MPC vs VORBIS vs MP3 vs AAC at 180 kbps
Reply #86 –
Thanks for the testing.
I can't help but think how the iTunes mpeg-4 AAC 160kbps VBR format tests up against these other encoders. Maybe someone will do a test using iTunes 5 and QuickTime 7. Just curious, why couldn't a 160kbps mpeg-4 AAC file be compared to others? I know the bitrate is lower than the others but does this cause a flaw in the tests?
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It makes the test more difficult to interpretate. If the codec tested at 160 kbps does worse than the others at higher bit rates (there is a reasonable chance this would happen), then one could always bring up the argument "but it used a lower bit rate", rendering the results meaningless. On the other hand, if the codec tested at 160 kpbs would do equal or better than the ones tested at higher bit rates, logic suggests that it would also do equal or better when tested at that same higher bit rate. So there is no reason to use 160 kbps.
Taking in account the amount of time such a test takes, and the large risk of getting an unuseable result, it would be better to test all codecs at the same bit rate.