Video - January 2017

January 2017

Video Test - Buffering Events and Startup Delay

TrueNet measures the number of buffer events that occur in our standard video test. Buffer events are when when the video stream appears to stop, while waiting for additional data.


TrueNet's video test chooses specific videos ( This month two videos, an HD one and an identical content 4K video)  The video will be cached (stored locally) by ISPs in NZ for all viewers, simply because we are downloading the video seven times a minute from 400+ different NZ addresses.

Each test downloads 10 seconds of content at a time, to fill any buffer to last 40 seconds.   So on startup, the test will immediately download (at full speed) 40 seconds of content, after a time gap (to allow for playback) it will then download a second 40 seconds of content, simulating keeping the 40 second playback buffer full.  This appears to be an international standard for consumer video testing.

TreuNet records buffer events by counting "Stops", where the simulated buffer would become empty.   We also record Resume and Finished events.   Chart 1 shows a count of the number of "Stops" (sometimes more than one in a single download attempt).

We also measure the start delay, ie the time taken for a video to start downloading so it can play.  The typical period for this is so small, usually less than 1 second, that we are unlikely to continue publishing this statistic without good reason.

The chart below shows the number of buffer events each day, from a sample size of roughly 600-700 tests per day

Chart 1: Video Test Buffering Events by Tecjhnology each day in January

The Start delay chart shows a count of the number of video delay starts in seconds, but the scale shows only from 1/10th of a second up to 1.2 seconds, ie an extremely short time.

Start Delay by technology shows faster technologies are quicker than others, but the actual start delay is almost always less than 1 second for any technology.  This simply shows that video delivery for cached videos in New Zealand on any ISP is excellent.

Chart 2: Video Test Start Delay by Technology in January


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