1/*
2 *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10#include "webrtc/modules/rtp_rtcp/source/h264_bitstream_parser.h"
11
12#include <vector>
13
14#include "webrtc/base/bitbuffer.h"
15#include "webrtc/base/bytebuffer.h"
16#include "webrtc/base/checks.h"
17#include "webrtc/base/logging.h"
18#include "webrtc/base/scoped_ptr.h"
19
20namespace webrtc {
21namespace {
22// The size of a NALU header {0 0 0 1}.
23static const size_t kNaluHeaderSize = 4;
24
25// The size of a NALU header plus the type byte.
26static const size_t kNaluHeaderAndTypeSize = kNaluHeaderSize + 1;
27
28// The NALU type.
29static const uint8_t kNaluSps = 0x7;
30static const uint8_t kNaluPps = 0x8;
31static const uint8_t kNaluIdr = 0x5;
32static const uint8_t kNaluTypeMask = 0x1F;
33
34static const uint8_t kSliceTypeP = 0x0;
35static const uint8_t kSliceTypeB = 0x1;
36static const uint8_t kSliceTypeSp = 0x3;
37
38// Returns a vector of the NALU start sequences (0 0 0 1) in the given buffer.
39std::vector<size_t> FindNaluStartSequences(const uint8_t* buffer,
40                                           size_t buffer_size) {
41  std::vector<size_t> sequences;
42  // This is sorta like Boyer-Moore, but with only the first optimization step:
43  // given a 4-byte sequence we're looking at, if the 4th byte isn't 1 or 0,
44  // skip ahead to the next 4-byte sequence. 0s and 1s are relatively rare, so
45  // this will skip the majority of reads/checks.
46  const uint8_t* end = buffer + buffer_size - 4;
47  for (const uint8_t* head = buffer; head < end;) {
48    if (head[3] > 1) {
49      head += 4;
50    } else if (head[3] == 1 && head[2] == 0 && head[1] == 0 && head[0] == 0) {
51      sequences.push_back(static_cast<size_t>(head - buffer));
52      head += 4;
53    } else {
54      head++;
55    }
56  }
57
58  return sequences;
59}
60}  // namespace
61
62// Parses RBSP from source bytes. Removes emulation bytes, but leaves the
63// rbsp_trailing_bits() in the stream, since none of the parsing reads all the
64// way to the end of a parsed RBSP sequence. When writing, that means the
65// rbsp_trailing_bits() should be preserved and don't need to be restored (i.e.
66// the rbsp_stop_one_bit, which is just a 1, then zero padded), and alignment
67// should "just work".
68// TODO(pbos): Make parsing RBSP something that can be integrated into BitBuffer
69// so we don't have to copy the entire frames when only interested in the
70// headers.
71rtc::ByteBuffer* ParseRbsp(const uint8_t* bytes, size_t length) {
72  // Copied from webrtc::H264SpsParser::Parse.
73  rtc::ByteBuffer* rbsp_buffer = new rtc::ByteBuffer;
74  for (size_t i = 0; i < length;) {
75    if (length - i >= 3 && bytes[i] == 0 && bytes[i + 1] == 0 &&
76        bytes[i + 2] == 3) {
77      rbsp_buffer->WriteBytes(reinterpret_cast<const char*>(bytes) + i, 2);
78      i += 3;
79    } else {
80      rbsp_buffer->WriteBytes(reinterpret_cast<const char*>(bytes) + i, 1);
81      i++;
82    }
83  }
84  return rbsp_buffer;
85}
86
87#define RETURN_FALSE_ON_FAIL(x)       \
88  if (!(x)) {                         \
89    LOG_F(LS_ERROR) << "FAILED: " #x; \
90    return false;                     \
91  }
92
93H264BitstreamParser::PpsState::PpsState() {}
94
95H264BitstreamParser::SpsState::SpsState() {}
96
97// These functions are similar to webrtc::H264SpsParser::Parse, and based on the
98// same version of the H.264 standard. You can find it here:
99// http://www.itu.int/rec/T-REC-H.264
100bool H264BitstreamParser::ParseSpsNalu(const uint8_t* sps, size_t length) {
101  // Reset SPS state.
