Alt-Preset Standard/Extreme Flaimbait
Reply #5 – 2003-05-01 14:16:47
Your original guesses aren't sufficient to tell the difference between standard and extreme. In fact audible quality is barely different (most artifacts are flaws in the psychoacoustic model (or limitations of the MP3 format), so most of the extra bits used by extreme are not directed to fixing the flaws because the encoder doesn't think there are flaws, and extreme might simply happen to make the artifacts quieter, though they're still audible. That's why standard is the standard. Insane is the best that MP3 can do, and is recommended for problem samples where lame APS (or APS-Z) still has problems. One difference that you might be able to analyse mathematically is the low-pass filter frequency. For music with insufficient high frequency content this won't work, but standard uses a fixed 19.0 kHz lowpass (polyphase, transition band 18671-19205 Hz), and extreme uses a 19.6 kHz lowpass (polyphase, transition band 19383 - 19916 Hz). Encspot will read the lowpass value from the LAME header, and 19000 Hz or 19600 Hz are the values for standard and extreme respectively. There's likely to be no audible difference on most samples. BTW, a lot of people use MP3 for encoding because they believe they're restricted to MP3 for a portable hardware MP3 player. If so, you might actually be able to use MP2 as well using the same decoder (and usually get away with renaming to MP3 if the MP2 extension is not recognised). TooLame can encode .MP2, which isn't a transform codec, and won't suffer the same types of artifact as MP3 if MP3 simply isn't good enough. It's available on the MP3 page of Rarewares.hydrogenaudio.org . I've heard that this works pretty well at very high bitrates (such as 384 kbps) and has pre-echo and transient resolution closer to MusePack (but it's less efficient than MPC and lacking in joint stereo). Its psychoacoustics aren't mature, well optimized and well-tested like LAME's, but you could try a CBR 224, 256, 320 or 384 kbps commandline liketoolame -p 3 -b 256 file.wav file.mp2 or try VBR (though it's not guaranteed to be supported by the decoder) such astoolame -p 3 -v 5 file.wav file.mp2 for VBR bitrates probably a fraction above those of lame --alt-preset extreme -Z. I wouldn't say either of these toolame settings is a secure mode, but it's a plausible alternative to Lame insane or extreme for portable players when you still have an artifact.