Add VP9 raw bits reader

TEST=media_unittests
BUG=509500

Review URL: https://codereview.chromium.org/1258083003

Cr-Commit-Position: refs/heads/master@{#342607}

5 files changed, 183 insertions, 0 deletions

diff --git a/media/BUILD.gn b/media/BUILD.gn
index 6861395..310cf4c 100644
--- a/media/BUILD.gn
+++ b/media/BUILD.gn
@@ -220,6 +220,8 @@ component("media") {
     "filters/vp8_bool_decoder.h",
     "filters/vp8_parser.cc",
     "filters/vp8_parser.h",
+    "filters/vp9_raw_bits_reader.cc",
+    "filters/vp9_raw_bits_reader.h",
     "filters/webvtt_util.h",
     "filters/wsola_internals.cc",
     "filters/wsola_internals.h",
@@ -570,6 +572,7 @@ test("media_unittests") {
     "filters/video_renderer_algorithm_unittest.cc",
     "filters/vp8_bool_decoder_unittest.cc",
     "filters/vp8_parser_unittest.cc",
+    "filters/vp9_raw_bits_reader_unittest.cc",
     "formats/common/offset_byte_queue_unittest.cc",
     "formats/webm/cluster_builder.cc",
     "formats/webm/cluster_builder.h",
diff --git a/media/filters/vp9_raw_bits_reader.cc b/media/filters/vp9_raw_bits_reader.cc
new file mode 100644
index 0000000..47014fd
--- /dev/null
+++ b/media/filters/vp9_raw_bits_reader.cc
@@ -0,0 +1,49 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/filters/vp9_raw_bits_reader.h"
+
+#include <limits.h>
+
+#include "base/logging.h"
+#include "media/base/bit_reader.h"
+
+namespace media {
+
+Vp9RawBitsReader::Vp9RawBitsReader() : valid_(true) {}
+
+Vp9RawBitsReader::~Vp9RawBitsReader() {}
+
+void Vp9RawBitsReader::Initialize(const uint8_t* data, size_t size) {
+  DCHECK(data);
+  reader_.reset(new BitReader(data, size));
+  valid_ = true;
+}
+
+int Vp9RawBitsReader::ReadBit() {
+  DCHECK(reader_);
+  int value = 0;
+  valid_ = valid_ && reader_->ReadBits(1, &value);
+  return value;
+}
+
+int Vp9RawBitsReader::ReadLiteral(int bits) {
+  DCHECK(reader_);
+  int value = 0;
+  DCHECK_LT(static_cast<size_t>(bits), sizeof(value) * 8);
+  valid_ = valid_ && reader_->ReadBits(bits, &value);
+  return value;
+}
+
+int Vp9RawBitsReader::ReadSignedLiteral(int bits) {
+  int value = ReadLiteral(bits);
+  return ReadBit() ? -value : value;
+}
+
+size_t Vp9RawBitsReader::GetBytesRead() const {
+  DCHECK(reader_);
+  return (reader_->bits_read() + 7) / 8;
+}
+
+}  // namespace media
diff --git a/media/filters/vp9_raw_bits_reader.h b/media/filters/vp9_raw_bits_reader.h
new file mode 100644
index 0000000..38f54a3
--- /dev/null
+++ b/media/filters/vp9_raw_bits_reader.h
@@ -0,0 +1,62 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_FILTERS_VP9_RAW_BITS_READER_
+#define MEDIA_FILTERS_VP9_RAW_BITS_READER_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+class BitReader;
+
+// A class to read raw bits stream. See VP9 spec, "RAW-BITS DECODING" section
+// for detail.
+class MEDIA_EXPORT Vp9RawBitsReader {
+ public:
+  Vp9RawBitsReader();
+  ~Vp9RawBitsReader();
+
+  // |data| is the input buffer with |size| bytes.
+  void Initialize(const uint8_t* data, size_t size);
+
+  // Returns true if none of the reads since the last Initialize() call has
+  // gone beyond the end of available data.
+  bool IsValid() const { return valid_; }
+
+  // Returns how many bytes were read since the last Initialize() call.
+  // Partial bytes will be counted as one byte. For example, it will return 1
+  // if 3 bits were read.
+  size_t GetBytesRead() const;
+
+  // Reads one bit.
+  // If the read goes beyond the end of buffer, the return value is undefined.
+  int ReadBit();
+
