Woodcliff Lake, NJ, May 16 2013
The H.264 video encoder IP cores available from semiconductor intellectual property provider CAST, Inc. now feature an option for ultra-low latency video encoding. This enables near-real time video transmission for streaming and wireless video applications, especially when coupled with CAST’s hardware stacks for fast, processor-less video processing.
Low Latency and Video Encoding
Latency is the delay incurred in processing and transmitting live video. Having a negligible delay of under 150 milliseconds (4.5 frames for 30 frames per second video) is critical in applications involving human interaction—such as video conferencing, remote surgery, online gaming, or high-value surveillance—and an even lower delay of 30ms (one frame for 30fps) or less is essential for many automotive, industrial, and medical systems.
While total latency is determined by the end-to-end process of video capture, encoding, transmission, decoding, and display, it is the encoding that typically has the most critical role. An ultra-low latency encoder needs to meet the target bit rate (e.g. 7 Mbps) over a small period of time (e.g. 1 frame). This allows the decoder to start the decoding process after buffering just a small amount of the compressed stream, and provides guarantees that the decoder buffer will not underflow throughout video playback.
Achieving Ultra-Low Latency Video Encoding
The H.264 video encoder cores available from CAST have always allowed a designer to regulate latency down to a few frames through a sophisticated rate control algorithm. The intra-only versions of these encoders can now go further, giving designers the ability to regulate latency at a deep sub-frame level. This enables latencies under 20ms for 30 frames per second video, and under 10ms for 60fps.
The sub-frame rate control feature for ultra-low latency is now a standard part of the intra-only version video encoder cores and available from CAST worldwide. These new ultra-low latency intra-only encoders support the Baseline, Main, and High Profiles of the H.264 standard (ISO/IEC 14496-10/ITU-T) and are sourced from technology partner Alma Technologies.
Video Streaming Hardware Stacks
Processing the encoded video stream for transmission also impacts end-to-end latency. Most video systems rely on a central system processor to handle this, but for many applications there is a quicker method.
Dedicated hardware stacks can more efficiently transmit video over specific channels. CAST has developed two such stacks that can prepare and transmit a video stream without the assistance of a processor: the UDP/IP Hardware Protocol Stack Core handles video transmission over an Ethernet LAN or similar Internet Protocol media, and the Hardware RTP Stack Core encapsulates H.264/NAL streams to Real-time Transport Protocol packets that are compliant with RFC 3894 and RFC 6184.
CAST has provided reusable semiconductor IP for 19 years, and today features royalty-free BA2x 32-bit processors and 8051 microcontrollers; advanced image/video compression and processing cores; and memory controllers, high-speed buses, peripherals, and other essential system functions. See the full line at www.cast-inc.com, or learn more by calling +1 201.391.8300 or emailing email@example.com.