feat: Create C++/OpenGL-based Video Pipeline for more efficient Recording and Frame Processing (#1721)

* Create `VideoPipeline` c++

* Remove folly C++ dependency

* Create `VideoPipeline` HybridClass

* Set up OpenGL

* Add outputs

* Update VideoPipeline.kt

* Bum `minSdkVersion` to `26`

* Create `VideoPipelineOutput`

* Create output funcs

* Set output pipelines

* Add FP/Recording on Output change

* Update VideoPipeline.cpp

* Create `PassThroughShader`

* Try to draw? I have honestly no idea

* fix: Fix `setFrameProcessor` nameclash

* fix: Fix `high-res-sizes` being null

* Add preview output

* Create `OpenGLContext.cpp`

* Make screen red

* This _should_ work (MESSY)

* FINALLY RENDER TEXTURE

* Rotate

* Mirror

* Clean up a bit

* Add `getWidth()`/`getHeight()`

* Cleanup

* fix: Use uniforms instead of attributes

* Draw with passed rotation/mirror mode

* feat: Use SurfaceTexture's transformMatrix in OpenGL pipeline (#1727)

* feat: Use Transform Matrix from SurfaceTexture

* Renam

* feat: Fix OpenGL Shader

* Update VideoPipeline.kt

* Measure elapsed time

* fix: Fix low resolution

* Render to offscreen

* Render to every context

* Release `SurfaceTexture` on close

* Use one OpenGL context to render to multiple EGLSurfaces

* Clean up a bit

* fix: Fix recording pipeline not triggering

* fix: Synchronize close to prevent nulls

* Update OpenGLRenderer.cpp

* fix: Hardcode Android recorder size

android/CMakeLists.txt

@@ -7,10 +7,6 @@ set(BUILD_DIR ${CMAKE_SOURCE_DIR}/build)
 set(CMAKE_VERBOSE_MAKEFILE ON)
 set(CMAKE_CXX_STANDARD 17)
 
-# Folly
-include("${NODE_MODULES_DIR}/react-native/ReactAndroid/cmake-utils/folly-flags.cmake")
-add_compile_options(${folly_FLAGS})
-
 # Third party libraries (Prefabs)
 find_package(ReactAndroid REQUIRED CONFIG)
 find_package(fbjni REQUIRED CONFIG)
@@ -25,6 +21,10 @@ add_library(
         SHARED
         ../cpp/JSITypedArray.cpp
         src/main/cpp/VisionCamera.cpp
+        src/main/cpp/VideoPipeline.cpp
+        src/main/cpp/PassThroughShader.cpp
+        src/main/cpp/OpenGLContext.cpp
+        src/main/cpp/OpenGLRenderer.cpp
         # Frame Processor
         src/main/cpp/frameprocessor/FrameHostObject.cpp
         src/main/cpp/frameprocessor/FrameProcessorPluginHostObject.cpp
@@ -60,7 +60,6 @@ target_link_libraries(
         android                             # <-- Android JNI core
         ReactAndroid::jsi                   # <-- RN: JSI
         ReactAndroid::reactnativejni        # <-- RN: React Native JNI bindings
-        ReactAndroid::folly_runtime         # <-- RN: For casting JSI <> Java objects
         fbjni::fbjni                        # <-- fbjni
 )
 

android/build.gradle

@@ -93,7 +93,7 @@ android {
   }
 
   defaultConfig {
-    minSdkVersion safeExtGet('minSdkVersion', 21)
+    minSdkVersion safeExtGet('minSdkVersion', 26)
     compileSdkVersion safeExtGet('compileSdkVersion', 33)
     targetSdkVersion safeExtGet('targetSdkVersion', 33)
     versionCode 1

android/gradle.properties

@@ -14,10 +14,6 @@ org.gradle.configureondemand=true
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
 # org.gradle.parallel=true
 #Fri Feb 19 20:46:14 CET 2021
-VisionCamera_buildToolsVersion=30.0.0
-VisionCamera_compileSdkVersion=31
 VisionCamera_kotlinVersion=1.7.20
-VisionCamera_targetSdkVersion=31
-VisionCamera_ndkVersion=21.4.7075529
 android.enableJetifier=true
 android.useAndroidX=true

android/src/main/cpp/OpenGLContext.cpp

@@ -0,0 +1,133 @@
+//
+// Created by Marc Rousavy on 29.08.23.
+//
+
+#include "OpenGLContext.h"
+
+#include <EGL/egl.h>
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
+#include <android/native_window.h>
+#include <android/log.h>
+
+#include "OpenGLError.h"
+
+namespace vision {
+
+std::shared_ptr<OpenGLContext> OpenGLContext::CreateWithOffscreenSurface(int width, int height) {
+  return std::unique_ptr<OpenGLContext>(new OpenGLContext(width, height));
+}
+
+OpenGLContext::OpenGLContext(int width, int height) {
+  _width = width;
+  _height = height;
+}
+
+OpenGLContext::~OpenGLContext() {
+  destroy();
+}
+
+void OpenGLContext::destroy() {
+  if (display != EGL_NO_DISPLAY) {
+    eglMakeCurrent(display, offscreenSurface, offscreenSurface, context);
+    if (offscreenSurface != EGL_NO_SURFACE) {
+      __android_log_print(ANDROID_LOG_INFO, TAG, "Destroying OpenGL Surface...");
+      eglDestroySurface(display, offscreenSurface);
+      offscreenSurface = EGL_NO_SURFACE;
+    }
+    if (context != EGL_NO_CONTEXT) {
+      __android_log_print(ANDROID_LOG_INFO, TAG, "Destroying OpenGL Context...");
+      eglDestroyContext(display, context);
+      context = EGL_NO_CONTEXT;
+    }
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Destroying OpenGL Display...");
+    eglTerminate(display);
+    display = EGL_NO_DISPLAY;
+    config = nullptr;
+  }
+}
+
+void OpenGLContext::ensureOpenGL() {
+  bool successful;
+  // EGLDisplay
+  if (display == EGL_NO_DISPLAY) {
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Initializing EGLDisplay..");
+    display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
+    if (display == EGL_NO_DISPLAY) throw OpenGLError("Failed to get default OpenGL Display!");
+
+    EGLint major;
+    EGLint minor;
+    successful = eglInitialize(display, &major, &minor);
+    if (!successful) throw OpenGLError("Failed to initialize OpenGL!");
+  }
+
+  // EGLConfig
+  if (config == nullptr) {
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Initializing EGLConfig..");
+    EGLint attributes[] = {EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
+                           EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
+                           EGL_ALPHA_SIZE, 8,
+                           EGL_BLUE_SIZE, 8,
+                           EGL_GREEN_SIZE, 8,
+                           EGL_RED_SIZE, 8,
+                           EGL_DEPTH_SIZE, 0,
+                           EGL_STENCIL_SIZE, 0,
+                           EGL_NONE};
+    EGLint numConfigs;
+    successful = eglChooseConfig(display, attributes, &config, 1, &numConfigs);
+    if (!successful || numConfigs == 0) throw OpenGLError("Failed to choose OpenGL config!");
+  }
+
+  // EGLContext
+  if (context == EGL_NO_CONTEXT) {
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Initializing EGLContext..");
+    EGLint contextAttributes[] = {EGL_CONTEXT_CLIENT_VERSION, 2, EGL_NONE};
+    context = eglCreateContext(display, config, nullptr, contextAttributes);
+    if (context == EGL_NO_CONTEXT) throw OpenGLError("Failed to create OpenGL context!");
+  }
+
+  // EGLSurface
+  if (offscreenSurface == EGL_NO_SURFACE) {
+    // If we don't have a surface at all
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Initializing %i x %i offscreen pbuffer EGLSurface..", _width, _height);
+    EGLint attributes[] = {EGL_WIDTH, _width,
+                           EGL_HEIGHT, _height,
+                           EGL_NONE};
+    offscreenSurface = eglCreatePbufferSurface(display, config, attributes);
+    if (offscreenSurface == EGL_NO_SURFACE) throw OpenGLError("Failed to create OpenGL Surface!");
+  }
+}
+
+void OpenGLContext::use() {
+  this->use(offscreenSurface);
+}
+
+void OpenGLContext::use(EGLSurface surface) {
+  if (surface == EGL_NO_SURFACE) throw OpenGLError("Cannot render to a null Surface!");
+
+  // 1. Make sure the OpenGL context is initialized
+  this->ensureOpenGL();
+
+  // 2. Make the OpenGL context current
+  bool successful = eglMakeCurrent(display, surface, surface, context);
+  if (!successful || eglGetError() != EGL_SUCCESS) throw OpenGLError("Failed to use current OpenGL context!");
+
+  // 3. Caller can now render to this surface
+}
+
+GLuint OpenGLContext::createTexture() {
+  // 1. Make sure the OpenGL context is initialized
+  this->ensureOpenGL();
+
+  // 2. Make the OpenGL context current
+  bool successful = eglMakeCurrent(display, offscreenSurface, offscreenSurface, context);
+  if (!successful || eglGetError() != EGL_SUCCESS) throw OpenGLError("Failed to use current OpenGL context!");
+
+  GLuint textureId;
+  glGenTextures(1, &textureId);
+
+  return textureId;
+}
+
+} // namespace vision

android/src/main/cpp/OpenGLContext.h

@@ -0,0 +1,68 @@
+//
+// Created by Marc Rousavy on 29.08.23.
+//
+
+#pragma once
+
+#include <EGL/egl.h>
+#include <GLES2/gl2.h>
+
+#include <memory>
+#include <functional>
+
+#include "PassThroughShader.h"
+
+namespace vision {
+
+/**
+ * An OpenGL Context that can be used to render to different surfaces.
+ * By default, it creates an off-screen PixelBuffer surface.
+ */
+class OpenGLContext {
+ public:
+  /**
+   * Create a new instance of the OpenGLContext that draws to an off-screen PixelBuffer surface.
+   * This will not perform any OpenGL operations yet, and is therefore safe to call from any Thread.
+   */
+  static std::shared_ptr<OpenGLContext> CreateWithOffscreenSurface(int width, int height);
+  /**
+   * Destroy the OpenGL Context. This needs to be called on the same thread that `use()` was called.
+   */
+  ~OpenGLContext();
+
+  /**
+   * Use this OpenGL Context to render to the given EGLSurface.
+   * After the `renderFunc` returns, the default offscreen PixelBuffer surface becomes active again.
+   */
+  void use(EGLSurface surface);
+
+  /**
+   * Use this OpenGL Context to render to the offscreen PixelBuffer surface.
+   */
+  void use();
+
+  /**
+   * Create a new texture on this context
+   */
+  GLuint createTexture();
+
+ public:
+  EGLDisplay display = EGL_NO_DISPLAY;
+  EGLContext context = EGL_NO_CONTEXT;
+  EGLSurface offscreenSurface = EGL_NO_SURFACE;
+  EGLConfig config = nullptr;
+
+ private:
+  int _width = 0, _height = 0;
+  explicit OpenGLContext(int width, int height);
+  void destroy();
+  void ensureOpenGL();
+
+ private:
+  PassThroughShader _passThroughShader;
+
+ private:
+  static constexpr auto TAG = "OpenGLContext";
+};
+
+} // namespace vision

android/src/main/cpp/OpenGLRenderer.cpp

@@ -0,0 +1,74 @@
+//
+// Created by Marc Rousavy on 29.08.23.
+//
+
+#include "OpenGLRenderer.h"
+
+#include <EGL/egl.h>
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
+#include <android/native_window.h>
+#include <android/log.h>
+
+#include <utility>
+
+#include "OpenGLError.h"
+
+namespace vision {
+
+std::unique_ptr<OpenGLRenderer> OpenGLRenderer::CreateWithWindowSurface(std::shared_ptr<OpenGLContext> context, ANativeWindow* surface) {
+  return std::unique_ptr<OpenGLRenderer>(new OpenGLRenderer(std::move(context), surface));
+}
+
+OpenGLRenderer::OpenGLRenderer(std::shared_ptr<OpenGLContext> context, ANativeWindow* surface) {
+  _context = std::move(context);
+  _outputSurface = surface;
+  _width = ANativeWindow_getWidth(surface);
+  _height = ANativeWindow_getHeight(surface);
+}
+
+OpenGLRenderer::~OpenGLRenderer() {
+  if (_outputSurface != nullptr) {
+    ANativeWindow_release(_outputSurface);
+  }
+  destroy();
+}
+
+void OpenGLRenderer::destroy() {
+  if (_context != nullptr && _surface != EGL_NO_DISPLAY) {
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Destroying OpenGL Surface...");
+    eglDestroySurface(_context->display, _surface);
+    _surface = EGL_NO_SURFACE;
+  }
+}
+
+void OpenGLRenderer::renderTextureToSurface(GLuint textureId, float* transformMatrix) {
+  if (_surface == EGL_NO_SURFACE) {
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Creating Window Surface...");
+    _context->use();
+    _surface = eglCreateWindowSurface(_context->display, _context->config, _outputSurface, nullptr);
+  }
+
+  // 1. Activate the OpenGL context for this surface
+  _context->use(_surface);
+
+  // 2. Set the viewport for rendering
+  glViewport(0, 0, _width, _height);
+  glDisable(GL_BLEND);
+
+  // 3. Bind the input texture
+  glBindTexture(GL_TEXTURE_EXTERNAL_OES, textureId);
+  glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+
+  // 4. Draw it using the pass-through shader which also applies transforms
+  _passThroughShader.draw(textureId, transformMatrix);
+
+  // 5. Swap buffers to pass it to the window surface
+  eglSwapBuffers(_context->display, _surface);
+}
+
+} // namespace vision

android/src/main/cpp/OpenGLRenderer.h

@@ -0,0 +1,58 @@
+//
+// Created by Marc Rousavy on 29.08.23.
+//
+
+#pragma once
+
+#include <EGL/egl.h>
+#include <GLES2/gl2.h>
+#include <android/native_window.h>
+#include <memory>
+#include "PassThroughShader.h"
+
+#include "OpenGLContext.h"
+
+namespace vision {
+
+class OpenGLRenderer {
+ public:
+  /**
+   * Create a new instance of the OpenGLRenderer that draws to an on-screen window surface.
+   * This will not perform any OpenGL operations yet, and is therefore safe to call from any Thread.
+   *
+   * Note: The `surface` is considered moved, and the OpenGL context will release it when it is being deleted.
+   */
+  static std::unique_ptr<OpenGLRenderer> CreateWithWindowSurface(std::shared_ptr<OpenGLContext> context, ANativeWindow* surface);
+  /**
+   * Destroy the OpenGL Context. This needs to be called on the same thread that `use()` was called.
+   */
+  ~OpenGLRenderer();
+
+  /**
+   * Renders the given Texture ID to the Surface
+   */
+  void renderTextureToSurface(GLuint textureId, float* transformMatrix);
+
+  /**
+   * Destroys the OpenGL context. This needs to be called on the same thread that `use()` was called.
+   * After calling `destroy()`, it is legal to call `use()` again, which will re-construct everything.
+   */
+  void destroy();
+
+ private:
+  explicit OpenGLRenderer(std::shared_ptr<OpenGLContext> context, ANativeWindow* surface);
+
+ private:
+  int _width = 0, _height = 0;
+  std::shared_ptr<OpenGLContext> _context;
+  ANativeWindow* _outputSurface;
+  EGLSurface _surface = EGL_NO_SURFACE;
+
+ private:
+  PassThroughShader _passThroughShader;
+
+ private:
+  static constexpr auto TAG = "OpenGLRenderer";
+};
+
+} // namespace vision

