Different Ape Sizes of the same Song
Reply #4 – 2005-01-13 01:13:49
There is a good change it could go the other way too since an mp3 encoder adds noise that is difficult to encode. [a href="index.php?act=findpost&pid=264909"][{POST_SNAPBACK}][/a] Well, from what I know about mp3, the noise added is only in terms of a difference between the original and encoded songs. That is, the energy at any particular frequency may be more or less than the original song. Assuming that more energy is harder to encode (which is a bit simplistic...), quantization noise will influence the lossless compression randomly. Basically: the noise added by MP3 may either help or hurt lossless compression, since it may add or remove from any given frequency. (This is all based on my view of MP3, which is by no means complete) I did a quick test of 11 songs which I had in FLAC format on my hard drive. I did 3 compression settings: 1) WAV > FLAC -6 2) WAV > MP3 aps > WAV (Foobar strong dither) > FLAC -6 3) WAV > MP3 aps > WAV (no dither) > FLAC -6(1) (2) (3)849 836 817 755 763 718 766 778 757 675 707 659 748 768 735 409 517 385 502 538 484 625 666 616 520 586 503 629 667 621 788 796 776 Total size in bytes: 1) 479,525,618 2) 509,609,843 3) 466,929,053 Basically, without dither, MP3-encoded FLAC is consistantly smaller than normal FLAC. However, the dithering process adds noise back into the HF area, increasing the FLAC bitrate. (Note that these songs are almost all classical, hence the low bitrates) I suppose I forgot to mention dither settings in my previous post. Dithered MP3 may compress more or less than the original song, depending on the song's initial HF content. In my experience, though, they compress worse than the original song. (Sorry for going completely off topic...)