1 files changed, 254 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/video_coding/rtp_vp8_ref_finder.cc b/third_party/libwebrtc/modules/video_coding/rtp_vp8_ref_finder.cc
new file mode 100644
index 0000000000..185756ce51
--- /dev/null
+++ b/third_party/libwebrtc/modules/video_coding/rtp_vp8_ref_finder.cc
@@ -0,0 +1,254 @@
+/*
+ *  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.
+ */
+
+#include "modules/video_coding/rtp_vp8_ref_finder.h"
+
+#include <utility>
+
+#include "rtc_base/logging.h"
+
+namespace webrtc {
+
+RtpFrameReferenceFinder::ReturnVector RtpVp8RefFinder::ManageFrame(
+    std::unique_ptr<RtpFrameObject> frame) {
+  const RTPVideoHeaderVP8& codec_header = absl::get<RTPVideoHeaderVP8>(
+      frame->GetRtpVideoHeader().video_type_header);
+
+  if (codec_header.temporalIdx != kNoTemporalIdx)
+    frame->SetTemporalIndex(codec_header.temporalIdx);
+
+  int64_t unwrapped_tl0 = tl0_unwrapper_.Unwrap(codec_header.tl0PicIdx & 0xFF);
+  FrameDecision decision =
+      ManageFrameInternal(frame.get(), codec_header, unwrapped_tl0);
+
+  RtpFrameReferenceFinder::ReturnVector res;
+  switch (decision) {
+    case kStash:
+      if (stashed_frames_.size() > kMaxStashedFrames) {
+        stashed_frames_.pop_back();
+      }
+      stashed_frames_.push_front(
+          {.unwrapped_tl0 = unwrapped_tl0, .frame = std::move(frame)});
+      return res;
+    case kHandOff:
+      res.push_back(std::move(frame));
+      RetryStashedFrames(res);
+      return res;
+    case kDrop:
+      return res;
+  }
+
+  return res;
+}
+
+RtpVp8RefFinder::FrameDecision RtpVp8RefFinder::ManageFrameInternal(
+    RtpFrameObject* frame,
+    const RTPVideoHeaderVP8& codec_header,
+    int64_t unwrapped_tl0) {
+  // Protect against corrupted packets with arbitrary large temporal idx.
+  if (codec_header.temporalIdx >= kMaxTemporalLayers)
+    return kDrop;
+
+  frame->SetSpatialIndex(0);
+  frame->SetId(codec_header.pictureId & 0x7FFF);
+
+  if (last_picture_id_ == -1)
+    last_picture_id_ = frame->Id();
+
+  // Clean up info about not yet received frames that are too old.
+  uint16_t old_picture_id =
+      Subtract<kFrameIdLength>(frame->Id(), kMaxNotYetReceivedFrames);
+  auto clean_frames_to = not_yet_received_frames_.lower_bound(old_picture_id);
+  not_yet_received_frames_.erase(not_yet_received_frames_.begin(),
+                                 clean_frames_to);
+  // Avoid re-adding picture ids that were just erased.
+  if (AheadOf<uint16_t, kFrameIdLength>(old_picture_id, last_picture_id_)) {
+    last_picture_id_ = old_picture_id;
+  }
+  // Find if there has been a gap in fully received frames and save the picture
+  // id of those frames in `not_yet_received_frames_`.
+  if (AheadOf<uint16_t, kFrameIdLength>(frame->Id(), last_picture_id_)) {
+    do {
+      last_picture_id_ = Add<kFrameIdLength>(last_picture_id_, 1);
+      not_yet_received_frames_.insert(last_picture_id_);
+    } while (last_picture_id_ != frame->Id());
+  }
+
+  // Clean up info for base layers that are too old.
+  int64_t old_tl0_pic_idx = unwrapped_tl0 - kMaxLayerInfo;
+  auto clean_layer_info_to = layer_info_.lower_bound(old_tl0_pic_idx);
+  layer_info_.erase(layer_info_.begin(), clean_layer_info_to);
+
+  if (frame->frame_type() == VideoFrameType::kVideoFrameKey) {
+    if (codec_header.temporalIdx != 0) {
+      return kDrop;
+    }
+    frame->num_references = 0;
+    layer_info_[unwrapped_tl0].fill(-1);
+    UpdateLayerInfoVp8(frame, unwrapped_tl0, codec_header.temporalIdx);
+    return kHandOff;
+  }
+
+  auto layer_info_it = layer_info_.find(
+      codec_header.temporalIdx == 0 ? unwrapped_tl0 - 1 : unwrapped_tl0);
+
+  // If we don't have the base layer frame yet, stash this frame.
+  if (layer_info_it == layer_info_.end())
+    return kStash;
+
+  // A non keyframe base layer frame has been received, copy the layer info
+  // from the previous base layer frame and set a reference to the previous
+  // base layer frame.
+  if (codec_header.temporalIdx == 0) {
+    layer_info_it =
+        layer_info_.emplace(unwrapped_tl0, layer_info_it->second).first;
+    frame->num_references = 1;
+    int64_t last_pid_on_layer = layer_info_it->second[0];
+
+    // Is this an old frame that has already been used to update the state? If
+    // so, drop it.
