Does 64bit double processing engine means more dither issues??

Hi, I always leave the 64bit double processing engine on  and dithering off during export. Recently had some subtle trouble with audio quality in a final mix export, it was subtle but bit obvious in the strings section. I record and render in 24bit. Since I was not satisfied with the way the strings section sounded after the  first export I turned on the dithering and made 2  more exports with tringular and power-r2 settings. The way the strings sounded improved in the later exports. Again, it was subtle but obvious to me since I was working on the mix for quite some time. 

Previously I thought there is no need to turn on dithering during export since I was exporting  the mixdowns in the same 24bit resolution. I have read many advices on using dithering only during mastering. But recent googleing has educated me that daws by default work at 32bit resolution so there is some internal conversion doing on from 32bit to 24bit even if you set the project at 24bit. Is this true? And is true with sonar?

So this also got me wondering, if that is the case each time I am rendering using 64bit double processing engine sonar has to convert the audio from 64bit to 24bit? Am I right? This can cause even more low level distortion? and thats why my export needed dithering to get it sound right? Please someone knowledgeable enlighten me. 

Here goes - I'm fast becoming the expert on this one, although some on here will howl me down - I am apparently a trained researcher these days (I've used a content analysis to get across this topic, but I probably need to do more qualitative study into the topic, scientific)...but since I taught myself and I'm in a protracted war with the university system here in Oz...who knows but here goes!

Firstly, well done on hearing there's a problem when going from 64bit FP to 24bit. This is not a condescending statement - some on this forum say you can't hear any differences because you only have 24bit converters. In fact it was on the strings or the sampled strings that I first heard the problem too.

One of things I cannot stress enough to you is switch on the 64bit fp record button, this is where you will encounter one of the problems that you can encounter down the line. I'm not sure how Sonar's internal dither system works, but if you're recording at 24 bit but processing at 64 bit...there might be dithering going on here. So not only are you dithering at the mastering stage, but also during the processing stage. I'm speculating, because I don't know your settings. Also, you've picked up on an important notion that I only realized myself a few weeks ago. This is not all audio programs programs process 64bit FP audio files. It was a revelation, when I heard this mistake for the first time. You see I use Vegas Video for my moving image editing...and I didn't realize that it's internal audio processing is done at 32bitfp. I would import my 64bit fp master into Vegas, but I kept hearing something, probably similar to what you're hearing...there was a graininess at the very outer edge of the resolution. It bothered me, but I thought it might just be a crap mix...it wasn't. About 2 months ago I decided to see what happend when I slapped Vegas Video's dither plug over the top of the master (I never put dither on my 64 bit masters before then you see), and it was a revelation. Gone was that nasty graininess you're hearing.

Here's my advice to sum up - first always record, mix and master at 64bitfp. Only dither when you need to. So if you're going to use the master file in a film clip check what bit depth the program processes audio and dither accordingly. Now I make a few mistakes here and there, it's why I get laughed at on this forum...but I'm still trying to work out whether to dither for MP3 and compressed audio formats...do some experiments and use your ears to determine whether or not to do so. At the moment I use 64bitfp master files, which I upload to soundcloud and convert to MP3 format. I will have to do some listening tests on this one. I also recommend junking powr dither - it is absolute rubbish. I will tell you why - when I slapped Vegas Video's dither over my 64bitfp master file...it was the first time ever I heard what the dither was doing. If you do a little research, you will find dither has some really basic settings...and these settings resemble film filters in many ways. Think gaussian blur, which is a setting on my dither. Being able to hear what the dither does, means you can set the dither accordingly and indeed not chop too much off. So my dither has rectangle, triangle, half triangle and gaussian off the top of my head and you can shift the noise floor to the top end and across the spectrum...off the top of my head again. It is so cool when you hear what you're doing, because you can keep more of the definition...which is super important if you're doing the amount of processing I do. Think the analogue emulation aesthetic, binaural time based effects and other audio ear goodies :). Its also why I suggest you record at 64bitfp too, it returns the digital realm to the analogue realm. You have probably more dynamic range (internally) than the best analogue system with 64bitfp audio files. And if you use Melodyne or digital varispeed - the manipulation doesn't create artifacts or a graininess again. And here's a clue too as to why you should record at 64bitfp audio, and it was my first clue in better understanding the 64bit digital audio paradigm. Are there times when you wouldn't use 64bitfp audio files? Yes! Let's say you're recording an acoustic troubadour with minimal processing...I would turn off 64bitfp and if I had good microphones and preamps use these to massage the sound. I would also switch off 64bit FP if i was going to do all external processing - going in and out of the box. You will get no benefit of the 64bit engine and audio file paradigm then and in fact it's quite possible artifacts could be introduced if you do.

