Question

.Wav tracks heavily distorted on the top end (hihats, white-noises, etc)

  • 14 February 2017
  • 7 replies
  • 3109 views

Thanks for stopping by, I've noticed that uploading both mp3 and top quality wav files, my songs here on Soundcloud sound kinda wierd, even when professionally mixed and mastered. Especially high frequencies (above say 7KHz) of hi-hats and high synths completely fall apart, making the sound quite unpleasant. Of course I have double checked the same files first with accurate headsets and studio monitors, nothing bad there. My guess is that there is something wrong taking place when Souncloud converts the tracks again. But how comes that other famous songs with a lot of dirty sounds usually do not present the same audio issues? I know that streaming is not meant to be accurate, but the difference btw what I upload and what I hear in my page is kinda astonishing.

Let me know if u have some advice. I have also tested an extreme case: while mastering a song I've rolled away frequencies starting from say 12-13 KHz, the issue is still there.

7 replies

Userlevel 3
Unfortunately, Soundcloud refuses to move to a better audio format at the same bitrate. Even the latest LAME MP3 encoder has most of the issues you mentioned, with clear distortions from about 12KHz upwards. I'm hesitant to make my new track public for this very reason.

To demonstrate just how unnecessary sticking with MP3 is in 2017, download the LameXP Audio Encoder (a free program which has the very latest audio codecs), drop your WAV into the main window, and under the Compression tab, select Opus at ~128 kbps VBR. Hit encode and give your track a listen (I use VLC). At that bitrate, Opus should sound nigh on identical to your original master!

Now try encoding your track again with Opus at ~96 kpbs, and compare the results to Soundcloud's 128 kbps MP3 transcode. If you're wondering why it still sounds head and shoulders above MP3 128 at a significantly lower bitrate, that's because MP3 is OLD - and has been long made obsolete by the likes of AAC, OGG Vorbis and now Opus. If Soundcloud is so concerned about keeping bitrates low for those with slow internets connections or restrictive data plans, I see literally no reason not to move to Opus at even lower bitrates than they use currently, which would still offer a significant improvement in audio quality.

In my opinion their audio team is neglecting this glaring issue for no good reason. Half of all Youtube videos now use Opus for audio; Spotify streams in OGG Vorbis; iTunes in AAC. All superior to MP3 at the same bitrates.

Please Soundcloud - for the love of all things holy - upgrade to a newer format!
Userlevel 3
Just as an addendum to my previous post:

Here are some spectrographs of one of my tracks - first as an MP3 file at 128kbps, then as an Opus file at 128kbps (both CBR to keep the file size exactly the same).

MP3 (Zoomed Out):



Opus (Zoomed Out):




Below I've zoomed in so you can see a section with lots of hi-hats, and what each codec does to them at 128kbps:

MP3 (Zoomed In):



Opus (Zoomed In):



There's the reason your hi-hats and high synths sound like they're "completely falling apart" - because that's what MP3s literally do at this bitrate. A hard ceiling at 16.5KHz, degradation and smearing of transients all the way down to about 7KHz. That's what gives low bitrate MP3s that characteristic "watery" sound. Opus on the other hand, closely resembles the original WAV file and sounds like it too - at exactly the same bitrate.

I rest my case.
Just as an addendum to my previous post:

Here are some spectrographs of one of my tracks - first as an MP3 file at 128kbps, then as an Opus file at 128kbps (both CBR to keep the file size exactly the same).

MP3 (Zoomed Out):



Opus (Zoomed Out):




Below I've zoomed in so you can see a section with lots of hi-hats, and what each codec does to them at 128kbps:

MP3 (Zoomed In):



Opus (Zoomed In):



There's the reason your hi-hats and high synths sound like they're "completely falling apart" - because that's what MP3s literally do at this bitrate. A hard ceiling at 16.5KHz, degradation and smearing of transients all the way down to about 7KHz. That's what gives low bitrate MP3s that characteristic "watery" sound. Opus on the other hand, closely resembles the original WAV file and sounds like it too - at exactly the same bitrate.

I rest my case.



I clearly see your point mate, and those pics u posted definitely show what I suspected, thank you. Ofc overall streaming quality should be improved in this platform, however reading here and there I found some interesting advices how to preserve the original master high-end, well actually how to partly prevent the transconding system of Soundcloud to destroy the top end of your mixes. I tried different things and combined together, with some trial and error, the results are pretty cool.

Once you get a balanced mixdown (with critical harmonics around 5Khz, 7 Khz and 12 Khz sitting smoothly), in your mastering chain u should try rolling off from 16-18 Khz (quite basic), while also reducing slighly (using Izotope stereo image for example) the stereo signal of the top end (say from 7-8Khz, from 5% to 20%), given the fact that, while converting lossless files into mp3, that section of the spectrum is affected the most, and if that signal is also very wide, the resulting low resolution version will definitely sound quite bad. Another cool thing I tried is to completely prevent the song to clip even after the conversion process. Indeed the resulting low-resolution track might present some clipping even if the orginal file does not. To fix that I activated the feature "true peak" in the limiter(like ozone's but not exclusively) while slighly lowering the output of the limiter itself. I found -0.3 dB acceptable, but even lower levels (-0.5 dB to -1.5) are safer and result in more accurate final result, not clipping even in a 128 Kbps vesion. I am not disturbed by an average RMS level of -9 dB to -8dB so applying a safer limiter does not really make any difference to me. Just try and listen for yourself. I have tested these tips on my latest electronic remix master, full of white noises, synths are percs patterns. it's not perfect but it's really another story with respect to the previous version without those fixes. Ofc with good headphones and monitors u can still hear artifacts on the hi-end, but at least it sounds less "empty" and watery.

Hope this can help ya, while we wait Soundcloud to improve their streaming option :P


Respect,

HST
Userlevel 3
Cheers for those mastering tips - I may have to grit my teeth and bear through it until they decide to upgrade to a better transcoder 😛
Userlevel 7
Badge +3
Hi there,

Just a heads up that this is being forwarded to our engineers for reference. Also, there's an interesting article on mixing and mastering for only streaming purposes by iZotope, which might be an interesting read for you.
hm i have this issue comparing MP3 with Soundcloud....soundcloud is still miles behind. MP3 vs. 32fpt is relatively imperceptable compared to what soundcloud does. Its clearly doing something else to our mixes...is it a problem with uploading mp3s to soundcloud or something? maybe they just reduce the bitrate to 40kbps or something, because that's the level of high frequency quality loss some of us experience...128kbps SOUND FINE when i playback, I'd still SELL higher quality like FLAC or even 320kbps if people must have mp3, but ultimately is only shaving like 2% of the quality off...not 50% like soundcloud does.

....I really want to get to the bottom of this!

all the guides are about conversion to 128kbps, not whatever soundcloud is doing....again my 128kbps sounds fine (with EXPECTED very minimal quality loss of an MP3) in winamp, WMP and my DAW....something else is going on.
Yea and this is still hapenning in 2019.
I had the hope that they would have optimized their artificial codec by now but sad to say that i kind of lost hope in this problem being resolved

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