Implemented HEVC video demuxing and parsing

media/filters/h265_parser.cc

+// 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 "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/stl_util.h"
+
+#include "media/base/decrypt_config.h"
+#include "media/filters/h265_parser.h"
+
+namespace media {
+
+#define READ_BITS_OR_RETURN(num_bits, out)                                 \
+  do {                                                                     \
+    int _out;                                                              \
+    if (!br_.ReadBits(num_bits, &_out)) {                                  \
+      DVLOG(1)                                                             \
+          << "Error in stream: unexpected EOS while trying to read " #out; \
+      return kInvalidStream;                                               \
+    }                                                                      \
+    *out = _out;                                                           \
+  } while (0)
+
+#define TRUE_OR_RETURN(a)                                            \
+  do {                                                               \
+    if (!(a)) {                                                      \
+      DVLOG(1) << "Error in stream: invalid value, expected " << #a; \
+      return kInvalidStream;                                         \
+    }                                                                \
+  } while (0)
+
+H265NALU::H265NALU() {
+  memset(this, 0, sizeof(*this));
+}
+
+H265Parser::H265Parser() {
+  Reset();
+}
+
+H265Parser::~H265Parser() {
+}
+
+void H265Parser::Reset() {
+  stream_ = NULL;
+  bytes_left_ = 0;
+  encrypted_ranges_.clear();
+}
+
+void H265Parser::SetStream(const uint8* stream, off_t stream_size) {
+  std::vector<SubsampleEntry> subsamples;
+  SetEncryptedStream(stream, stream_size, subsamples);
+}
+
+void H265Parser::SetEncryptedStream(
+    const uint8* stream, off_t stream_size,
+    const std::vector<SubsampleEntry>& subsamples) {
+  DCHECK(stream);
+  DCHECK_GT(stream_size, 0);
+
+  stream_ = stream;
+  bytes_left_ = stream_size;
+
+  encrypted_ranges_.clear();
+  const uint8* start = stream;
+  const uint8* stream_end = stream_ + bytes_left_;
+  for (size_t i = 0; i < subsamples.size() && start < stream_end; ++i) {
+    start += subsamples[i].clear_bytes;
+
+    const uint8* end = std::min(start + subsamples[i].cypher_bytes, stream_end);
+    encrypted_ranges_.Add(start, end);
+    start = end;
+  }
+}
+
+bool H265Parser::LocateNALU(off_t* nalu_size, off_t* start_code_size) {
+  // Find the start code of next NALU.
+  off_t nalu_start_off = 0;
+  off_t annexb_start_code_size = 0;
+
+  if (!H264Parser::FindStartCodeInClearRanges(stream_, bytes_left_,
+                                              encrypted_ranges_,
+                                              &nalu_start_off,
+                                              &annexb_start_code_size)) {
+    DVLOG(4) << "Could not find start code, end of stream?";
+    return false;
+  }
+
+  // Move the stream to the beginning of the NALU (pointing at the start code).
+  stream_ += nalu_start_off;
+  bytes_left_ -= nalu_start_off;
+
+  const uint8* nalu_data = stream_ + annexb_start_code_size;
+  off_t max_nalu_data_size = bytes_left_ - annexb_start_code_size;
+  if (max_nalu_data_size <= 0) {
+    DVLOG(3) << "End of stream";
+    return false;
+  }
+
+  // Find the start code of next NALU;
+  // if successful, |nalu_size_without_start_code| is the number of bytes from
+  // after previous start code to before this one;
+  // if next start code is not found, it is still a valid NALU since there
+  // are some bytes left after the first start code: all the remaining bytes
+  // belong to the current NALU.
+  off_t next_start_code_size = 0;
+  off_t nalu_size_without_start_code = 0;
+  if (!H264Parser::FindStartCodeInClearRanges(nalu_data, max_nalu_data_size,
+                                              encrypted_ranges_,
+                                              &nalu_size_without_start_code,
+                                              &next_start_code_size)) {
+    nalu_size_without_start_code = max_nalu_data_size;
+  }
+  *nalu_size = nalu_size_without_start_code + annexb_start_code_size;
+  *start_code_size = annexb_start_code_size;
+  return true;
+}
+
+H265Parser::Result H265Parser::AdvanceToNextNALU(H265NALU* nalu) {
+  off_t start_code_size;
+  off_t nalu_size_with_start_code;
+  if (!LocateNALU(&nalu_size_with_start_code, &start_code_size)) {
+    DVLOG(4) << "Could not find next NALU, bytes left in stream: "
+             << bytes_left_;
+    return kEOStream;
+  }
+
+  nalu->data = stream_ + start_code_size;
+  nalu->size = nalu_size_with_start_code - start_code_size;
+  DVLOG(4) << "NALU found: size=" << nalu_size_with_start_code;
+
+  // Initialize bit reader at the start of found NALU.
+  if (!br_.Initialize(nalu->data, nalu->size))
+    return kEOStream;
+
+  // Move parser state to after this NALU, so next time AdvanceToNextNALU
+  // is called, we will effectively be skipping it;
+  // other parsing functions will use the position saved
+  // in bit reader for parsing, so we don't have to remember it here.
+  stream_ += nalu_size_with_start_code;
+  bytes_left_ -= nalu_size_with_start_code;
+
+  // Read NALU header, skip the forbidden_zero_bit, but check for it.
+  int data;
+  READ_BITS_OR_RETURN(1, &data);
+  TRUE_OR_RETURN(data == 0);
+
+  READ_BITS_OR_RETURN(6, &nalu->nal_unit_type);
+  READ_BITS_OR_RETURN(6, &nalu->nuh_layer_id);
+  READ_BITS_OR_RETURN(3, &nalu->nuh_temporal_id_plus1);
+
+  DVLOG(4) << "NALU type: " << static_cast<int>(nalu->nal_unit_type)
+           << " at: " << reinterpret_cast<const void*>(nalu->data)
+           << " size: " << nalu->size;
+
+  return kOk;
+}
+
+}  // namespace media