"DVD-A vs. CD" & "Nyquist was Wrong"
Reply #17 – 2003-10-20 19:46:27
- I can't download properly any of the samples. The wavpack samples seem to decode OK full length, but wavpack decoder reports CRC mismatches. I can't decompress the zip files either, because files are reported to be corrupted. It seems that part of the files is always cutted off. I hope now everything works using the PAR2 files.- The wavpack samples are faded-in and out. It's not very recommendable to be so, because a tricky listener could identify dither noise at the processed files playing the beginning or the end of the samples at high volumes. Well, in real life - outside of tests like this - there are fadeins and fadeouts as well; often these fades are even much slower, so a listener has more time to focus on low volume noise than in this test. If someone really wants to cheat, this can't be prevented, no matter if fades are used or not.Fade-in or out is OK only if you apply it exactly same way at both (original and processed) test samples, but after all processing. I don't understand why. Of course there's a point where fading makes the original signal so quiet that dither noise becomes audible if volume is high enough (and equipment noise-less enough), but this will happen no matter what's the order of applying fade <-> processing (=resampling/changing resolution 24->16bit), won't it? ATM I'm not persuaded yet that the problems that could be caused by the fades are big enough to justify the extra work of re-creating the samples and uploading again ...- After some testing, I think best tradeoff between to pre- and post-ringing and resampling artifacts is obtained using fast SSRC resampling on downsampling and slow (normal) resampling on upsampling. Fast resampling causes minimal worse performance when downsampling, and sets the ringing behaviour. From what I've seen from CEP spectral view / frequency analysis, the ringing caused by SSRC/fb2k is at > 21kHz. May I ask what makes you believe that this ringing can cause any problems so a 'tradeoff' is needed - or have I misunderstood? I don't want to question your results/recommendations but I'm curious about details ...I'd use ATH noiseshaping dither. I'd use soft ATH noiseshaping instead of strong ATH noiseshaping, because it's more than enough in this case, and because results in lower dither amplitude, including less risk of clipping. Anyway, as a side-test, flat dither could be tested to check if it makes for an audible difference. Fine. If you don't mind I'll edit this in the test proposal somehow.There's no need to use foobar2000 to perform the processing of the samples. It's way easier to use SSRC 1.29 and run a bat file that performs the whole process for each file. I'll upload a bat file that does this as soon as I learn how to do it Thanks alot for the effort! A while back (before fb2k diskwriter existed) I used SSRC for some tracks and noticed problems with too loud (clipping) signals - This was the main reason why I wanted to use fb2k for it. As you said - the samples aren't mastered at such a high volume so using SSRC is save. If noone decides to pay more than I'm willing to at ebay I'll have got a 24/96 soundcard soon B) and can perform the test myself.