Sharp or smooth?: comparing the effects of quantization vs. frame rate for streamed video

  • Authors:

  • John D. McCarthy;M. Angela Sasse;Dimitrios Miras

  • Affiliations:

  • University College London, London, UK;University College London, London, UK;University College London, London, UK

  • Venue:
  • Proceedings of the SIGCHI Conference on Human Factors in Computing Systems
  • Year:
  • 2004

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Abstract

We introduce a new methodology to evaluate the perceived quality of video with variable physical quality. The methodology is used to evaluate existing guidelines - that high frame rate is more important than quantization when watching high motion video, such as sports coverage. We test this claim in two studies that examine the relationship between these physical quality metrics and perceived quality. In Study 1, 41 soccer fans viewed CIF-sized images on a desktop computer. Study 2 repeated the experiment with 37 soccer fans, viewing the same content, in QCIF size, on a palmtop device. Contrary to existing guidelines, we found that users prefer high-resolution images to high frame rate. We conclude that the rule "high motion = high frame rate" does not apply to small screens. With small screen devices, reducing quantization removes important information about the players and the ball. These findings have important implications for service providers and designers of streamed video applications.