AUDIOGEEK: Has YouTube Started Normalizing Audio For Uploads?

YouTube is by far one of the most popular ways to consume music the world over. The traffic that Tower of Doom videos (Tower Sessions, Re/Amp, etc.) receive from YouTube viewers literally dwarfs anything we have ever tried to use as a media platform for our company before and it seems like it is only getting more prevalent with time.

As a music producer and audio engineer myself, I know how this has affected my own workflow and thousands of other aspiring producers out there as well. However, lately we’ve noticed some changes to the way YouTube handles audio, so we ran some tests and wanted to share our findings in case any of you have been noticing some discrepancies. But first let’s look at the big picture:


Some of the concepts and issues discussed below are super
nerdy and will be incredibly boring  for the average music fan. 
Continue reading at your own risk!

Seriously though, if you're not into longass articles about audio
production please feel free to click on another article link to the right.

The Good

The good thing with it is that YouTube has made it super easy for ​literally anyone and their mother to upload and release content to the world, and its global audience is growing exponentially everyday.

At the time of this writing, our own TOWERofDOOM YouTube channel has amassed over 164,000 subscribers and has over 51 million views. That's a lot of traffic!

What's even more surprising is that this channel growth actually began to take off during the lifespan of our YouTube show, Tower Sessions. The channel has actually been active since 2006 (there are some really dumb early uploads that you can all still watch if you dig deep enough) but it really only hit its stride when we started producing and uploading our live performance episodes, and this really made us start paying more and more attention to how our audio was translating on YouTube.

The Bad​

The bad thing about YouTube is the audio quality.

Sound engineers will spend hours or even days obsessing about how to translate their mixes onto the platform properly, in the hopes that whatever you're hearing on your headphones or studio monitors will hopefully be what everyone else is hearing throughout the world.

So, you spend absurd amounts of time mixing and mastering your work until you have the perfect audio upload, only to be sorely disappointed when you watch it live online and it's streaming at a whopping 128kbps! What is this 1995? Take note: this is even before reading any comments, which are undoubtedly just ready and waiting to rip your engineer ego a new one.

Is YouTube F*cking With Your Master?​

Initially, we were quite happy with the way YouTube represented our Tower Sessions audio and you could even upgrade the quality by switching over to a higher resolution if you wanted to (480p, 720p, 1080p and so on).

Unfortunately this doesn't seem to be the case anymore and there have been other tests performed by other fellow audiogeeks out there that have found that YouTube is now consistently streaming audio at a lowly 128kbps for all video resolutions.

Upon discovering this, I decided to conduct some tests of my own just to see if this was all true and I actually stumbled across something entirely different in the process!

YouTube is Most Likely Auto-Normalizing Audio for Uploads

I spent some time running the YouTube audio output through my Focusrite Saffire Pro 40 Stereo In Loop feature direct into my trusty Cubase DAW and recorded audio streaming from video to video (awesome functionality by the way: it lets you record anything playing back in your web browser, or anything else running on your computer for that matter)​.

I made sure to pick songs from different producers, artists, genres, etc. The YouTube audio controls were left maxed out and streaming into my DAW on one long continuous track.​

After going through several videos, I noticed that while some of the videos were streaming your average "super-loud mastered" audio, most of them (especially those uploaded recently in 2015) were averaging at relatively "soft" -4 to -3 on my Cubase meters.

At first, I chalked it up to engineers uploading softer masters in general, since the whole loudness wars thing has been debated to death... but then I noticed that almost every audio stream I had recorded was being displayed at the same -4 to -3 readings from video to video.

Here's a long audio recording of several different YouTube videos played in succession. The waveforms look different but most of them averaged at around -4 to -3. Seen above, only 2 of the songs I randomly selected were still as loud as your usual master. The waveforms are displayed in white against a yellow background.

So, here I started thinking: there's just no way that ALL the engineers who mixed all these different songs, between different genres and different artists, are ALL reading or watching the exact same "YouTube Audio Loudness" tutorial!

Even our own catalog of uploads will differ from year to year as our own tastes and audio preferences mature through time. It's just impossible that everyone was uploading this audio at the same average loudness, So, I decided to conduct a test to be sure.

Testing 1, 2 , 3...

