs->format_ctx->pb, vs->device_name, AVIO_FLAG_WRITE);
     if (ret < 0) {
         LOGE("Failed to open output device: %s", vs->device_name);

doc/device.md

@@ -107,10 +107,10 @@ with the device IP address you found)_.
 7. Run `scrcpy` as usual.
 8. Run `adb disconnect` once you're done.
 
-Since Android 11, a [Wireless debugging option][adb-wireless] allows to bypass
+Since Android 11, a [wireless debugging option][adb-wireless] allows to bypass
 having to physically connect your device directly to your computer.
 
-[adb-wireless]: https://developer.android.com/studio/command-line/adb#connect-to-a-device-over-wi-fi-android-11+
+[adb-wireless]: https://developer.android.com/studio/command-line/adb#wireless-android11-command-line
 
 
 ## Autostart

doc/linux.md

@@ -61,6 +61,8 @@ _See [build.md](build.md) to build and install the app manually._
 
 ## Run
 
+_Make sure that your device meets the [prerequisites](/README.md#prerequisites)._
+
 Once installed, run from a terminal:
 
 ```bash

doc/macos.md

@@ -29,6 +29,8 @@ _See [build.md](build.md) to build and install the app manually._
 
 ## Run
 
+_Make sure that your device meets the [prerequisites](/README.md#prerequisites)._
+
 Once installed, run from a terminal:
 
 ```bash

doc/shortcuts.md

@@ -49,7 +49,7 @@ _<kbd>[Super]</kbd> is typically the <kbd>Windows</kbd> or <kbd>Cmd</kbd> key._
  | Enable/disable FPS counter (on stdout)      | <kbd>MOD</kbd>+<kbd>i</kbd>
  | Pinch-to-zoom                               | <kbd>Ctrl</kbd>+_click-and-move_
  | Drag & drop APK file                        | Install APK from computer
- | Drag & drop non-APK file                    | [Push file to device](#push-file-to-device)
+ | Drag & drop non-APK file                    | [Push file to device](control.md#push-file-to-device)
 
 _¹Double-click on black borders to remove them._  
 _²Right-click turns the screen on if it was off, presses BACK otherwise._  

doc/windows.md

@@ -9,7 +9,7 @@ Download the [latest release]:
  - [`scrcpy-win32-v2.0.zip`][direct-win32] (32-bit)  
    <sub>SHA-256: `15d98c02cb0e0bbd84f8b5d54991e0f6925569b1286a86a40743944fcb1c2d8c`</sub>
 
-[release]: https://github.com/Genymobile/scrcpy/releases/latest
+[latest release]: https://github.com/Genymobile/scrcpy/releases/latest
 [direct-win64]: https://github.com/Genymobile/scrcpy/releases/download/v2.0/scrcpy-win64-v2.0.zip
 [direct-win32]: https://github.com/Genymobile/scrcpy/releases/download/v2.0/scrcpy-win32-v2.0.zip
 
@@ -38,6 +38,8 @@ _See [build.md](build.md) to build and install the app manually._
 
 ## Run
 
+_Make sure that your device meets the [prerequisites](/README.md#prerequisites)._
+
 Scrcpy is a command line application: it is mainly intended to be executed from
 a terminal with command line arguments.
 

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

@@ -111,7 +111,7 @@ public final class AudioCapture {
     @TargetApi(Build.VERSION_CODES.N)
     public int read(ByteBuffer directBuffer, int size, MediaCodec.BufferInfo outBufferInfo) {
         int r = recorder.read(directBuffer, size);
-        if (r < 0) {
+        if (r <= 0) {
             return r;
         }
 

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

@@ -92,7 +92,7 @@ public final class AudioEncoder implements AsyncProcessor {
             InputTask task = inputTasks.take();
             ByteBuffer buffer = mediaCodec.getInputBuffer(task.index);
             int r = capture.read(buffer, READ_SIZE, bufferInfo);
-            if (r < 0) {
+            if (r <= 0) {
                 throw new IOException("Could not read audio: " + r);
             }
 

