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.h

@@ -0,0 +1,37 @@
+/*
+ *  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.
+ */
+
+#ifndef MODULES_VIDEO_CODING_UTILITY_QP_PARSER_H_
+#define MODULES_VIDEO_CODING_UTILITY_QP_PARSER_H_
+
+#include <map>
+
+#include "absl/types/optional.h"
+#include "api/video/video_codec_type.h"
+#include "common_video/h264/h264_bitstream_parser.h"
+
+namespace webrtc {
+
+class QpParser {
+ public:
+  absl::optional<uint32_t> Parse(VideoCodecType codec_type,
+                                 size_t spatial_idx,
+                                 const uint8_t* frame_data,
+                                 size_t frame_size);
+
+ private:
+  H264BitstreamParser& FetchOrCreateH264Parser(size_t spatial_idx);
+
+  std::map<size_t, H264BitstreamParser> h264_parsers_;
+};
+
+}  // namespace webrtc
+
+#endif  // MODULES_VIDEO_CODING_UTILITY_QP_PARSER_H_