android/src/main/cpp/PassThroughShader.cpp

@@ -0,0 +1,119 @@
+//
+// Created by Marc Rousavy on 28.08.23.
+//
+
+#include "PassThroughShader.h"
+#include <EGL/egl.h>
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+#include <memory>
+#include "OpenGLError.h"
+#include <string>
+
+namespace vision {
+
+PassThroughShader::~PassThroughShader() {
+  if (_programId != NO_SHADER) {
+    glDeleteProgram(_programId);
+    _programId = NO_SHADER;
+  }
+
+  if (_vertexBuffer != NO_BUFFER) {
+    glDeleteBuffers(1, &_vertexBuffer);
+    _vertexBuffer = NO_BUFFER;
+  }
+}
+
+void PassThroughShader::draw(GLuint textureId, float* transformMatrix) {
+  // 1. Set up Shader Program
+  if (_programId == NO_SHADER) {
+    _programId = createProgram();
+  }
+
+  glUseProgram(_programId);
+
+  if (_vertexParameters.aPosition == NO_POSITION) {
+    _vertexParameters = {
+        .aPosition = glGetAttribLocation(_programId, "aPosition"),
+        .aTexCoord = glGetAttribLocation(_programId, "aTexCoord"),
+        .uTransformMatrix = glGetUniformLocation(_programId, "uTransformMatrix"),
+    };
+    _fragmentParameters = {
+        .uTexture = glGetUniformLocation(_programId, "uTexture"),
+    };
+  }
+
+  // 2. Set up Vertices Buffer
+  if (_vertexBuffer == NO_BUFFER) {
+    glGenBuffers(1, &_vertexBuffer);
+    glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(VERTICES), VERTICES, GL_STATIC_DRAW);
+  }
+
+  // 3. Pass all uniforms/attributes for vertex shader
+  glEnableVertexAttribArray(_vertexParameters.aPosition);
+  glVertexAttribPointer(_vertexParameters.aPosition,
+                        2,
+                        GL_FLOAT,
+                        GL_FALSE,
+                        sizeof(Vertex),
+                        reinterpret_cast<void*>(offsetof(Vertex, position)));
+
+  glEnableVertexAttribArray(_vertexParameters.aTexCoord);
+  glVertexAttribPointer(_vertexParameters.aTexCoord,
+                        2,
+                        GL_FLOAT,
+                        GL_FALSE,
+                        sizeof(Vertex),
+                        reinterpret_cast<void*>(offsetof(Vertex, texCoord)));
+
+  glUniformMatrix4fv(_vertexParameters.uTransformMatrix, 1, GL_FALSE, transformMatrix);
+
+  // 4. Pass texture to fragment shader
+  glActiveTexture(GL_TEXTURE0);
+  glBindTexture(GL_TEXTURE_EXTERNAL_OES, textureId);
+  glUniform1i(_fragmentParameters.uTexture, 0);
+
+  // 5. Draw!
+  glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+}
+
+GLuint PassThroughShader::loadShader(GLenum shaderType, const char* shaderCode) {
+  GLuint shader = glCreateShader(shaderType);
+  if (shader == 0) throw OpenGLError("Failed to load shader!");
+
+  glShaderSource(shader, 1, &shaderCode, nullptr);
+  glCompileShader(shader);
+  GLint compileStatus = GL_FALSE;
+  glGetShaderiv(shader, GL_COMPILE_STATUS, &compileStatus);
+  if (compileStatus == GL_FALSE) {
+    glDeleteShader(shader);
+    throw OpenGLError("Failed to compile shader!");
+  }
+  return shader;
+}
+
+GLuint PassThroughShader::createProgram() {
+  GLuint vertexShader = loadShader(GL_VERTEX_SHADER, VERTEX_SHADER);
+  GLuint fragmentShader = loadShader(GL_FRAGMENT_SHADER, FRAGMENT_SHADER);
+
+  GLuint program = glCreateProgram();
+  if (program == 0) throw OpenGLError("Failed to create pass-through program!");
+
+  glAttachShader(program, vertexShader);
+  if (glGetError() != GL_NO_ERROR) throw OpenGLError("Failed to attach Vertex Shader!");
+
+  glAttachShader(program, fragmentShader);
+  if (glGetError() != GL_NO_ERROR) throw OpenGLError("Failed to attach Fragment Shader!");
+
+  glLinkProgram(program);
+  GLint linkStatus = GL_FALSE;
+  glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);
+  if (!linkStatus) {
+    glDeleteProgram(program);
+    throw OpenGLError("Failed to load pass-through program!");
+  }
+  return program;
+}
+
+} // namespace vision

android/src/main/cpp/PassThroughShader.h

@@ -0,0 +1,81 @@
+//
+// Created by Marc Rousavy on 28.08.23.
+//
+
+#pragma once
+
+#include <EGL/egl.h>
+#include <GLES2/gl2.h>
+
+namespace vision {
+
+#define NO_SHADER 0
+#define NO_POSITION 0
+#define NO_BUFFER 0
+
+struct Vertex {
+  GLfloat position[2];
+  GLfloat texCoord[2];
+};
+
+class PassThroughShader {
+ public:
+  PassThroughShader() = default;
+  ~PassThroughShader();
+
+  /**
+   * Draw the texture using this shader.
+   */
+  void draw(GLuint textureId, float* transformMatrix);
+
+ private:
+  // Loading
+  static GLuint loadShader(GLenum shaderType, const char* shaderCode);
+  static GLuint createProgram();
+
+ private:
+  // Parameters
+  GLuint _programId = NO_SHADER;
+  GLuint _vertexBuffer = NO_BUFFER;
+  struct VertexParameters {
+    GLint aPosition = NO_POSITION;
+    GLint aTexCoord = NO_POSITION;
+    GLint uTransformMatrix = NO_POSITION;
+  } _vertexParameters;
+  struct FragmentParameters {
+    GLint uTexture = NO_POSITION;
+  } _fragmentParameters;
+
+ private:
+  // Statics
+  static constexpr Vertex VERTICES[] = {
+      {{-1.0f, -1.0f}, {0.0f, 0.0f}}, // bottom-left
+      {{1.0f, -1.0f}, {1.0f, 0.0f}},  // bottom-right
+      {{-1.0f, 1.0f}, {0.0f, 1.0f}},  // top-left
+      {{1.0f, 1.0f}, {1.0f, 1.0f}}    // top-right
+  };
+
+  static constexpr char VERTEX_SHADER[] = R"(
+    attribute vec4 aPosition;
+    attribute vec2 aTexCoord;
+    uniform mat4 uTransformMatrix;
+    varying vec2 vTexCoord;
+
+    void main() {
+        gl_Position = aPosition;
+        vTexCoord = (uTransformMatrix * vec4(aTexCoord, 0.0, 1.0)).xy;
+    }
+  )";
+  static constexpr char FRAGMENT_SHADER[] = R"(
+    #extension GL_OES_EGL_image_external : require
+    precision mediump float;
+    varying vec2 vTexCoord;
+    uniform samplerExternalOES uTexture;
+
+    void main() {
+        gl_FragColor = texture2D(uTexture, vTexCoord);
+    }
+  )";
+};
+
+} // namespace vision