I used some of my favorite loudness measurement tools and plugins (any true audiogeek knows what I'm talking about)​ and measured the loudness of one of my own recent uploads. The audio I mastered for it was leveled out like any other modern loud master would be. I gave it a few measures of headroom for the AAC conversion that our Tower of Doom video team uses for our YouTube uploads. I quickly dialed in some rough compliance settings dictated by MFIT loudness standards, and called it a day.

SHAMELESS PLUG: By the way, I am a certified Mastered for iTunes mastering engineer for any of you in the Philippines that might need one... as far as I know, there aren't too many of us down here in the ASEAN region so please feel free to let me know if you guys need any help with MFIT compliance.

​We then uploaded the video to YouTube and once it went live I took sample recordings of my uploaded audio, one at every resolution available (this was to help me wrap my head around the whole 128 Kbps issue at different video resolutions) and I saved them within my Cubase project.

Here is the same upload being recorded at different video resolutions.
They are all playing at 128 Kbps.

A week later, I rerecorded the same uploaded audio into the same Cubase project, making sure that all of the same factors were in place so I could easily compare the 2 recordings.

Low and behold, there it was! YouTube had auto normalized my initial audio by the same -4 to -3 db. It was clear as day from the moment I saw the waveform coming together within my project and the week old audio was actually visibly smaller within the waveform display than the one I had recorded on the upload day.

The file to the left is the recorded audio from upload day. Notice the Cubase channel meter displaying -0.0.

The file to the right is the audio from a week later. The channel meter is now displaying -3.9 for the same audio.

My Findings​

My theory is that YouTube is auto-normalizing audio for uploaded content across the board. It will leave things as is initially when your upload is fresh, but will end up normalizing your audio as soon as it finds time to get around to it!

During this test, I also decided to compare​ waveforms from past uploads in the same manner and also found the same things. Several of our videos that were all uploaded close to your usual loud master levels were all now normalized to the same levels retroactively.

It should be said though; some of our Tower of Doom uploads have not been affected just yet and are still playing at the super loud standard you'd expect. I found this to be true for other uploads as well around YouTube, but I actually had a harder time finding loud uploads overall. This certainly wasn't the case only a few months ago in 2014. Is it only a matter of time before all of them are normalized this way?

YouTube is a BEAST

All of this is particularly interesting to me because it means that YouTube is somehow feeding ALL the audio from ALL their videos through some sort of normalizing beast of an algorithm, that is churning out re-mastered versions for uploads.

This is not only happening to brand new uploads rather quickly (one week after the fact is an incredible turn around time if you consider that almost 300 hours of video is uploaded to YouTube every single minute) but it is also happening to ALL of the existing content already uploaded to their site! Audio quality aside, this really must be some sort of technical feat to put into motion. 

Another possibility could be that YouTube is encoding the video playback in real-time along with the audio normalization. This would explain how it is retroactively adjusting other videos from the past but it also doesn't explain the random old videos that haven't been affected or the fact that my upload was not normalized during the initial recording on day one.

Questions, questions, questions...​


I think all of this is actually a good thing, but it sure is surprising that no one from YouTube or Google has really announced it. All I found searching for it were Google and YouTube support forum requests for an auto normalize feature, so it would seem that they are actually rolling this out silently.

At the end of the day, this will possibly bring life and dynamics back to the audio engineer realm. It won't really matter for audio to be mastered super loud anymore, because an auto-normalizing feature will make crushed masters sound quite small after being processed.

I found this to be true for some of the louder masters we uploaded over the last three years that were affected by YouTube's alleged normalizing feature. In comparison to the softer uploads that were also normalized, the louder masters were given less perceptive volume by the algorithm and sounded weaker or smaller by default.

This is most likely an effect of less dynamic transient information being available in the waveform upon encoding. I'm guessing the algorithm probably analyzes this and gives louder uploads lower overall volume capacity, thus normalizing the file to a much softer perceptive volume than more dynamic uploads with more transient information available within the file.

Of course, all of this is really just conjecture until we have someone from within YouTube or Google come out with some real specs about the issue. Until then, I hope this analysis helps any of you out there wondering why your uploads are sounding different!

