Use sps and pps to determine decodability of H.264 frames.

webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc b/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
index 19467ca6513421cbb628fe0f7f35bb9fe77190c8..d4729afba1577eff93a0ab60d87e46c04d51cf7a 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
@@ -484,6 +484,8 @@ bool RtpDepacketizerH264::ProcessStapAOrSingleNalu(
           parsed_payload->type.Video.width = sps->width;
           parsed_payload->type.Video.height = sps->height;
           nalu.sps_id = sps->id;
+        } else {
+          LOG(LS_WARNING) << "Failed to parse SPS id from SPS slice.";
         }
         parsed_payload->frame_type = kVideoFrameKey;
         break;
@@ -510,8 +512,12 @@ bool RtpDepacketizerH264::ProcessStapAOrSingleNalu(
       default: {
         rtc::Optional<uint32_t> pps_id = PpsParser::ParsePpsIdFromSlice(
             &payload_data[start_offset], end_offset - start_offset);
-        if (pps_id)
+        if (pps_id) {
           nalu.pps_id = *pps_id;
+        } else {
+          LOG(LS_WARNING) << "Failed to parse PPS id from slice of type: "
+                          << static_cast<int>(nalu.type);
+        }
         break;
       }
     }
@@ -547,8 +553,13 @@ bool RtpDepacketizerH264::ParseFuaNalu(
     length_ -= kNalHeaderSize;
     rtc::Optional<uint32_t> pps_id = PpsParser::ParsePpsIdFromSlice(
         payload_data + 2 * kNalHeaderSize, length_ - kNalHeaderSize);
-    if (pps_id)
+    if (pps_id) {
       nalu.pps_id = *pps_id;
+    } else {
+      LOG(LS_WARNING) << "Failed to parse PPS from first fragment of FU-A NAL "
+                         "unit with original type: "
+                      << static_cast<int>(nalu.type);
+    }
     uint8_t original_nal_header = fnri | original_nal_type;
     modified_buffer_.reset(new rtc::Buffer());
     modified_buffer_->AppendData(payload_data + kNalHeaderSize, length_);
@@ -570,8 +581,10 @@ bool RtpDepacketizerH264::ParseFuaNalu(
   RTPVideoHeaderH264* h264 = &parsed_payload->type.Video.codecHeader.H264;
   h264->packetization_type = kH264FuA;
   h264->nalu_type = original_nal_type;
-  h264->nalus[h264->nalus_length] = nalu;
-  h264->nalus_length = 1;
+  if (first_fragment) {
+    h264->nalus[h264->nalus_length] = nalu;
+    h264->nalus_length = 1;
+  }
   return true;
 }