102  sps_ = SpsState();
103  sps_parsed_ = false;
104  // Parse out the SPS RBSP. It should be small, so it's ok that we create a
105  // copy. We'll eventually write this back.
106  rtc::scoped_ptr<rtc::ByteBuffer> sps_rbsp(
107      ParseRbsp(sps + kNaluHeaderAndTypeSize, length - kNaluHeaderAndTypeSize));
108  rtc::BitBuffer sps_parser(reinterpret_cast<const uint8_t*>(sps_rbsp->Data()),
109                            sps_rbsp->Length());
110
111  uint8_t byte_tmp;
112  uint32_t golomb_tmp;
113  uint32_t bits_tmp;
114
115  // profile_idc: u(8).
116  uint8_t profile_idc;
117  RETURN_FALSE_ON_FAIL(sps_parser.ReadUInt8(&profile_idc));
118  // constraint_set0_flag through constraint_set5_flag + reserved_zero_2bits
119  // 1 bit each for the flags + 2 bits = 8 bits = 1 byte.
120  RETURN_FALSE_ON_FAIL(sps_parser.ReadUInt8(&byte_tmp));
121  // level_idc: u(8)
122  RETURN_FALSE_ON_FAIL(sps_parser.ReadUInt8(&byte_tmp));
123  // seq_parameter_set_id: ue(v)
124  RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp));
125  sps_.separate_colour_plane_flag = 0;
126  // See if profile_idc has chroma format information.
127  if (profile_idc == 100 || profile_idc == 110 || profile_idc == 122 ||
128      profile_idc == 244 || profile_idc == 44 || profile_idc == 83 ||
129      profile_idc == 86 || profile_idc == 118 || profile_idc == 128 ||
130      profile_idc == 138 || profile_idc == 139 || profile_idc == 134) {
131    // chroma_format_idc: ue(v)
132    uint32_t chroma_format_idc;
133    RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&chroma_format_idc));
134    if (chroma_format_idc == 3) {
135      // separate_colour_plane_flag: u(1)
136      RETURN_FALSE_ON_FAIL(
137          sps_parser.ReadBits(&sps_.separate_colour_plane_flag, 1));
138    }
139    // bit_depth_luma_minus8: ue(v)
140    RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp));
141    // bit_depth_chroma_minus8: ue(v)
142    RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp));
143    // qpprime_y_zero_transform_bypass_flag: u(1)
144    RETURN_FALSE_ON_FAIL(sps_parser.ReadBits(&bits_tmp, 1));
145    // seq_scaling_matrix_present_flag: u(1)
146    uint32_t seq_scaling_matrix_present_flag;
147    RETURN_FALSE_ON_FAIL(
148        sps_parser.ReadBits(&seq_scaling_matrix_present_flag, 1));
149    if (seq_scaling_matrix_present_flag) {
150      // seq_scaling_list_present_flags. Either 8 or 12, depending on
151      // chroma_format_idc.
152      uint32_t seq_scaling_list_present_flags;
153      if (chroma_format_idc != 3) {
154        RETURN_FALSE_ON_FAIL(
155            sps_parser.ReadBits(&seq_scaling_list_present_flags, 8));
156      } else {
157        RETURN_FALSE_ON_FAIL(
158            sps_parser.ReadBits(&seq_scaling_list_present_flags, 12));
159      }
160      // TODO(pbos): Support parsing scaling lists if they're seen in practice.
161      RTC_CHECK(seq_scaling_list_present_flags == 0)
162          << "SPS contains scaling lists, which are unsupported.";
163    }
164  }
165  // log2_max_frame_num_minus4: ue(v)
166  RETURN_FALSE_ON_FAIL(
167      sps_parser.ReadExponentialGolomb(&sps_.log2_max_frame_num_minus4));
168  // pic_order_cnt_type: ue(v)
169  RETURN_FALSE_ON_FAIL(
170      sps_parser.ReadExponentialGolomb(&sps_.pic_order_cnt_type));
171
172  if (sps_.pic_order_cnt_type == 0) {
173    // log2_max_pic_order_cnt_lsb_minus4: ue(v)
174    RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(
175        &sps_.log2_max_pic_order_cnt_lsb_minus4));
176  } else if (sps_.pic_order_cnt_type == 1) {
177    // delta_pic_order_always_zero_flag: u(1)
178    RETURN_FALSE_ON_FAIL(
179        sps_parser.ReadBits(&sps_.delta_pic_order_always_zero_flag, 1));
180    // offset_for_non_ref_pic: se(v)
181    RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp));
182    // offset_for_top_to_bottom_field: se(v)
183    RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp));
184    uint32_t num_ref_frames_in_pic_order_cnt_cycle;
185    // num_ref_frames_in_pic_order_cnt_cycle: ue(v)
186    RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(
187        &num_ref_frames_in_pic_order_cnt_cycle));
188    for (uint32_t i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; i++) {
189      // offset_for_ref_frame[i]: se(v)
190      RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp));
191    }
192  }
193  // max_num_ref_frames: ue(v)
194  RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp));
195  // gaps_in_frame_num_value_allowed_flag: u(1)
196  RETURN_FALSE_ON_FAIL(sps_parser.ReadBits(&bits_tmp, 1));
197  // pic_width_in_mbs_minus1: ue(v)
198  RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp));
199  // pic_height_in_map_units_minus1: ue(v)
200  RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp));
201  // frame_mbs_only_flag: u(1)
202  RETURN_FALSE_ON_FAIL(sps_parser.ReadBits(&sps_.frame_mbs_only_flag, 1));
203  sps_parsed_ = true;
204  return true;
205}
206
207bool H264BitstreamParser::ParsePpsNalu(const uint8_t* pps, size_t length) {
208  RTC_CHECK(sps_parsed_);
209  // We're starting a new stream, so reset picture type rewriting values.
210  pps_ = PpsState();
211  pps_parsed_ = false;
212  rtc::scoped_ptr<rtc::ByteBuffer> buffer(
213      ParseRbsp(pps + kNaluHeaderAndTypeSize, length - kNaluHeaderAndTypeSize));
214  rtc::BitBuffer parser(reinterpret_cast<const uint8_t*>(buffer->Data()),
215                        buffer->Length());
216
217  uint32_t bits_tmp;
218  uint32_t golomb_ignored;
219  // pic_parameter_set_id: ue(v)
220  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
221  // seq_parameter_set_id: ue(v)
222  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
223  // entropy_coding_mode_flag: u(1)
224  uint32_t entropy_coding_mode_flag;
225  RETURN_FALSE_ON_FAIL(parser.ReadBits(&entropy_coding_mode_flag, 1));
226  // TODO(pbos): Implement CABAC support if spotted in the wild.
