Add H264 bitstream rewriting to limit frame reordering marker in header

webrtc/modules/rtp_rtcp/source/h264/h264_common.h

+/*
+ *  Copyright (c) 2016 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_RTP_RTCP_SOURCE_H264_H264_COMMON_H_
+#define WEBRTC_MODULES_RTP_RTCP_SOURCE_H264_H264_COMMON_H_
+
+#include <memory>
+#include <vector>
+
+#include "webrtc/base/common.h"
+#include "webrtc/base/buffer.h"
+
+namespace webrtc {
+
+class H264Common {

[stefan-webrtc, 2016/05/22 23:11:50]

Should this be a namespace instead, maybe?

[sprang_webrtc, 2016/05/25 09:06:02]

Done.

+ public:
+  // The size of a full NALU start sequence {0 0 0 1}, used for the first NALU
+  // of an access unit, and for SPS and PPS blocks.
+  static const size_t kNaluLongStartSequenceSize;
+
+  // The size of a shortened NALU start sequence {0 0 1}, that may be used if
+  // not the first NALU of an access unit or an SPS or PPS block.
+  static const size_t kNaluShortStartSequenceSize;
+
+  // The size of the NALU type byte (1).
+  static const size_t kNaluTypeSize;
+
+  enum NaluType : uint8_t {
+    kIdr = 5,
+    kSei = 6,
+    kSps = 7,
+    kPps = 8,
+    kAud = 9,
+    kEndOfSequence = 10,
+    kEndOfStream = 11,
+    kFiller = 12
+  };
+  enum SliceType : uint8_t { P = 0, B = 1, I = 2, Sp = 3, Si = 4 };

[stefan-webrtc, 2016/05/22 23:11:50]

Empty line above.

You should probably add k before each enum value too, right?

[sprang_webrtc, 2016/05/25 09:06:02]

Done.

+
+  struct NaluIndex {
+    // Start index of NALU, including start sequence.
+    size_t start_offset;
+    // Start index of NALU payload, typically type header.
+    size_t payload_start_offset;
+    // Length of NALU payload, in bytes, counting from payload_start_offset.
+    size_t payload_size;
+  };
+
+  // Returns a vector of the NALU indices in the given buffer.
+  static std::vector<NaluIndex> FindNaluIndices(const uint8_t* buffer,
+                                                size_t buffer_size);
+
+  // Get the NAL type from the header byte immediately following start sequence.
+  static NaluType ParseNaluType(uint8_t data);
+
+  // Parse the given data and remove any emulation byte escaping.
+  static std::unique_ptr<rtc::Buffer> ParseRbsp(const uint8_t* data,
+                                                size_t length);
+
+  // Write the given data to the destination buffer, inserting and emulation
+  // bytes in order to escape any data the could be interpreted as a start
+  // sequence.
+  static void WriteRbsp(const uint8_t* bytes,
+                        size_t length,
+                        rtc::Buffer* destination);
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_H264_H264_COMMON_H_