Reland "Rename stereo video codec to multiplex"

This is a reland of bbdabe50db0cf09f6007dda12a6476dc4602b174.
This was reverted because of breaking internal build. I contacted sheriff
and looked at logs but cannot find anything related to this CL. This was landed
with #3850 build which caused exception, but 3847-3855 seem to all have failed.
I am relanding to see if it will work this time or it will give some related
error message that can guide me.

Original change's description:
> Rename stereo video codec to multiplex
>
> This CL only does the rename from"stereo" to multiplex". With this we have a
> better name that doesn't clash with audio's usage of stereo.
>
> Bug: webrtc:7671
> Change-Id: Iebc3fc20839025f1bc8bcf0e16141bf9744ef652
> Reviewed-on: https://webrtc-review.googlesource.com/43242
> Commit-Queue: Emircan Uysaler <emircan@webrtc.org>
> Reviewed-by: Niklas Enbom <niklas.enbom@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#21769}

TBR=niklas.enbom@webrtc.org

Bug: webrtc:7671
Change-Id: I5934abad1ce28acf02842ea8ee2af7768a826eb8
Reviewed-on: https://webrtc-review.googlesource.com/44520
Reviewed-by: Emircan Uysaler <emircan@webrtc.org>
Commit-Queue: Emircan Uysaler <emircan@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21780}

