1 files changed, 81 insertions, 0 deletions
diff --git a/third_party/libwebrtc/audio/channel_send_frame_transformer_delegate.h b/third_party/libwebrtc/audio/channel_send_frame_transformer_delegate.h
new file mode 100644
index 0000000000..6d9f0a8613
--- /dev/null
+++ b/third_party/libwebrtc/audio/channel_send_frame_transformer_delegate.h
@@ -0,0 +1,81 @@
+/*
+ *  Copyright (c) 2020 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.
+ */
+
+#ifndef AUDIO_CHANNEL_SEND_FRAME_TRANSFORMER_DELEGATE_H_
+#define AUDIO_CHANNEL_SEND_FRAME_TRANSFORMER_DELEGATE_H_
+
+#include <memory>
+
+#include "api/frame_transformer_interface.h"
+#include "api/sequence_checker.h"
+#include "modules/audio_coding/include/audio_coding_module_typedefs.h"
+#include "rtc_base/buffer.h"
+#include "rtc_base/synchronization/mutex.h"
+#include "rtc_base/task_queue.h"
+
+namespace webrtc {
+
+// Delegates calls to FrameTransformerInterface to transform frames, and to
+// ChannelSend to send the transformed frames using `send_frame_callback_` on
+// the `encoder_queue_`.
+// OnTransformedFrame() can be called from any thread, the delegate ensures
+// thread-safe access to the ChannelSend callback.
+class ChannelSendFrameTransformerDelegate : public TransformedFrameCallback {
+ public:
+  using SendFrameCallback =
+      std::function<int32_t(AudioFrameType frameType,
+                            uint8_t payloadType,
+                            uint32_t rtp_timestamp,
+                            rtc::ArrayView<const uint8_t> payload,
+                            int64_t absolute_capture_timestamp_ms)>;
+  ChannelSendFrameTransformerDelegate(
+      SendFrameCallback send_frame_callback,
+      rtc::scoped_refptr<FrameTransformerInterface> frame_transformer,
+      rtc::TaskQueue* encoder_queue);
+
+  // Registers `this` as callback for `frame_transformer_`, to get the
+  // transformed frames.
+  void Init();
+
+  // Unregisters and releases the `frame_transformer_` reference, and resets
+  // `send_frame_callback_` under lock. Called from ChannelSend destructor to
+  // prevent running the callback on a dangling channel.
+  void Reset();
+
+  // Delegates the call to FrameTransformerInterface::TransformFrame, to
+  // transform the frame asynchronously.
+  void Transform(AudioFrameType frame_type,
+                 uint8_t payload_type,
+                 uint32_t rtp_timestamp,
+                 uint32_t rtp_start_timestamp,
+                 const uint8_t* payload_data,
+                 size_t payload_size,
+                 int64_t absolute_capture_timestamp_ms,
+                 uint32_t ssrc);
+
+  // Implements TransformedFrameCallback. Can be called on any thread.
+  void OnTransformedFrame(
+      std::unique_ptr<TransformableFrameInterface> frame) override;
+
+  // Delegates the call to ChannelSend::SendRtpAudio on the `encoder_queue_`,
+  // by calling `send_audio_callback_`.
+  void SendFrame(std::unique_ptr<TransformableFrameInterface> frame) const;
+
+ protected:
+  ~ChannelSendFrameTransformerDelegate() override = default;
+
+ private:
+  mutable Mutex send_lock_;
+  SendFrameCallback send_frame_callback_ RTC_GUARDED_BY(send_lock_);
+  rtc::scoped_refptr<FrameTransformerInterface> frame_transformer_;
+  rtc::TaskQueue* encoder_queue_ RTC_GUARDED_BY(send_lock_);
+};
+}  // namespace webrtc
+#endif  // AUDIO_CHANNEL_SEND_FRAME_TRANSFORMER_DELEGATE_H_