It seems to me that recently some people are starting to say/think that 3.96.1 is just as good as 3.90.x (I guess from their own tests and the inconclusive one here), but to me what is notably regressing is lower bitrate CBR/ABR tunings. I compared 3.96.1 and 3.90.3 in CBR96 mode (--[alt-]preset cbr 96) using mc_sich_short.wav. I have tested a bunch of other files also in even lower bitrates, and noticed similar results.
ABC/HR Version 0.9b, 30 August 2002
Testname: cbr96
1L = C:\sich\cbr96-3961.mp3.wav
2R = C:\sich\cbr96-3903.mp3.wav
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General Comments:
ABXing #1 vs original was easy. #2 vs orig needed much more concentration.
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1L File: C:\sich\cbr96-3961.mp3.wav
1L Rating: 3.0
1L Comment: Swishing/watery noise is obvious.
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2R File: C:\sich\cbr96-3903.mp3.wav
2R Rating: 4.0
2R Comment: This is not bad at all. In noisy environments, it should sound really good. The distortion heard in #1 is mostly absent in this.
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ABX Results:
Original vs C:\sich\cbr96-3961.mp3.wav
10 out of 10, pval < 0.001
Original vs C:\sich\cbr96-3903.mp3.wav
9 out of 10, pval = 0.011
C:\sich\cbr96-3961.mp3.wav vs C:\sich\cbr96-3903.mp3.wav
9 out of 11, pval = 0.033
If you use any old test sample, the difference is quite obvious. Of course, there probably are exceptions, but with my personal samples, 3.90.3 CBR/ABR presets (128kbps and lower) tend to be almost always superior to 3.96.1.
I understand that the recent development is concentrated on the lower VBR modes, and I am glad to see the development (Thank You!), but I just wanted to point this out here, because if 3.96.1 becomes the recommended version due to the growing popularity, people should know that there is a possible quality regression in some modes/settings like above, and there should be further testing around these bitrates in CBR/ABR presets.
Edit: for grammar & clarity
