It is the recommendation of many streaming services, as well as many pro mastering engineers, that you master your songs to peak no louder than -1 dBTP (-1 decibel true peak). But what does that mean, and how do we achieve it? In this lesson, we’ll break down what true peak means, why your songs should peak no higher than -1 decibel true peak, and how to use true peak limiters and true peak metering. That way, you can master your tracks to sound their best when they’re released.
What is true peak in audio?
To understand what ‘true peak’ means, it helps to think about what happens to songs once they’ve left your DAW and have been released to the world. When releasing music for streaming, digital download, or CD, your songs exist as digital files. To hear those songs, the digital files need to be converted from digital to analog. The digital to analog conversion carried out by your phone, laptop, Bluetooth speaker, etc, can result in changes in the level of the audio as it converts the stepped digital samples to a smooth analog wave.
If you have a song that is mastered to peak at 0 dBFS, this could present a problem. That’s because the analog reconstruction of two consecutive digital samples peaking at 0 dBFS may result in an analog wave that peaks higher than either of the samples. This creates what is known as an ‘inter-sample peak‘. Some high-end audio equipment will have headroom to compensate. But the result on many consumer playback systems will be audible clipping.
Many meters detect only ‘sample peaks’, which represent the level of the highest digital sample. A true peak meter, however, is designed to indicate when inter-sample peaks are likely to occur. Similarly, a true peak limiter is designed to apply limiting based on when inter-sample peaks are likely to occur. We’ll talk more about both of those shortly.
dBTP for streaming
Because a true peak meter is designed to indicate when inter-sample peaks may occur, it may seem safe to assume that you can master your songs to peak at 0 dBTP… So why then do many mastering engineers and streaming platforms recommend that your songs peak no higher than -1 dBTP?
Well, the majority of streaming platforms encode your original lossless files (e.g. WAV) into data-compressed file formats (e.g. AAC). This is done to save data when streaming. The processing used to achieve this is another instance in which level increases can occur. True peak meters aim to anticipate such changes. But it’s not uncommon to see a track that was mastered to peak at -1 dBTP, peaking higher than that once encoded to a data compressed format. As such, it’s important to keep 1dB of true peak headroom. This compensates for such level changes, minimizing the risk of clipping.
It’s worth noting that the louder it is that a song is mastered, and/or the lower the data rate of the encoded file, the greater the risk of clipping. As such, Spotify recommends that if your song has an integrated loudness of more than -14 LUFS, then it should peak no higher than -2 dBTP. Personally, however, I find -1 dBTP to be adequate as long as your short-term loudness is no higher than -10 LUFS. Learn how to do that, and more about the different LUFS measurements, here.
A useful way of checking to see if clipping is likely when your song is encoded to a data compressed format is to use a plugin like ‘Codec Toolbox‘ by Sonnox, or ‘Codec Preview‘ in Ozone. Such plugins allow you to audition different codecs and check for any potential clipping that might occur.
How do you control true peak?
So, how do you ensure that you master your songs to peak no higher than -1 dBTP? Well, the peak level of a song is usually controlled through the use of a limiter at the mastering stage. Some limiters apply true peak limiting by default. Others limit only sample peaks. Some let you toggle between sample peak and true peak. Then there are those that limit sample peaks, but their meters let you know when inter-sample peaks may occur.
Whichever of these limiter types you have, start with the limiter’s ceiling/output set to -1dB. Then, monitor the true peak meter at the loudest part of the song. Some DAWs have true peak meters built-in. If yours doesn’t, the Youlean Loudness Meter has a great free version that measures both True Peak and LUFS, both of which are essential for mastering. Even with a true peak limiter’s ceiling set to -1 dB, a true peak meter may give a reading higher than -1 dBTP. If you’re using a sample peak limiter set to -1dB, then the true peak meter’s reading may be quite a bit higher than -1 dBTP. In either case, the required process is the same. Pull the limiter’s ceiling down to a level that ensures that your true peak meter doesn’t detect any peaks higher than -1dBTP.
Some people don’t like the sound of true peak limiters. That’s ok! As long as you’re using a true peak meter, you can ensure that your songs don’t peak higher than -1 dBTP by using either true peak limiters or sample peak limiters alike.
What should my true peak be?
So, let’s recap… When mastering songs, be sure to measure their peak level using a true peak meter. Adjust your limiter’s ceiling/output to ensure that your true peak meter detects peaks no higher than -1 dBTP. This gives you the best chance of producing masters which will not clip when played on consumer playback systems. Peaking no higher than -1 dBTP also means that you’ll meet the recommendation of the streaming platforms. Plus, it gives you the best chance of producing songs that will not clip when encoded for streaming.
Do you release music for online streaming? If so, do you make sure that your songs peak no louder than -1 dBTP? Leave your thoughts, comments, and questions below.
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