Add H264 bitstream rewriting to limit frame reordering marker in header

webrtc/modules/rtp_rtcp/source/h264/bitstream_rewriter_unittest.cc

Index: webrtc/modules/rtp_rtcp/source/h264/bitstream_rewriter_unittest.cc
diff --git a/webrtc/modules/rtp_rtcp/source/h264/bitstream_rewriter_unittest.cc b/webrtc/modules/rtp_rtcp/source/h264/bitstream_rewriter_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9acb4a6c5ed383654ce59e5ca7260a294e7c9f61
--- /dev/null
+++ b/webrtc/modules/rtp_rtcp/source/h264/bitstream_rewriter_unittest.cc
@@ -0,0 +1,198 @@
+/*
+ *  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.
+ */
+
+#include <vector>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+#include "webrtc/base/bitbuffer.h"
+#include "webrtc/base/bytebuffer.h"
+#include "webrtc/base/fileutils.h"
+#include "webrtc/base/logging.h"
+#include "webrtc/base/pathutils.h"
+#include "webrtc/base/stream.h"
+
+#include "webrtc/modules/rtp_rtcp/source/h264/bitstream_rewriter.h"
+#include "webrtc/modules/rtp_rtcp/source/h264/h264_common.h"
+
+namespace webrtc {
+
+enum SpsMode {
+  kNoRewriteRequired_PocCorrect,
+  kNoRewriteRequired_VuiOptimal,
+  kRewriteRequired_NoVui,
+  kRewriteRequired_NoBitstreamRestriction,
+  kRewriteRequired_VuiSuboptimal,
+};
+
+static const size_t kSpsBufferMaxSize = 256;
+static const size_t kWidth = 640;
+static const size_t kHeight = 480;
+
+// Generates a fake SPS with basically everything empty and with characteristics
+// based off SpsMode.
+// Pass in a buffer of at least kSpsBufferMaxSize.
+// The fake SPS that this generates also always has at least one emulation byte
+// at offset 2, since the first two bytes are always 0, and has a 0x3 as the
+// level_idc, to make sure the parser doesn't eat all 0x3 bytes.
+void GenerateFakeSps(SpsMode mode, uint8_t buffer[]) {
+  uint8_t rbsp[kSpsBufferMaxSize] = {0};
+  rtc::BitBufferWriter writer(rbsp, kSpsBufferMaxSize);
+  // Profile byte.
+  writer.WriteUInt8(0);
+  // Constraint sets and reserved zero bits.
+  writer.WriteUInt8(0);
+  // level_idc.
+  writer.WriteUInt8(0x3u);
+  // seq_paramter_set_id.
+  writer.WriteExponentialGolomb(0);
+  // Profile is not special, so we skip all the chroma format settings.
+
+  // Now some bit magic.
+  // log2_max_frame_num_minus4: ue(v). 0 is fine.
+  writer.WriteExponentialGolomb(0);
+  // pic_order_cnt_type: ue(v).
+  // POC type 2 is the one that doesn't need to be rewritten.
+  if (mode == kNoRewriteRequired_PocCorrect) {
+    writer.WriteExponentialGolomb(2);
+  } else {
+    writer.WriteExponentialGolomb(0);
+    // log2_max_pic_order_cnt_lsb_minus4: ue(v). 0 is fine.
+    writer.WriteExponentialGolomb(0);
+  }
+  // max_num_ref_frames: ue(v). Use 1, to make optimal/suboptimal more obvious.
+  writer.WriteExponentialGolomb(1);
+  // gaps_in_frame_num_value_allowed_flag: u(1).
+  writer.WriteBits(0, 1);
+  // Next are width/height. First, calculate the mbs/map_units versions.
+  uint16_t width_in_mbs_minus1 = (kWidth + 15) / 16 - 1;
+
+  // For the height, we're going to define frame_mbs_only_flag, so we need to
+  // divide by 2. See the parser for the full calculation.
+  uint16_t height_in_map_units_minus1 = ((kHeight + 15) / 16 - 1) / 2;
+  // Write each as ue(v).
+  writer.WriteExponentialGolomb(width_in_mbs_minus1);
+  writer.WriteExponentialGolomb(height_in_map_units_minus1);
+  // frame_mbs_only_flag: u(1). Needs to be false.
+  writer.WriteBits(0, 1);
+  // mb_adaptive_frame_field_flag: u(1).
+  writer.WriteBits(0, 1);
+  // direct_8x8_inferene_flag: u(1).
+  writer.WriteBits(0, 1);
+  // frame_cropping_flag: u(1). 1, so we can supply crop.
+  writer.WriteBits(1, 1);
+  // Now we write the left/right/top/bottom crop. For simplicity, we'll put all
+  // the crop at the left/top.
+  // We picked a 4:2:0 format, so the crops are 1/2 the pixel crop values.
+  // Left/right.