227  RTC_CHECK(entropy_coding_mode_flag == 0)
228      << "Don't know how to parse CABAC streams.";
229  // bottom_field_pic_order_in_frame_present_flag: u(1)
230  uint32_t bottom_field_pic_order_in_frame_present_flag;
231  RETURN_FALSE_ON_FAIL(
232      parser.ReadBits(&bottom_field_pic_order_in_frame_present_flag, 1));
233  pps_.bottom_field_pic_order_in_frame_present_flag =
234      bottom_field_pic_order_in_frame_present_flag != 0;
235
236  // num_slice_groups_minus1: ue(v)
237  uint32_t num_slice_groups_minus1;
238  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&num_slice_groups_minus1));
239  if (num_slice_groups_minus1 > 0) {
240    uint32_t slice_group_map_type;
241    // slice_group_map_type: ue(v)
242    RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&slice_group_map_type));
243    if (slice_group_map_type == 0) {
244      for (uint32_t i_group = 0; i_group <= num_slice_groups_minus1;
245           ++i_group) {
246        // run_length_minus1[iGroup]: ue(v)
247        RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
248      }
249    } else if (slice_group_map_type == 2) {
250      for (uint32_t i_group = 0; i_group <= num_slice_groups_minus1;
251           ++i_group) {
252        // top_left[iGroup]: ue(v)
253        RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
254        // bottom_right[iGroup]: ue(v)
255        RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
256      }
257    } else if (slice_group_map_type == 3 || slice_group_map_type == 4 ||
258               slice_group_map_type == 5) {
259      // slice_group_change_direction_flag: u(1)
260      RETURN_FALSE_ON_FAIL(parser.ReadBits(&bits_tmp, 1));
261      // slice_group_change_rate_minus1: ue(v)
262      RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
263    } else if (slice_group_map_type == 6) {
264      // pic_size_in_map_units_minus1: ue(v)
265      uint32_t pic_size_in_map_units_minus1;
266      RETURN_FALSE_ON_FAIL(
267          parser.ReadExponentialGolomb(&pic_size_in_map_units_minus1));
268      uint32_t slice_group_id_bits = 0;
269      uint32_t num_slice_groups = num_slice_groups_minus1 + 1;
270      // If num_slice_groups is not a power of two an additional bit is required
271      // to account for the ceil() of log2() below.
272      if ((num_slice_groups & (num_slice_groups - 1)) != 0)
273        ++slice_group_id_bits;
274      while (num_slice_groups > 0) {
275        num_slice_groups >>= 1;
276        ++slice_group_id_bits;
277      }
278      for (uint32_t i = 0; i <= pic_size_in_map_units_minus1; i++) {
279        // slice_group_id[i]: u(v)
280        // Represented by ceil(log2(num_slice_groups_minus1 + 1)) bits.
281        RETURN_FALSE_ON_FAIL(parser.ReadBits(&bits_tmp, slice_group_id_bits));
282      }
283    }
284  }
285  // num_ref_idx_l0_default_active_minus1: ue(v)
286  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
287  // num_ref_idx_l1_default_active_minus1: ue(v)
288  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
289  // weighted_pred_flag: u(1)
290  uint32_t weighted_pred_flag;
291  RETURN_FALSE_ON_FAIL(parser.ReadBits(&weighted_pred_flag, 1));
292  pps_.weighted_pred_flag = weighted_pred_flag != 0;
293  // weighted_bipred_idc: u(2)
294  RETURN_FALSE_ON_FAIL(parser.ReadBits(&pps_.weighted_bipred_idc, 2));
295
296  // pic_init_qp_minus26: se(v)
297  RETURN_FALSE_ON_FAIL(
298      parser.ReadSignedExponentialGolomb(&pps_.pic_init_qp_minus26));
299  // pic_init_qs_minus26: se(v)
300  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
301  // chroma_qp_index_offset: se(v)
302  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
303  // deblocking_filter_control_present_flag: u(1)
304  // constrained_intra_pred_flag: u(1)
305  RETURN_FALSE_ON_FAIL(parser.ReadBits(&bits_tmp, 2));
306  // redundant_pic_cnt_present_flag: u(1)
307  RETURN_FALSE_ON_FAIL(
308      parser.ReadBits(&pps_.redundant_pic_cnt_present_flag, 1));
309
310  pps_parsed_ = true;
311  return true;
312}
313
314bool H264BitstreamParser::ParseNonParameterSetNalu(const uint8_t* source,
315                                                   size_t source_length,
316                                                   uint8_t nalu_type) {
317  RTC_CHECK(sps_parsed_);
318  RTC_CHECK(pps_parsed_);
319  last_slice_qp_delta_parsed_ = false;
320  rtc::scoped_ptr<rtc::ByteBuffer> slice_rbsp(ParseRbsp(
321      source + kNaluHeaderAndTypeSize, source_length - kNaluHeaderAndTypeSize));
322  rtc::BitBuffer slice_reader(
323      reinterpret_cast<const uint8_t*>(slice_rbsp->Data()),
324      slice_rbsp->Length());
325  // Check to see if this is an IDR slice, which has an extra field to parse
326  // out.
