H264 bitstream parser.

webrtc/base/bitbuffer.cc

Index: webrtc/base/bitbuffer.cc
diff --git a/webrtc/base/bitbuffer.cc b/webrtc/base/bitbuffer.cc
index cd3661343b290ae25aed1e34a04a7390643c5ead..9000c9b87021e3fd9bf99174520b8727900fd6e6 100644
--- a/webrtc/base/bitbuffer.cc
+++ b/webrtc/base/bitbuffer.cc
@@ -187,6 +187,21 @@ bool BitBuffer::ReadExponentialGolomb(uint32_t* val) {
   return true;
 }
 
+bool BitBuffer::ReadSignedExponentialGolomb(int32_t* val) {
+  // Signed exponential golomb values are just the unsigned values
+  // mapped to the sequence 0, 1, -1, 2, -2, etc. in order.
+  uint32_t unsigned_val;
+  if (!ReadExponentialGolomb(&unsigned_val)) {
+    return false;
+  }
+  if ((unsigned_val & 1) == 0) {
+    *val = -static_cast<int32_t>(unsigned_val / 2);
+  } else {
+    *val = (unsigned_val + 1) / 2;
+  }
+  return true;
+}
+
 void BitBuffer::GetCurrentOffset(
     size_t* out_byte_offset, size_t* out_bit_offset) {
   CHECK(out_byte_offset != NULL);