android/src/main/cpp/VideoPipeline.cpp

@@ -0,0 +1,133 @@
+//
+// Created by Marc Rousavy on 25.08.23.
+//
+
+#include "VideoPipeline.h"
+#include "OpenGLError.h"
+
+#include <android/native_window_jni.h>
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+#include <EGL/egl.h>
+
+namespace vision {
+
+jni::local_ref<VideoPipeline::jhybriddata> VideoPipeline::initHybrid(jni::alias_ref<jhybridobject> jThis, int width, int height) {
+  return makeCxxInstance(jThis, width, height);
+}
+
+VideoPipeline::VideoPipeline(jni::alias_ref<jhybridobject> jThis, int width, int height): _javaPart(jni::make_global(jThis)) {
+  _width = width;
+  _height = height;
+  _context = OpenGLContext::CreateWithOffscreenSurface(width, height);
+}
+
+VideoPipeline::~VideoPipeline() {
+  // 1. Remove output surfaces
+  removeFrameProcessorOutputSurface();
+  removeRecordingSessionOutputSurface();
+  removePreviewOutputSurface();
+  // 2. Delete the input textures
+  if (_inputTextureId != NO_TEXTURE) {
+    glDeleteTextures(1, &_inputTextureId);
+    _inputTextureId = NO_TEXTURE;
+  }
+  // 4. Destroy all surfaces
+  _previewOutput = nullptr;
+  _frameProcessorOutput = nullptr;
+  _recordingSessionOutput = nullptr;
+  // 5. Destroy the OpenGL context
+  _context = nullptr;
+}
+
+void VideoPipeline::removeFrameProcessorOutputSurface() {
+  if (_frameProcessorOutput) _frameProcessorOutput->destroy();
+  _frameProcessorOutput = nullptr;
+}
+
+void VideoPipeline::setFrameProcessorOutputSurface(jobject surface) {
+  // 1. Delete existing output surface
+  removeFrameProcessorOutputSurface();
+
+  // 2. Set new output surface if it is not null
+  ANativeWindow* window = ANativeWindow_fromSurface(jni::Environment::current(), surface);
+  _frameProcessorOutput = OpenGLRenderer::CreateWithWindowSurface(_context, window);
+}
+
+void VideoPipeline::removeRecordingSessionOutputSurface() {
+  if (_recordingSessionOutput) _recordingSessionOutput->destroy();
+  _recordingSessionOutput = nullptr;
+}
+
+void VideoPipeline::setRecordingSessionOutputSurface(jobject surface) {
+  // 1. Delete existing output surface
+  removeRecordingSessionOutputSurface();
+
+  // 2. Set new output surface if it is not null
+  ANativeWindow* window = ANativeWindow_fromSurface(jni::Environment::current(), surface);
+  _recordingSessionOutput = OpenGLRenderer::CreateWithWindowSurface(_context, window);
+}
+
+void VideoPipeline::removePreviewOutputSurface() {
+  if (_previewOutput) _previewOutput->destroy();
+  _previewOutput = nullptr;
+}
+
+void VideoPipeline::setPreviewOutputSurface(jobject surface) {
+  // 1. Delete existing output surface
+  removePreviewOutputSurface();
+
+  // 2. Set new output surface if it is not null
+  ANativeWindow* window = ANativeWindow_fromSurface(jni::Environment::current(), surface);
+  _previewOutput = OpenGLRenderer::CreateWithWindowSurface(_context, window);
+}
+
+int VideoPipeline::getInputTextureId() {
+  if (_inputTextureId != NO_TEXTURE) return static_cast<int>(_inputTextureId);
+
+  _inputTextureId = _context->createTexture();
+
+  return static_cast<int>(_inputTextureId);
+}
+
+void VideoPipeline::onBeforeFrame() {
+  _context->use();
+
+  glBindTexture(GL_TEXTURE_EXTERNAL_OES, _inputTextureId);
+}
+
+void VideoPipeline::onFrame(jni::alias_ref<jni::JArrayFloat> transformMatrixParam) {
+  // Get the OpenGL transform Matrix (transforms, scales, rotations)
+  float transformMatrix[16];
+  transformMatrixParam->getRegion(0, 16, transformMatrix);
+
+  if (_previewOutput) {
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Rendering to Preview..");
+    _previewOutput->renderTextureToSurface(_inputTextureId, transformMatrix);
+  }
+  if (_frameProcessorOutput) {
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Rendering to FrameProcessor..");
+    _frameProcessorOutput->renderTextureToSurface(_inputTextureId, transformMatrix);
+  }
+  if (_recordingSessionOutput) {
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Rendering to RecordingSession..");
+    _recordingSessionOutput->renderTextureToSurface(_inputTextureId, transformMatrix);
+  }
+}
+
+void VideoPipeline::registerNatives() {
+  registerHybrid({
+    makeNativeMethod("initHybrid", VideoPipeline::initHybrid),
+    makeNativeMethod("setFrameProcessorOutputSurface", VideoPipeline::setFrameProcessorOutputSurface),
+    makeNativeMethod("removeFrameProcessorOutputSurface", VideoPipeline::removeFrameProcessorOutputSurface),
+    makeNativeMethod("setRecordingSessionOutputSurface", VideoPipeline::setRecordingSessionOutputSurface),
+    makeNativeMethod("removeRecordingSessionOutputSurface", VideoPipeline::removeRecordingSessionOutputSurface),
+    makeNativeMethod("setPreviewOutputSurface", VideoPipeline::setPreviewOutputSurface),
+    makeNativeMethod("removePreviewOutputSurface", VideoPipeline::removePreviewOutputSurface),
+    makeNativeMethod("getInputTextureId", VideoPipeline::getInputTextureId),
+    makeNativeMethod("onBeforeFrame", VideoPipeline::onBeforeFrame),
+    makeNativeMethod("onFrame", VideoPipeline::onFrame),
+  });
+}
+
+} // namespace vision

android/src/main/cpp/VideoPipeline.h

@@ -0,0 +1,72 @@
+//
+// Created by Marc Rousavy on 25.08.23.
+//
+
+#pragma once
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+#include <EGL/egl.h>
+#include <android/native_window.h>
+#include "PassThroughShader.h"
+#include "OpenGLRenderer.h"
+#include "OpenGLContext.h"
+#include <memory>
+
+namespace vision {
+
+#define NO_TEXTURE 0
+
+using namespace facebook;
+
+class VideoPipeline: public jni::HybridClass<VideoPipeline> {
+ public:
+  static auto constexpr kJavaDescriptor = "Lcom/mrousavy/camera/utils/VideoPipeline;";
+  static jni::local_ref<jhybriddata> initHybrid(jni::alias_ref<jhybridobject> jThis, int width, int height);
+  static void registerNatives();
+
+ public:
+  ~VideoPipeline();
+
+  // -> SurfaceTexture input
+  int getInputTextureId();
+
+  // <- Frame Processor output
+  void setFrameProcessorOutputSurface(jobject surface);
+  void removeFrameProcessorOutputSurface();
+
+  // <- MediaRecorder output
+  void setRecordingSessionOutputSurface(jobject surface);
+  void removeRecordingSessionOutputSurface();
+
+  // <- Preview output
+  void setPreviewOutputSurface(jobject surface);
+  void removePreviewOutputSurface();
+
+  // Frame callbacks
+  void onBeforeFrame();
+  void onFrame(jni::alias_ref<jni::JArrayFloat> transformMatrix);
+
+ private:
+  // Private constructor. Use `create(..)` to create new instances.
+  explicit VideoPipeline(jni::alias_ref<jhybridobject> jThis, int width, int height);
+
+ private:
+  // Input Surface Texture
+  GLuint _inputTextureId = NO_TEXTURE;
+  int _width = 0;
+  int _height = 0;
+
+  // Output Contexts
+  std::shared_ptr<OpenGLContext> _context = nullptr;
+  std::unique_ptr<OpenGLRenderer> _frameProcessorOutput = nullptr;
+  std::unique_ptr<OpenGLRenderer> _recordingSessionOutput = nullptr;
+  std::unique_ptr<OpenGLRenderer> _previewOutput = nullptr;
+
+ private:
+  friend HybridBase;
+  jni::global_ref<javaobject> _javaPart;
+  static constexpr auto TAG = "VideoPipeline";
+};
+
+} // namespace vision

android/src/main/cpp/VisionCamera.cpp

@@ -5,12 +5,14 @@
 #include "JVisionCameraProxy.h"
 #include "VisionCameraProxy.h"
 #include "SkiaRenderer.h"
+#include "VideoPipeline.h"
 
 JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *) {
   return facebook::jni::initialize(vm, [] {
     vision::VisionCameraInstaller::registerNatives();
     vision::JVisionCameraProxy::registerNatives();
     vision::JVisionCameraScheduler::registerNatives();
+    vision::VideoPipeline::registerNatives();
 #if VISION_CAMERA_ENABLE_FRAME_PROCESSORS
     vision::JFrameProcessor::registerNatives();
 #endif

android/src/main/cpp/frameprocessor/FrameHostObject.cpp

@@ -4,7 +4,6 @@
 
 #include "FrameHostObject.h"
 
-#include <android/log.h>
 #include <fbjni/fbjni.h>
 #include <jni.h>
 

android/src/main/cpp/frameprocessor/FrameHostObject.h

@@ -27,9 +27,6 @@ class JSI_EXPORT FrameHostObject : public jsi::HostObject {
 
  public:
   jni::global_ref<JFrame> frame;
-
- private:
-  static auto constexpr TAG = "VisionCamera";
 };
 
 } // namespace vision

android/src/main/cpp/frameprocessor/JSIJNIConversion.cpp

@@ -68,7 +68,6 @@ jni::local_ref<jni::JMap<jstring, jobject>> JSIJNIConversion::convertJSIObjectTo
 
         auto map = convertJSIObjectToJNIMap(runtime, valueAsObject);
         hashMap->put(key, map);
-
       }
 
     } else {
@@ -139,8 +138,7 @@ jsi::Value JSIJNIConversion::convertJNIObjectToJSIValue(jsi::Runtime &runtime, c
       result.setProperty(runtime, key.c_str(), jsiValue);
     }
     return result;
-
-  } if (object->isInstanceOf(JFrame::javaClassStatic())) {
+  } else if (object->isInstanceOf(JFrame::javaClassStatic())) {
     // Frame
     auto frame = static_ref_cast<JFrame>(object);
 

android/src/main/cpp/frameprocessor/java-bindings/JVisionCameraScheduler.cpp

@@ -22,8 +22,8 @@ void JVisionCameraScheduler::dispatchAsync(const std::function<void()>& job) {
 
 void JVisionCameraScheduler::scheduleTrigger() {
   // 2. schedule `triggerUI` to be called on the java thread
-  static auto method = javaPart_->getClass()->getMethod<void()>("scheduleTrigger");
-  method(javaPart_.get());
+  static auto method = _javaPart->getClass()->getMethod<void()>("scheduleTrigger");
+  method(_javaPart.get());
 }
 
 void JVisionCameraScheduler::trigger() {

android/src/main/cpp/frameprocessor/java-bindings/JVisionCameraScheduler.h

@@ -33,12 +33,12 @@ class JVisionCameraScheduler : public jni::HybridClass<JVisionCameraScheduler> {
 
  private:
   friend HybridBase;
-  jni::global_ref<JVisionCameraScheduler::javaobject> javaPart_;
+  jni::global_ref<JVisionCameraScheduler::javaobject> _javaPart;
   std::queue<std::function<void()>> _jobs;
   std::mutex _mutex;
 
   explicit JVisionCameraScheduler(jni::alias_ref<JVisionCameraScheduler::jhybridobject> jThis):
-    javaPart_(jni::make_global(jThis)) {}
+    _javaPart(jni::make_global(jThis)) {}
 
   // Schedules a call to `trigger` on the VisionCamera FP Thread
   void scheduleTrigger();

android/src/main/java/com/mrousavy/camera/CameraSession.kt

@@ -23,7 +23,6 @@ import com.mrousavy.camera.extensions.createPhotoCaptureRequest
 import com.mrousavy.camera.extensions.openCamera
 import com.mrousavy.camera.extensions.tryClose
 import com.mrousavy.camera.extensions.zoomed
-import com.mrousavy.camera.frameprocessor.Frame
 import com.mrousavy.camera.frameprocessor.FrameProcessor
 import com.mrousavy.camera.parsers.Flash
 import com.mrousavy.camera.parsers.Orientation
@@ -88,8 +87,17 @@ class CameraSession(private val context: Context,
   private val mutex = Mutex()
   private var isRunning = false
   private var enableTorch = false
+  // Video Outputs
   private var recording: RecordingSession? = null
-  private var frameProcessor: FrameProcessor? = null
+    set(value) {
+      field = value
+      updateVideoOutputs()
+    }
+  var frameProcessor: FrameProcessor? = null
+    set(value) {
+      field = value
+      updateVideoOutputs()
+    }
 
   override val coroutineContext: CoroutineContext = CameraQueues.cameraQueue.coroutineDispatcher
 
@@ -130,8 +138,14 @@ class CameraSession(private val context: Context,
       Log.i(TAG, "Nothing changed in configuration, canceling..")
     }
 
-    this.cameraId = cameraId
+    // 1. Close previous outputs
+    this.outputs?.close()
+    // 2. Assign new outputs
     this.outputs = outputs
+    // 3. Update with existing render targets (surfaces)
+    updateVideoOutputs()
+
+    this.cameraId = cameraId
     launch {
       startRunning()
     }
@@ -183,8 +197,12 @@ class CameraSession(private val context: Context,
     }
   }
 
-  fun setFrameProcessor(frameProcessor: FrameProcessor?) {
-    this.frameProcessor = frameProcessor
+  private fun updateVideoOutputs() {
+    val videoPipeline = outputs?.videoOutput?.videoPipeline ?: return
+    val previewOutput = outputs?.previewOutput
+    videoPipeline.setRecordingSessionOutput(this.recording)
+    videoPipeline.setFrameProcessorOutput(this.frameProcessor)
+    videoPipeline.setPreviewOutput(previewOutput?.surface)
   }
 
   suspend fun takePhoto(qualityPrioritization: QualityPrioritization,
@@ -229,20 +247,6 @@ class CameraSession(private val context: Context,
     photoOutputSynchronizer.set(image.timestamp, image)
   }
 
-  override fun onVideoFrameCaptured(image: Image) {
-    // TODO: Correctly get orientation and everything
-    val frame = Frame(image, System.currentTimeMillis(), Orientation.PORTRAIT, false)
-    frame.incrementRefCount()
-
-    // Call (Skia-) Frame Processor
-    frameProcessor?.call(frame)
-
-    // Write Image to the Recording
-    recording?.appendImage(image)
-
-    frame.decrementRefCount()
-  }
-
   suspend fun startRecording(enableAudio: Boolean,
                              codec: VideoCodec,
                              fileType: VideoFileType,
@@ -253,7 +257,7 @@ class CameraSession(private val context: Context,
       val outputs = outputs ?: throw CameraNotReadyError()
       val videoOutput = outputs.videoOutput ?: throw VideoNotEnabledError()
 
-      val recording = RecordingSession(context, enableAudio, videoOutput.size, fps, codec, orientation, fileType, callback, onError)
+      val recording = RecordingSession(context, videoOutput.size, enableAudio, fps, codec, orientation, fileType, callback, onError)
       recording.start()
       this.recording = recording
     }
@@ -497,7 +501,8 @@ class CameraSession(private val context: Context,
         val captureRequest = camera.createCaptureRequest(template)
         outputs.previewOutput?.let { output ->
           Log.i(TAG, "Adding output surface ${output.outputType}..")
-          captureRequest.addTarget(output.surface)
+          // TODO: Add here again?
+          // captureRequest.addTarget(output.surface)
         }
         outputs.videoOutput?.let { output ->
           Log.i(TAG, "Adding output surface ${output.outputType}..")

