When should I Dither?ĭithering is pretty simple to do, just pick an algorithm and go to town! However, there are many plug-ins, virtual instruments and effects that are capable of working in 24-bit resolution even if your sequence is in 16-bit-so it's something you're going to want to be aware of even if you are working in 16-bit end to end. Generally, you'll only hear this when you are mixing down from a 24-bit file to a 16-bit one. The 'edges' of your sound can be a bit fuzzy and distortion happens at the upper frequencies a bit quicker. You'll hear quantization errors most in classical music, jazz music, acoustic music or just about anything that has soft passages with large dynamic range, and you can also hear them more clearly during fade-ins and fade-outs. Effects, compression, pumping vocals, thunderous bass and bashing drums all do a good job of masking the distortion that happens when you reduce bit rates and start to add in quantization noise. In modern commercial music, hearing quantization noise (the sound of the errors you get when reducing from 24-bit to 16-bit resolution) can be difficult, because it is masked by all of the 'stuff' we love to layer into our mixes. The result is we trade off some weird, angular sounding harmonics for something that is closer to the original sound, but with a teensy bit of (hopefully unnoticeable) noise. Between points A and D, a dithering plug-in or process will interject some white noise (random noise) which will 'smooth out' that straight line. The space between point A and D used to have a little bit of fluctuation in it, and now it's a straight line from A to D. How Can We Fix It?Īll right, so we know when we move from 24-bit to 16-bit resolution we are now trying to get the same sound wave with less 'points on the graph' to represent it. Where the sound was at points B and C is no longer concrete, the computer plots a trajectory between A and D and the stuff that used to exist at points B and C is now approximated. We used to be able to represent a waveform with points A, B, C and D, but now we just have points A and D. This reduction, or 'shift' of audio data is referred to as quantization. You have less points to graph the same amount of data, so you can imagine that your nice smooth waveform becomes more angular in nature. This is a simplified illustration of the same thing that happens when you move from 24-bit audio to 16-bit audio. The result is a shape which resembles a curve, but has a lot more angular points to it. Trying to get the same data as the original waveform is impossible with 10 less points, so I have to settle for 'as good as I can get'. This results in a much more 'blocky' appearance. I've only allowed myself 8 points to 'graph' the waveform. While WB runs at 32bit float, some plug-ins can run at a higher internal resolution inside WB such as Ozone which runs at 64bit float.Now have a look at this second image. It works quite well but it would be nice to have other options. This way it's only limiting on the overlapping regions where it exceeds 0.0dbfs. The only way I've been able to overcome this problem effectively is to use Ozone's limiter as a region plug-in on both overlapping audio files & set the limiter's threshold to 0 & the output to say -0.3. At the moment we only have fades or the whole track's overall volume, which doesn't help in this situation. What I'd like to see Apple do is incorporate volume automation handles so you can at least lower the 2 overlapping sections so they don't clip. This is where the Sonic products would be better suited for this type of master. Doing crossfades when one or both audio files are close to 0.0dbfs is a real problem in WB. Don't know exactly, but I've donw numerous crossfades with full pop material starting during a fade out with no audible clipping, however the meters were redlighting : - ) I'm pretty sure it's 32 bit float, anyone else?Hey Jerry, be very careful with 'red lighting' in WB, even though it's not audibly clipping during playback in the application (because of the 32bit float resolution), if you burn the CD & play it back you will get nasty crackling distortion at the points the clipping occurred.
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