+  // Reads a literal with |bits| bits.
+  // If the read goes beyond the end of buffer, the return value is undefined.
+  int ReadLiteral(int bits);
+
+  // Reads a signed literal with |bits| bits (not including the sign bit).
+  // If the read goes beyond the end of buffer, the return value is undefined.
+  int ReadSignedLiteral(int bits);
+
+ private:
+  scoped_ptr<BitReader> reader_;
+
+  // Indicates if none of the reads since the last Initialize() call has gone
+  // beyond the end of available data.
+  bool valid_;
+
+  DISALLOW_COPY_AND_ASSIGN(Vp9RawBitsReader);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_VP9_RAW_BITS_READER_
diff --git a/media/filters/vp9_raw_bits_reader_unittest.cc b/media/filters/vp9_raw_bits_reader_unittest.cc
new file mode 100644
index 0000000..d798f22
--- /dev/null
+++ b/media/filters/vp9_raw_bits_reader_unittest.cc
@@ -0,0 +1,66 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/filters/vp9_raw_bits_reader.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace media {
+
+TEST(Vp9RawBitsReaderTest, ReadBit) {
+  uint8_t data[] = {0xf1};
+  Vp9RawBitsReader reader;
+  reader.Initialize(data, 1);
+
+  EXPECT_TRUE(reader.IsValid());
+  EXPECT_EQ(0u, reader.GetBytesRead());
+  EXPECT_EQ(1, reader.ReadBit());
+  EXPECT_EQ(1u, reader.GetBytesRead());
+  EXPECT_EQ(1, reader.ReadBit());
+  EXPECT_EQ(1, reader.ReadBit());
+  EXPECT_EQ(1, reader.ReadBit());
+  EXPECT_EQ(0, reader.ReadBit());
+  EXPECT_EQ(0, reader.ReadBit());
+  EXPECT_EQ(0, reader.ReadBit());
+  EXPECT_EQ(1, reader.ReadBit());
+  EXPECT_TRUE(reader.IsValid());
+
+  // The return value is undefined.
+  ignore_result(reader.ReadBit());
+  EXPECT_FALSE(reader.IsValid());
+  EXPECT_EQ(1u, reader.GetBytesRead());
+}
+
+TEST(Vp9RawBitsReader, ReadLiteral) {
+  uint8_t data[] = {0x3d, 0x67, 0x9a};
+  Vp9RawBitsReader reader;
+  reader.Initialize(data, 3);
+
+  EXPECT_TRUE(reader.IsValid());
+  EXPECT_EQ(0x03, reader.ReadLiteral(4));
+  EXPECT_EQ(0xd679, reader.ReadLiteral(16));
+  EXPECT_TRUE(reader.IsValid());
+
+  // The return value is undefined.
+  ignore_result(reader.ReadLiteral(8));
+  EXPECT_FALSE(reader.IsValid());
+  EXPECT_EQ(3u, reader.GetBytesRead());
+}
+
+TEST(Vp9RawBitsReader, ReadSignedLiteral) {
+  uint8_t data[] = {0x3d, 0x67, 0x9a};
+  Vp9RawBitsReader reader;
+  reader.Initialize(data, 3);
+
+  EXPECT_TRUE(reader.IsValid());
+  EXPECT_EQ(-0x03, reader.ReadSignedLiteral(4));
+  EXPECT_EQ(-0x5679, reader.ReadSignedLiteral(15));
+  EXPECT_TRUE(reader.IsValid());
+
+  // The return value is undefined.
+  ignore_result(reader.ReadSignedLiteral(7));
+  EXPECT_FALSE(reader.IsValid());
+  EXPECT_EQ(3u, reader.GetBytesRead());
+}
+
+}  // namespace media
diff --git a/media/media.gyp b/media/media.gyp
index a6bfe01..3c53ad2 100644
--- a/media/media.gyp
+++ b/media/media.gyp
@@ -561,6 +561,8 @@
         'filters/vp8_bool_decoder.h',
         'filters/vp8_parser.cc',
         'filters/vp8_parser.h',
+        'filters/vp9_raw_bits_reader.cc',
+        'filters/vp9_raw_bits_reader.h',
         'filters/vpx_video_decoder.cc',
         'filters/vpx_video_decoder.h',
         'filters/webvtt_util.h',
@@ -1265,6 +1267,7 @@
         'filters/video_renderer_algorithm_unittest.cc',
         'filters/vp8_bool_decoder_unittest.cc',
         'filters/vp8_parser_unittest.cc',
+        'filters/vp9_raw_bits_reader_unittest.cc',
         'capture/webm_muxer_unittest.cc',
         'formats/common/offset_byte_queue_unittest.cc',
         'formats/webm/cluster_builder.cc',