Analysis

The visual representation of all the data reveals a correlation between decreasing bitrate and reduced execution time, furthermore, the CIs do not overlap for either encode or decode (Figure 3.7 & 3.8) effectively making an ANOVA-test unnecessary.

Hence the null hypothesis for RQ1 is rejected and thus the following is true: There is a significant difference in execution time between the selected pairs of codecs and bitrates.

3.2Experiment

The upcoming figures visualizes the ratings of the different samples from the MUSHRA test.

Figure 3.9: MUSHRA (raw data)

In order to compile and analyze these results the raw data (Figure 3.9) had to be filtered and validated, which was done in two steps. First, the post-screening method (see the implementation section) was utilized, resulting in a fall out of 7 out of 21 participants, effectively excluding their results. As a second step, each rated sample was checked for outliers. Two were noted, one for LC3 (64) and one for LC3 (256). In the aftermath there was no way to verify the nature of these odd ratings, and thus, to avoid contaminating the results they were excluded from the data shown in the upcoming figures.

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Figure 3.10: MUSHRA means, with SD

The SD for the rated audio samples (Figure 3.10), the reference excluded, is quite large and varies between 12.85 - 21.10, and the majority of rated samples between 12.85 - 14.48. This gives an indication that there is a wide spread of the perceived audio quality for every individual bitrate.

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Figure 3.11: MUSHRA means, with SE

The SE for the rated audio samples (Figure 3.11) is quite consistent and varies between 3.43 - 5.64.

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Figure 3.12: MUSHRA means, with a CI of 95%

The CI of 95% for the rated audio samples (Figure 3.12) lies within the range of 7.41 - 12.18.

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