How does a video encoder achieve low-latency transmission and ensure uninterrupted real-time performance when converting HDMI high-definition video into a network video stream?
Publish Time: 2026-02-25
In critical fields such as telemedicine, industrial control, emergency command, and high-definition live streaming, the video encoder undertakes the core task of converting local HDMI high-definition signals into network video streams. Whether transmitting via wired networks, Wi-Fi, or 4G/5G wireless networks, or even achieving wireless HDMI extension and remote control, "low latency" and "high real-time performance" remain the gold standard for measuring its performance. Behind the millisecond-level time difference between pressing a button and the remote screen's response lies the extreme optimization of the video encoder across the entire chain of acquisition, encoding, transmission, and decoding.
1. Hardware-level Acquisition and Zero-Copy Architecture: Seizing the Starting Line of Time
The journey to low latency begins at the moment of signal acquisition. Traditional software acquisition solutions often require multiple buffering processes within the operating system kernel, resulting in significant input latency. High-end video encoders employ dedicated FPGAs or high-performance ASIC chips for hardware-level HDMI signal acquisition. This architecture can directly read TMDS differential signals, bypassing the operating system's graphics stack, achieving "zero-copy" data processing. Once an image frame is output from the HDMI source, the encoder immediately captures it and sends it to the processing pipeline, compressing the acquisition latency to the microsecond level. Furthermore, for wireless HDMI transmission scenarios, the device integrates a low-latency wireless RF module, connecting directly via a proprietary protocol to avoid the waiting time caused by the handshake of the universal Wi-Fi protocol, ensuring that the source image can immediately enter the encoding stage.
2. Intelligent Encoding Strategy and Inter-Frame Compression Optimization: Balancing Image Quality and Speed
In the encoding stage, significantly reducing latency while maintaining high-definition image quality is a key technical challenge. Universal video encoding typically relies on a large number of reference frames to improve the compression ratio, but this introduces significant encoding and decoding latency. To ensure real-time performance, professional video encoders employ a "low-latency mode" configuration: forcing the use of I-frames and P-frames, abandoning or strictly limiting the use of B-frames, thereby eliminating the waiting time caused by inter-frame dependencies. Quantization parameters are dynamically adjusted according to the intensity of motion in the image. The bitrate is reduced to save bandwidth when the motion is still, and the bitrate is instantly increased during rapid motion to prevent blurring, with the entire process completed within milliseconds. Some high-end devices also support ROI encoding, performing high-quality, low-latency encoding on the core areas of the image and high compression on the background to further reduce the overall data volume in exchange for speed.
3. Adaptive Network Transmission and Packet Loss Reduction Mechanism: A Bridge Through Complex Networks
When video streams enter the network channel, network jitter and packet loss are major enemies of real-time performance. The video encoder incorporates intelligent network adaptation algorithms. First, it uses the RTP/RTCP protocol to monitor network conditions in real time and dynamically adjust the transmission rate to avoid queuing delays caused by congestion. Second, to address the instability of the wireless environment, it employs a hybrid strategy of forward error correction (FEC) and automatic retransmission requests (ARP). FEC adds redundant information to data packets, enabling the receiver to directly recover data even with minimal packet loss, eliminating the need for retransmissions and significantly reducing latency spikes caused by retransmissions. For 4G/5G networks, the encoder also supports multi-link aggregation technology, simultaneously using multiple operator networks to transmit data segments, providing mutual backup and ensuring smooth, real-time video streaming even with fluctuations in a single network.
Beyond optimizing individual stages, a system-level parallel processing architecture is the ultimate guarantee of low latency. Modern video encoders employ a fully pipelined design, with acquisition, preprocessing, encoding, encapsulation, and transmission all operating in parallel, rather than sequentially waiting. While the first frame is being encoded, the second frame is already being preprocessed, and the third frame is being acquired; this "overlapping execution" mode maximizes hardware utilization. At the receiving end, the decoder also employs a fast decoding strategy, combined with the display device's low-latency mode, forming a high-speed end-to-end closed loop. Furthermore, for remote control needs, the encoder establishes a bidirectional low-latency signaling channel, prioritizing keyboard, mouse, or PTZ control commands over video data, ensuring that operation commands arrive before screen changes, achieving a precise "point-and-shoot" control experience.
In summary, the video encoder constructs a robust low-latency transmission system through hardware-level acquisition, intelligent encoding strategies, adaptive network transmission, and end-to-end parallel processing. Whether in a stable wired network or a complex wireless environment, it can convert HDMI high-definition video into a smooth real-time network stream, making remote viewing feel like being there in person, providing solid technical support for the efficient operation of various industries.
