Subjective video quality as a function of bit rate frame rate, packet loss, and codec

We present results regarding the impact on video quality of the factors: packet loss, bit rate, frame rate, and codec. The domain of this study is small-screen, mobile, low bit-rate video; the screen sizes covered are QCIF, CIF, and VGA. Bit rates are mainly in the range 64-1536 kb/s. Packet loss rates cover both typical wireline and wireless situations. The data on which this report is based come from a 15-lab study, the Multimedia Test by the Video Quality Experts Group. Forty-one separate experiments were conducted, each one using a different set of 166 specially-prepared video sequences, and each sequence being rated by a different set of 24 observers. The VQEG data can be analyzed to show the impacts of the factors packet loss, bit rate, frame rate, and codec. Our analysis consists of statistically relating the subjective judgments to these objective parameters.