android/src/main/java/com/mrousavy/camera/CameraView.kt

@@ -96,7 +96,7 @@ class CameraView(context: Context) : FrameLayout(context) {
   internal var frameProcessor: FrameProcessor? = null
     set(value) {
       field = value
-      cameraSession.setFrameProcessor(frameProcessor)
+      cameraSession.frameProcessor = frameProcessor
     }
 
   private val inputOrientation: Orientation

android/src/main/java/com/mrousavy/camera/CameraViewModule.kt

@@ -180,11 +180,6 @@ class CameraViewModule(reactContext: ReactApplicationContext): ReactContextBaseJ
 
   @ReactMethod
   fun requestCameraPermission(promise: Promise) {
-    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
-      // API 21 and below always grants permission on app install
-      return promise.resolve(PermissionStatus.GRANTED.unionValue)
-    }
-
     val activity = reactApplicationContext.currentActivity
     if (activity is PermissionAwareActivity) {
       val currentRequestCode = RequestCode++
@@ -205,11 +200,6 @@ class CameraViewModule(reactContext: ReactApplicationContext): ReactContextBaseJ
 
   @ReactMethod
   fun requestMicrophonePermission(promise: Promise) {
-    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
-      // API 21 and below always grants permission on app install
-      return promise.resolve(PermissionStatus.GRANTED.unionValue)
-    }
-
     val activity = reactApplicationContext.currentActivity
     if (activity is PermissionAwareActivity) {
       val currentRequestCode = RequestCode++

android/src/main/java/com/mrousavy/camera/extensions/CameraCharacteristics+getOutputSizes.kt

@@ -63,10 +63,6 @@ fun CameraCharacteristics.getVideoSizes(cameraId: String, format: Int): List<Siz
 fun CameraCharacteristics.getPhotoSizes(format: Int): List<Size> {
   val config = this.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP)!!
   val sizes = config.getOutputSizes(format) ?: emptyArray()
-  val highResSizes = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
-    config.getHighResolutionOutputSizes(format)
-  } else {
-    null
-  } ?: emptyArray()
+  val highResSizes = config.getHighResolutionOutputSizes(format) ?: emptyArray()
   return sizes.plus(highResSizes).toList()
 }

android/src/main/java/com/mrousavy/camera/extensions/CameraDevice+createCaptureSession.kt

@@ -8,7 +8,6 @@ import android.hardware.camera2.params.OutputConfiguration
 import android.hardware.camera2.params.SessionConfiguration
 import android.os.Build
 import android.util.Log
-import android.view.Surface
 import androidx.annotation.RequiresApi
 import com.mrousavy.camera.CameraQueues
 import com.mrousavy.camera.CameraSessionCannotBeConfiguredError
@@ -63,47 +62,35 @@ suspend fun CameraDevice.createCaptureSession(cameraManager: CameraManager,
       }
     }
 
-    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
-      // API >= 24
-      val outputConfigurations = arrayListOf<OutputConfiguration>()
-      outputs.previewOutput?.let { output ->
-        outputConfigurations.add(output.toOutputConfiguration(characteristics))
-      }
-      outputs.photoOutput?.let { output ->
-        outputConfigurations.add(output.toOutputConfiguration(characteristics))
-      }
-      outputs.videoOutput?.let { output ->
-        outputConfigurations.add(output.toOutputConfiguration(characteristics))
-      }
-      if (outputs.enableHdr == true && Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
-        val supportedProfiles = characteristics.get(CameraCharacteristics.REQUEST_AVAILABLE_DYNAMIC_RANGE_PROFILES)
-        val hdrProfile = supportedProfiles?.bestProfile ?: supportedProfiles?.supportedProfiles?.firstOrNull()
-        if (hdrProfile != null) {
-          Log.i(TAG, "Camera $id: Using HDR Profile $hdrProfile...")
-          outputConfigurations.forEach { it.dynamicRangeProfile = hdrProfile }
-        } else {
-          Log.w(TAG, "Camera $id: HDR was enabled, but the device does not support any matching HDR profile!")
-        }
-      }
-
-      if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
-        // API >=28
-        Log.i(TAG, "Using new API (>=28)")
-        val config = SessionConfiguration(sessionType.toSessionType(), outputConfigurations, queue.executor, callback)
-        this.createCaptureSession(config)
+    val outputConfigurations = arrayListOf<OutputConfiguration>()
+    outputs.previewOutput?.let { output ->
+      // TODO: add here again?
+      // outputConfigurations.add(output.toOutputConfiguration(characteristics))
+    }
+    outputs.photoOutput?.let { output ->
+      outputConfigurations.add(output.toOutputConfiguration(characteristics))
+    }
+    outputs.videoOutput?.let { output ->
+      outputConfigurations.add(output.toOutputConfiguration(characteristics))
+    }
+    if (outputs.enableHdr == true && Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+      val supportedProfiles = characteristics.get(CameraCharacteristics.REQUEST_AVAILABLE_DYNAMIC_RANGE_PROFILES)
+      val hdrProfile = supportedProfiles?.bestProfile ?: supportedProfiles?.supportedProfiles?.firstOrNull()
+      if (hdrProfile != null) {
+        Log.i(TAG, "Camera $id: Using HDR Profile $hdrProfile...")
+        outputConfigurations.forEach { it.dynamicRangeProfile = hdrProfile }
       } else {
-        // API >=24
-        Log.i(TAG, "Using legacy API (<28)")
-        this.createCaptureSessionByOutputConfigurations(outputConfigurations, callback, queue.handler)
+        Log.w(TAG, "Camera $id: HDR was enabled, but the device does not support any matching HDR profile!")
       }
+    }
+
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
+      Log.i(TAG, "Using new API (>=28)")
+      val config = SessionConfiguration(sessionType.toSessionType(), outputConfigurations, queue.executor, callback)
+      this.createCaptureSession(config)
     } else {
-      // API <24
-      Log.i(TAG, "Using legacy API (<24)")
-      val surfaces = arrayListOf<Surface>()
-      outputs.previewOutput?.let { surfaces.add(it.surface) }
-      outputs.photoOutput?.let { surfaces.add(it.surface) }
-      outputs.videoOutput?.let { surfaces.add(it.surface) }
-      this.createCaptureSession(surfaces, callback, queue.handler)
+      Log.i(TAG, "Using legacy API (<28)")
+      this.createCaptureSessionByOutputConfigurations(outputConfigurations, callback, queue.handler)
     }
   }
 }

android/src/main/java/com/mrousavy/camera/utils/RecordingSession.kt

@@ -1,7 +1,6 @@
 package com.mrousavy.camera.utils
 
 import android.content.Context
-import android.media.Image
 import android.media.ImageWriter
 import android.media.MediaCodec
 import android.media.MediaRecorder
@@ -13,12 +12,11 @@ import com.mrousavy.camera.RecorderError
 import com.mrousavy.camera.parsers.Orientation
 import com.mrousavy.camera.parsers.VideoCodec
 import com.mrousavy.camera.parsers.VideoFileType
-import com.mrousavy.camera.utils.outputs.CameraOutputs
 import java.io.File
 
 class RecordingSession(context: Context,
+                       val size: Size,
                        private val enableAudio: Boolean,
-                       private val videoSize: Size,
                        private val fps: Int? = null,
                        private val codec: VideoCodec = VideoCodec.H264,
                        private val orientation: Orientation,
@@ -40,14 +38,9 @@ class RecordingSession(context: Context,
   private val outputFile: File
   private var startTime: Long? = null
   private var imageWriter: ImageWriter? = null
-  val surface: Surface
+  val surface: Surface = MediaCodec.createPersistentInputSurface()
 
   init {
-    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
-      throw Error("Video Recording is only supported on Devices running Android version 23 (M) or newer.")
-    }
-
-    surface = MediaCodec.createPersistentInputSurface()
 
     outputFile = File.createTempFile("mrousavy", fileType.toExtension(), context.cacheDir)
 
@@ -61,7 +54,7 @@ class RecordingSession(context: Context,
     recorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4)
     recorder.setOutputFile(outputFile.absolutePath)
     recorder.setVideoEncodingBitRate(VIDEO_BIT_RATE)
-    recorder.setVideoSize(videoSize.width, videoSize.height)
+    recorder.setVideoSize(size.height, size.width)
     if (fps != null) recorder.setVideoFrameRate(fps)
 