Here's a video explanation (from the f*ckin man, Ian Shepherd #masteringlikeaboss) of how crushing transients in exchange for loudness will affect your audio upon auto-normalization. Of course, listening to everything through your studio monitors at 128Kbps kind of defeats the purpose but the argument is explained pretty well. Though I personally believe in adjusting my own loudness tastes in order to properly serve our clients at Tower of Doom, I think it's also really important for engineers to appreciate creating music in both forms (softer with dynamic punch / super loud ghetto blaster explosion). Everyone should at least try to do a little bit of both and then at least you've learned a bit more.

Eric Perlas El Presidente of Doom

Hi everyone! This is AudioGeek--a new segment I decided to start that will contain more technical audio engineer information for any of you out there looking for new resources.

Back in 2001-2002 when I started my journey as an audio engineer and producer, there was nothing available to me other than super technical forums and websites that I had to wade through on my own. I only had a very basic understanding of audio engineering in general and it was very difficult to learn how to properly create and record music without someone to guide me.

Nowadays, things are WAY different and there is a YouTube tutorial for almost anything I can think of! Sometimes, I wish I could rewind time and tell myself from all those years ago about all the mistakes I was making on my work, but it is what it is and here we are today,​ with more help available than most of us even know what to do with, all at the cost of a quick Google search.

I'm sure any of you budding producers out there will know: there is already a WEALTH of audio engineering tutorials available online and I really don't want to waste anyone's time repeating anything. Instead, I'd like to try to write about things that haven't been talked about too much and add to the knowledge that is already out there.

I spend most of my time working in Tower of Doom studios so I don't really know how often I will be able to work on these posts but let's see how it goes! If any of you have any ideas for topics or questions you'd like me to answer, please feel free to let me know in the comments below and I will try my best to get back to you.

Hopefully, I can write these articles for any of you out there that may be interested in learning more about audio production and the like.​ I only hope I can offer some help to someone out there that is starting out like I was all those years ago, with no one to approach for guidance.

Thanks and I hope you guys enjoyed my first article!

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16 thoughts on “AUDIOGEEK: Has YouTube Started Normalizing Audio For Uploads?

  1. I think uploading songs in soundcloud somewhat changes something in the Audio as well. Im just not too sure if its the samething as to what you guys are explaining here,lol. -newbie mixer here.

    • Hi Marts, in our experience SoundCloud does indeed limit it’s streaming to the same 128Kbps. We purchased a premium account a few years back for some projects but I am pretty sure that it didn’t have an option to upgrade the audio quality. I think this is also the same for the SoundCloud downloads. We ended up focusing on YouTube at some point though, just because of the raw traffic potential and ended up not really renewing our account with SoundCloud. Things could be different now… One thing that I do really miss from the premium SoundCloud service is having the ability to change/swap the audio for uploads that have already gone live! What an awesome feature, albeit a bit sneaky hehe. It probably won’t happen with YouTube though; once you upload, it’s a commitment!

  2. Are you sure about the 128 kbps issue? Youtube used to play at different audio qualities depending on the selected resolution, 480p and below were about 100 kbps, 720p and 1080p at around 180 for most of the files I’ve checked, and it was very easily distinguished, but in the last few months it always sounds the same. And when downloaded MediaInfo shows much higher values for audio in the file. I just downloaded a video in order to check ( using ChrisPC YouTube Downloader and this is what it shows if using MP4 DASH setting, regardless of video resolution:

    ID : 2
    Format : AAC
    Format/Info : Advanced Audio Codec
    Format profile : LC
    Codec ID : 40
    Duration : 3mn 45s
    Bit rate mode : Constant
    Bit rate : 254 Kbps
    Channel(s) : 2 channels
    Channel positions : Front: L R
    Sampling rate : 44.1 KHz
    Compression mode : Lossy
    Stream size : 6.82 MiB (11%)

    Some other settings do yield smaller bitrates, but youtube nowadays prefers DASH if their “stats for nerds” aren’t lying so it normally does indeed play at this quality.

    • Hi Mirko, I haven’t had the opportunity to test extensively on the 128Kbps issue but I am assuming the study found at this link is an accurate enough resource:

      The test is carried out by Nick Vogt and he goes into detail about the audio streaming from YouTube in the recent months and his study measures an average of 128Kbps across all resolutions. He even covers data from YouTube video-streaming over the last few years (when YouTube was still offering higher bitrates at higher video resolutions) until the recent downgrade to 128Kbps for all resolution settings. It’s a great article and is actually what inspired me to do my own tests above so please check it out if you have the time!