modules/video_coding/codecs/multiplex/multiplex_encoder_adapter.cc

@@ -0,0 +1,263 @@
+/*
+ *  Copyright (c) 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 "modules/video_coding/codecs/multiplex/include/multiplex_encoder_adapter.h"
+
+#include <cstring>
+
+#include "common_video/include/video_frame.h"
+#include "common_video/include/video_frame_buffer.h"
+#include "common_video/libyuv/include/webrtc_libyuv.h"
+#include "modules/include/module_common_types.h"
+#include "rtc_base/keep_ref_until_done.h"
+#include "rtc_base/logging.h"
+
+namespace webrtc {
+
+// Callback wrapper that helps distinguish returned results from |encoders_|
+// instances.
+class MultiplexEncoderAdapter::AdapterEncodedImageCallback
+    : public webrtc::EncodedImageCallback {
+ public:
+  AdapterEncodedImageCallback(webrtc::MultiplexEncoderAdapter* adapter,
+                              AlphaCodecStream stream_idx)
+      : adapter_(adapter), stream_idx_(stream_idx) {}
+
+  EncodedImageCallback::Result OnEncodedImage(
+      const EncodedImage& encoded_image,
+      const CodecSpecificInfo* codec_specific_info,
+      const RTPFragmentationHeader* fragmentation) override {
+    if (!adapter_)
+      return Result(Result::OK);
+    return adapter_->OnEncodedImage(stream_idx_, encoded_image,
+                                    codec_specific_info, fragmentation);
+  }
+
+ private:
+  MultiplexEncoderAdapter* adapter_;
+  const AlphaCodecStream stream_idx_;
+};
+
+MultiplexEncoderAdapter::MultiplexEncoderAdapter(
+    VideoEncoderFactory* factory,
+    const SdpVideoFormat& associated_format)
+    : factory_(factory),
+      associated_format_(associated_format),
+      encoded_complete_callback_(nullptr) {}
+
+MultiplexEncoderAdapter::~MultiplexEncoderAdapter() {
+  Release();
+}
+
+int MultiplexEncoderAdapter::InitEncode(const VideoCodec* inst,
+                                        int number_of_cores,
+                                        size_t max_payload_size) {
+  const size_t buffer_size =
+      CalcBufferSize(VideoType::kI420, inst->width, inst->height);
+  multiplex_dummy_planes_.resize(buffer_size);
+  // It is more expensive to encode 0x00, so use 0x80 instead.
+  std::fill(multiplex_dummy_planes_.begin(), multiplex_dummy_planes_.end(),
+            0x80);
+
+  RTC_DCHECK_EQ(kVideoCodecMultiplex, inst->codecType);
+  VideoCodec settings = *inst;
+  settings.codecType = PayloadStringToCodecType(associated_format_.name);
+
+  // Take over the key frame interval at adapter level, because we have to
+  // sync the key frames for both sub-encoders.
+  switch (settings.codecType) {
+    case kVideoCodecVP8:
+      key_frame_interval_ = settings.VP8()->keyFrameInterval;
+      settings.VP8()->keyFrameInterval = 0;
+      break;
+    case kVideoCodecVP9:
+      key_frame_interval_ = settings.VP9()->keyFrameInterval;
+      settings.VP9()->keyFrameInterval = 0;
+      break;
+    case kVideoCodecH264:
+      key_frame_interval_ = settings.H264()->keyFrameInterval;
+      settings.H264()->keyFrameInterval = 0;
+      break;
+    default:
+      break;
+  }
+
+  for (size_t i = 0; i < kAlphaCodecStreams; ++i) {
+    std::unique_ptr<VideoEncoder> encoder =
+        factory_->CreateVideoEncoder(associated_format_);
+    const int rv =
+        encoder->InitEncode(&settings, number_of_cores, max_payload_size);
+    if (rv) {
+      RTC_LOG(LS_ERROR) << "Failed to create multiplex codec index " << i;
+      return rv;
+    }
+    adapter_callbacks_.emplace_back(new AdapterEncodedImageCallback(
+        this, static_cast<AlphaCodecStream>(i)));
+    encoder->RegisterEncodeCompleteCallback(adapter_callbacks_.back().get());
+    encoders_.emplace_back(std::move(encoder));
+  }
+  return WEBRTC_VIDEO_CODEC_OK;
+}
+
+int MultiplexEncoderAdapter::Encode(
+    const VideoFrame& input_image,
+    const CodecSpecificInfo* codec_specific_info,
+    const std::vector<FrameType>* frame_types) {
+  if (!encoded_complete_callback_) {
+    return WEBRTC_VIDEO_CODEC_UNINITIALIZED;
+  }
+
+  std::vector<FrameType> adjusted_frame_types;
+  if (key_frame_interval_ > 0 && picture_index_ % key_frame_interval_ == 0) {
+    adjusted_frame_types.push_back(kVideoFrameKey);
+  } else {
+    adjusted_frame_types.push_back(kVideoFrameDelta);
+  }
+  const bool has_alpha = input_image.video_frame_buffer()->type() ==
+                         VideoFrameBuffer::Type::kI420A;
+  stashed_images_.emplace(
+      std::piecewise_construct, std::forward_as_tuple(input_image.timestamp()),
+      std::forward_as_tuple(picture_index_,
+                            has_alpha ? kAlphaCodecStreams : 1));
+
+  ++picture_index_;
+
+  // Encode YUV
+  int rv = encoders_[kYUVStream]->Encode(input_image, codec_specific_info,
+                                         &adjusted_frame_types);
+  // If we do not receive an alpha frame, we send a single frame for this
+  // |picture_index_|. The receiver will receive |frame_count| as 1 which
