A new report on mobile video quality of experience examined the causes of stalls during mobile viewing, as well as the strain that video puts on the mobile network.
The study from Allot Communications was based on 300,000 video detail records randomly selected from hundreds of millions during one week in December 2013 to provide a snapshot of video quality of experience. The data came from a 3G commercial mobile data network in a developed country, but according to Jay Klein, CTO of Allot, the findings apply to LTE networks as well.
Stalled video is typically cited as the primary cause of low quality of experience for viewers. Using stalls as a metric for quality of experience, Klein said, “is basic, but it’s very useful.”
“It seems that while consumers will settle for low resolutions on smaller screens, they are usually very dissatisfied with stalls,” Allot noted in the report. While stalls were usually remedied in the past by increasing the allotted bandwidth for the session, network congestion has made it harder to do that, the company added.
Findings from the report included:
– Insufficient allocated bandwidth for the video session will result in video stalls.
– Actual bandwidth allocation by the network has no correlation to the video stream requirements. Allot found that “neither the content resolution nor the [format] appears to influence the actual bandwidth resource allocation by the network. This indicates that the network seems to disregard the nature of the content (i.e., resolution) resulting in inefficiency of network resource allocation.”
Klein added that Allot saw the network parceling out resources without regard for the fact that video is more sensitive to delays and limited resources than other types of usage.
“The network seems to behave ignorantly, or agnostically, to the content types being delivered,” Klein said. “If you are downloading a file or browsing the web or video streaming, the network will try to react in a fair way — but not in a thoughtful way.”
And, he noted, despite the fact that LTE has more bandwidth than the 3G network which produced the study’s conclusions, “the mechanism for this is all basically still the same. Issues that we encounter in a 3G network with video, we will definitely encounter also with an LTE network.”
– Laptops with dongles experience more video stalls than smartphones, probably because users were attempting to utilize high-quality video content for which there was not enough network resources; but users still watched videos on them for a longer duration.
Klein called this finding evidence of the human element in quality of experience. Smartphone users were perhaps viewing shorter video clips on the go, Klein said, and had low tolerance for stalls. But a user who was watching via laptop, perhaps viewing a favorite TV series or a movie, was likely to stick with the viewing despite stalls.
– The video delivery container or format (3GP and MP4) affects the mobile viewing experience. 3GP format mobile videos, which are considered a more mobile-friendly delivery, were watched longer and had fewer stalls on average than MP4 files, which are often associated with HD-quality video.
– Videos watched for a longer duration tend to have more stalls.
Klein said that video providers can encode content in ways that make it more likely to play well via mobile viewing, but that ultimately the responsibility for the video quality of experience lies with operators who can increase the intelligence of how their networks handle video.
“You cannot rely on content owners that everything will be okay regarding the delivery of the video over the network,” he said.