327  bool is_idr = (source[kNaluHeaderSize] & 0x0F) == kNaluIdr;
328  uint8_t nal_ref_idc = (source[kNaluHeaderSize] & 0x60) >> 5;
329  uint32_t golomb_tmp;
330  uint32_t bits_tmp;
331
332  // first_mb_in_slice: ue(v)
333  RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
334  // slice_type: ue(v)
335  uint32_t slice_type;
336  RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&slice_type));
337  // slice_type's 5..9 range is used to indicate that all slices of a picture
338  // have the same value of slice_type % 5, we don't care about that, so we map
339  // to the corresponding 0..4 range.
340  slice_type %= 5;
341  // pic_parameter_set_id: ue(v)
342  RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
343  if (sps_.separate_colour_plane_flag == 1) {
344    // colour_plane_id
345    RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(&bits_tmp, 2));
346  }
347  // frame_num: u(v)
348  // Represented by log2_max_frame_num_minus4 + 4 bits.
349  RETURN_FALSE_ON_FAIL(
350      slice_reader.ReadBits(&bits_tmp, sps_.log2_max_frame_num_minus4 + 4));
351  uint32_t field_pic_flag = 0;
352  if (sps_.frame_mbs_only_flag == 0) {
353    // field_pic_flag: u(1)
354    RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(&field_pic_flag, 1));
355    if (field_pic_flag != 0) {
356      // bottom_field_flag: u(1)
357      RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(&bits_tmp, 1));
358    }
359  }
360  if (is_idr) {
361    // idr_pic_id: ue(v)
362    RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
363  }
364  // pic_order_cnt_lsb: u(v)
365  // Represented by sps_.log2_max_pic_order_cnt_lsb_minus4 + 4 bits.
366  if (sps_.pic_order_cnt_type == 0) {
367    RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(
368        &bits_tmp, sps_.log2_max_pic_order_cnt_lsb_minus4 + 4));
369    if (pps_.bottom_field_pic_order_in_frame_present_flag &&
370        field_pic_flag == 0) {
371      // delta_pic_order_cnt_bottom: se(v)
372      RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
373    }
374  }
375  if (sps_.pic_order_cnt_type == 1 && !sps_.delta_pic_order_always_zero_flag) {
376    // delta_pic_order_cnt[0]: se(v)
377    RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
378    if (pps_.bottom_field_pic_order_in_frame_present_flag && !field_pic_flag) {
379      // delta_pic_order_cnt[1]: se(v)
380      RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
381    }
382  }
383  if (pps_.redundant_pic_cnt_present_flag) {
384    // redundant_pic_cnt: ue(v)
385    RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
386  }
387  if (slice_type == kSliceTypeB) {
388    // direct_spatial_mv_pred_flag: u(1)
389    RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(&bits_tmp, 1));
390  }
391  if (slice_type == kSliceTypeP || slice_type == kSliceTypeSp ||
392      slice_type == kSliceTypeB) {
393    uint32_t num_ref_idx_active_override_flag;
394    // num_ref_idx_active_override_flag: u(1)
395    RETURN_FALSE_ON_FAIL(
396        slice_reader.ReadBits(&num_ref_idx_active_override_flag, 1));
397    if (num_ref_idx_active_override_flag != 0) {
398      // num_ref_idx_l0_active_minus1: ue(v)
399      RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
400      if (slice_type == kSliceTypeB) {
401        // num_ref_idx_l1_active_minus1: ue(v)
402        RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
403      }
404    }
405  }
406  // assume nal_unit_type != 20 && nal_unit_type != 21:
407  RTC_CHECK_NE(nalu_type, 20);
408  RTC_CHECK_NE(nalu_type, 21);
409  // if (nal_unit_type == 20 || nal_unit_type == 21)
410  //   ref_pic_list_mvc_modification()
411  // else
412  {
413    // ref_pic_list_modification():
414    // |slice_type| checks here don't use named constants as they aren't named
415    // in the spec for this segment. Keeping them consistent makes it easier to
416    // verify that they are both the same.