+  writer.WriteExponentialGolomb(((16 - (kWidth % 16)) % 16) / 2);
+  writer.WriteExponentialGolomb(0);
+  // Top/bottom.
+  writer.WriteExponentialGolomb(((16 - (kHeight % 16)) % 16) / 2);
+  writer.WriteExponentialGolomb(0);
+
+  // Finally! The VUI.
+  // vui_parameters_present_flag: u(1)
+  if (mode == kNoRewriteRequired_PocCorrect || mode == kRewriteRequired_NoVui) {
+    writer.WriteBits(0, 1);
+  } else {
+    writer.WriteBits(1, 1);
+    // VUI time. 8 flags to ignore followed by the bitstream restriction flag.
+    writer.WriteBits(0, 8);
+    if (mode == kRewriteRequired_NoBitstreamRestriction) {
+      writer.WriteBits(0, 1);
+    } else {
+      writer.WriteBits(1, 1);
+      // Write some defaults. Shouldn't matter for parsing, though.
+      // motion_vectors_over_pic_boundaries_flag: u(1)
+      writer.WriteBits(1, 1);
+      // max_bytes_per_pic_denom: ue(v)
+      writer.WriteExponentialGolomb(2);
+      // max_bits_per_mb_denom: ue(v)
+      writer.WriteExponentialGolomb(1);
+      // log2_max_mv_length_horizontal: ue(v)
+      // log2_max_mv_length_vertical: ue(v)
+      writer.WriteExponentialGolomb(16);
+      writer.WriteExponentialGolomb(16);
+
+      // Next are the limits we care about.
+      // max_num_reorder_frames: ue(v)
+      // max_dec_frame_buffering: ue(v)
+      if (mode == kRewriteRequired_VuiSuboptimal) {
+        writer.WriteExponentialGolomb(4);
+        writer.WriteExponentialGolomb(4);
+      } else if (kNoRewriteRequired_VuiOptimal) {
+        writer.WriteExponentialGolomb(0);
+        writer.WriteExponentialGolomb(1);
+      }
+    }
+  }
+
+  // Get the number of bytes written (including the last partial byte).
+  size_t byte_count, bit_offset;
+  writer.GetCurrentOffset(&byte_count, &bit_offset);
+  if (bit_offset > 0) {
+    byte_count++;
+  }
+
+  // Write the NALU header and type; {0 0 0 1} and 7 for the SPS header type.
+  *buffer++ = 0;
+  *buffer++ = 0;
+  *buffer++ = 0;
+  *buffer++ = 1;
+  *buffer++ = 7;
+
+  // Now, we need to write the rbsp into bytes. To do that, we'll need to add
+  // emulation 0x03 bytes if there's ever a sequence of 00 00 01 or 00 00 00 01.
+  // To be simple, just add a 0x03 after every 0x00. Extra emulation doesn't
+  // hurt.
+  for (size_t i = 0; i < byte_count;) {
+    // The -3 is intentional; we never need to write an emulation byte if the 00
+    // is at the end.
+    if (i < byte_count - 3 && rbsp[i] == 0 && rbsp[i + 1] == 0) {
+      *buffer++ = rbsp[i];
+      *buffer++ = rbsp[i + 1];
+      *buffer++ = 0x3u;
+      i += 2;
+    } else {
+      *buffer++ = rbsp[i];
+      ++i;
+    }
+  }
+}
+
+void TestSps(SpsMode mode, bool should_be_rewritten) {
+  rtc::LogMessage::LogToDebug(rtc::LS_VERBOSE);
+  uint8_t buffer[kSpsBufferMaxSize] = {0};
+  GenerateFakeSps(mode, buffer);
+  std::vector<size_t> start_offsets =
+      H264Common::FindNaluStartOffsets(buffer, kSpsBufferMaxSize);
+  EXPECT_EQ(1u, start_offsets.size());
+  size_t offset = start_offsets[0] + H264Common::kNaluHeaderSize;
+  H264BitstreamRewriter bitstream_rewriter;
+  bool success = bitstream_rewriter.ParseAndRewriteSps(
+      &buffer[offset], kSpsBufferMaxSize - offset);
+  EXPECT_EQ(should_be_rewritten, success);
+}
+
+#define REWRITE_TEST(test_name, mode, should_be_rewritten) \
+  TEST(H264BitstreamRewriterTest, test_name) {             \
+    TestSps(mode, should_be_rewritten);                    \
+  }
+
+REWRITE_TEST(PocCorrect, kNoRewriteRequired_PocCorrect, false);
+REWRITE_TEST(VuiAlreadyOptimal, kNoRewriteRequired_VuiOptimal, false);
+REWRITE_TEST(RewriteFullVui, kRewriteRequired_NoVui, true);
+REWRITE_TEST(AddBitstreamRestriction,
+             kRewriteRequired_NoBitstreamRestriction,
+             true);
+REWRITE_TEST(RewriteSuboptimalVui, kRewriteRequired_VuiSuboptimal, true);
+
+}  // namespace webrtc