Add stats for average QP per frame for VP8 (for received video streams):

"WebRTC.Video.Decoded.VP8.Qp"

BUG=chromium:512752

Review URL: https://codereview.webrtc.org/1340623002

Cr-Commit-Position: refs/heads/master@{#10349}

webrtc/modules/video_coding/utility/include/qp_parser.h

@@ -0,0 +1,30 @@
+/*
+ *  Copyright (c) 2015 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 WEBRTC_MODULES_VIDEO_CODING_UTILITY_QP_PARSER_H_
+#define WEBRTC_MODULES_VIDEO_CODING_UTILITY_QP_PARSER_H_
+
+#include "webrtc/modules/video_coding/main/source/encoded_frame.h"
+
+namespace webrtc {
+
+class QpParser {
+ public:
+  QpParser() {}
+  ~QpParser() {}
+
+  // Parses an encoded |frame| and extracts the |qp|.
+  // Returns true on success, false otherwise.
+  bool GetQp(const VCMEncodedFrame& frame, int* qp);
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_VIDEO_CODING_UTILITY_QP_PARSER_H_

webrtc/modules/video_coding/utility/include/vp8_header_parser.h

@@ -66,7 +66,9 @@ const uint8_t kVP8NewRange[128] = {
   241, 243, 245, 247, 249, 251, 253, 127
 };
 
-int GetQP(uint8_t* buf);
+// Gets the QP, QP range: [0, 127].
+// Returns true on success, false otherwise.
+bool GetQp(const uint8_t* buf, size_t length, int* qp);
 
 }  // namespace vp8
 

webrtc/modules/video_coding/utility/qp_parser.cc

@@ -0,0 +1,28 @@
+/*
+ *  Copyright (c) 2015 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 "webrtc/modules/video_coding/utility/include/qp_parser.h"
+
+#include "webrtc/common_types.h"
+#include "webrtc/modules/video_coding/utility/include/vp8_header_parser.h"
+
+namespace webrtc {
+
+bool QpParser::GetQp(const VCMEncodedFrame& frame, int* qp) {
+  switch (frame.CodecSpecific()->codecType) {
+    case kVideoCodecVP8:
+      // QP range: [0, 127].
+      return vp8::GetQp(frame.Buffer(), frame.Length(), qp);
+    default:
+      return false;
+  }
+}
+
+}  // namespace webrtc

webrtc/modules/video_coding/utility/video_coding_utility.gyp

@@ -21,8 +21,10 @@
         'frame_dropper.cc',
         'include/frame_dropper.h',
         'include/moving_average.h',
+        'include/qp_parser.h',
         'include/quality_scaler.h',
         'include/vp8_header_parser.h',
+        'qp_parser.cc',
         'quality_scaler.cc',
         'vp8_header_parser.cc',
       ],

webrtc/modules/video_coding/utility/vp8_header_parser.cc

@@ -12,9 +12,15 @@
 
 #include "webrtc/modules/video_coding/utility/include/vp8_header_parser.h"
 
+#include "webrtc/system_wrappers/interface/logging.h"
+
 namespace webrtc {
 
 namespace vp8 {
+namespace {
+const size_t kCommonPayloadHeaderLength = 3;
+const size_t kKeyPayloadHeaderLength = 10;
+}  // namespace
 
 static uint32_t BSwap32(uint32_t x) {
   return (x >> 24) | ((x >> 8) & 0xff00) | ((x << 8) & 0xff0000) | (x << 24);
@@ -156,18 +162,26 @@ static void ParseFilterHeader(VP8BitReader* br) {
   }
 }
 
-int GetQP(uint8_t* buf) {
+bool GetQp(const uint8_t* buf, size_t length, int* qp) {
+  if (length < kCommonPayloadHeaderLength) {
+    LOG(LS_WARNING) << "Failed to get QP, invalid length.";
+    return false;
+  }
   VP8BitReader br;
   const uint32_t bits = buf[0] | (buf[1] << 8) | (buf[2] << 16);
   int key_frame = !(bits & 1);
   // Size of first partition in bytes.
-  int partition_length = (bits >> 5);
-  // Skip past uncompressed header: 10bytes for key, 3bytes for delta frames.
+  uint32_t partition_length = (bits >> 5);
+  size_t header_length = kCommonPayloadHeaderLength;
   if (key_frame) {
-    buf += 10;
-  } else {
-    buf += 3;
+    header_length = kKeyPayloadHeaderLength;
   }
+  if (header_length + partition_length > length) {
+    LOG(LS_WARNING) << "Failed to get QP, invalid length: " << length;
+    return false;
+  }
+  buf += header_length;
+
   VP8InitBitReader(&br, buf, buf + partition_length);
   if (key_frame) {
     // Color space and pixel type.
@@ -180,7 +194,12 @@ int GetQP(uint8_t* buf) {
   VP8GetValue(&br, 2);
   // Base QP.
   const int base_q0 = VP8GetValue(&br, 7);
-  return base_q0;
+  if (br.eof_ == 1) {
+    LOG(LS_WARNING) << "Failed to get QP, end of file reached.";
+    return false;
+  }
+  *qp = base_q0;
+  return true;
 }
 
 }  // namespace vp8