417    if (slice_type % 5 != 2 && slice_type % 5 != 4) {
418      // ref_pic_list_modification_flag_l0: u(1)
419      uint32_t ref_pic_list_modification_flag_l0;
420      RETURN_FALSE_ON_FAIL(
421          slice_reader.ReadBits(&ref_pic_list_modification_flag_l0, 1));
422      if (ref_pic_list_modification_flag_l0) {
423        uint32_t modification_of_pic_nums_idc;
424        do {
425          // modification_of_pic_nums_idc: ue(v)
426          RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(
427              &modification_of_pic_nums_idc));
428          if (modification_of_pic_nums_idc == 0 ||
429              modification_of_pic_nums_idc == 1) {
430            // abs_diff_pic_num_minus1: ue(v)
431            RETURN_FALSE_ON_FAIL(
432                slice_reader.ReadExponentialGolomb(&golomb_tmp));
433          } else if (modification_of_pic_nums_idc == 2) {
434            // long_term_pic_num: ue(v)
435            RETURN_FALSE_ON_FAIL(
436                slice_reader.ReadExponentialGolomb(&golomb_tmp));
437          }
438        } while (modification_of_pic_nums_idc != 3);
439      }
440    }
441    if (slice_type % 5 == 1) {
442      // ref_pic_list_modification_flag_l1: u(1)
443      uint32_t ref_pic_list_modification_flag_l1;
444      RETURN_FALSE_ON_FAIL(
445          slice_reader.ReadBits(&ref_pic_list_modification_flag_l1, 1));
446      if (ref_pic_list_modification_flag_l1) {
447        uint32_t modification_of_pic_nums_idc;
448        do {
449          // modification_of_pic_nums_idc: ue(v)
450          RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(
451              &modification_of_pic_nums_idc));
452          if (modification_of_pic_nums_idc == 0 ||
453              modification_of_pic_nums_idc == 1) {
454            // abs_diff_pic_num_minus1: ue(v)
455            RETURN_FALSE_ON_FAIL(
456                slice_reader.ReadExponentialGolomb(&golomb_tmp));
457          } else if (modification_of_pic_nums_idc == 2) {
458            // long_term_pic_num: ue(v)
459            RETURN_FALSE_ON_FAIL(
460                slice_reader.ReadExponentialGolomb(&golomb_tmp));
461          }
462        } while (modification_of_pic_nums_idc != 3);
463      }
464    }
465  }
466  // TODO(pbos): Do we need support for pred_weight_table()?