      • Hi! Thanks for the link, but I have seen that article quite some time ago when I was wondering about youtube video quality for the first time.

        Are you familiar with youtube-dl app?

        This is the output it gives about available streams for the video I linked in my previous comment:

        D:DOWNLOADS>youtube-dl -F
        [youtube] J9NQFACZYEU: Downloading webpage
        [youtube] J9NQFACZYEU: Extracting video information
        [youtube] J9NQFACZYEU: Downloading DASH manifest
        [info] Available formats for J9NQFACZYEU:
        format code extension resolution note
        140 m4a audio only DASH audio 129k , m4a_dash container, aac @128k (44100Hz), 3.46MiB
        171 webm audio only DASH audio 136k , audio@128k (44100Hz), 3.48MiB
        141 m4a audio only DASH audio 255k , m4a_dash container, aac @256k (44100Hz), 6.86MiB
        278 webm 256×144 DASH video 92k , webm container, VP9, 12fps, video only, 2.19MiB
        160 mp4 256×144 DASH video 111k , 12fps, video only, 2.94MiB
        242 webm 426×240 DASH video 201k , 24fps, video only, 3.73MiB
        133 mp4 426×240 DASH video 248k , 24fps, video only, 6.59MiB
        243 webm 640×360 DASH video 363k , 24fps, video only, 6.80MiB
        134 mp4 640×360 DASH video 451k , 24fps, video only, 7.26MiB
        244 webm 854×480 DASH video 673k , 24fps, video only, 11.65MiB
        135 mp4 854×480 DASH video 806k , 24fps, video only, 14.42MiB
        247 webm 1280×720 DASH video 1250k , 24fps, video only, 22.37MiB
        136 mp4 1280×720 DASH video 1409k , 24fps, video only, 27.64MiB
        248 webm 1920×1080 DASH video 2145k , 24fps, video only, 37.82MiB
        137 mp4 1920×1080 DASH video 2648k , 24fps, video only, 53.92MiB
        17 3gp 176×144
        36 3gp 320×240
        5 flv 400×240
        43 webm 640×360
        18 mp4 640×360
        22 mp4 1280×720 (best)

        Now don’t get me wrong, I’m not saying that you or Nick Vogt are wrong, I’m just saying that there is a 256 kbps aac stream there. If Nick is right, then I really don’t understand why is Google keeping millions of those streams on their servers, seems like an utter waste of space.

        • Hi Mirko, yup no problem and thanks for the link! I will check it out once I get a chance… as I said earlier though, I haven’t really had any opportunity to test the 128Kbps issue too thoroughly and I actually only recorded the streams from different resolutions just so I could hear the different recordings side by side and test whether Nick’s theory was correct. Unfortunately, they did sound the same to me as I switched from file to file across all resolutions. Furthermore, none of them really represented my original uploaded audio too well at all. To be honest though, once I realized the normalization was occurring I got pretty distracted and decided to test that out a bit more instead.

          I am aware that YouTube has the data available for users to switch between, and I do know that I was able to upgrade audio streaming quality in the past. But I would have to agree with Nick on his point that as of this writing, the audio is not switching to higher bitrates regardless of the video resolution. Whether or not this is a resource hog on their end is really anyone’s guess!

          • In case you’re interested, I checked a little more and unfortunately I was wrong and youtube really always plays the 128 kbps stream. It appears that you can also check this by right clicking the video and copying debug info. There’s an fmt value which determines what video track is played and afmt which is the audio track. afmt always has a value of 140 (check the format codes in my previous comment).

            I tried several youtube scripts and browser addons but none of them changes audio quality, only video, so no luck with that. I also checked Kodi (ex. XBMC) and a foobar youtube addon and it appears that they can play a 192 kbps audio track that is contained within the 720p format code 22 stream. I believe that’s the old higher quality audio that you would get when setting playback to HD. It’s not much, but I guess it’s somewhat better than 128.

            Anyway, I’ve been wondering lately how come most of the music I was listening on youtube wasn’t going over some -4 dBFS, so thanks for the great article that explained that. 🙂

          • No worries Mirko! Thanks for explaining, I didn’t know you could access the debug info like that… Yes, 192Kbps is not that much of an improvement but at least there are options. Hopefully, this bitrate issue is just a temporary situation that YouTube is testing on its users. For the meantime though, I suggest everyone continues uploading their audio as best as possible so that if they do decide to bring back the higher bitrates, at least our uploads will also be affected.

