Parse encoded frame QP if not provided by encoder

Bug: webrtc:12542
Change-Id: Ic70b46e226f158db7a478a9f20e1f940804febba
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/210966
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33434}

modules/video_coding/utility/qp_parser.cc

@@ -0,0 +1,55 @@
+/*
+ *  Copyright (c) 2021 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/utility/qp_parser.h"
+
+#include <utility>
+
+#include "modules/video_coding/utility/vp8_header_parser.h"
+#include "modules/video_coding/utility/vp9_uncompressed_header_parser.h"
+
+namespace webrtc {
+
+absl::optional<uint32_t> QpParser::Parse(VideoCodecType codec_type,
+                                         size_t spatial_idx,
+                                         const uint8_t* frame_data,
+                                         size_t frame_size) {
+  if (frame_data == nullptr || frame_size == 0) {
+    return absl::nullopt;
+  }
+
+  if (codec_type == kVideoCodecVP8) {
+    int qp = -1;
+    if (vp8::GetQp(frame_data, frame_size, &qp)) {
+      return qp;
+    }
+  } else if (codec_type == kVideoCodecVP9) {
+    int qp = -1;
+    if (vp9::GetQp(frame_data, frame_size, &qp)) {
+      return qp;
+    }
+  } else if (codec_type == kVideoCodecH264) {
+    H264BitstreamParser& parser = FetchOrCreateH264Parser(spatial_idx);
+    parser.ParseBitstream(
+        rtc::ArrayView<const uint8_t>(frame_data, frame_size));
+    return parser.GetLastSliceQp();
+  }
+
+  return absl::nullopt;
+}
+
+H264BitstreamParser& QpParser::FetchOrCreateH264Parser(size_t spatial_idx) {
+  if (h264_parsers_.find(spatial_idx) == h264_parsers_.end()) {
+    h264_parsers_.emplace(std::make_pair(spatial_idx, H264BitstreamParser()));
+  }
+  return h264_parsers_.at(spatial_idx);
+}
+
+}  // namespace webrtc