Implement AndroidTextureBuffer::NativeToI420.

talk/app/webrtc/java/jni/native_handle_impl.cc

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 #include "talk/app/webrtc/java/jni/native_handle_impl.h"
 
+#include "talk/app/webrtc/java/jni/jni_helpers.h"
+#include "webrtc/base/bind.h"
 #include "webrtc/base/checks.h"
 #include "webrtc/base/keep_ref_until_done.h"
+#include "webrtc/base/scoped_ptr.h"
 #include "webrtc/base/scoped_ref_ptr.h"
 
 using webrtc::NativeHandleBuffer;
 
 namespace webrtc_jni {
 
+// Aligning pointer to 64 bytes for improved performance, e.g. use SIMD.
+static const int kBufferAlignment = 64;
+
 NativeHandleImpl::NativeHandleImpl(JNIEnv* jni,
                                    jint j_oes_texture_id,
                                    jfloatArray j_transform_matrix)
-    : oes_texture_id(j_oes_texture_id) {
+  : oes_texture_id(j_oes_texture_id) {
   RTC_CHECK_EQ(16, jni->GetArrayLength(j_transform_matrix));
   jfloat* transform_matrix_ptr =
       jni->GetFloatArrayElements(j_transform_matrix, nullptr);
+  // TODO(nisse): Hold on to java float array instead, since it is

[perkj_webrtc, 2015/12/09 09:28:28]

remove this todo. It will not be true when I land the cvo patch.

[nisse-webrtc, 2015/12/09 12:02:21]

Done.

+  // used only for callbacks into java.
   for (int i = 0; i < 16; ++i) {
     sampling_matrix[i] = transform_matrix_ptr[i];
   }
   jni->ReleaseFloatArrayElements(j_transform_matrix, transform_matrix_ptr, 0);
 }
 
 AndroidTextureBuffer::AndroidTextureBuffer(
     int width,
     int height,
     const NativeHandleImpl& native_handle,
+    jobject surface_texture_helper,
     const rtc::Callback0<void>& no_longer_used)
     : webrtc::NativeHandleBuffer(&native_handle_, width, height),
       native_handle_(native_handle),
+      surface_texture_helper_(surface_texture_helper),
       no_longer_used_cb_(no_longer_used) {}
 
 AndroidTextureBuffer::~AndroidTextureBuffer() {
   no_longer_used_cb_();
 }
 
 rtc::scoped_refptr<webrtc::VideoFrameBuffer>
 AndroidTextureBuffer::NativeToI420Buffer() {
-  RTC_NOTREACHED()
-      << "AndroidTextureBuffer::NativeToI420Buffer not implemented.";
-  return nullptr;
+  int y_width = (width()+3) / 4;

[perkj_webrtc, 2015/12/09 09:28:28]

please add comment about the memory layout.

[nisse-webrtc, 2015/12/09 12:02:22]

Done, but I put the comment in SurfaceTextureHelper.java instead.

+  int uv_width = (width()+7) / 8;
+  int stride = 8 * uv_width;
+  int uv_height = (height()+1)/2;
+  size_t size = stride * (height() + uv_height);
+  // The data is owned by the frame, and the normal case is that the
+  // data is deleted by the frame's destructor callback.

[perkj_webrtc, 2015/12/09 09:28:28]

Add TODO to not allocate on each frame. I think we should look into using a pool
here as we talked about earlier.

[nisse-webrtc, 2015/12/09 12:02:22]

Done.

+  rtc::scoped_ptr<uint8_t, webrtc::AlignedFreeDeleter> yuv_data(
+      static_cast<uint8_t*>(webrtc::AlignedMalloc(size, kBufferAlignment)));
+  uint8_t* y_data = yuv_data.get();
+  uint8_t* u_data = y_data + height() * stride;
+  uint8_t* v_data = u_data + stride/2;
+
+  rtc::scoped_refptr<webrtc::VideoFrameBuffer> copy =
+    new rtc::RefCountedObject<webrtc::WrappedI420Buffer>(
+        width(), height(),
+        y_data, stride,
+        u_data, stride,
+        v_data, stride,
+        rtc::Bind(&webrtc::AlignedFree, yuv_data.release()));
+
+  JNIEnv* jni = AttachCurrentThreadIfNeeded();
+  ScopedLocalRefFrame local_ref_frame(jni);
+
+  jmethodID transform_mid = GetMethodID(
+      jni,
+      GetObjectClass(jni, surface_texture_helper_),
+      "textureToYUV",
+      "(Ljava/nio/ByteBuffer;IIII[F)V");
+
+  jobject byte_buffer = jni->NewDirectByteBuffer(y_data, size);
+
+  /* Set u = v = 0. */
+  memset(u_data, 0x80, stride * uv_height);
+
+  // TODO(nisse): Keep java transform matrix around.
+  jfloatArray sampling_matrix = jni->NewFloatArray(16);
+  jni->SetFloatArrayRegion(sampling_matrix, 0, 16,
+                           native_handle_.sampling_matrix);
+
+  jni->CallVoidMethod(surface_texture_helper_,
+                      transform_mid,
+                      byte_buffer, width(), height(), stride,
+                      native_handle_.oes_texture_id, sampling_matrix);
+  CHECK_EXCEPTION(jni) << "textureToYUV throwed an exception";
+
+  return copy;
 }
 
 rtc::scoped_refptr<AndroidTextureBuffer> AndroidTextureBuffer::CropAndScale(
     int cropped_input_width,
     int cropped_input_height,
     int dst_widht,
     int dst_height) {
   // TODO(perkj) Implement cropping.
   RTC_CHECK_EQ(cropped_input_width, width_);
   RTC_CHECK_EQ(cropped_input_height, height_);
 
   // Here we use Bind magic to add a reference count to |this| until the newly
   // created AndroidTextureBuffer is destructed. ScaledFrameNotInUse will be
   // called that happens and when it finishes, the reference count to |this|
   // will be decreased by one.
   return new rtc::RefCountedObject<AndroidTextureBuffer>(
-      dst_widht, dst_height, native_handle_,
+      dst_widht, dst_height, native_handle_, surface_texture_helper_,
       rtc::KeepRefUntilDone(this));
 }
 
 }  // namespace webrtc_jni