Finally, to fix the issue you have I suggest this - switch on the 64bit fp audio file button, and make sure you've hit the up upsampling or x2 button and enabled the plugin to process with upsampling...upper left hand section of the plug. Most plugs apparently these days have this already punched in, but with modern computers and SSD drives these days...there's no point in not switching on these devices (unless as I said above). Then freeze each of your tracks, what this will do is wrap your 24bit audio files into 64bitaudio files...giving you the added benefits of 64bitfp audio files. This should fix the graininess you hear on your strings. Make sure you turn off Sonar's internal dither first...but maybe experiment and do an a b test. So freeze a track at 64bit fp with and without Sonar's internal dither on. I haven't really tired this, but now I've mentioned it...I will probably give it a burl.

Hope that helps:)

Ben.

Wow, this stuff is so far above my head. What about music for full orchestra? Should dithering be used there? I usually just go with the default setting. Should I change it?

bitflipper

michael diemer
Wow, this stuff is so far above my head. What about music for full orchestra? Should dithering be used there? I usually just go with the default setting. Should I change it?

No. The violins will supply all the dithering noise you need.

Yeah, you got that right! The low strings also do a great job muddying up the mids, too. Strings remain the most challenging thing to get right. but then I have heard actual performances where the high violins sound terrible. Just too many instruments, no way they can be in tune and in time with each other.
 
So, I guess I should turn dithering off altogether? 

Thanks to everyone for shedding some knowledge. 

bitflipper
No, the only downside to 64-bit processing is that it places greater strain on system resources: more RAM used, more CPU cycles, more disk storage.
 
Dither is irrelevant in either 32- or 64-bit processing. There is some debate over whether it is relevant to 24-bit integers, but a strong case can be made that it is also a non-factor in that scenario. Yes, your 64-bit files do need to be truncated to 24 bits, but the resolution is high enough that no significant precision is lost. Remember, all this is happening at ridiculously quiet levels way below the level of audibility.

True the difference is very subtle. Two factors might have made it quite evident in my export. 

1. I had bounced the strings from another project and imported the strings track to the current project. I might have added dithering during the first export from there as well. So successive dithering might have made my case obvious on the strings.

2. I did terrible sound staging prior to the mix and ended up with a mix with master bus peaking at abt -12dbfs. Not willing to restage the already good sounding mix I simply kept the master fader at +6. I guess by doing this I might have brought up the noise level and this might have somehow affected my track when I bounced at 24bit with no dithering. 

michael diemer

bitflipper

michael diemer
Wow, this stuff is so far above my head. What about music for full orchestra? Should dithering be used there? I usually just go with the default setting. Should I change it?

No. The violins will supply all the dithering noise you need.

Yeah, you got that right! The low strings also do a great job muddying up the mids, too. Strings remain the most challenging thing to get right. but then I have heard actual performances where the high violins sound terrible. Just too many instruments, no way they can be in tune and in time with each other.
 
So, I guess I should turn dithering off altogether? 

Whats interesting is I heard Yoad Nevo telling he would keep the dithering off since the waves plugins he used already emulate some analog noise in the background. 
https://www.youtube.com/watch?v=2V9d6zQzcrg

Noel Borthwick [Cakewalk]
 
 
It will still benefit because irrespective of the source formats of 16/24 bit all internal mixing is done at 32 or 64 bit float. So exporting to a float format is keeping the data at a lossless resolution. With a float format you can literally bounce or process thousands of times with no audible noise build up since floating point errors are infinitesimal.
 
There is no point setting the record depth at anything higher than 24 unless your audio interface has floating point support. Most do not... You should leave the import depth to same as original - that way if you import a float file it will stay in floating point and not get truncated to integer.

Thanks. Where in the world could I get answers from such knowledgeable people.  Let me consider myself privileged to be here. 
 

 

bvideo

I tried what u suggested. As you said I could only hear only the noise and everything else gets phase canceled. I had to put a limiter with 30db gain to get the noise to audible levels. 

Yea, the dither noise was actually much lower in level compared to the noise added by analog emulation plugins. Now I understand why Yoad Nevo doesn't use dither when there is analog noise at the background.