Capture packets on the MPU corresponding to the camera. 1. Log in to the MPU where the camera is located as user root and run tcpdump-i any -s 1500 -w /home/XXX.cap host X.X.X.X -vvt (X.X.X.X is set to the IP address of the FiberHome platform). 2. Check whether packet loss occurs between the Huawei platform and the FiberHome platform. According to the analysis on the data packets sent from Huawei MPU 172.21.238.8 to FiberHome platform 172.21.239.170, no packet loss or packet disorder occurs. See the following figure.
3. Check whether flames fail to be decoded by the FiberHome platform. It is found that the packet sent by Huawei platform to the FiberHome platform is abnormal. The timestamp of the abnormal frame is 3014160144. In this PS packet, two P-frames (SEQ = 2454 and SEQ = 2468) exist at the same time. See the following figure.
(In the H264 protocol, if the frame header of the PS stream contains 00 00 00 01 61, it indicates that the frame is a P-frame. According to the coding specifications, the PS stream can be encapsulated with only one P-frame within the same time stamp.) Check the PES packet by using the Elecard Stream Analyzer. It is found that in the timestamp 3014160144, two P-frames are encapsulated in a PES packet. See the following figure.
4. On the Huawei platform, capture the data packets from the Dahua camera to Huawei platform and the data packets forwarded by Huawei platform to the FiberHome platform to determine whether the fault is caused by the Huawei platform or the Dahua camera. According to the analysis on the PES code stream sent by the Huawei platform, two P-frames are sent at the time stamp 64213139.
5. Locate the time stamp 64213139 and analyze the ES code stream sent by the Dahua camera to the Huawei platform.
It can be seen that two P-frames exist in this time stamp. (The middle mark indicates that a frame ends. Therefore, it is determined that there are two P-frames. The first P-frame is above the mark, and the second P-frame is the below the mark. In this case, the code stream sent by the camera is an ES code stream, and the P-frame cannot be found by using the 00 00 00 01 61 method described previously. This method applies to PS code streams.) 6. Two P-frames are encoded in the same time stamp. As a result, the FiberHome platform fails to decode the video. 7. The Huawei platform performs compatibility processing on the abnormal code. Although two P-frames exist at a time stamp, the Huawei Platform does not discard the second P-frame, and the video can be decoded normally. The FiberHome platform discards the second P-frame by default. Therefore, video smearing and frame freezing occur on the FiberHome platform. 8. Dahua engineers upgrade the camera and rectify the fault.