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

webrtc/modules/video_coding/utility/vp8_header_parser.cc

 /*
  *  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 <stdint.h>
 #include <stdio.h>
 
 #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);
 }
 
 static void VP8LoadFinalBytes(VP8BitReader* const br) {
   // Only read 8bits at a time.
   if (br->buf_ < br->buf_end_) {
     br->bits_ += 8;
     br->value_ = static_cast<uint32_t>(*br->buf_++) | (br->value_ << 8);
@@ skipping 121 matching lines @@
       }
       for (i = 0; i < NUM_MODE_LF_DELTAS; ++i) {
         if (VP8Get(br)) {
           VP8GetSignedValue(br, 6);
         }
       }
     }
   }
 }
 
-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.
     VP8Get(&br);
     VP8Get(&br);
   }
   ParseSegmentHeader(&br);
   ParseFilterHeader(&br);
   // Number of coefficient data partitions.
   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
 
 }  // namespace webrtc