lossyWAV Development
Reply #491 – 2007-11-12 14:17:06
Target b) for -3: OK, so we should think about the details. Identical -spf and -skew values for all of the three quality levels? I don't like the idea. From my test when finding useful values for -spf I know some values really hurt bitrate efficiency wise (most of all the bold 1 in '111 24' for the 64 sample FFT of -1) but may be vital for being real defensive with respect to the critical band at the lower edge of the corresponding frequency range. So I think it's neceesary for -1 (and would be most welcome for -2 too but it's expensive and the more economic way of treating this within -2 may be by doing the additional 128 sample FFT). With -skew it's similar. -skew is important for diffentiating resulting bitrate between regular and problematic spots, but with a value >24 the improved defensiveness is getting more and more expensive. So I think a value of 24 is very appropriate for -2, but it should be significantly higher only for -1. For -3 it should be <24. Using very high values for -snr helps differentiating between regular and problematic spots too but with these values there's a rather high price to pay bitrate wise. So again high values of -snr should be used with -1 only IMO. So I strongly think -1, -2, and -3 should consist of different -fft, -spf, -skew, -snr, and -nts settings in such a way that the overkill defensiveness, standard defensiveness, reduced defensiveness are represented best. If you want to keep -1 and -2 clean of user options I suggest you do it for -3 as well, and instead create an experimental quality option -x which enables all the advanced options. advanced options = any option except for -1, -2, -3, -nts x (and -flac etc. in case these are ever needed - guess they won't). I like the idea of the -x quality parameter (-0?) enabling the advanced options and also keeping -1, -2 & -3 "clean". This would be a copy of -2 and only those settings that the user input would be over-written, the rest being taken as per -2 for the processing. On the -skew, -spf and -snr settings I am inclined to agree with you. The only difficult bit being agreeing what those settings will be.....