media/filters/h265_parser.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/logging.h"
   6 #include "base/memory/scoped_ptr.h"
   7 #include "base/stl_util.h"
   8
   9 #include "media/base/decrypt_config.h"
  10 #include "media/filters/h265_parser.h"
  11
  12 namespace media {
  13
  14 #define READ_BITS_OR_RETURN(num_bits, out)                                 \
  15   do {                                                                     \
  16     int _out;                                                              \
  17     if (!br_.ReadBits(num_bits, &_out)) {                                  \
  18       DVLOG(1)                                                             \
  19           << "Error in stream: unexpected EOS while trying to read " #out; \
  20       return kInvalidStream;                                               \
  21     }                                                                      \
  22     *out = _out;                                                           \
  23   } while (0)
  24
  25 #define TRUE_OR_RETURN(a)                                            \
  26   do {                                                               \
  27     if (!(a)) {                                                      \
  28       DVLOG(1) << "Error in stream: invalid value, expected " << #a; \
  29       return kInvalidStream;                                         \
  30     }                                                                \
  31   } while (0)
  32
  33 H265NALU::H265NALU() {
  34   memset(this, 0, sizeof(*this));
  35 }
  36
  37 H265Parser::H265Parser() {
  38   Reset();
  39 }
  40
  41 H265Parser::~H265Parser() {
  42 }
  43
  44 void H265Parser::Reset() {
  45   stream_ = NULL;
  46   bytes_left_ = 0;
  47   encrypted_ranges_.clear();
  48 }
  49
  50 void H265Parser::SetStream(const uint8* stream, off_t stream_size) {
  51   std::vector<SubsampleEntry> subsamples;
  52   SetEncryptedStream(stream, stream_size, subsamples);
  53 }
  54
  55 void H265Parser::SetEncryptedStream(
  56     const uint8* stream, off_t stream_size,
  57     const std::vector<SubsampleEntry>& subsamples) {
  58   DCHECK(stream);
  59   DCHECK_GT(stream_size, 0);
  60
  61   stream_ = stream;
  62   bytes_left_ = stream_size;
  63
  64   encrypted_ranges_.clear();
  65   const uint8* start = stream;
  66   const uint8* stream_end = stream_ + bytes_left_;
  67   for (size_t i = 0; i < subsamples.size() && start < stream_end; ++i) {
  68     start += subsamples[i].clear_bytes;
  69
  70     const uint8* end = std::min(start + subsamples[i].cypher_bytes, stream_end);
  71     encrypted_ranges_.Add(start, end);
  72     start = end;
  73   }
  74 }
  75
  76 bool H265Parser::LocateNALU(off_t* nalu_size, off_t* start_code_size) {
  77   // Find the start code of next NALU.
  78   off_t nalu_start_off = 0;
  79   off_t annexb_start_code_size = 0;
  80
  81   if (!H264Parser::FindStartCodeInClearRanges(stream_, bytes_left_,
  82                                               encrypted_ranges_,
  83                                               &nalu_start_off,
  84                                               &annexb_start_code_size)) {
  85     DVLOG(4) << "Could not find start code, end of stream?";
  86     return false;
  87   }
  88
  89   // Move the stream to the beginning of the NALU (pointing at the start code).
  90   stream_ += nalu_start_off;
  91   bytes_left_ -= nalu_start_off;
  92
  93   const uint8* nalu_data = stream_ + annexb_start_code_size;
  94   off_t max_nalu_data_size = bytes_left_ - annexb_start_code_size;
  95   if (max_nalu_data_size <= 0) {
  96     DVLOG(3) << "End of stream";
  97     return false;
  98   }
  99
 100   // Find the start code of next NALU;
 101   // if successful, |nalu_size_without_start_code| is the number of bytes from
 102   // after previous start code to before this one;
 103   // if next start code is not found, it is still a valid NALU since there
 104   // are some bytes left after the first start code: all the remaining bytes
 105   // belong to the current NALU.
 106   off_t next_start_code_size = 0;
 107   off_t nalu_size_without_start_code = 0;
 108   if (!H264Parser::FindStartCodeInClearRanges(nalu_data, max_nalu_data_size,
 109                                               encrypted_ranges_,
 110                                               &nalu_size_without_start_code,
 111                                               &next_start_code_size)) {
 112     nalu_size_without_start_code = max_nalu_data_size;
 113   }
 114   *nalu_size = nalu_size_without_start_code + annexb_start_code_size;
 115   *start_code_size = annexb_start_code_size;
 116   return true;
 117 }
 118
 119 H265Parser::Result H265Parser::AdvanceToNextNALU(H265NALU* nalu) {
 120   off_t start_code_size;
 121   off_t nalu_size_with_start_code;
 122   if (!LocateNALU(&nalu_size_with_start_code, &start_code_size)) {
 123     DVLOG(4) << "Could not find next NALU, bytes left in stream: "
 124              << bytes_left_;
 125     return kEOStream;
 126   }
 127
 128   nalu->data = stream_ + start_code_size;
 129   nalu->size = nalu_size_with_start_code - start_code_size;
 130   DVLOG(4) << "NALU found: size=" << nalu_size_with_start_code;
 131
 132   // Initialize bit reader at the start of found NALU.
 133   if (!br_.Initialize(nalu->data, nalu->size))
 134     return kEOStream;
 135
 136   // Move parser state to after this NALU, so next time AdvanceToNextNALU
 137   // is called, we will effectively be skipping it;
 138   // other parsing functions will use the position saved
 139   // in bit reader for parsing, so we don't have to remember it here.
 140   stream_ += nalu_size_with_start_code;
 141   bytes_left_ -= nalu_size_with_start_code;
 142
 143   // Read NALU header, skip the forbidden_zero_bit, but check for it.
 144   int data;
 145   READ_BITS_OR_RETURN(1, &data);
 146   TRUE_OR_RETURN(data == 0);
 147
 148   READ_BITS_OR_RETURN(6, &nalu->nal_unit_type);
 149   READ_BITS_OR_RETURN(6, &nalu->nuh_layer_id);
 150   READ_BITS_OR_RETURN(3, &nalu->nuh_temporal_id_plus1);
 151
 152   DVLOG(4) << "NALU type: " << static_cast<int>(nalu->nal_unit_type)
 153            << " at: " << reinterpret_cast<const void*>(nalu->data)
 154            << " size: " << nalu->size;
 155
 156   return kOk;
 157 }
 158
 159 }  // namespace media