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Some of it is people ask the wrong questions. On a loudness-war-wrecked pop song I may not be able to tell 128Kbps from the original, but on specific content I
by jerf 3y ago
Some of it is people ask the wrong questions. On a loudness-war-wrecked pop song I may not be able to tell 128Kbps from the original, but on specific content I have been able to tell. I'm not even claiming golden ears or anything; some specific audio content is the audio equivalent of visual confetti [1], and anyone can hear the difference, because the codec isn't even close. And let me underline, I mean, anyone. No special claims being made here.
But all in all, that content is relatively rare, and generally transient even in the music they appear in.
[1]: https://www.youtube.com/watch?v=r6Rp-uo6HmI https://www.youtube.com/watch?v=r6Rp-uo6HmI
- TylerE 3y agoThe giveaway for low-mid nitrate MP3 is the high hats. The lower the nitrate, the more you get a sort of temporal ghosting that sounds like an almost “crunchy” swishy sizzle sort of sound, a bit like a jazz player using brushes, but more lo fi.
- tedunangst 3y agoLow nitrate MP3 is a fantastic typo.
- hunter2_ 3y agoI agree, and my hypothesis is that it's exacerbated by the combination of three particular things: 1. It's a high frequency complex waveform with a fast envelope, so it demands bitrate. 2. Drum miking often involves multiple mics spaced apart, so more than one typically picks up any given cymbal with a phase offset, and those mics are panned quite differently, leading to a very "wide" result, i.e., left and right output is fairly uncorrelated as seen on a vectorscope [0]. 3. A perceptual codec at a given total bitrate often sounds better when stored as a mid-side transformation (instead of storing a left channel and a right channel, store a L+R "mid" a.k.a. sum channel and a L-R "side" a.k.a. difference channel), also known as "joint stereo" which is a common flag on MP3 encoders, because it allows for assigning more bits to the mid channel (correlated signals) and fewer bits to the side channel (uncorrelated signals). More bits for mono center-panned stuff like vocals is the goal, which is generally for the best, but fewer bits remain available for wide stuff like those cymbals! Contrast with regular stereo mode where half of the total bitrate is assigned to each channel. MP3 below 256kbps typically needs joint stereo mode enabled in order to sound decent. [0] https://en.m.wikipedia.org/wiki/Vectorscope#Audio https://en.m.wikipedia.org/wiki/Vectorscope#Audio
- pushedx 3y agoA realistic take on the issues invovled. I never knew what “joint stereo” meant. Great explanation. If anyone has a good cymbal crash sample at 24/96 or better that they can provide, it seems like it would be a great example for intentional differentiation of various compressed versions.
- TylerE 3y agoVinyl actually encodes stereo much the same way.
- hunter2_ 3y agoFM radio as well: originally one channel, then a second was added, and the second is used for the difference signal (the first already being the sum signal, as with any conversion to mono). Overhauling the whole thing to broadcast left and right discretely would destroy backwards compatibility, and the newly-added subcarrier had worse SNR (thus receivers ignore it until reception is sufficiently strong) so it only made sense to use it for the difference.
- musicale 3y agoI was going to say this - cymbals are often very noticeably bad on MP3 recordings.
- ahofmann 3y agoWell, most classical songs are very well compressible, because not much is going on. Punk Rock or any other music were a lot is happening, at the same time, can suffer very audible from 128 kbit lossy compression. So you can hear lossy compression better in a loud pop song than other music.
- esquivalience 3y agoI don't agree with this from my own experience. To me, classical music at high compression suffers far worse than modern bands.
- colejohnson66 3y agoMy unscientific guess would be that classical music might have wider dynamic range than “normal” music. So the same compression amount affects the one with more range first (classical).
- nuancebydefault 3y agoHigher dynamic range and typically also more 'pure'. The introduced compression artifacts stand out more in simpler waveforms than in wavevorms that are an addition of many more layers of sound.
- thefilmore 3y agoYour guess would be correct [1]. Some samples [2]. [1] https://www.mdpi.com/2624-599X/4/3/42 https://www.mdpi.com/2624-599X/4/3/42 [2] http://www.harmjschoonhoven.com/mp3-quality.html http://www.harmjschoonhoven.com/mp3-quality.html
- munchler 3y agoA typical classical symphony requires 50-80 instruments, several dozen of which might play at the same time, while a typical punk song has maybe four.
- 3y ago