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

@@ -81,15 +81,15 @@ public final class Server {
         // But only apply when strictly necessary, since workarounds can cause other issues:
         //  - <https://github.com/Genymobile/scrcpy/issues/940>
         //  - <https://github.com/Genymobile/scrcpy/issues/994>
-        boolean mustFillAppInfo = Build.BRAND.equalsIgnoreCase("meizu");
+        if (Build.BRAND.equalsIgnoreCase("meizu")) {
+            Workarounds.fillAppInfo();
+        }
 
         // Before Android 11, audio is not supported.
         // Since Android 12, we can properly set a context on the AudioRecord.
-        // Only on Android 11 we must fill app info for the AudioRecord to work.
+        // Only on Android 11 we must fill the application context for the AudioRecord to work.
-        mustFillAppInfo |= audio && Build.VERSION.SDK_INT == Build.VERSION_CODES.R;
+        if (audio && Build.VERSION.SDK_INT == Build.VERSION_CODES.R) {
-
+            Workarounds.fillAppContext();
-        if (mustFillAppInfo) {
-            Workarounds.fillAppInfo();
         }
 
         List<AsyncProcessor> asyncProcessors = new ArrayList<>();

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

@@ -10,6 +10,10 @@ import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 
 public final class Workarounds {
+
+    private static Class<?> activityThreadClass;
+    private static Object activityThread;
+
     private Workarounds() {
         // not instantiable
     }
@@ -28,18 +32,25 @@ public final class Workarounds {
     }
 
     @SuppressLint("PrivateApi,DiscouragedPrivateApi")
-    public static void fillAppInfo() {
+    private static void fillActivityThread() throws Exception {
-        try {
+        if (activityThread == null) {
             // ActivityThread activityThread = new ActivityThread();
-            Class<?> activityThreadClass = Class.forName("android.app.ActivityThread");
+            activityThreadClass = Class.forName("android.app.ActivityThread");
             Constructor<?> activityThreadConstructor = activityThreadClass.getDeclaredConstructor();
             activityThreadConstructor.setAccessible(true);
-            Object activityThread = activityThreadConstructor.newInstance();
+            activityThread = activityThreadConstructor.newInstance();
 
             // ActivityThread.sCurrentActivityThread = activityThread;
             Field sCurrentActivityThreadField = activityThreadClass.getDeclaredField("sCurrentActivityThread");
             sCurrentActivityThreadField.setAccessible(true);
             sCurrentActivityThreadField.set(null, activityThread);
+        }
+    }
+
+    @SuppressLint("PrivateApi,DiscouragedPrivateApi")
+    public static void fillAppInfo() {
+        try {
+            fillActivityThread();
 
             // ActivityThread.AppBindData appBindData = new ActivityThread.AppBindData();
             Class<?> appBindDataClass = Class.forName("android.app.ActivityThread$AppBindData");
@@ -59,6 +70,16 @@ public final class Workarounds {
             Field mBoundApplicationField = activityThreadClass.getDeclaredField("mBoundApplication");
             mBoundApplicationField.setAccessible(true);
             mBoundApplicationField.set(activityThread, appBindData);
+        } catch (Throwable throwable) {
+            // this is a workaround, so failing is not an error
+            Ln.d("Could not fill app info: " + throwable.getMessage());
+        }
+    }
+
+    @SuppressLint("PrivateApi,DiscouragedPrivateApi")
+    public static void fillAppContext() {
+        try {
+            fillActivityThread();
 
             Application app = Application.class.newInstance();
             Field baseField = ContextWrapper.class.getDeclaredField("mBase");
@@ -71,7 +92,7 @@ public final class Workarounds {
             mInitialApplicationField.set(activityThread, app);
         } catch (Throwable throwable) {
             // this is a workaround, so failing is not an error
-            Ln.d("Could not fill app info: " + throwable.getMessage());
+            Ln.d("Could not fill app context: " + throwable.getMessage());
         }
     }
 }