+  // soecifies this case.
+  if (rv || !has_alpha)
+    return rv;
+
+  // Encode AXX
+  const I420ABufferInterface* yuva_buffer =
+      input_image.video_frame_buffer()->GetI420A();
+  rtc::scoped_refptr<I420BufferInterface> alpha_buffer =
+      WrapI420Buffer(input_image.width(), input_image.height(),
+                     yuva_buffer->DataA(), yuva_buffer->StrideA(),
+                     multiplex_dummy_planes_.data(), yuva_buffer->StrideU(),
+                     multiplex_dummy_planes_.data(), yuva_buffer->StrideV(),
+                     rtc::KeepRefUntilDone(input_image.video_frame_buffer()));
+  VideoFrame alpha_image(alpha_buffer, input_image.timestamp(),
+                         input_image.render_time_ms(), input_image.rotation());
+  rv = encoders_[kAXXStream]->Encode(alpha_image, codec_specific_info,
+                                     &adjusted_frame_types);
+  return rv;
+}
+
+int MultiplexEncoderAdapter::RegisterEncodeCompleteCallback(
+    EncodedImageCallback* callback) {
+  encoded_complete_callback_ = callback;
+  return WEBRTC_VIDEO_CODEC_OK;
+}
+
+int MultiplexEncoderAdapter::SetChannelParameters(uint32_t packet_loss,
+                                                  int64_t rtt) {
+  for (auto& encoder : encoders_) {
+    const int rv = encoder->SetChannelParameters(packet_loss, rtt);
+    if (rv)
+      return rv;
+  }
+  return WEBRTC_VIDEO_CODEC_OK;
+}
+
+int MultiplexEncoderAdapter::SetRateAllocation(const BitrateAllocation& bitrate,
+                                               uint32_t framerate) {
+  for (auto& encoder : encoders_) {
+    // TODO(emircan): |framerate| is used to calculate duration in encoder
+    // instances. We report the total frame rate to keep real time for now.
+    // Remove this after refactoring duration logic.
+    const int rv = encoder->SetRateAllocation(
+        bitrate, static_cast<uint32_t>(encoders_.size()) * framerate);
+    if (rv)
+      return rv;
+  }
+  return WEBRTC_VIDEO_CODEC_OK;
+}
+
+int MultiplexEncoderAdapter::Release() {
+  for (auto& encoder : encoders_) {
+    const int rv = encoder->Release();
+    if (rv)
+      return rv;
+  }
+  encoders_.clear();
+  adapter_callbacks_.clear();
+  for (auto& stashed_image : stashed_images_) {
+    for (auto& image_component : stashed_image.second.image_components) {
+      delete[] image_component.encoded_image._buffer;
+    }
+  }
+  stashed_images_.clear();
+  if (combined_image_._buffer) {
+    delete[] combined_image_._buffer;
+    combined_image_._buffer = nullptr;
+  }
+  return WEBRTC_VIDEO_CODEC_OK;
+}
+
+const char* MultiplexEncoderAdapter::ImplementationName() const {
+  return "MultiplexEncoderAdapter";
+}
+
+EncodedImageCallback::Result MultiplexEncoderAdapter::OnEncodedImage(
+    AlphaCodecStream stream_idx,
+    const EncodedImage& encodedImage,
+    const CodecSpecificInfo* codecSpecificInfo,
+    const RTPFragmentationHeader* fragmentation) {
+  const auto& stashed_image_itr = stashed_images_.find(encodedImage._timeStamp);
+  const auto& stashed_image_next_itr = std::next(stashed_image_itr, 1);
+  RTC_DCHECK(stashed_image_itr != stashed_images_.end());
+  MultiplexImage& stashed_image = stashed_image_itr->second;
+  const uint8_t frame_count = stashed_image.component_count;
+
+  // Save the image
+  MultiplexImageComponent image_component;
+  image_component.component_index = stream_idx;
+  image_component.codec_type =
+      PayloadStringToCodecType(associated_format_.name);
+  image_component.encoded_image = encodedImage;
+  image_component.encoded_image._buffer = new uint8_t[encodedImage._length];
+  std::memcpy(image_component.encoded_image._buffer, encodedImage._buffer,
+              encodedImage._length);
+
+  stashed_image.image_components.push_back(image_component);
+
+  if (stashed_image.image_components.size() == frame_count) {
+    // Complete case
+    auto iter = stashed_images_.begin();
+    while (iter != stashed_images_.end() && iter != stashed_image_next_itr) {
+      // No image at all, skip.
+      if (iter->second.image_components.size() == 0)
+        continue;
+
+      // We have to send out those stashed frames, otherwise the delta frame
+      // dependency chain is broken.
+      if (combined_image_._buffer)
+        delete[] combined_image_._buffer;
+      combined_image_ =
+          MultiplexEncodedImagePacker::PackAndRelease(iter->second);
+
+      CodecSpecificInfo codec_info = *codecSpecificInfo;
+      codec_info.codecType = kVideoCodecMultiplex;
+      codec_info.codecSpecific.generic.simulcast_idx = 0;
+      encoded_complete_callback_->OnEncodedImage(combined_image_, &codec_info,
+                                                 fragmentation);
+      iter++;
+    }
+
+    stashed_images_.erase(stashed_images_.begin(), stashed_image_next_itr);
+  }
+  return EncodedImageCallback::Result(EncodedImageCallback::Result::OK);
+}
+
+}  // namespace webrtc