+    if (AheadOrAt<uint16_t, kFrameIdLength>(last_pid_on_layer, frame->Id())) {
+      return kDrop;
+    }
+
+    frame->references[0] = last_pid_on_layer;
+    UpdateLayerInfoVp8(frame, unwrapped_tl0, codec_header.temporalIdx);
+    return kHandOff;
+  }
+
+  // Layer sync frame, this frame only references its base layer frame.
+  if (codec_header.layerSync) {
+    frame->num_references = 1;
+    int64_t last_pid_on_layer = layer_info_it->second[codec_header.temporalIdx];
+
+    // Is this an old frame that has already been used to update the state? If
+    // so, drop it.
+    if (last_pid_on_layer != -1 &&
+        AheadOrAt<uint16_t, kFrameIdLength>(last_pid_on_layer, frame->Id())) {
+      return kDrop;
+    }
+
+    frame->references[0] = layer_info_it->second[0];
+    UpdateLayerInfoVp8(frame, unwrapped_tl0, codec_header.temporalIdx);
+    return kHandOff;
+  }
+
+  // Find all references for this frame.
+  frame->num_references = 0;
+  for (uint8_t layer = 0; layer <= codec_header.temporalIdx; ++layer) {
+    // If we have not yet received a previous frame on this temporal layer,
+    // stash this frame.
+    if (layer_info_it->second[layer] == -1)
+      return kStash;
+
+    // If the last frame on this layer is ahead of this frame it means that
+    // a layer sync frame has been received after this frame for the same
+    // base layer frame, drop this frame.
+    if (AheadOf<uint16_t, kFrameIdLength>(layer_info_it->second[layer],
+                                          frame->Id())) {
+      return kDrop;
+    }
+
+    // If we have not yet received a frame between this frame and the referenced
+    // frame then we have to wait for that frame to be completed first.
+    auto not_received_frame_it =
+        not_yet_received_frames_.upper_bound(layer_info_it->second[layer]);
+    if (not_received_frame_it != not_yet_received_frames_.end() &&
+        AheadOf<uint16_t, kFrameIdLength>(frame->Id(),
+                                          *not_received_frame_it)) {
+      return kStash;
+    }
+
+    if (!(AheadOf<uint16_t, kFrameIdLength>(frame->Id(),
+                                            layer_info_it->second[layer]))) {
+      RTC_LOG(LS_WARNING) << "Frame with picture id " << frame->Id()
+                          << " and packet range [" << frame->first_seq_num()
+                          << ", " << frame->last_seq_num()
+                          << "] already received, "
+                             " dropping frame.";
+      return kDrop;
+    }
+
+    ++frame->num_references;
+    frame->references[layer] = layer_info_it->second[layer];
+  }
+
+  UpdateLayerInfoVp8(frame, unwrapped_tl0, codec_header.temporalIdx);
+  return kHandOff;
+}
+
+void RtpVp8RefFinder::UpdateLayerInfoVp8(RtpFrameObject* frame,
+                                         int64_t unwrapped_tl0,
+                                         uint8_t temporal_idx) {
+  auto layer_info_it = layer_info_.find(unwrapped_tl0);
+
+  // Update this layer info and newer.
+  while (layer_info_it != layer_info_.end()) {
+    if (layer_info_it->second[temporal_idx] != -1 &&
+        AheadOf<uint16_t, kFrameIdLength>(layer_info_it->second[temporal_idx],
+                                          frame->Id())) {
+      // The frame was not newer, then no subsequent layer info have to be
+      // update.
+      break;
+    }
+
+    layer_info_it->second[temporal_idx] = frame->Id();
+    ++unwrapped_tl0;
+    layer_info_it = layer_info_.find(unwrapped_tl0);
+  }
+  not_yet_received_frames_.erase(frame->Id());
+
+  UnwrapPictureIds(frame);
+}
+
+void RtpVp8RefFinder::RetryStashedFrames(
+    RtpFrameReferenceFinder::ReturnVector& res) {
+  bool complete_frame = false;
+  do {
+    complete_frame = false;
+    for (auto it = stashed_frames_.begin(); it != stashed_frames_.end();) {
+      const RTPVideoHeaderVP8& codec_header = absl::get<RTPVideoHeaderVP8>(
+          it->frame->GetRtpVideoHeader().video_type_header);
+      FrameDecision decision =
+          ManageFrameInternal(it->frame.get(), codec_header, it->unwrapped_tl0);
+
+      switch (decision) {
+        case kStash:
+          ++it;
+          break;
+        case kHandOff:
+          complete_frame = true;
+          res.push_back(std::move(it->frame));
+          [[fallthrough]];
+        case kDrop:
+          it = stashed_frames_.erase(it);
+      }
+    }
+  } while (complete_frame);
+}
+
+void RtpVp8RefFinder::UnwrapPictureIds(RtpFrameObject* frame) {
+  for (size_t i = 0; i < frame->num_references; ++i)
+    frame->references[i] = unwrapper_.Unwrap(frame->references[i]);
+  frame->SetId(unwrapper_.Unwrap(frame->Id()));
+}
+
+void RtpVp8RefFinder::ClearTo(uint16_t seq_num) {
+  auto it = stashed_frames_.begin();
+  while (it != stashed_frames_.end()) {
+    if (AheadOf<uint16_t>(seq_num, it->frame->first_seq_num())) {
+      it = stashed_frames_.erase(it);
+    } else {
+      ++it;
+    }
+  }
+}
+
+}  // namespace webrtc