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5
Opus / Re: Opus frequency notching at 15.5 kHz
Last post by kode54 -
If you look at his graph, you'll see that the Opus file has a slight notch of less than 5 dB between 15.5kHz and 16.5kHz, and then goes up to match the source material again. It doesn't really have any further low pass filtering until it hits 20kHz.

Not that this is a fair comparison of how a codec works. The notch is also less than -75dB, so it would take some seriously sensitive equipment to pick out just that difference over any other differences in the signal.
6
Scientific Discussion / Re: Pathological example of a intersample peak, 11dB, discussion.
Last post by Porcus -
More necromancy. I was curious enough to test a little bit, and found a +11 dBTP measurement in one of my CDs using one of the algorithms. Merzbow, not surprising - so you may wonder if all clipping is part of the music the way the artist intended it :-o

But I also tested a selection of albums with positive album gain, because here is where the peak value stored will limit upon playback. (The Merzbow album has an album gain of -21 dB, so the +11 won't bring it across zero.) General findings: a couple of dB suffices on everything I tested. Which excluded classical music (where there is too much that peaks too low, it would take much more work), test signal CDs, HDCDs and pre-emphasis CDs.  All were lossless CDs/Bandcamp downloads in the FLAC format.


The "positive gain" selection: Initially I set some criteria for entire albums, but ended up searching up tracks with high peaks from albums with positive RG album gain (calculated by fb2k, new algorithm), which is where clipping prevention according to peak would kick in.  I ended up scanning some 163 tracks, but that was because I was too lazy to remove stuff.
Then I picked a handful of tracks and scanned them with several "True peak" settings using foobar2000 1.4beta13. 
Music: Lots of prog.rock and the like. Diamanda Galás, Pink Floyd: "Mother" from the Shine On version of The Wall, The opening track from Demon's "British Standard Approved", Jonas Hellborg - and Bobby McFerrin (the "Voice" album).
Some general remarks:
* Turns out that in my setup, the SoX resampler does not find any intersample peaks at all.  Maybe it could have something to do with my setup, using SoX resampler to get rid of some odd sample frequencies.  Anyway, SoX excluded.
* Auto 2x/4x/8x return precisely the same figures. 

Results:
* Nothing in this selection went above +1.30 dBTP.  That track is White Willow: "John Dee's Lament" from their debut Ignis Fatuus, RG track peak was 0.98something.
* Other were close to or above +1 dBTP: McFerrin, Demon, Hellborg.
* Those who are worried about their Pink Floyd: +0.48 dBTP.
* Differences between algorithms are smallish, less than 0.1 dB.

Learnings: a couple of dB seems to take care of everything I tested, and algorithms make little difference on these tracks.


Then the LOUD albums: 12 albums (112 tracks) with album gain -16.00 dB (fb2k, new algorithm) and below.  Quite a lot of industrial/noise (three involving Merzbow),  a couple of black and death metal albums, and the infamous Stooges "Raw Power" reissue.  All tracks 16/44.1 but one track 24/44.1 in a Bandcamp purchase; that didn't turn out to matter.
* "No oversampling" track peaks overview: Six of twelve albums at full (.9999969 or 1 for all tracks).  Four more albums entirely within -0.12 dB.  The last two a bit particular: Deathstorm: We are Deathstorm, all at -0.2 dB and one -0.48 dB - and then a 41 minutes Merzbow concert in a single track, at -1 dB.
* Every track "above" the Stooges: Raw Power peak have Deathstorm or Merzbow involved.  Only here the choice of algorithm makes big differences in numbers:  The "worst" is Merzbow: Venereology, and here a track ranges +7.15 dBTP to +11.30 dBTP  depending on algorithm (the highest using dBpoweramp/SSRC - both are still way short of the album gain of -21.76 dB though).
* Stooges: Raw Power: variation among tracks in the interval [+1.95 dBTP, +2.98 dBTP] for PPHS default. Variations among algorithms: from PPHS default and and .3 to .4 dBTP upwards (PPHS ultra, dBpoweramp/SSRC), with "auto Nx" in between.
* None of the albums get album peaks below +1.77 dB (PPHS, both default and Ultra) to +1.84 (auto Nx). 
* Two to three of the 112 tracks stay below 0.  All Deathstorms. The "third" of these range -0.02 dBTP to +0.14 dBTP.

Learnings: All these albums bump up ~ 2dB or more, up to a whopping 11 dB. Only on one album did the algorithm really matter for the number - but remember again, the large negative RG album gain will more than compensate.
7
Vinyl / Re: How stable are record decks in terms of tempo/pitch? (Drifting)
Last post by Atmasphere -
You could also look for an old Dual turntable. I still have mine. They are belt driven, have a 7 1/2 lb. platter, and a speed adjustment with a built in strobe.
TTs for DJ-ing on the other used to have ultra light platters made of aluminium. This allowed them to reach or change target speed extremely quickly, useful for beat matching etc. They also often came with a slipmat made specifically to have very low friction for easy scratching and pitching.

Needless to say, if you want to record the vinyl true to its intended sound (and don't want to spend money on digital versions) you would want to invest in one of the first types of turntables and stay away from the DJ types.

The old SL1200 did not have an ultra-light platter and yet is very popular with  DJs. It had a fairly robust drive and so was able to get up to speed quite quickly (the new one can do it in 1/10th of a second). If you are on a budget, the older SL1200s are a pretty good deal for LP playback- DJ or no.
8
Support - (fb2k) / Re: Pioneer u-05 DSD issue
Last post by dejanm -
That is actually the problem. DSDTranscoder + Wasapi works fine with Shiit Loki (pure DSD DAC) without Shiit driver. But it does not work at all with Pioneer U-05. For some reason ... Therefore I went the ASIO path, but with the latest versions it does not work as well (unless you use this trick with JRver). Obviously I should install the older versions of ASIO Proxy ... but somehow I did not want to go back in the past (maybe I should). All this is rather messy affair and I still believe that it should be simplified and resolved within Foobar.
9
Uploads - (fb2k) / Re: foo_musical_spectrum
Last post by EpicForever -
For some reason I dont think I'm seeing the full spectrum analyzer from left to right. I only see A B C1 thru A B C9.
I think you squeezed component horizontally. Just stretch it and you will see whole spectrum.

Thanx, great spectrum..

Question 1:  I want to display 20to20Khz, the audible band... what are you using for "Notes"?  I have it set to F0 - D#10
Question 2:  Why are the low frequencies show spread across multiple bars?  I have a test disc that plays sine waves... when I play low frequencies such as 20 HZ or 80 HZ, the spectrum should have only one bar displayed, but plays a hump... higher frequencies are no problem with a single bar.
Question 3: Any plans to show Hertz and not notes?

Thanx
Bruce in Philly
1. Here I set C0 - F10, but D#10 should be enough.
2. Sorry, but you just need some education, which is far beyond this subforum. This component by design shows BANDS of frequencies, not just frequencies themselves. These bands are called terces and are fixed "by design" - it is a long story of creation of "equal temperament", which eliminated flaws of ancient (like Greek) musical temperaments. It's something on border of acoustics and music theory.
3. I am not author, but I don't think so. It is "Musical Spectrum", not "Yet Another Spectrograph". Term "Musical" in name suggests that it is all about music - composition and playing on instruments, which involves usage of notes, not frequencies. And those terces and octaves play important role, related to pitch of notes.
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