Media traffic over IP sees dropped frames; cached packets can help
Broadcast equipment maker Videoflow has completed tests and initial trials of HEVC for its patent-pending technology that ensures no packet is lost and nullifies the jitter caused by transiting the Internet for SD, HD and the new codecs.
"While we are agnostic to the encoding technology and handle packets only, the interesting thing to see was the higher sensitivity of UHD and HEVC to packet loss and jitter which creates deeper ripple effects that last longer," said the company. "We saw a noticeable ripple effect with H.264 1080p which increases substantially with HEVC. As the encoding is deeper the sensitivity to packet loss and jitter is higher causing substantial degradation to the video quality."
Video delivery over the internet for Content Delivery Networks, such as Netflix or YouTube, works by sending files. Live video broadcast is sent instead as a continuous bit stream, which the Internet was never designed to handle, resulting in artefacts caused by jitter, and packet loss. More than a couple of seconds of latency is unacceptable by customers expecting to enjoy the excitement of live events such as sport as they happen.
Traditionally this means premium live video channels require a "pair of leased lines" so that there is always a backup in case the first one fails. Although this ensures a 24×7 service, it is very costly. Industry reports show that Service Level Agreements that guarantee bitrate and bandwidth along with limiting packet loss are expensive. Leased lines can cost thousands of dollars a month and satellite channels tens of thousands of dollars a month and this provides the one-off capital cost of VideoFlow’s products with a very rapid ROI as the operational costs are around a hundredth of leased line solutions.
The equipment comes as a "Plug and Play" pair – a Protector, which stores the packets until it is certain that they have been correctly received, and a Sentinel which monitors the health of the video stream by watching for packet loss and requests packets to be resent from the Protector’s cache only if required. This is ensured by VideoFlow’s patents, which cover techniques to minimise the number of packets that have to be resent. This solution enables the bandwidth requirement to be reduced to keep operational costs down compared to the traditional solution of using Forward Error Correction that requires additional bandwidth of up to 50% to enable lost data to be recovered. This is not always successful. VideoFlow’s solution can work with internet connectionss as slow as 200 kb/sec and yet can deliver the desired quality.
VideoFlow will be announcing solutions at the IBC show in September for even greater numbers of video streams enabling large and complex content gathering networks to be created. For example, a number of its DVP10 Protectors can feed into one DVP100 Sentinel creating one-to-many and many-to-one arrangements.
VideoFlow; www.videoflow.com
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