467  RTC_CHECK(!((pps_.weighted_pred_flag &&
468               (slice_type == kSliceTypeP || slice_type == kSliceTypeSp)) ||
469              (pps_.weighted_bipred_idc != 0 && slice_type == kSliceTypeB)))
470      << "Missing support for pred_weight_table().";
471  // if ((weighted_pred_flag && (slice_type == P || slice_type == SP)) ||
472  //    (weighted_bipred_idc == 1 && slice_type == B)) {
473  //  pred_weight_table()
474  // }
475  if (nal_ref_idc != 0) {
476    // dec_ref_pic_marking():
477    if (is_idr) {
478      // no_output_of_prior_pics_flag: u(1)
479      // long_term_reference_flag: u(1)
480      RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(&bits_tmp, 2));
481    } else {
482      // adaptive_ref_pic_marking_mode_flag: u(1)
483      uint32_t adaptive_ref_pic_marking_mode_flag;
484      RETURN_FALSE_ON_FAIL(
485          slice_reader.ReadBits(&adaptive_ref_pic_marking_mode_flag, 1));
486      if (adaptive_ref_pic_marking_mode_flag) {
487        uint32_t memory_management_control_operation;
488        do {
489          // memory_management_control_operation: ue(v)
490          RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(
491              &memory_management_control_operation));
492          if (memory_management_control_operation == 1 ||
493              memory_management_control_operation == 3) {
494            // difference_of_pic_nums_minus1: ue(v)
495            RETURN_FALSE_ON_FAIL(
496                slice_reader.ReadExponentialGolomb(&golomb_tmp));
497          }
498          if (memory_management_control_operation == 2) {
499            // long_term_pic_num: ue(v)
500            RETURN_FALSE_ON_FAIL(
501                slice_reader.ReadExponentialGolomb(&golomb_tmp));
502          }
503          if (memory_management_control_operation == 3 ||
504              memory_management_control_operation == 6) {
505            // long_term_frame_idx: ue(v)
506            RETURN_FALSE_ON_FAIL(
507                slice_reader.ReadExponentialGolomb(&golomb_tmp));
508          }
509          if (memory_management_control_operation == 4) {
510            // max_long_term_frame_idx_plus1: ue(v)
511            RETURN_FALSE_ON_FAIL(
512                slice_reader.ReadExponentialGolomb(&golomb_tmp));
513          }
514        } while (memory_management_control_operation != 0);
515      }
516    }
517  }
518  // cabac not supported: entropy_coding_mode_flag == 0 asserted above.
519  // if (entropy_coding_mode_flag && slice_type != I && slice_type != SI)
520  //   cabac_init_idc
521  RETURN_FALSE_ON_FAIL(
522      slice_reader.ReadSignedExponentialGolomb(&last_slice_qp_delta_));
523  last_slice_qp_delta_parsed_ = true;
524  return true;
525}
526
527void H264BitstreamParser::ParseSlice(const uint8_t* slice, size_t length) {
528  uint8_t nalu_type = slice[4] & kNaluTypeMask;
529  switch (nalu_type) {
530    case kNaluSps:
531      RTC_CHECK(ParseSpsNalu(slice, length))
532          << "Failed to parse bitstream SPS.";
533      break;
534    case kNaluPps:
535      RTC_CHECK(ParsePpsNalu(slice, length))
536          << "Failed to parse bitstream PPS.";
537      break;
538    default:
539      RTC_CHECK(ParseNonParameterSetNalu(slice, length, nalu_type))
540          << "Failed to parse picture slice.";
541      break;
542  }
543}
544
545void H264BitstreamParser::ParseBitstream(const uint8_t* bitstream,
546                                         size_t length) {
547  RTC_CHECK_GE(length, 4u);
548  std::vector<size_t> slice_markers = FindNaluStartSequences(bitstream, length);
549  RTC_CHECK(!slice_markers.empty());
550  for (size_t i = 0; i < slice_markers.size() - 1; ++i) {
551    ParseSlice(bitstream + slice_markers[i],
552               slice_markers[i + 1] - slice_markers[i]);
553  }
554  // Parse the last slice.
555  ParseSlice(bitstream + slice_markers.back(), length - slice_markers.back());
556}
557
558bool H264BitstreamParser::GetLastSliceQp(int* qp) const {
559  if (!last_slice_qp_delta_parsed_)
560    return false;
561  *qp = 26 + pps_.pic_init_qp_minus26 + last_slice_qp_delta_;
562  return true;
563}
564
565}  // namespace webrtc
566