     Log.i(TAG, "Using $codec Video Codec..")
@@ -74,7 +67,7 @@ class RecordingSession(context: Context,
       recorder.setAudioChannels(AUDIO_CHANNELS)
     }
     recorder.setInputSurface(surface)
-    recorder.setOrientationHint(orientation.toDegrees())
+    //recorder.setOrientationHint(orientation.toDegrees())
 
     recorder.setOnErrorListener { _, what, extra ->
       Log.e(TAG, "MediaRecorder Error: $what ($extra)")
@@ -109,10 +102,8 @@ class RecordingSession(context: Context,
         recorder.stop()
         recorder.release()
 
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
-          imageWriter?.close()
-          imageWriter = null
-        }
+        imageWriter?.close()
+        imageWriter = null
       } catch (e: Error) {
         Log.e(TAG, "Failed to stop MediaRecorder!", e)
       }
@@ -125,9 +116,6 @@ class RecordingSession(context: Context,
 
   fun pause() {
     synchronized(this) {
-      if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) {
-        throw Error("Pausing a recording is only supported on Devices running Android version 24 (N) or newer.")
-      }
       Log.i(TAG, "Pausing Recording Session..")
       recorder.pause()
     }
@@ -135,32 +123,13 @@ class RecordingSession(context: Context,
 
   fun resume() {
     synchronized(this) {
-      if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) {
-        throw Error("Resuming a recording is only supported on Devices running Android version 24 (N) or newer.")
-      }
       Log.i(TAG, "Resuming Recording Session..")
       recorder.resume()
     }
   }
 
-  fun appendImage(image: Image) {
-    synchronized(this) {
-      if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
-        throw Error("Video Recording is only supported on Devices running Android version 23 (M) or newer.")
-      }
-
-      // TODO: Correctly mirror/flip Image in OpenGL pipeline, otherwise flipping camera while recording results in inverted frames
-
-      if (imageWriter == null) {
-        imageWriter = ImageWriter.newInstance(surface, CameraOutputs.VIDEO_OUTPUT_BUFFER_SIZE)
-      }
-      image.timestamp = System.nanoTime()
-      imageWriter!!.queueInputImage(image)
-    }
-  }
-
   override fun toString(): String {
     val audio = if (enableAudio) "with audio" else "without audio"
-    return "${videoSize.width} x ${videoSize.height} @ $fps FPS $codec $fileType $orientation RecordingSession ($audio)"
+    return "${size.width} x ${size.height} @ $fps FPS $codec $fileType $orientation RecordingSession ($audio)"
   }
 }

android/src/main/java/com/mrousavy/camera/utils/VideoPipeline.kt

@@ -0,0 +1,185 @@
+package com.mrousavy.camera.utils
+
+import android.graphics.ImageFormat
+import android.graphics.SurfaceTexture
+import android.media.ImageReader
+import android.media.ImageWriter
+import android.media.MediaRecorder
+import android.util.Log
+import android.view.Surface
+import com.facebook.jni.HybridData
+import com.mrousavy.camera.frameprocessor.Frame
+import com.mrousavy.camera.frameprocessor.FrameProcessor
+import com.mrousavy.camera.parsers.Orientation
+import java.io.Closeable
+
+/**
+ * An OpenGL pipeline for streaming Camera Frames to one or more outputs.
+ * Currently, [VideoPipeline] can stream to a [FrameProcessor] and a [MediaRecorder].
+ *
+ * @param [width] The width of the Frames to stream (> 0)
+ * @param [height] The height of the Frames to stream (> 0)
+ * @param [format] The format of the Frames to stream. ([ImageFormat.PRIVATE], [ImageFormat.YUV_420_888] or [ImageFormat.JPEG])
+ */
+@Suppress("KotlinJniMissingFunction")
+class VideoPipeline(val width: Int,
+                    val height: Int,
+                    val format: Int = ImageFormat.PRIVATE): SurfaceTexture.OnFrameAvailableListener, Closeable {
+  companion object {
+    private const val MAX_IMAGES = 5
+    private const val TAG = "VideoPipeline"
+  }
+
+  private val mHybridData: HybridData
+  private var openGLTextureId: Int? = null
+  private var transformMatrix = FloatArray(16)
+  private var isActive = true
+
+  // Output 1
+  private var frameProcessor: FrameProcessor? = null
+  private var imageReader: ImageReader? = null
+
+  // Output 2
+  private var recordingSession: RecordingSession? = null
+
+  // Output 3
+  private var previewSurface: Surface? = null
+
+  // Input
+  private val surfaceTexture: SurfaceTexture
+  val surface: Surface
+
+  init {
+    mHybridData = initHybrid(width, height)
+    surfaceTexture = SurfaceTexture(false)
+    surfaceTexture.setDefaultBufferSize(width, height)
+    surfaceTexture.setOnFrameAvailableListener(this)
+    surface = Surface(surfaceTexture)
+  }
+
+  override fun close() {
+    synchronized(this) {
+      isActive = false
+      imageReader?.close()
+      imageReader = null
+      frameProcessor = null
+      recordingSession = null
+      surfaceTexture.release()
+      mHybridData.resetNative()
+    }
+  }
+
+  override fun onFrameAvailable(surfaceTexture: SurfaceTexture) {
+    synchronized(this) {
+      if (!isActive) return@synchronized
+
+      // 1. Attach Surface to OpenGL context
+      if (openGLTextureId == null) {
+        openGLTextureId = getInputTextureId()
+        surfaceTexture.attachToGLContext(openGLTextureId!!)
+        Log.i(TAG, "Attached Texture to Context $openGLTextureId")
+      }
+
+      // 2. Prepare the OpenGL context (eglMakeCurrent)
+      onBeforeFrame()
+
+      // 3. Update the OpenGL texture
+      surfaceTexture.updateTexImage()
+
+      // 4. Get the transform matrix from the SurfaceTexture (rotations/scales applied by Camera)
+      surfaceTexture.getTransformMatrix(transformMatrix)
+
+      // 5. Draw it with applied rotation/mirroring
+      onFrame(transformMatrix)
+    }
+  }
+
+  private fun getImageReader(): ImageReader {
+    val imageReader = ImageReader.newInstance(width, height, format, MAX_IMAGES)
+    imageReader.setOnImageAvailableListener({ reader ->
+      Log.i("VideoPipeline", "ImageReader::onImageAvailable!")
+      val image = reader.acquireLatestImage() ?: return@setOnImageAvailableListener
+
+      // TODO: Get correct orientation and isMirrored
+      val frame = Frame(image, image.timestamp, Orientation.PORTRAIT, false)
+      frame.incrementRefCount()
+      frameProcessor?.call(frame)
+      frame.decrementRefCount()
+    }, null)
+    return imageReader
+  }
+
+  /**
+   * Configures the Pipeline to also call the given [FrameProcessor].
+   * * If the [frameProcessor] is `null`, this output channel will be removed.
+   * * If the [frameProcessor] is not `null`, the [VideoPipeline] will create Frames
+   * using an [ImageWriter] and call the [FrameProcessor] with those Frames.
+   */
+  fun setFrameProcessorOutput(frameProcessor: FrameProcessor?) {
+    synchronized(this) {
+      Log.i(TAG, "Setting $width x $height FrameProcessor Output...")
+      this.frameProcessor = frameProcessor
+
+      if (frameProcessor != null) {
+        if (this.imageReader == null) {
+          // 1. Create new ImageReader that just calls the Frame Processor
+          this.imageReader = getImageReader()
+        }
+
+        // 2. Configure OpenGL pipeline to stream Frames into the ImageReader's surface
+        setFrameProcessorOutputSurface(imageReader!!.surface)
+      } else {
+        // 1. Configure OpenGL pipeline to stop streaming Frames into the ImageReader's surface
+        removeFrameProcessorOutputSurface()
+
+        // 2. Close the ImageReader
+        this.imageReader?.close()
+        this.imageReader = null
+      }
+    }
+  }
+
+  /**
+   * Configures the Pipeline to also write Frames to a Surface from a [MediaRecorder].
+   * * If the [surface] is `null`, this output channel will be removed.
+   * * If the [surface] is not `null`, the [VideoPipeline] will write Frames to this Surface.
+   */
+  fun setRecordingSessionOutput(recordingSession: RecordingSession?) {
+    synchronized(this) {
+      Log.i(TAG, "Setting $width x $height RecordingSession Output...")
+      if (recordingSession != null) {
+        // Configure OpenGL pipeline to stream Frames into the Recording Session's surface
+        setRecordingSessionOutputSurface(recordingSession.surface)
+        this.recordingSession = recordingSession
+      } else {
+        // Configure OpenGL pipeline to stop streaming Frames into the Recording Session's surface
+        removeRecordingSessionOutputSurface()
+        this.recordingSession = null
+      }
+    }
+  }
+
+  fun setPreviewOutput(surface: Surface?) {
+    synchronized(this) {
+      Log.i(TAG, "Setting Preview Output...")
+      if (surface != null) {
+        setPreviewOutputSurface(surface)
+        this.previewSurface = surface
+      } else {
+        removePreviewOutputSurface()
+        this.previewSurface = null
+      }
+    }
+  }
+
+  private external fun getInputTextureId(): Int
+  private external fun onBeforeFrame()
+  private external fun onFrame(transformMatrix: FloatArray)
+  private external fun setFrameProcessorOutputSurface(surface: Any)
+  private external fun removeFrameProcessorOutputSurface()
+  private external fun setRecordingSessionOutputSurface(surface: Any)
+  private external fun removeRecordingSessionOutputSurface()
+  private external fun setPreviewOutputSurface(surface: Any)
+  private external fun removePreviewOutputSurface()
+  private external fun initHybrid(width: Int, height: Int): HybridData
+}