          • Actually I just checked the same video Mirko linked above and when you right-click on the video and click “stats for nerds” it shows what streams are currently playing. For me it shows itag 251 for the audio stream, this means it’s 160 kbps Opus. That should be noticeably better than 128 kbps AAC. So it seems like nowadays it’s either 128 kbps AAC or 160 kbps Opus, depending on the video.

      • Sorry for the long comment, I should have cut some of it. Btw if youtube really doesn’t normally use that 256 kbps stream, it would be interesting to find out if it can be forced somehow, like &hd=true command used to force hd playback.

  3. There’s a good amount of uncertainty and doubt regarding YouTube’s quality and codec choices, and I’d like to straighten it out.

    First off, for the last few years, YouTube has had two different video formats – AVC and WebM, the former being the incumbant format that is almost compatible anywhere while WebM is the newer format that only works on newer browsers, devices, etc. (YouTube technically has more formats for this, but they are only for 360p and lower resolutions and are only retained for fallback compatibility reasons)

    Now in addition to these two formats, as you may know, YouTube encodes various different qualities and resolutions, and they do this for both formats; this applies to audio as well. The main difference for both audio and video formats are between 480p and 720p so I will be using them as a baseline for the comparison (in particular, everything 720p and higher use the exact same audio stream while everything 480p and lower use the exact same audio stream).

    In the middle of 2013, this is what YouTube formats were for 480p and 720p:
    -480p AVC/FLV + 128kbps AAC 44.1KHz
    -480p VP8/WebM + 128kbps Vorbis 44.1KHz
    -720p AVC/MP4 + 192kbps AAC 44.1KHz
    -720p VP8/WebM + 192kbps Vorbis 44.1KHz

    In the middle of 2014 this is what it looked like on YouTube:
    -480p AVC/DASH + 128kbps AAC 44.1KHz
    -480p VP9/DASH + 128kps Vorbis 44.1KHz
    -720p AVC/MP4 + 192kbps AAC 44.1KHz
    -720p AVC/DASH + 256kbps AAC 44.1KHz
    -720p VP9/WebM + 192kbps Vorbis 44.1KHz

    The main changes are that YouTube switched over to DASH streams (while still retaining the old 720p non-DASH AVC/MP4 for fallback reasons), replaced VP8 with VP9, and introduced a higher-quality AAC stream (it must be noted however that YouTube’s AAC encoder is not that great, so 192kbps Vorbis normally sounded better than their 256kbps AAC).

    And as of today, in the middle of 2015, this is what it looks like:
    -480p AVC/DASH + 128kbps AAC 44.1KHz
    -480p VP9/DASH + 160kbps Opus 48KHz
    -720p AVC/MP4 + 192kbps AAC 44.1KHz
    -720p AVC/DASH + 128kbps AAC 44.1KHz
    -720p VP9/WebM + 160kbps Opus 48KHz

    Now YouTube has dropped 256kbps AAC, possibly because they now use the WebM formats as the default unless your browser/device doesn’t support it. Vorbis has been replaced by Opus but the 720p bitrate for WebM audio was reduced to 160kbps; Opus however is THE best lossy audio codec at this current time on Earth, so even at 160kbps the audio quality is comparable to Vorbis 192kbps and is definitely miles ahead of YouTube’s 128kbps AAC. One thing is that Opus as a codec is actually incapable of 44.1KHz which is why YouTube uses 48KHz; it should be noted that 48KHz is actually the standard audio sampling rate used in the broadcast industry, so this isn’t at all unprecedented and it should give a nice boost in quality for most modern audio which are usually recorded in 48KHz or 96KHz initially anyway.

    It must be mentioned however that the old 256kbps AAC format can actually be found on some older videos even today, but new uploads do not have these formats; 192kbps Vorbis can also sometimes still be found on older video, but it’s very rare (much rarer nowadays than 256kbps AAC). Lastly, it must be noted that sometimes (but rarely) the Opus formats don’t even get encoded for some WebM encodes, resulting in them being stuck with 128kbps Vorbis at best.

