Sorry if this has been answered before, but: how much error amplification do you apply at 128 kbps stereo? 1 dB, or more?
And I'm surprised Fraunhofer's AAC encoder averages only 112 kbps on this item set. Do some samples include silence?
Not all test items were amplified, only those with unnoticeable artifacts.
QuoteNot all test items were amplified, only those with unnoticeable artifacts.I assume the same amplification would be applied to all codecs for that item?
... each test item is degraded by each codec differently, in each item/codec case the amplification is applied differently (if at all). If applied - three gradually degraded versions of an item are produced.
Quote from: Serge Smirnoff on 25 March, 2014, 08:26:33 AM... each test item is degraded by each codec differently, in each item/codec case the amplification is applied differently (if at all). If applied - three gradually degraded versions of an item are produced.But then how can you rank the codecs for such items?
When it comes to consistency of quality or anytime because consistency is important as much as level of quality (average score) then geometric mean score should be/is more representative.
outputScore(itemScore) = 5 * sqrt(0.4*itemScore - 1) if itemScore > 5andoutputScore(itemScore) = itemScore otherwise.
Oh, and that formula? Reminds me of a formulating of my rules of thumbs
The whole point of me bringing this up is that I fear that encoders aiming for CONSTANT quality (i.e. small quality variance and NO overcoding for scores > 5, i.e. following the VBR principle) are being punished in this evaluation. This isn't so much the case in the lower-bit-rate rankings.
Following codecs were added to 128kbit/s section:AAC VBR@112.0 (Winamp 5.666) - VBR, AAC LCAAC VBR@118.4 (iTunes 11.1.3) - TrueVBR, AAC LCAAC VBR@117.5 (NeroRef 1540) - CVBR, AAC LCVorbis VBR@119.4 (Xiph 1.3.3) Opus VBR@115.7 (libopus 1.1) mp3 VBR@113.7 (Lame 3.99.5) - MPEG-1 Layer 3, VBRAAC VBR@110.9 (libfdk 3.4.12) - MPEG-4 AAC LC, VBRmpc VBR@123.3 (SV8)All encoders have integer/discrete quality settings - http://soundexpert.org/news/-/blogs/opus-a...c-at-128-kbit-s
despite questionable artifact amplification technique