ST2110-21 Packet Pacing function

Normally, data transmission on general-purpose servers located in data centers, etc., will be sent at full power as long as there is bandwidth. On the other hand, SMPTE ST2110-21 requires packet transmission at a constant rate for each video stream. The images projected on the screen can be viewed as moving images by displaying, for example, 59.94 frames per second like a picture-story show. Since the display speed is constant, it is quite natural to want to receive video data as an IP stream at regular intervals. However, in the network/server world, this is not always the case.

When trying to send packets from the server at regular intervals, if you try to process this with the CPU, it will be extremely difficult to implement due to fluctuations caused by factors such as external load factors on the CPU. Therefore, the ConnectX series NIC has implemented this function called Packet Pacing in NIC hardware.

When used in combination with Rivermax software, Packet Pacing that conforms to the video format you want to send is realized on the NIC hardware and sent at regular intervals with high accuracy. Because it is implemented in hardware, it is less susceptible to fluctuations due to external factors such as CPU, OS, and application load, and can achieve packet pacing at a level that complies with SMPTE.

ST2059 PTP function

SMPTE ST2110 requires a time stamp function using the Precision Time Protocol (PTP) that complies with ST2059. In ST2110, video, audio, and ancillary are each exchanged in separate streams, so they must be synchronized with high precision. As with packet pacing, it is difficult to stably achieve this high-precision time stamp function using software, which is why hardware offload functions are introduced.

The ConnectX series NIC implements hardware logic for PTP timestamp processing, even though it is a general-purpose NIC. By linking with general-purpose PTP software such as Linux PTP, it is possible to process packet time stamps with ultra-high accuracy.

ST2022-7 Redundancy function

SMPTE has a standard called ST2022-7 for stream redundancy. This ensures the redundancy of streams such as video and their uninterrupted switching. As a broadcasting device,

Transmitting side: Simultaneous transmission of two primary/secondary streams

Receiving side: Receives two streams, Primary/Secondary, and immediately switches to the normal system when an abnormality occurs in one system

action is required.

When using Rivermax and ConnectX-6 DX or later NICs, these operations can be implemented in hardware. Specifically, it works as follows.

Sending side: The application prepares a memory area for the stream to be sent and stores the stream data here, but prepares only one stream at this time. When sending in ST2022-7 mode, Rivermax copies one stream of data and sends it to the port assigned to Primary/Secondary on ConnectX-6 DX.

Receiving side: Streams are received from the physical ports assigned to Primary/Secondary of ConnectX-6 DX, respectively, and these are stored in the memory area of Rivermax. At that time, RTP header information stores Primary/Secondary information, stream data is formed into SMPTE2110/2022 format by combining two streams, and stored in one memory area. By referencing the memory area for this stream, the application can receive data correctly even if one of the streams is lost.

As benefits of using these various functions, we will introduce evidence from two perspectives: performance and accuracy/accuracy.

In terms of transmission and reception performance, information is available on the NVIDIA website.

Achieving Higher Performance & lower CPU Using Rivermax The graph of the part expresses it. Four measurement conditions are shown as examples, with the green graph showing CPU usage and throughput when Rivermax is used and the light blue graph when Rivermax is not used. If you refer to this, you can see that by using Rivermax, the CPU usage rate is reduced to 1/3 to 1/6, and the throughput is improved by 6 to 17 times at the same time.

It is important to note that the server resource consumption such as CPU shown here is used only for packetizing and transmitting data such as video, and other processes such as video processing are not included. We do not. In terms of accuracy, Rivermax solutions are also JT-MN Tested certified.

At Macnica, we have developed a variety of sample applications on top of Rivermax, as well as an adapter that connects them to Rivermax. As part of these efforts, we have also begun measuring performance up to the application layer. We can provide this information separately, so please feel free to contact us.