    To sum it up, this is the quality rankings I’d give regarding audio quality based on my own testing and others.

    Audio uploaded with a sampling rate that is a multiple of 11025Hz:
    256kbps AAC =* 160kbps Opus > 128kbps Vorbis > 128kbps AAC

    Audio uploaded with a sampling rate that is a multiple of 8000Hz:
    160kbps Opus > 256kbps AAC > 128kbps Vorbis > 128kbps AAC

    (I left out 192kbps Vorbis because its extreme rarity makes it kind of pointless but also makes it very difficult to test; from my experience I’d say it’s at least equal to YouTube’s 256kbps AAC)

    *they don’t actually sound the same but rather they both have their own pros and cons regarding the resulting audio quality

    As a reference, 128kps Vorbis has commonly been compared to the likes of 192kbps MP3, but I wouldn’t be surprised if with modern versions of the LAME encoder that 192kbps MP3 would be more on-level with 160kbps Vorbis.

    This is the YouTube downloader that I use which happens to support every single format they have (though as of this comment it seems to lack support for the lowest-quality Opus format, which is used for 144p):

      • Wow, thanks for the super in-depth comment Nintendo Maniac 64! Based on your findings it would seem that there is really much more going on under the hood over at YouTube… and perhaps it would be safe to say that the use of several different formats is really more of an effort to keep viewer experience consistent over several platforms, as opposed to an effort to elevate or degrade quality.

        With several billion views a day being the norm at this point, there are probably just too many variables to consider to stream a consistent format or codec at any given moment. Server speed, connection speed, internet browser, PC or tablet specs, etc. …the list just goes on and on and none of these are really even related to audio!

        It’s been a while since I posted this article. Maybe it’s time for an update! I wonder if the normalizing is still in effect.

  4. So that’s the reason why after a couple of days youtube turns the volume of my music videos down. And when I say down I mean that my videos sound weak compared to the other ones that people upload nowadays. That’s really frustrating, I’m doing some upload tests and I don’t understand how to mantain a decent level of loudness, I’m messing with peak levels in the master and things like that but nothing at all, what do you suggest? to turn the master volume down in the rendered video so youtube normalizing turns the volume of my video up?

    • Hi Andrea! Yes, I believe that if you upload audio that is softer than the limiting threshold of YouTube’s audio protocol it will most likely bump up your audio to match everything else it has “normalized” across the site. I haven’t really been able to test this though so it’s just my best guess at this point.

      Unfortunately, once YouTube has adjusted the level of your audio there’s not too much anyone can do about it. It will continue streaming to viewers at that volume until YouTube decides to change up the protocol again.

      Every new upload still seems to retain a few days of “expected” loudness but this has actually seemed to have sped up since I last conducted this test. I haven’t checked exactly how long it takes nowadays but at the time I performed the test above, it was around a whole week before I noticed my upload audio change. Recently, I have noticed our uploads are affected in only a couple of days.

  5. Within the last few months YouTube has downgraded the 720p quality from 192 to 128 kbit. I watch this format exclusively with SMPlayer or VLC. Older videos are still available in better quality, but no new ones are.

    There isn’t any practical reason for “saving” 64 kilobits, given the size of the video stream, container overhead, and web bloat. I think YouTube wants to gently nudge users over to new formats for market control reasons. The MP4/720p format is/was all-round the best choice: compatibility, low data rate, low decode requirements, excellent quality downscaled by 2. I’d rather see all the lower qualities go. Today it is better to agree on one common format, instead of trying to save a kilobits at the cost of inconvenience. I very much dislike Google’s VP codecs, which have very short life span.

    I believe that loudness normalizing is a good thing. It has been a feature of music players for more than a decade. No engineer is in control over the volume knob (I for instance keep it a notch down to allow for some headroom). However, since they are actually re-encoding the audio, it will result in quality loss. I’ve read that YouTube does keep the source upload archived for some time, but does not do so indefinitely, and eventually performs encoding from a reduced quality intermediate. This also explains the terrible quality of user uploads that are several years old, and have been transcoded for one reason or another.

    I also welcome the switch to 48 kHz, which is the standard rate for video and PC equipment (since dvd / AC’97). I do wonder if there might be a double conversion going on, with YouTube internally still working at 44.1 / 16-bit, and feeding that to the Opus codec, and which is the best rate to upload at.

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