Data transmission mechanism

INFINICAM is equipped with a proprietary data transmission module optimized for the characteristics of its communication interface (USB / Ethernet).

1. UC-1.1 (USB 3.1 Gen1 5Gbps) transmission mechanism

The UC-1.1 employs the highly reliable USB bulk transfer mode.

With bulk transfer, retransmission may occur in the event of a communication error, and if the next image data is overwritten during a transfer, image corruption can result. To prevent this, the camera internally maintains memory for three frames (triple buffering) to transmit data safely.

Three-buffer configuration

• Write buffer: The area to which the latest compressed image data is written
• Standby buffer: The area that holds a completed image in preparation for the next transfer
• Transfer buffer: The area that holds the image data currently being sent to the PC

Buffer switching flow

1. Alternating between write and standby

   The latest compressed image data is written frame by frame, alternating between the “write buffer” and the “standby buffer.”

2. Rotation into the transfer buffer

   When it is time to start transferring data to the PC, the “standby buffer” whose image has finished writing is switched to the “transfer buffer,” and all of its data is sent out at once.

3. Reuse of the original buffer

   Once transmission is complete, the original “transfer buffer” is reused as the new “standby buffer.”

Benefits of triple buffering

By completely separating the area being transferred from the area being written to, stable streaming is possible without data being corrupted by overwrites, even when transfer time fluctuates due to USB retransmission or similar factors.

2. GbE-2 (1Gbps Ethernet) transmission mechanism

To prioritize real-time performance, the GbE-2 uses Ethernet UDP (User Datagram Protocol) to stream image data directly to the PC.

“Ultra-low latency” through immediate single-packet transmission

Rather than waiting for data to accumulate on a frame-by-frame basis, a UDP packet is sent out the instant enough data for one packet has accumulated. This minimizes the communication delay (latency) from capture by the camera to reception by the PC.

Packet creation using HDL (Hardware Description Language)

Rather than going through a conventional OS (such as Linux) network stack, UDP packets are created and sent by dedicated hardware logic written directly in HDL inside the FPGA.

The effect of hardware implementation

Because there is no overhead whatsoever from OS interrupt processing or the protocol stack, ultra-fast, stable packet processing close to the hardware limit is achieved.