android/src/main/java/com/mrousavy/camera/utils/outputs/CameraOutputs.kt

@@ -1,11 +1,9 @@
 package com.mrousavy.camera.utils.outputs
 
 import android.graphics.ImageFormat
-import android.hardware.HardwareBuffer
 import android.hardware.camera2.CameraManager
 import android.media.Image
 import android.media.ImageReader
-import android.os.Build
 import android.util.Log
 import android.util.Size
 import android.view.Surface
@@ -14,6 +12,7 @@ import com.mrousavy.camera.extensions.closestToOrMax
 import com.mrousavy.camera.extensions.getPhotoSizes
 import com.mrousavy.camera.extensions.getPreviewSize
 import com.mrousavy.camera.extensions.getVideoSizes
+import com.mrousavy.camera.utils.VideoPipeline
 import java.io.Closeable
 
 class CameraOutputs(val cameraId: String,
@@ -25,7 +24,6 @@ class CameraOutputs(val cameraId: String,
                     val callback: Callback): Closeable {
   companion object {
     private const val TAG = "CameraOutputs"
-    const val VIDEO_OUTPUT_BUFFER_SIZE = 3
     const val PHOTO_OUTPUT_BUFFER_SIZE = 3
   }
 
@@ -39,14 +37,13 @@ class CameraOutputs(val cameraId: String,
 
   interface Callback {
     fun onPhotoCaptured(image: Image)
-    fun onVideoFrameCaptured(image: Image)
   }
 
   var previewOutput: SurfaceOutput? = null
     private set
   var photoOutput: ImageReaderOutput? = null
     private set
-  var videoOutput: SurfaceOutput? = null
+  var videoOutput: VideoPipelineOutput? = null
     private set
 
   val size: Int
@@ -118,23 +115,11 @@ class CameraOutputs(val cameraId: String,
 
     // Video output: High resolution repeating images (startRecording() or useFrameProcessor())
     if (video != null) {
-      if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) throw Error("Video Recordings and/or Frame Processors are only available on API 29 and above!")
-
       val size = characteristics.getVideoSizes(cameraId, video.format).closestToOrMax(video.targetSize)
-
-      val flags = HardwareBuffer.USAGE_GPU_SAMPLED_IMAGE or HardwareBuffer.USAGE_VIDEO_ENCODE
-      val imageReader = ImageReader.newInstance(size.width, size.height, video.format, VIDEO_OUTPUT_BUFFER_SIZE, flags)
-      imageReader.setOnImageAvailableListener({ reader ->
-        try {
-          val image = reader.acquireNextImage() ?: return@setOnImageAvailableListener
-          callback.onVideoFrameCaptured(image)
-        } catch (e: IllegalStateException) {
-          Log.e(TAG, "Failed to acquire a new Image, dropping a Frame.. The Frame Processor cannot keep up with the Camera's FPS!", e)
-        }
-      }, CameraQueues.videoQueue.handler)
+      val videoPipeline = VideoPipeline(size.width, size.height, video.format)
 
       Log.i(TAG, "Adding ${size.width}x${size.height} video output. (Format: ${video.format})")
-      videoOutput = ImageReaderOutput(imageReader, SurfaceOutput.OutputType.VIDEO)
+      videoOutput = VideoPipelineOutput(videoPipeline, SurfaceOutput.OutputType.VIDEO)
     }
 
     Log.i(TAG, "Prepared $size Outputs for Camera $cameraId!")

android/src/main/java/com/mrousavy/camera/utils/outputs/SurfaceOutput.kt

@@ -35,7 +35,6 @@ open class SurfaceOutput(val surface: Surface,
     }
   }
 
-  @RequiresApi(Build.VERSION_CODES.N)
   fun toOutputConfiguration(characteristics: CameraCharacteristics): OutputConfiguration {
     val result = OutputConfiguration(surface)
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {

android/src/main/java/com/mrousavy/camera/utils/outputs/VideoPipelineOutput.kt

@@ -0,0 +1,22 @@
+package com.mrousavy.camera.utils.outputs
+
+import android.util.Log
+import android.util.Size
+import com.mrousavy.camera.utils.VideoPipeline
+import java.io.Closeable
+
+/**
+ * A [SurfaceOutput] that uses a [VideoPipeline] as it's surface.
+ */
+class VideoPipelineOutput(val videoPipeline: VideoPipeline,
+                          outputType: OutputType,
+                          dynamicRangeProfile: Long? = null): Closeable, SurfaceOutput(videoPipeline.surface, Size(videoPipeline.width, videoPipeline.height), outputType, dynamicRangeProfile) {
+  override fun close() {
+    Log.i(TAG, "Closing ${videoPipeline.width}x${videoPipeline.height} Video Pipeline..")
+    videoPipeline.close()
+  }
+
+  override fun toString(): String {
+    return "$outputType (${videoPipeline.width} x ${videoPipeline.height} in format #${videoPipeline.format})"
+  }
+}

docs/docs/guides/TROUBLESHOOTING.mdx

@@ -75,7 +75,7 @@ Before opening an issue, make sure you try the following:
    2. Set `buildToolsVersion` to `33.0.0` or higher
    3. Set `compileSdkVersion` to `33` or higher
    4. Set `targetSdkVersion` to `33` or higher
-   5. Set `minSdkVersion` to `21` or higher
+   5. Set `minSdkVersion` to `26` or higher
    6. Set `ndkVersion` to `"23.1.7779620"` or higher
    7. Update the Gradle Build-Tools version to `7.3.1` or higher:
       ```

example/android/build.gradle

@@ -3,7 +3,7 @@
 buildscript {
     ext {
         buildToolsVersion = "33.0.0"
-        minSdkVersion = 21
+        minSdkVersion = 26
         compileSdkVersion = 33
         targetSdkVersion = 33
         ndkVersion = "23.1.7779620"