Add a field trial to produce VideoFrames in camera capturers.

webrtc/sdk/android/src/jni/camera1session_jni.cc

+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <jni.h>
+
+#include "third_party/libyuv/include/libyuv/convert.h"
+#include "webrtc/rtc_base/checks.h"
+#include "webrtc/rtc_base/logging.h"
+
+namespace webrtc_jni {
+
+extern "C" JNIEXPORT void JNICALL
+Java_org_webrtc_Camera1Session_nativeNV21ToI420(JNIEnv* jni,
+                                                jclass,
+                                                jint width,
+                                                jint height,
+                                                jbyteArray j_src,
+                                                jobject j_dst) {
+  int dst_stride_y = width;
+  int dst_stride_uv = (width + 1) / 2;
+  int dst_chroma_height = (height + 1) / 2;
+
+  RTC_CHECK_GE(jni->GetArrayLength(j_src), width * height * 3 / 2);
+  RTC_CHECK_GE(jni->GetDirectBufferCapacity(j_dst),
+               dst_stride_y * height + 2 * dst_stride_uv * dst_chroma_height);
+
+  jbyte* src_bytes = jni->GetByteArrayElements(j_src, 0);
+  uint8_t* src_y = reinterpret_cast<uint8_t*>(src_bytes);
+  uint8_t* src_uv = src_y + width * height;
+
+  uint8_t* dst_y = static_cast<uint8_t*>(jni->GetDirectBufferAddress(j_dst));
+  uint8_t* dst_u = dst_y + dst_stride_y * height;
+  uint8_t* dst_v = dst_u + dst_stride_uv * dst_chroma_height;
+
+  int ret = libyuv::NV21ToI420(src_y, width, src_uv, width, dst_y, dst_stride_y,

[magjed_webrtc, 2017/07/24 09:51:18]

This is a performance regression compared to the existing
AndroidVideoTrackSource::OnByteBufferFrameCaptured conversion which uses
webrtc::NV12ToI420Scaler. Is it possible to fix?

[sakal, 2017/08/15 12:41:05]

NV21Buffer class should fix this.

+                               dst_u, dst_stride_uv, dst_v, dst_stride_uv,
+                               width, height);
+  if (ret) {
+    LOG(LS_ERROR) << "Error converting NV21 frame to I420: " << ret;
+  }
+
+  jni->ReleaseByteArrayElements(j_src, src_bytes, 0);
+}
+
+}  // namespace webrtc_jni