Add pps id and sps id parsing to the h.264 depacketizer.

webrtc/common_video/h264/pps_parser.cc

Index: webrtc/common_video/h264/pps_parser.cc
diff --git a/webrtc/common_video/h264/pps_parser.cc b/webrtc/common_video/h264/pps_parser.cc
index dd5d63d24619339a37d0402f1c3bdc1ea4c42c80..01a6c76d911ed4670016cf439ae1d8dd01cae52f 100644
--- a/webrtc/common_video/h264/pps_parser.cc
+++ b/webrtc/common_video/h264/pps_parser.cc
@@ -10,6 +10,8 @@
 
 #include "webrtc/common_video/h264/pps_parser.h"
 
+#include <memory>
+
 #include "webrtc/common_video/h264/h264_common.h"
 #include "webrtc/base/bitbuffer.h"
 #include "webrtc/base/buffer.h"
@@ -36,6 +38,25 @@ rtc::Optional<PpsParser::PpsState> PpsParser::ParsePps(const uint8_t* data,
   return ParseInternal(&bit_buffer);
 }
 
+rtc::Optional<uint32_t> PpsParser::ParsePpsIdFromSlice(const uint8_t* data,
+                                                       size_t length) {
+  std::unique_ptr<rtc::Buffer> slice_rbsp(H264::ParseRbsp(data, length));
+  rtc::BitBuffer slice_reader(slice_rbsp->data(), slice_rbsp->size());
+
+  uint32_t golomb_tmp;
+  // first_mb_in_slice: ue(v)
+  if (!slice_reader.ReadExponentialGolomb(&golomb_tmp))
+    return rtc::Optional<uint32_t>();
+  // slice_type: ue(v)
+  if (!slice_reader.ReadExponentialGolomb(&golomb_tmp))
+    return rtc::Optional<uint32_t>();
+  // pic_parameter_set_id: ue(v)
+  uint32_t slice_pps_id;
+  if (!slice_reader.ReadExponentialGolomb(&slice_pps_id))
+    return rtc::Optional<uint32_t>();
+  return rtc::Optional<uint32_t>(slice_pps_id);
+}
+
 rtc::Optional<PpsParser::PpsState> PpsParser::ParseInternal(
     rtc::BitBuffer* bit_buffer) {
   PpsState pps;
@@ -43,9 +64,9 @@ rtc::Optional<PpsParser::PpsState> PpsParser::ParseInternal(
   uint32_t bits_tmp;
   uint32_t golomb_ignored;
   // pic_parameter_set_id: ue(v)
-  RETURN_EMPTY_ON_FAIL(bit_buffer->ReadExponentialGolomb(&golomb_ignored));
+  RETURN_EMPTY_ON_FAIL(bit_buffer->ReadExponentialGolomb(&pps.id));
   // seq_parameter_set_id: ue(v)
-  RETURN_EMPTY_ON_FAIL(bit_buffer->ReadExponentialGolomb(&golomb_ignored));
+  RETURN_EMPTY_ON_FAIL(bit_buffer->ReadExponentialGolomb(&pps.sps_id));
   // entropy_coding_mode_flag: u(1)
   uint32_t entropy_coding_mode_flag;
   RETURN_EMPTY_ON_FAIL(bit_buffer->ReadBits(&entropy_coding_mode_flag, 1));