OpenGL filter prototype (does not work)

server/src/main/java/com/genymobile/scrcpy/video/SurfaceEncoder.java

@@ -88,6 +88,9 @@ public class SurfaceEncoder implements AsyncProcessor {
                     mediaCodec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
                     surface = mediaCodec.createInputSurface();
 
+                    VideoFilter filter = new VideoFilter(surface);
+                    surface = filter.getInputSurface();
+
                     capture.start(surface);
 
                     mediaCodec.start();
@@ -95,6 +98,7 @@ public class SurfaceEncoder implements AsyncProcessor {
                     alive = encode(mediaCodec, streamer);
                     // do not call stop() on exception, it would trigger an IllegalStateException
                     mediaCodec.stop();
+                    filter.release();
                 } catch (IllegalStateException | IllegalArgumentException e) {
                     Ln.e("Encoding error: " + e.getClass().getName() + ": " + e.getMessage());
                     if (!prepareRetry(size)) {

server/src/main/java/com/genymobile/scrcpy/video/VideoFilter.java

@@ -0,0 +1,116 @@
+package com.genymobile.scrcpy.video;
+
+import com.genymobile.scrcpy.util.Ln;
+
+import android.graphics.SurfaceTexture;
+import android.opengl.EGL14;
+import android.opengl.EGLConfig;
+import android.opengl.EGLContext;
+import android.opengl.EGLDisplay;
+import android.opengl.EGLSurface;
+import android.opengl.GLES11Ext;
+import android.opengl.GLES20;
+import android.view.Surface;
+
+public class VideoFilter {
+    private EGLDisplay eglDisplay;
+    private EGLContext eglContext;
+    private EGLSurface eglSurface;
+    private SurfaceTexture surfaceTexture;
+    private Surface inputSurface;
+    private int textureId;
+
+    public VideoFilter(Surface outputSurface) {
+        eglDisplay = EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY);
+        if (eglDisplay == EGL14.EGL_NO_DISPLAY) {
+            throw new RuntimeException("Unable to get EGL14 display");
+        }
+
+        int[] version = new int[2];
+        if (!EGL14.eglInitialize(eglDisplay, version, 0, version, 1)) {
+            throw new RuntimeException("Unable to initialize EGL14");
+        }
+
+        int[] attribList = {
+                EGL14.EGL_RED_SIZE, 8,
+                EGL14.EGL_GREEN_SIZE, 8,
+                EGL14.EGL_BLUE_SIZE, 8,
+                EGL14.EGL_ALPHA_SIZE, 8,
+                EGL14.EGL_RENDERABLE_TYPE, EGL14.EGL_OPENGL_ES2_BIT,
+                EGL14.EGL_NONE
+        };
+        EGLConfig[] configs = new EGLConfig[1];
+        int[] numConfigs = new int[1];
+        EGL14.eglChooseConfig(eglDisplay, attribList, 0, configs, 0, configs.length, numConfigs, 0);
+        if (numConfigs[0] <= 0) {
+            throw new RuntimeException("Unable to find ES2 EGL config");
+        }
+        EGLConfig eglConfig = configs[0];
+
+        int[] contextAttribList = {
+                EGL14.EGL_CONTEXT_CLIENT_VERSION, 2,
+                EGL14.EGL_NONE
+        };
+        eglContext = EGL14.eglCreateContext(eglDisplay, eglConfig, EGL14.EGL_NO_CONTEXT, contextAttribList, 0);
+        if (eglContext == null) {
+            throw new RuntimeException("Failed to create EGL context");
+        }
+
+        int[] surfaceAttribList = {
+                EGL14.EGL_NONE
+        };
+        eglSurface = EGL14.eglCreateWindowSurface(eglDisplay, eglConfig, outputSurface, surfaceAttribList, 0);
+        if (eglSurface == null) {
+            throw new RuntimeException("Failed to create EGL window surface");
+        }
+
+        if (!EGL14.eglMakeCurrent(eglDisplay, eglSurface, eglSurface, eglContext)) {
+            throw new RuntimeException("Failed to make EGL context current");
+        }
+
+        int[] textures = new int[1];
+        GLES20.glGenTextures(1, textures, 0);
+        textureId = textures[0];
+
+        surfaceTexture = new SurfaceTexture(textureId);
+        inputSurface = new Surface(surfaceTexture);
+
+        surfaceTexture.setOnFrameAvailableListener(new SurfaceTexture.OnFrameAvailableListener() {
+            @Override
+            public void onFrameAvailable(SurfaceTexture surfaceTexture) {
+                // XXX This should be called when the VirtualDisplay has rendered a new frame
+                Ln.i("==== render");
+                render();
+            }
+        });
+    }
+
+    public Surface getInputSurface() {
+        return inputSurface;
+    }
+
+    public void render() {
+        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);
+
+        // For now, just paint with a color
+        GLES20.glClearColor(0.0f, 0.5f, 0.5f, 1.0f);
+        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
+
+        GLES20.glViewport(0, 0, 1920, 1080);
+
+        EGL14.eglSwapBuffers(eglDisplay, eglSurface);
+    }
+
+    public void release() {
+        if (eglDisplay != EGL14.EGL_NO_DISPLAY) {
+            EGL14.eglDestroySurface(eglDisplay, eglSurface);
+            EGL14.eglDestroyContext(eglDisplay, eglContext);
+            EGL14.eglTerminate(eglDisplay);
+        }
+        eglDisplay = EGL14.EGL_NO_DISPLAY;
+        eglContext = EGL14.EGL_NO_CONTEXT;
+        eglSurface = EGL14.EGL_NO_SURFACE;
+        surfaceTexture.release();
+        inputSurface.release();
+    }
+}