Hi,
there is an interesting case when the FLAC encoder (using 1.2.0) is given simple waves. Simple waves means: I have a list of {frequency, duration, pause} tuples that define the monophonic tune. In other words, exactly one frequency is played at a time. This is the original dataset from 1989 (driving a PC speaker back then): $ ls -l ihold.sd -rw-r--r-- 1 jengelh users 20616 Aug 14 00:57 ihold.sd Since driving the PC speaker is mostly a privileged operation these days, one would just convert it to PCM and use soundcard output. The program "sd" I have written does just that. The two numerical parameters a and b denote the square and sine rate. # 0:1 rate <=> 0% square, 100% sine generation $ ./sd ihold.sd 0 1 | sox -r48000 -s -w -t raw - ihold-sine.wav # 1:2 rate <=> 33% square, 66% sine generation $ ./sd ihold.sd 1 2 | sox -r48000 -s -w -t raw - ihold-square1-sine2.wav # 1:0 rate <=> 100% square, 0% sine generation $ ./sd ihold.sd 1 0 | sox -r48000 -s -w -t raw - ihold-square.wav Now this is what happens when encoding to FLAC: $ flac -8 ihold-sine.wav ihold-sine.wav: wrote 2422225 bytes, ratio=0.353 $ flac -8 ihold-sine2-square1.wav ihold-sine2-square1.wav: wrote 5474921 bytes, ratio=0.798 $ flac -8 ihold-square.wav ihold-square.wav: wrote 5573016 bytes, ratio=0.813 As soon as square waves are mixed in, the FLAC compression ratio drops rapidly up to the point where it equals the ratio of typical day-to-day music. While I do not request FLAC to compress the wave back to its original 20KB, I think it could improve on the sine and square compression. Are there any plans to address this? If you would like to have the data files and/or transformation program for testing, let me know and I'll upload :) thanks, Jan -- _______________________________________________ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev